Does it really take 40 complete and consequitive drive cycles to clear a DTC? - Bimmerfest - BMW Forums



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E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 03-18-2017, 08:08 PM
arthurwood arthurwood is offline
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Does it really take 40 complete and consequitive drive cycles to clear a DTC?

Does it really take 40 consequitive complete drive cycles just to make pending DTCs go away?


I read every word in the FTC thread but nobody mentioned how many drive cycles it takes to completely clear the pending DTCs. They just talk about the drive cycle setting the monitors and the drive cycle clearing the check engine light but not the number of drive cycles that are needed to get rid of all pending DTCs.

I have 10 DTCs but no check engine light and I don't want to clear them with my $15 OBD scanner because it took about six months the last time to set all the readiness monitors.

So I just want the DTCs to go away.

Looking up how long it takes to make the DTCs go away on their own, I found this which says it takes 40 consequtive ignition cycles to clear them.
Quote:
The PCM clears at DTC when the required number ignition cycles, 40 cycles for an emission TTC, have occurred without a recurring failure
Looking for somethign for BMW specifically, I found this which says it's 40(asterik) consequtive drive cycles, but what does the asterik mean?
Quote:
The fault code will also be cleared from memory automatically if the specific function is checked through 40* consecutive drive cycles without the fault being detected or with the use of either the DIS, MODIC, or Scan tool.
Looking for what the asterik means for BMW, I find on page 14 of this which again says I need 40 consequitive drive cycles just to turn off the pending codes!
Quote:
Row 6 - The fault code will also be cleared from memory automatically if the specific function is checked through 40 consequtive drive cycles without the fault being detected.
From the FTP thread even one complete drive cycle is a bitch let alone 40 of them.

So my question is one of incredularity.

Can it really take over 40 starts (probably about double that to complete 40 drive cycles?

Just the 40 times 5 minutes idling is over 3 consequitive hours of 5 minute idling just to erease a code?
The 15 minutes of highway driving is 40 times 15 which is over 10 hours of highway driving on 40 consequitive days!

Does it really take 40 consequitive complete drive cycles just to make pending DTCs go away?

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  #2  
Old 04-11-2017, 12:01 PM
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Nobody?
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Old 04-11-2017, 12:12 PM
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It takes one drive cycle to set the readiness monitors after clearing the codes. Google the BMW drive cycle. It takes about 20 minutes to complete.

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Old 04-11-2017, 12:53 PM
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Examine row 4 on both documents. That implies that pending codes (not set, not illuminating) are cleared after two (2) complete drive cycles (or at least where that sensor is tested. I say implies as it doesn't state that but does require two consecutive to set and illuminate the MIL.

If the MIL illuminates then either 40 or 80 are required to clear.

Using a tool to clear is much faster.
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Old 04-11-2017, 01:21 PM
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Quote:
Originally Posted by Brandon002 View Post
It takes one drive cycle to set the readiness monitors after clearing the codes. Google the BMW drive cycle. It takes about 20 minutes to complete.
I do appreciate that finally someone tried to help because this is probably one of the hardest questions ever asked on this forum.

Before I respond to your kind suggestions I have to clearly say that I understand that this is a HARD question.

It's a VERY HARD question.
It's perhaps the hardest question ever asked on this forum.

I have read all the threads that mention the "BMW DRIVE CYCLE" on the entire internet and none of them even come close to asking or answering this specific question (nor the secondary questions that arise from this primary question).

No part of this question is about setting the readiness monitors.
It's not even about clearing the codes directly with the diagnostic tester.

The primary question is how many drive cycles does it take for the car to clear itself of all the pending codes?

The articles that I listed say it takes 40 complete drive cycles.

If the drive cycles have to be complete, and if they have to be done in order, and if each phase has to be done in order, then that's almost impossible to complete in any reasonable time!

It would take YEARS before you completed 40 drive cycles under those circumstances!

For example you can start cold and idle for two minutes and ten seconds (or more) and that completes phase 1 of the first drive cycle but if you don't complete all the other phases of the first drive cycle, can you START the second drive cycle the next day by starting cold and idling for two minutes and ten seconds or more?

