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Discussion Starter #1
I was able to search up a couple threads on various forums where people complained of "cold engine shuddering," but only one that really seemed to describe exactly what I'm experiencing. It was helpful in suggesting a few things to look for (usual culprits like IAC, DISA, vac leaks, VANOS), but I thought I'd go ahead and post it here to get some input.

Most folks say they get a "cold start shudder." Mine is more of a "shudder when it is cold outside (ambient temps)"..and, of course, it is worse when the engine is cold, but I still get the behavior even with a warm engine if the ambient temps are really cold.

It also isn't so much of a "start up shudder" as it is an "idle shudder." When I stop at red lights, it feels almost like the car is "throbbing" under my feet. Not shaking terribly like a misfire (and I have no misfire codes, though I need to check again). More of a rhythmic throbbing sensation (that's what she said!). It is at its worst when I have it in drive and foot on the brake. Putting it in neutral decreases it some but doens't make it entirely go away. When the shudder is at its most severe, it does move the tach, but there are times I can feel more subtle shuddering and it doesn't reflect on the tach.

I have not gone as far to check mounts yet. I'm probably wrongly assuming trans mount was replaced by AAMCO when the transmission had to be repaired by the PO.

My mind went to VANOS as the car has 165k+ on it and I'm sure it has never never been done. Oil consumption on the last top-off has seemed to increase a bit versus what it was just after my piston soak (one year and 12k miles ago), which seems to coincide with this shuddering behavior becoming more pronounced. Could be coincidence...idk.

Or could it be that my hairline-cracked valve cover is finally getting bad enough to allow a more significant leak?

I've been putting off installing my new old VC and new VCG until I'm ready to spend on a Dr. VANOS at the same time. May be time to pull the trigger on that project?
 

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This could very well have nothing to do with your issues, read it and do what you will with it :)

I had similar sounding issues a while back. It's a new car for me so I don't know what role the ambient temperatures played. At the beginning of the day where the car had been sitting around for a long time to really cool down when I'd start it and drive off it would run really rough. On one occasion it died when coming to a stop at a stoplight, forcing me to restart it. Once it had been driven a couple of miles (5+) it would usually run ok but not great. I tried letting the car get to operating temps before driving off with no significant change, also it would idle fine in neutral. I finally decided to have my mechanic change the transmission fluid when it was there for another issue (a broken brake line) and since then it's been running perfectly. There were no significant amount of metal in the fluid but black and gunky.

I suspect the fluid was getting really weird viscosity and perhaps heating up would make it behave more as intended, but what do I know.
 

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Discussion Starter #3
Funny you mention trans fluid. I was worried that it has something to do with the trans only because of where it feels like the shudder is originating from (feels like it is under my butt/feet more than it feels like it is from the engine bay) and the fact that I know this car has had trans failure in the past. I believe the trans pump went out on the prior owner, necessitating a repair. Notice I said “repair” and not rebuild.

I have never serviced/drained/flushed the trans bc I know the trans work was done just prior to my purchase. I have the AAMCO receipt to prove it. So, I obviously assumed that fresh fluid had to be part of the deal.

I’ve been thinking it would probably be wise for me to at least do a few rounds of spill and fill of ATF just for peace of mind. Maybe it will be like your issue and resolve the shuddering as well.
 

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I've had coolant hoses rub against the alternator (?) and spring a leak (improperly mounted coolant reservoir), a brake hose rub against the front driver side wheel and spring a leak (wrong hose for my car). The engine oil was black as tar when I changed it and the gunk on the oil fill cap makes me shudder at the abuse this car has had to take.

I assume nothing of the previous owner and the work that has been done on the car at this point :rofl:

Let us know how the flush works out!
 

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Discussion Starter #5
Oh, I’ve found the PO’s DIYs to be pitiful...but I am guilty of assuming a transmission shop knows what they’re doing. I even called and talked to that AAMCO’s mgr before buying the car. But, point taken....never assume someone didn’t take a shortcut or cheap out on work done under a POs ownership.
 

