Also, could the mystery codes that the machine wont identify be a result for the misfire? Or could that be causing the misfire? Im just trying not to spend 500$ on coils.


"That almost looks right"

 

Mystery Codes

The codes that the reader didn't identify may be important to your problem. Many of the lower priced ODB readers do not have make or model specific codes in their lists. It will tell you the code, but you have to look it up here or elsewhere. This may give you more information.

 

Okay thanks! Ill see what the other codes are and go from there.


"That almost looks right"

 

Okay, so the codes are
P1250-fuel regulator
P0300-random misfire
P0306-cylinder 6 misfire
P0303-cylinder 3 misfire
The misfire seems to be going everywhere, since in the past, cylinders 1,2,3,4, and 6 have shown up.
Im assuming that the P1250 code is most likely the problem?



"That almost looks right"

 

Fared01 thanks so much for responding by the way!


"That almost looks right"

 

One last hint as i said earlier, this happened over time. It was not an immediate problem. The idle would slowly get rougher and rougher over the course of a couple months


"That almost looks right"

 

I had the same type of situation happen recently,,I suspect a vacuum leak causing the problem--How long has it been that the CCV valve has been replaced. I just replaced mine and found that the return line from the CCV to the oil dipstick had a huge hole in it..There are many spots to check for vac leaks..behind the intake manifold are vac hoses that because of all the heat back there, they will wither away. The hoses connected to the CCV valve along with the 0 rings in the distribution unit sitting on top of the intake manifold, along with the Disa valve , which is mounted to the side of the intake--If the CCV valve has been replaced,,than look elsewhere,,but from what you stating in your post--it sounds like a vac leak,,just have to find out where it is--another spot to check,,would be to find out what your fuel pressure is at idle--there is a valve on the fuel rail that you can hook up too and find the reading--should be somewhere around 45psi--lower than that can cause problems..and point to the fuel pump--or the filter

 

All of my misfire troubles were due to vacuum leak. Rubber hoses near the firewall end of intake manifold leading to SAS pump often get overlooked. Rubber seal on DISA is a big leak. You can get by with wrapping teflon tape until you replace the DiSA. Oil filter housing, valve cover seals and rear main are common leaking spots too.

 

I'm with vac leak. That code p1250 always comes on with low fuel level. I would ignore it for now

 

vac leak,
Or primary input like a cam or crank angle sensor... (something that distrupts timing)

 

Anyway to test for vac leak? Im not familiar with this car yet so i am not sure where to start. I looked around didnt see any cracked hoses.


"That almost looks right"

 

Anyway to test for vac leak?

First thing I would do is type /vacuum f3 in the bestlinks.

That brings up a few places to start, for example:
- Poolman's canonical thread on battling vacuum leaks on the BMW I6 with lean-condition misfire DTCs (1)

See also:
- Poolman's canonical thread on battling vacuum leaks on the BMW I6 with lean-condition misfire DTCs (1) & where to find all the vacuum hoses, tubes, pipes, and endcaps in the E39 engine bay (1) & where are all the fuel injection o-rings (1) & how to locate all the o-rings (1) and gaskets (1) & where in the USA to get new vacuum tubing & end caps (1) & what SAE sizes to get for all the metric M54 engine vacuum tubes, hoses, pipes, and caps (1) & how do we correct the F-connector errors in the realoem diagrams (1) & where do some of those hard-to-locate vacuum hoses end (1) & what is the sorely needed clarification on how the M54 CCV vacuum port works on the M52 CCV valve connection to the fuel pressure regulator connection (1) & how to make, borrow, or buy lean-condition misfire test tools to test for vacuum leaks & lean conditions (1)

 

try spraying brake cleaner around the intake manifold and pay attention if the engine revs up

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I tried that carb spray trick, and, for me, I'd go with a smoke machine any day over that method, simply because my leak was in the CCV hoses, nested deep in there, and on the BOTTOM of the snorkel, so, the carb spray didn't do anything useful.