And what if you complete the phases of any one drive cycle out of order?

To be very clear, these are hard (VERY HARD) questions I am asking.
I do not think these questions have EVER been asked.
Nor have I found the answers.

Only an EXPERT in BMW engines can know the answers to these questions.
I am NOT that expert!

But these are the questions.

<1> How many complete drive cycles does it take for the BMW to clear all codes (set & pending)?
(Is it really 40 complete BMW drive cycles as the documents suggest?)

<2> Do you have to COMPLETE each phase of any one BMW drive cycle to start the NEXT BMW drive cycle?
(It is almost impossible to complete 40 drive cycles in less than about a year if you have to complete every phase of one drive cycle before starting the next drive cycle).

<3> In any one BMW drive cycle, do the phases have to be in order (1,2,3,4) to count as one BMW drive cycle?
(Can you do phase 3 and then phase 2 and then phase 1 and then phase 4 of any one drive cycle to count as one completed drive cycle?)
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Old 04-11-2017, 01:29 PM
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I tried in post 4 but you may not have seen it.
Clearly it can be done out of order and incomplete. Otherwise, by your logic, the mil would never be illuminated in the first place.
But there are intriguing details that require more examination and thought.
More when I get some time tonight.
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Old 04-11-2017, 01:51 PM
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Quote:
Originally Posted by TheAngryBear View Post
I tried in post 4 but you may not have seen it.
I saw it and I thank you for tackling what is likely an extremely hard question that has never been asked before so it won't be easy to answer by anyone.

We just have to work together on TRYING to answer the question.
You did the first step which is understanding the question and the second step which is trying to understand what the documents say.

Quote:
Originally Posted by TheAngryBear View Post
Examine row 4 on both documents. That implies that pending codes (not set, not illuminating) are cleared after two (2) complete drive cycles (or at least where that sensor is tested. I say implies as it doesn't state that but does require two consecutive to set and illuminate the MIL.
LIke you noticed yourself the documents I found are not very clear with regards to these three related questions.
<1> How many BMW drive cycles does it take the car to clear itself of all codes (wether pending or set)?
<2> Do you have to do each phase of any one BMW drive cycle in order?
<3> Do you have to complete one BMW drive cycle before moving on to the next ?
<4> What then happens if the computer throws a pending code in a BMW drive cycle less than 40?
(What if on BMW drive cycle 38, there is a pending code slung? Do you have to start all over at BMW drive cycle number 1?)

Quote:
Originally Posted by TheAngryBear View Post
If the MIL illuminates then either 40 or 80 are required to clear.
Let's just stick with 40 for now although I saw that part about 80 also but 40 already is impossible to complete in any reasonable period of time so we can forget ever completing 80 if it all has to be in sequence.

I appreciate that you took a brave step by trying to answer what is a very hard question.

I understand you in that you think the documents imply that if the MIL is not set, then the documents imply that only a couple of BMW drive cycles are needed but if the MIL is set then the documents SAY that 40 (or 80) complete sequential drive cycles are needed before the vehicle can clear its own codes.

If you have to complete 40 (or 80 but 40 is already nearly impossible) and if any one BMW drive cycle has to be done in phase sequence and if one drive cycle has to be completed before you can even start the next BMW drive cycle (and if it starts all over if the engine messes up in just one drive cycle!), then it's almost impossible to complete all 40 (or 80) in any reasonable period of time (like less than a year or two).

Quote:
Originally Posted by TheAngryBear View Post
Using a tool to clear is much faster.
I do understand and appreciate the advice but that is not the qustion.

I want the BMW to reset itself because my monitors won't set but even if the monitors did set easily I still want to know the answer to the four related questions.

Quote:
Originally Posted by TheAngryBear View Post
Clearly it can be done out of order and incomplete.
Can it?
If it can be done out of order and incomplete, then that makes it MUCH EASIER to complete 40 (or 80) BMW drive cycles!