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Putting it in neutral decreases it some but doens't make it entirely go away. When the shudder is at its most severe, it does move the tach, but there are times I can feel more subtle shuddering and it doesn't reflect on the tach.
Idle control valve? Check for free movement; Clean it with carb-cleaner spray; Replace if necessary. When my 525i has idle surging, a quick blip of the throttle stops it, but I have a manual trans., so it is easier than with an automatic. Still, you might try a little revving in neutral rather than just shifting to neutral. See if that helps.
 

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Wingnut
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have you taken a look at fuel mixtures, at idle, 2k rpm and 3.5k rpm? this could quickly prove or disprove a vac leak. its not unusual for vac leaks to manifest themselves in more extreme temps.
 

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Discussion Starter #8
have you taken a look at fuel mixtures, at idle, 2k rpm and 3.5k rpm? this could quickly prove or disprove a vac leak. its not unusual for vac leaks to manifest themselves in more extreme temps.
No. Can't say I'm that well versed in acquiring that kind of data.

Can that be done with a bluetooth OBD2 adapter and Torque or some other such app?
 

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Wingnut
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torque app and an elm 327 bluetooth OBD adapter are ideal for this. ive the same, used the pair many a time in troubleshooting. have the app on both my phone and an old samsung tablet. just know itll only read engine stuff, the OBDII protocol, not the BMW specific stuff. but im ok with that, ive other stuff for that.
 

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No. Can't say I'm that well versed in acquiring that kind of data.

Can that be done with a bluetooth OBD2 adapter and Torque or some other such app?
Yes, I just got back from a 130 mile drive. I had my BAFX OBD II dongle for iPhone connected and I am using OBD Fusion App for iPhone.

I can make multiple screens to monitor different values.

In this shot below I am monitoring Short Term Fuel Trim Bank #1 (Upper Left), Short Term Fuel Trim Bank #2 (Upper Right),
Long Term Fuel Trim Bank #1 (Lower Left) and Long Term Fuel Trim Bank #2 (Lower Right), out of the screen shot is Temperature and Volts.

The other screen I can swipe over to with my finger reads Pre-cat O2 sensors Bank #1 & Bank #2, and Post-cat O2 Sensors Bank #1 & Bank #2, MAF readings and Intake Air Temperature.

12 values on 2 screens
 

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Discussion Starter #11
Yes, I just got back from a 130 mile drive. I had my BAFX OBD II dongle for iPhone connected and I am using OBD Fusion App for iPhone.

I can make multiple screens to monitor different values.

In this shot below I am monitoring Short Term Fuel Trim Bank #1 (Upper Left), Short Term Fuel Trim Bank #2 (Upper Right),
Long Term Fuel Trim Bank #1 (Lower Left) and Long Term Fuel Trim Bank #2 (Lower Right), out of the screen shot is Temperature and Volts.

The other screen I can swipe over to with my finger reads Pre-cat O2 sensors Bank #1 & Bank #2, and Post-cat O2 Sensors Bank #1 & Bank #2, MAF readings and Intake Air Temperature.

12 values on 2 screens
Good deal. I should be equipped to collect that kind of data then. I'll take a look at it.

Should I note the data when it is cold, warmed up, or both?
 

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Wingnut
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nice trims there blue.
pwgoo, the torque app is for droid, i shoulda stated that. if youve droid devices, itll allow you to show a display just like blue's. by using my 10" tablet, i can show many things at once.
warmed up to start to read the data. for your immediate issue, id look at short term trims (STFT). look at the reading at idle. then increase to 3k rpm and look for any difference. if the trims drop any appreciable amount at 3k, youve definitely got a vac leak, as a vac leak is a smaller proportion of the air drawn in to the engine at higher rpms. at idle its a larger proportion.
 

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Discussion Starter #13
I'm kind of dumb about this fuel trim stuff. I just read an article about it that I Googled up and think I understand it at a conceptual level.

I had to run over to the MIL's house across the street just now, so I thought I'd play with the BT adapter and Torque. Didn't exactly get scientific with it.

What I can tell you is that:
- The car wasn't doing the surging/shuddering just now like usual. Maybe because I just came home from work about a couple hours earlier and the weather has been relatively warm today versus prior days.
- At idle, the STFT readout moved between -0.8 and 2.3.
- Holding briefly at 3500rpm, it moved between about 3.2 and 7.9. Similar behavior while driving. If I knew how to log in the app, I would have tried that.
- Never saw it go negative except for the occasional blip to no more than -0.8 at idle.