Full and complete details found by typing /misfire f3 in the bestlinks ...
- How to diagnose a BMW E39 engine misfire (1) & how to battle E39 vacuum leaks (1) (2) (3) & how to solve specific vacuum leak diagnostic trouble codes such as P0171, P0174, P0313 (1) & P0170, P0173 (1) & where to find all the vacuum hoses in the E39 (1)

 

Although multiple misfires usually point to a vacuum leak, I still wouldn't rule out bad ignition coils. When the codes are reset, it can take a while before they reappear, even if the coils are bad. I didn't quite follow your test sequence. It sounded as if at least one of the misfires followed the coil swap. If so, I'd repeat the process and see what specific cylinders have the resultant misfire. By the way, I'm not sure whether you intended to or not, but you almost made it sound to me like you thought the coil swap at one point made the car run better. Unless it's the result of a bad coil connector (the piece between the coil itself and the spark plug), this would be unlikely.

 

Bobdmac
When i reset the codes then go to start the car the SES light comes back almost instantly, espcially if i hit the gas.


"That almost looks right"

 

Ok update.
If i reset the codes, the car will run fine, with an occasional skip that you can hear or see in the tach. It will idle fine, i can even put it and gear and drive around as if normal as long as i dont put my foot into. However, if i try to acclerate quickly or leave from a dead stop the SES will turn on and the car will turn to **** again, run and idle extremely rough, and not idle correctly, as if its only running on 3 cylinders.

Im confused and bummed out. A 16 year old trying to figure out his own car is difficult, espcially when he is broke.


"That almost looks right"

 

Sounds like a fuel issue now--check the fuel pressure at the schrader valve on the fuel rail,,should be reading 45psi at idle ..might be able to borrow a pressure tester at one of you auto part stores.

 

Like a bad fuel pump? could they go out slowly like that, or do they go out instantly? Is there a specific fuel pressure gauge i should look for or?


"That almost looks right"

 

Unplug your maf and see if it runs good without it.

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What does the MAF do?


"That almost looks right"

 

What does the MAF do?

"That almost looks right"

It tells how much air is being pulled into the engine.

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I may have missed this, but it's still not clear to me what codes have re-appeared. Are they the same original four?

 

No, different codes keep coming up. Except P0300, and P01250 or whatever it is. Besides those, different codes for different individual cylinders will keep popping up.


"That almost looks right"

 

My knowledge in this department is only superficial, but here's what I think, and maybe others with more experience can chime in. Misfires spread over several cylinders are, by definition, caused by something that affects all the cylinders, which typically means an intake manifold vacuum leak or a fuel pressure problem. Simultaneous coil failures in three cylinders is pretty unlikely.

In this situation, with the codes changing specific cylinders, rather than the OBD reporting "multiple misfires," (more typical of a vacuum leak) it sounds like individual injectors are shutting down. The deterioration in drivability under increased fuel demand (depressing the gas pedal) makes it sound like a fuel pressure problem, and I agree with Poolman that you need to test the fuel pressure, but not just at idle, since it seems to idle okay, but stepping on the gas seems to provoke the problem. If the fuel pump isn't creating enough pressure, or the fuel filter is clogged, it may run okay at idle but be unable to keep up with the fuel demand under heavier load.

In most states, you can go to an auto parts store like Autozone or O'Reilly's and borrow a pressure gauge to hook onto the Schrader Valve on the fuel line. You could have someone read the pressures while you have your foot on the brakes and give it gas. I don't know the specs for normal pressures, but Poolman probably does.

As for the MAF, I suppose it's possible but this sounds different. Supposedly, if you unplug it and the drivability improves, that implicates the MAF, but I don't know how reliable this test is.

At any rate, if some of the more experienced forum members disagree with this, I hope they'll correct me.

 

Also, I don't know whether this is consistent with the OBD codes you're getting or not, but at 196,000 miles, given the way performance deteriorated gradually, it may be the catalytic converters. Just something to consider.

 

Poolman

So i tried the fuel pressure tester at the valve at the top of the rail, and the tester i got from autozone wouldnt fit. I had the bit, tightened it on there and it wouldnt stop leaking. All was tight as possible. Due to leak, did not get any readings.


"That almost looks right"