That's why the question is so very important.

I sure HOPE that it can be done out of order and incomplete but I don't see any proof that it can.

Quote:
Originally Posted by TheAngryBear View Post
Otherwise, by your logic, the mil would never be illuminated in the first place.
I'm sorry but I do not understand what that sentence means.
Can you clarify what you are asking?

Quote:
Originally Posted by TheAngryBear View Post
But there are intriguing details that require more examination and thought.
More when I get some time tonight.
Thank you for understanding that this is not an easy question to answer.
Also that it has never been asked before as far as many searches can reveal to me.

Here are the four questions that come out of the first question.
Let's forget about 80 for now and just stick with the 40 since that may be impossible (or nearly impoossible) if all four conditions have to be met.

<1> How many complete BMW drive cycles does it take for the computer to completely clear any codes (whether pending or fault and whether MIL or no MIL)?

<2> Does each complete BMW drive cycle have to be done in phase order?

<3> Can the next BMW drive cycle start before the previous BMW drive cycle has finished?

<4> Do we have to start all over from the beginning if the engine sees a pending code in BMW drive cycle 38?
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Old 04-11-2017, 02:24 PM
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To actually remove it from pending... yes...

but to clear the cel by it self.. No
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Old 04-11-2017, 03:27 PM
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The sequential testing is per "customer drive cycle ... where the system is monitored".
So to me, this states that a "drive cycle" is relative to the system being monitored.
I believe a "complete drive cycle" in these documents is when a monitor is specifically tested in full.
Thus you can do a series of closed loop tests (say O2 monitors) without having to test the other monitors first.
The "total drive cycle" (my term) is the 20-40 min drive of varying speeds etc that measures every monitor. So you can set/test all monitors in a single drive.

To clear the codes the documents are unambiguous regarding when the MIL goes away (40 or 80 tests).
It takes two consecutive test failures to set the MIL.
There is nothing that states pending will ever clear (hence your questions) but in theory it should.

Will see if I can find another document to determine one way or the other.
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Old 04-11-2017, 03:31 PM
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i saw this as more of a question about the programing language of obd2

the cylce count does not actually mean you have to drive the car 40 times *or start the car 40 times

It will satisfy multiply times during a given drive event
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Old 04-11-2017, 03:32 PM
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So in answer to your specific questions

<1> How many BMW drive cycles does it take the car to clear itself of all codes (wether pending or set)?
MIL set - 40 or 80
<2> Do you have to do each phase of any one BMW drive cycle in order?
No but there are some that would naturally follow each other.
<3> Do you have to complete one BMW drive cycle before moving on to the next ?
By drive cycle being monitor test, no you do not.
<4> What then happens if the computer throws a pending code in a BMW drive cycle less than 40?
I suspect it would restart the count to clear the MIL.
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Old 04-11-2017, 03:37 PM
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Quote:
Originally Posted by Burning2nd View Post
i saw this as more of a question about the programing language of obd2

the cylce count does not actually mean you have to drive the car 40 times *or start the car 40 times

It will satisfy multiply times during a given drive event
Yes, this is what I meant by specific monitor testing as a "drive cycle".
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Old 04-11-2017, 04:06 PM
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Its basic PLC language

run time events.
and or's
and or not's
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Old 04-11-2017, 07:01 PM
E39Hoon E39Hoon is offline
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I've cleared my codes and then driven about 300 miles over 2 days with several starts and cycles but nowhere near 40, and then I went for my smog those 2 days later and the monitors were ready and codes (stored and pending) were gone after my fix worked. So the answer is no, it does not take 40 but you need to drive a bit. just give it a week of normal driving.
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Old 04-11-2017, 11:35 PM
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Also, the BMW official drive cycle is the driver procedure that is assured to set all the monitors in one session. This is only meaningful if you are trying to immediately set monitors ready after codes have been cleared.

