1997 m3 CEL help!

[m3f_Duvany]

Hey guys,



I've had my m3 for a little more than a month now and have had some intermittent check engine lights here and there. I resolved one of the codes by replacing a short vacuum line but now it's giving me the following codes :



P0170 - fuel trim malfunction (bank 1)

P1188 - manufacturer contrl fuel air metering

P0134 - O2 sensor ckt no activity (bank 1 sensor 1)



I've done some searches but I haven't gotten anywhere with this slew of codes. The PO told me that he had just replaced both O2 sensors, and I checked the connections under the engine cover and added some dielectric grease so it doesn't seem to be a faulty connection.



If it's relevant (and even if it's not your opinions might help) I do get some wispy white smoke at start up that does not go away when warm so I don't think it's condensation. And I've been having issues with coolant loss (no obvious leaks) so I'm afraid it's a head gasket issue, and if it is, maybe it's related. Keep in mind though, it's not billows of white smoke and there isn't an obvious smell to the exhaust either. I originally thought it was a bleeding problem and there was air in the system which over time attributed to the apparent loss of coolant.

I was thinking of getting. A smoke test done to check for leaks in the intake system.



Any advice you guys can give me I will definitely appreciate. And if anyone has had this same or similar issue please let me know what resolved it for you.



Thanks in advance!

[m3f_Duvany]

Any insight?


I still have to do a compression test, but it seems like theres slightly more smoke/odor coming out of the exhaust.

[m3f_Duvany]

bump unresolved

[m3f_abcurran]

P1188 is generally symptomatic of either a vacuum leak or faulty 02 sensor. Not sure what reader you're using to bring up the description you have, but P1188 is Fuel Control - (Bank 1 - Sensor 1) and generally means the adaptation limit is exceeded.


What the hell does that mean?


In the event of a vacuum leak (assuming you have one), your 02 sensors are reading too much 02 after combustion. The 02 sensor is telling the ECU to add fuel to the mix to compensate for the lean condition post combustion. The ECU adds the fuel, but can only do so to within a certain percentage (that's the ECU "adapting" the condition). When the amount of fuel added is still not enough to bring the A/F mix to within spec as read by the 02 sensors, the adaptation limit is exceeded and up pops the CEL.


Generally, if you have a vacuum leak, you would more likely than not also be triggering P1189, Fuel Control (Bank 2- Sensor 2) because the leak in the intake is felt across all cylinders/both banks as the unmetered air fills the intake manifold after the MAF.


Considering you the CEL popped up for one bank only, I'm leaning toward a faulty bank 1 sensor and not a vacuum leak.


Did you see the receipt for the work order on the 02 sensor or for the purchase of the 02 sensor? Not unheard of for a sensor to be DOA out of the box, too.


Hope this helps.

[m3f_Duvany]

Thanks for the input!


I'm definitely going to look into the sensor. But since I'm also burning coolant I'm going to run a compression test to see what's going on.


Do you think that the coolant is unrelated to the O2 fault?

[m3f_Duvany]

i took apart my engine and redid my head gasket over the last couple of weeks. definitely had an issue as their was coolant in the 3rd cylinder. cel keeps coming on so I'm thinking it is just the O2 sensor itself. will replace soon and update.

only getting codes p0170 and p0134 now

[m3f_Eclipsetrbo420A]

Swap O2s see if code follows and find all vacuum leaks, check injector orings too

[m3f_Duvany]

Will do that on saturday, thanks.

[m3f_Duvany]

Ok guys, so long story short here is what has been done to the car


Complete head gasket rebuild

Vanos rebuild

Both precat O2 sensors replaced

Ignition coil boots replaced

Spark plugs replaced


The problem (which surfaced about a month after the engine/vanos work, is that the car runs rough once it's warm. It feels like it's running on half as many cylinders and there's the occasional misfire.


The codes I'm getting are same as first post 0170 1188 0134 except that now I'm also getting P0340 for the camshaft position sensor if I read the codes with the engine on. Could this be the root of the problem in its entirety?


Any help would be appreciated. I'm going to go ahead and buy the new sensor anyway to have it but if you guys have some insight it would e much appreciated.

[m3f_Radmobile]

Have you been doing all this work yourself or have you been using a qualified, reputable BMW tech?



If you DIY'ed it, you could still have a timing issue and HG leak. Just because you put in a new VANOS and HG doesn't mean you fixed the problem. If you didn't have the head checked out by a machine shop to make sure it was true and level, then throwing on a new HG would result in the same issues. And when the VANOS was done, did you just do the VANOS kit or did you address the timing chain, tensioner, camshaft sprockets, etc? Again, DIY or independent shop?



A camshaft position sensor error means you have a timing issue or simply a bad sensor.



There's so much up in there air. I think you're not getting responses because it could be a multitude of things and likely only a qualified tech can give you a proper diagnosis after diving into the car firsthand and with the proper tools and diagnostics equipment.



And the misfiring could be a bad coil (not just the coil boot) or a sticking piston ring. Or, it could be a result of the camshaft timing and errors. Again, there can be so many possibilities.

[m3f_Duvany]

It was all DIY. me and my father dove into it and he has countless years of experience. Of course we did have the head machined, and there are no signs of leaks anywhere.


The timing chain and sprockets were in great shape but the tensioner was replaced. All the work was done in detail.


The symptoms did not surface until about a month after the HG job, and are completely different from previous issues. The cam sensor is en route from the dealer, so I'll update once that gets put in.


The misfire was on all cylinders, unlikely that all coils went bad, boots were due to be replaced either way.


No offense, i just prefer not to spend my money on having a stranger mess with my car.


I also apologize because I'm sure I haven't included everything in my posts, much less have kept them up to date.

[m3f_Radmobile]

No offense taken. A lot of people don't send their head out for inspection thinking 'it didn't overheat so it's not warped.' But with higher mileage, it's just best practice. So that's why I asked. This forum is filled with DIYers and prefer it that way, so you're in common company. Wish I could help further. Hope someone chimes in with some good advice.

[m3f_Duvany]

Thanks for the support!


In other news, after the cam sensor replacement, everything is *almost* back to normal. I'm still getting a small rumble at idle but barely any loss of power.


in order to remove any doubts, I'm going to replace all 6 ignition cylinders when they arrive tomorrow night and hopefully that will be the end of that so i can move on to other things.


i will update as soon as i can, and if anyone comes across this thread and happens to have similar symptoms and don't know where to start please feel free to ask me and ill try my best to help you out.

[m3f_abcurran]

Thanks for the support!



In other news, after the cam sensor replacement, everything is *almost* back to normal. I'm still getting a small rumble at idle but barely any loss of power.



in order to remove any doubts, I'm going to replace all 6 ignition cylinders when they arrive tomorrow night and hopefully that will be the end of that so i can move on to other things.



i will update as soon as i can, and if anyone comes across this thread and happens to have similar symptoms and don't know where to start please feel free to ask me and ill try my best to help you out.

If the new coils don't fix the idle rumble, maybe there's a slight air leak still, or timing could be off by a hair. That's my guess, but glad it's nearly resolved.

[m3f_Duvany]

Same small intermittent misfire at idle. Maybe the spark plugs are on the fritz. Going to get dealer originals soon to be doubt free.


Ran a vacuum test right on the intake manifold and everything checks out so no issues with valve timing. No need to kick myself for not replacing the springs while I was in there. Maybe something is wrong with my exhaust and the back pressure is messed up?


I'll have more time to trouble shoot after next week.