I'll play around with trying to figure out how to get the app to log the data. At a minimum, I'll note the STFM in the morning and during the drive to work when the shuddering is usually at its worst.
 

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Discussion Starter #14 (Edited)
Still can't figure out how to get Torque to log the fuel trims (maybe that is a paid app feature), but I did have STFM1 running this morning on the way to work.

For the most part, it stayed in single digits with one exception: when I was backing out of my driveway this morning and then puttering thru my neighborhood, it did hit the -17 to -20 range very briefly.

On the 70-75mph drive to work, it pretty much stayed in + single digits. It also didn't seem to shudder quite as bad this morning during stops as it has bee, though at low speeds in parking lots, etc, it did get in neg single digits a few times. Not going to complain, but seems about right that it would stop acting up as severely as soon as I start looking for help!

One thing I forgot to mention that perhaps is important....I forgot that I've been getting an intermittent secondary air pump code. I've also been dealing with what I think it is a bad ABS module, which I think is tripping a speed sensor CEL. So, for better or worse, I've gotten used to driving it with the CEL on until I can send off the ABS module for repair. That caused me to forget that recently when I checked/cleared the CEL, new codes for the secondary air pump showed up.

FWIW, I cleared the codes last night just to see if or how long it would take to reappear. What was odd is that the first time I started the car after clearing, it ran kind of rough. It didn't trip the CEL and it soon "came out of it," but it was noticeable. Didn't trip CEL for the entire drive to work, but I expect soon it will reappear. I"ll check codes again when it does.

I think perhaps I need to check the vac lines on each end of the hard line going to/from the secondary air pump. The one in the front definitely could be baked, though it didn't appear to be crumbly when I looked at it this morning.
 

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Wingnut
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if i were you id get my hands on BMW specific scanner and look at the ABS, make sure its not a wheel speed sensor thats giving you the road speed sensor fault and CEL. I take it youre getting a P0500 code?
the intermittent negative trim leads one away from a vac leak towards a MAF or O2 sensor,
 

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Discussion Starter #16 (Edited)
Yes, P0500 is one of the codes. It showed up about the time I got the ABS trifecta (which only lights up when the car is hot and sitting in traffic/park). To add to that story, I also had water infiltration in the left floor board front and back due to a firewall plug (throttle cable plug) coming loose. As a result of that, I replaced a couple sensors located in the left floor board: 1) SRS sensor (I think a side impact crash sensor) and 2) yaw/speed sensor (is this diff than the P0500 speed sensor?) due to possibility they had been submerged.

P0500 never went away after all that. I’d reset it, it would come back on after awhile. One of the times it came back on and I went to check it, I noticed I also had secondary air pump codes suddenly. I did not note the specific codes.
 

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Wingnut
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yaw sensor is a totally different animal. its part of the DSC system. wont lite up a CEL, but will a DSC lite. not really much on the left floorboard that will give you a P0500. the P0500 translates to road speed sensor in BMW speak, or sensor a generically. basically it means that the DME isnt getting either a trans speed from the trans or a road speed from the ABS and isnt making sense of what its seeing, so it sets the P0500 and CEL. an OBDII reader wont read the ABS system for fault, it takes a BMW specific scanner. It could very well be that a WSS is causing the P0500. the ABS is pretty good about telling you whats going on with it. that it goes away after reset then comes back after some miles make me tend to believe its an ABS issue. I wouldnt spend any time on the trans til thats eliminated.
SAI codes are P0491 and P0493 IIRC, and yes those would be a separate issue from your other issues.
 