The monitors usually become ready long before the full drive cycle is complete. As mentioned by another poster, this process is continuous and most monitors are tested, set (or unset as the case may be) many times in a single drive.
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Old 04-12-2017, 02:21 AM
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I love it when people dont read the bottom of the thread b4 saying what was just said
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Old 04-12-2017, 06:23 AM
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Personally, I wouldn't consider this the hardest or one of the hardest question ever asked/answered on the forum. If one understands the OBD II mandate and how the emission system sets pending fault codes...and that after multiple detection of a fault code...the warning light is illuminated. Also, understanding the difference between a "customer drive cycle" and the FTP drive cycle...and knowing what it takes to initiate the official FTP drive cycle tests...it doesn't take long to run a driving scenario that can complete the official FTP drive cycle to see if all codes (pending codes, too) have been cleared.

The initial question asked in the 1st post was - "Does it really take 40 {consecutive} complete drive cycles just to make pending DTCs go away?"

The answer to that question is...no, it does NOT take 40 drive cycles to make pending DTCs go away. What makes "pending" DTCs go away is for whatever reason a sensor set a fault code...that reason needs to be corrected, then the system reset with a proper tool...or a complete FTP drive cycle completed with no fault codes being detected. The MIL/CEL/SES warning light only illuminates when a (pending) DTC code has been detected twice in a drive cycle.

Also, not all driving scenarios (customer drive cycle) fit the criteria of the FTP (federal test protocol) drive cycle. In the chart below (top half)...shows under what condition the area of the emissions system is being tested (lower half of chart). If your driving scenario doesn't cover one of those situations...then you could have been driving for hours & many miles...but yet did not complete a FTP "drive cycle" if you did not complete one of the criteria in the chart below:


Take note of the 4th paragraph below (or 2nd paragraph in the 3rd bullet)...it explains when "pending codes" will eventually illuminate the MIL/CEL/SES warning light:

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Old 04-15-2017, 09:59 PM
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Quote:
Originally Posted by Burning2nd View Post
the cylce count does not actually mean you have to drive the car 40 times *or start the car 40 times

It will satisfy multiply times during a given drive event
This is very confusing to me.

You can only start "cold" once in many hours so, effectively, it's 40 (or 80) "cold starts", in order to complete 40 (or 80) complete drive cycles.

How can you do more than one "cold start" in a "given drive event"?
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Old 04-15-2017, 10:08 PM
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Quote:
Originally Posted by arthurwood View Post
This is very confusing to me.

You can only start "cold" once in many hours so, effectively, it's 40 (or 80) "cold starts", in order to complete 40 (or 80) complete drive cycles.

How can you do more than one "cold start" in a "given drive event"?
You're probably confused because it sounds like you've convinced yourself that it takes 40 drive cycles to do whatever it is you think it requires. Since you have based your assumption on incorrect understanding...every attempt to make it clearer...you get more confused because you're still holding on to faulty information at the base of your conception.

The FTP drive cycle chart was given in a few posts above...once the car has completed one of the 4 FTP tests...and there's no fault codes from the sensors...then that portion of the FTP drive cycle is complete. There's no need to do 40 "cold starts" if the initial cold start didn't turn up any faults.
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Old 04-15-2017, 10:15 PM
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Quote:
Originally Posted by TheAngryBear View Post
So in answer to your specific questions

<1> How many BMW drive cycles does it take the car to clear itself of all codes (wether pending or set)?
MIL set - 40 or 80
What that means is that it seems to be almost impossible for the computer to clear all the codes if the MIL is set, if 40 (or 80) complete error-free drive cycles must be run in phase sequence!

Quote:
Originally Posted by TheAngryBear View Post
<2> Do you have to do each phase of any one BMW drive cycle in order?
No but there are some that would naturally follow each other.
Knowing that the BMW Drive Cycle has 4 phases.
<1> start engine, cold idle 130 seconds (checks SAS, EVAP)
<2> steady 20-30mph for 195 seconds (checks O2 sensors)
<3> steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
<4> stop vehicle, hot idle 300 seconds (checks EVAP)

Does your answer indicate that we can do phase 4 before phase 1 for example
If so, they have to be done on different days because phase 1 requres a cold start.

Quote:
Originally Posted by TheAngryBear View Post
<3> Do you have to complete one BMW drive cycle before moving on to the next ?
By drive cycle being monitor test, no you do not.
This is the most confusing answer.
Can you clarify your answer?

Are you saying you can complete phases 1,2,3 of drive cycle 1, and then phases 1,2,3, of drive cycle 2 without ever completing phase 4 of drive cycle 1?

Quote:
Originally Posted by TheAngryBear View Post
<4> What then happens if the computer throws a pending code in a BMW drive cycle less than 40?
I suspect it would restart the count to clear the MIL.
This is the only answer that is easy to understand!
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Old 04-15-2017, 10:26 PM
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Quote:
Originally Posted by E39Hoon View Post
I've cleared my codes and then driven about 300 miles over 2 days with several starts and cycles but nowhere near 40, and then I went for my smog those 2 days later and the monitors were ready and codes (stored and pending) were gone after my fix worked. So the answer is no, it does not take 40 but you need to drive a bit. just give it a week of normal driving.
Thank you for helping to answer the question but this question has nothing to do with "clearing the codes" with a scanner.

You are talking about something completely different than we are.

Clearing the codes with a scanner or setting the registers is NOT what we are talking about here.

We are talking about the computer clearing ALL the codes on its own, which according to the documents takes either 40 or 80 drive cycles.

The question is all about those 40 (or 80) drive cycles.

One question is wether they have to be done in phase sequence
< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

Or can tehy be done out of phase sequence
< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

Another question is wether all four phases have to be complete before the next cycle can begin.
< Cycle 1 >< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 1 >< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 1 >< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 1 >< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 2 >< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 2 >< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 2 >< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 >< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

Or if the cycles can be done out of order
< Cycle 1 >< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 2 >< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 1 >< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 1 >< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 >< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 1 >< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 2 >< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 >< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)

The documents don't say which is why I asked the question becuase it could take forever to complete 40 (or 80) drive cycles if they have to be both in phase order and in cycle order.

Last edited by arthurwood; 04-15-2017 at 10:28 PM.
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Old 04-15-2017, 10:46 PM
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Quote:
Originally Posted by QSilver7 View Post
Personally, I wouldn't consider this the hardest or one of the hardest question ever asked/answered on the forum.
A lot of teh confusion here is my own.
Plus some of the helping people are actuelly answering the wrong questions.

I am sorry if I impled the wrong thing.

What I mean is that this is not the same question everyone always asks.
Even after saying that we still had people talking about setting the monitors.
ANd people talked about clearing the codes with the scanner.

I was just trying to indicate that the only way to answer this question is to truly understand how the engine computer works.

Obviously I don't understand how the engine computer works or I would have been able to figure out the answer all by myself without asking for help.

Quote:
Originally Posted by QSilver7 View Post
If one understands the OBD II mandate and how the emission system sets pending fault codes...and that after multiple detection of a fault code...the warning light is illuminated.
Yes. That is basic OBD II but this question has nothing to do with SETTING the faults.
This question is only about the computer CLEARING the faults completely.

Quote:
Originally Posted by QSilver7 View Post
Also, understanding the difference between a "customer drive cycle" and the FTP drive cycle...and knowing what it takes to initiate the official FTP drive cycle tests...it doesn't take long to run a driving scenario that can complete the official FTP drive cycle to see if all codes (pending codes, too) have been cleared.
I am very confused by that sentence.
I thank you for taking the risk to post this becuase you bring up something I do not understand.

There is only one "drive cycle" that I know of which is summarized as
< Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

What do you call that?
I call that the "BMW Drive Cycle" or the "FTP Drive Cycle".
Isn't that the drive cycle that is talked about in the documents in the first post of this thread?

Or is there some other "customer drive cycle" just to add to my confusion?
Quote:
Originally Posted by QSilver7 View Post
The initial question asked in the 1st post was - "Does it really take 40 {consecutive} complete drive cycles just to make pending DTCs go away?"