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Discussion Starter #18 (Edited)
yaw sensor is a totally different animal. its part of the DSC system. wont lite up a CEL, but will a DSC lite.
Oh, well...since I'm afraid it was under water and a replacement was cheap, just as well that I replaced.


not really much on the left floorboard that will give you a P0500. the P0500 translates to road speed sensor in BMW speak, or sensor a generically. basically it means that the DME isnt getting either a trans speed from the trans or a road speed from the ABS and isnt making sense of what its seeing, so it sets the P0500 and CEL.
Is it typical that you can get a legitimate WSS P0500 yet everything works? Speedo, cruise, mpg calc, etc?

the ABS is pretty good about telling you whats going on with it. that it goes away after reset then comes back after some miles make me tend to believe its an ABS issue. I wouldnt spend any time on the trans til thats eliminated.
SAI codes are P0491 and P0493 IIRC, and yes those would be a separate issue from your other issues.
From a separate thread I had on here just about my ABS trifecta (and some Googling), the fact it comes on when the car is warmed up and sitting in traffic (no airflow thru the engine bay) has led others to agree that the ABS module has finally succumbed to the heat in the engine bay. I should say that the trifecta doesn't necessarily just "come back on after some miles"...it seems that it only comes back on when I have to sit still with the car idling. If the car is allowed to cool down, it won't be on next time I get it in it and go. If I take the car on a long highway trip w/o traffic, it will never come on...only when sitting and hot. Also, I believe you are right about the codes. Those look familiar to what I had. FWIW, I've put quite a few miles on the car since I reset CEL last night. It hasn't come back yet (I'm sure it will).

But, yes, this is why I haven't gone out investigating buying and installing a new WSS. Figured I needed to get the ABS module rebuilt. I've just been trying to make it thru the winter and some bad weather because I didn't want to have to drive my 2wd truck in any cold wet/snow while my ABS module was being sent out (I'm told it is best to not start or drive the car when you have ABS module removed...not so much bc of "safety" but because it will cause codes that may not be able to be cleared by a simple OBDII tool).
 

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Wingnut
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Oh, well...since I'm afraid it was under water and a replacement was cheap, just as well that I replaced.

good insurance




Is it typical that you can get a legitimate WSS P0500 yet everything works? Speedo, cruise, mpg calc, etc?

yes, if the LF wheel sensor is the problem, iirc


From a separate thread I had on here just about my ABS trifecta (and some Googling), the fact it comes on when the car is warmed up and sitting in traffic (no airflow thru the engine bay) has led others to agree that the ABS module has finally succumbed to the heat in the engine bay. I should say that the trifecta doesn't necessarily just "come back on after some miles"...it seems that it only comes back on when I have to sit still with the car idling. If the car is allowed to cool down, it won't be on next time I get it in it and go. If I take the car on a long highway trip w/o traffic, it will never come on...only when sitting and hot. Also, I believe you are right about the codes. Those look familiar to what I had. FWIW, I've put quite a few miles on the car since I reset CEL last night. It hasn't come back yet (I'm sure it will).

reasonable train of thought, but i still recommend investing in a BMW specific scanner (creator 310 is cheap enough) just to verify the diagnosis

But, yes, this is why I haven't gone out investigating buying and installing a new WSS. Figured I needed to get the ABS module rebuilt. I've just been trying to make it thru the winter and some bad weather because I didn't want to have to drive my 2wd truck in any cold wet/snow while my ABS module was being sent out (I'm told it is best to not start or drive the car when you have ABS module removed...not so much bc of "safety" but because it will cause codes that may not be able to be cleared by a simple OBDII tool).
not having the ABS module installed wont give you an error code that you cant reset. again, investing in a BMW specific scanner will erase any doubts. as you did have the trifecta set, but it has cleared itself, the code is still stored in the ABS module, just isnt an active DTC. but do keep in mind that if the module does need to be repaired, you wont have any ABS or DSC functionality, nor will you have speedo cruise and a few other things,

edit....dunno if youve an auto or manual trans, auto has speed sensor, manual doesnt. so if youre getting the P0500 with a manual, its definitely the ABS thats at fault, auto could be either way.
 

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Wingnut
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one thing that just happened to me, few days ago started getting an intermittent shuddering on my 528. felt like i had an intermittent vac leak, checked all vac lines and connections, no help, ran fine for a day then started again. finally popped a code, cyl 5 misfire. swapped coil and plug tween 5 and 2. ran good for 2 days then started again, popped a cyl 2 misfire, had extra coil on hand, got a new plug and replaced both. no issues so far.
 
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