The answer to that question is...no, it does NOT take 40 drive cycles to make pending DTCs go away. What makes "pending" DTCs go away is for whatever reason a sensor set a fault code...that reason needs to be corrected, then the system reset with a proper tool...or a complete FTP drive cycle completed with no fault codes being detected. The MIL/CEL/SES warning light only illuminates when a (pending) DTC code has been detected twice in a drive cycle.
I am confused by what you said above because NOTHING in this thread has anything to do with clearing the codes with a scan tool. Also nothing in this thread has anything to do with setting the monitors to the READY state.

Those are the normal questions everyone asks, and which are answered many times over.

I don't think the questions I'm asking have ever been asked before.

I think I'm confused though becuase it seems that it takes 40 (or 80) complete drive cycles for the engine computer to clear all the codes and that would be nearly impossible to accomplish if all four phases of any one drive cycle have to be completed in order, and worse, if all 40 (or 80) drive cycles have to be completed in order.

What I would hope can happen is instead of something like this
< Cycle 1 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 1 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 1 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 1 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 2 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 2 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 2 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 3 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 3 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 3 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 3 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

That what can actually happen (I hope!) is something like this
< Cycle 1 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 2 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 3 > < Phase 1 > start engine, cold idle 130 seconds (checks SAS, EVAP)
< Cycle 2 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 1 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 1 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 1 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)
< Cycle 3 > < Phase 2 > steady 20-30mph for 195 seconds (checks O2 sensors)
< Cycle 3 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 2 > < Phase 3 > steady 40-60mph for 15 minutes (checks CAT & O2 sensors)
< Cycle 3 > < Phase 4 > stop vehicle, hot idle 300 seconds (checks EVAP)

If we can't do the cycles out of order and if we can't also do the phases out of order, then it will take forever (years maybe!) to complete 40 (or 80) conseqetive cycles!

Quote:
Originally Posted by QSilver7 View Post
Also, not all driving scenarios (customer drive cycle) fit the criteria of the FTP (federal test protocol) drive cycle. In the chart below (top half)...shows under what condition the area of the emissions system is being tested (lower half of chart). If your driving scenario doesn't cover one of those situations...then you could have been driving for hours & many miles...but yet did not complete a FTP "drive cycle" if you did not complete one of the criteria in the chart below:


Take note of the 4th paragraph below (or 2nd paragraph in the 3rd bullet)...it explains when "pending codes" will eventually illuminate the MIL/CEL/SES warning light:

You confuse me with this "customer drive cycle".
The only drive cycle that matters for this question is what teh engine computer itself considers a drive cycle.

As far as I know that one and only drive cycle is the same as you pictured in this JPEG file!
http://bimmerboard.com/members/q/ori...ve%20Cycle.jpg
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  #23  
Old 04-15-2017, 11:03 PM
arthurwood arthurwood is offline
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Quote:
Originally Posted by QSilver7 View Post
You're probably confused because it sounds like you've convinced yourself that it takes 40 drive cycles to do whatever it is you think it requires.
The only thing I'm asking about is what the documents in the original post are telling us.

You ahve to remember this question has never been asked before on this forum from my searches.

This is NOT a question you ahve seen before.

The question is based ONLY on the documents!

If the documents are correct, then it does take 40 (or 80) "complete" drive cycles (each of which has 4 distinct phases).

Are you saying that you know the document to NOT be correct?
If that is the case that the documents are dead wrong then that simplifies things.

But if the documents are not dead wrong then we are stuck with the fact that it takes 40 (or 80) complete drive cycles.

The only thing that is left if the documents are NOT wrong is that we need to understand if those drive cycles can be done out of phase and or out of sequence since completing them in phase and in sequence could take a year or more.

Quote:
Originally Posted by QSilver7 View Post
Since you have based your assumption on incorrect understanding...every attempt to make it clearer...you get more confused because you're still holding on to faulty information at the base of your conception.
I agree that I am confused becuase I read the documents and the documents are not clear themselves.

But NOBODY is going to answer this question correctly without READING the documents and without understanding what teh documents mean when they say it takes 40 (or 80) drive cycles.

I didn't make that up.
It's in the documents.

What's left is for us to understand what the documents say.
If it really does take 40 (or 80) drive cycles, and if those drive cycles have to be done in phase and in sequence, then it could take a very long time (maybe even a year!) before 40 (or 80) complete drive cycles are performed simply becuase normal driving does not do those things in sequence.

Quote:
Originally Posted by QSilver7 View Post

The FTP drive cycle chart was given in a few posts above...once the car has completed one of the 4 FTP tests...and there's no fault codes from the sensors...then that portion of the FTP drive cycle is complete. There's no need to do 40 "cold starts" if the initial cold start didn't turn up any faults.
That's not how I interpret what the documents said.
The documents say it takes 40 (or 80) drive cycles for teh engine to clear all pending or set codes.

Did I read the document wrong?

If someone who knows more than I do can read the section in those documents where they talk about the 40 (or 80) drive cycles and then EXPLAIN it to the rest of us that would be lesson the confusion.

This thread is not asking the normal questions.
< 1 > This thread is not asking about setting any codes.
< 2 > Nor is this thread asking about setting any registers.
< 3 > Nor is this thread asking about clearing the codes with a scanner.

To make things simpler, allow me to rephrase the questions.

If a pending code is set or if a MIL is set, and if you want the engine computer to erase all indication of that pending code or MIL having been set in the past, it is my understanding from reading the documents that it takes 40 (or 80) drive cycles to completely clear that pending or set indication from the engine computer.

So the first question to reaffirm is wether my understanding is corect.
Is that a correct understanding of what the documents say?

If that is the correct understanding, then my next questions about the sequence come into play.
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  #24  
Old 04-16-2017, 04:37 AM
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TheAngryBear TheAngryBear is online now
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So let's try to find a middle ground on understanding and terms. I trust that Q and others will correct technical details but conceptually here we go

1. Using the documents terms as you have but with adjustments:
A. Drive cycle: a complete series of tests sufficient to determine monitor readiness and performance. Any number of Drive Cycles can be completed during a phase as long as the conditions are met.
B. Phase: 1-4 the specific monitors being examined. Any number of phases can be completed during a Customer Drive Cycle if conditions are met.
C. Customer Drive Cycle: key on to key off. This may not include every phase.
D. FTP Drive Cycle: the chart provided that will set readiness and test all monitors in a single Customer Drive Cycle.

So first off your order of terms is wrong. It should be

It is possible to complete 80 Drive Cycles in a single Customer Drive Cycle. Say you Drive for 5 hours at 50 mph at temp. That would at least be 20 Drive Cycles and in reality a whole lot more (likely thousands or hundreds).
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  #25  
Old 04-16-2017, 03:26 PM
arthurwood arthurwood is offline
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Quote:
Originally Posted by TheAngryBear View Post
So let's try to find a middle ground on understanding and terms. I trust that Q and others will correct technical details but conceptually here we go
Thank you for trying to help us all understand what exactly the documents are talking about.
I agree with you that the key term to agree on is what they mean by a "drive cycle".
So we need to move slowly here, one step at a time.

The key step is this "drive cycle" definition!

Is it the "customer drive cycle" which is key on to key off?
Or is it the "BMW drive cycle" which can span multiple ignition starts?

This document in the first post says, in row 6, that the fault code will be cleared if the fault isn't detected when the function is checked in 40 conseqetive drive cycles.


The words in that explaination of row 6 that we all need to be consistent on are.
< 1 > fault code
< 2 > function checked
< 3 > drive cycles

Am I correct in assuming that
< 1 > the "fault code" is any "pending" code (whether or not it sets the CEL)?
< 2 > the "function checked" is any of the sensor inputs or outputs that indicate a fault
< 3 > the "drive cycles" are ?

I used to think the "drive cycle" was the "BMW drive cycle" but is your argument that the "drive cycle" in that document just a key-on-to-key-off cycle (which could last from one second to ten hours)?
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