[BoostedE90]

My car has always had a stumbling idle issue when warm. Even after new injectors, plugs, and HPFP. It seems that once the car has been warmed up, usually after some spirited highway driving, when i am stopped at a light it stumbles like it is going to stall and then the RPMs raise to keep it from stalling. It's doesn't do it all the time but it definitely happens from time to time. Also lately I've noticed a slight oscillation when at first going WOT.

On Friday I installed an AFE intake and ETS chargepipe. When I removed the stock chargepipe I noticed some oil in the pipe and when I removed the TMAP sensor it had some oil accumulation on it. So I decided to remove the TMAP sensor on the intake manifold as well and it also had oil on it. I wiped both of them down and lightly blew the oil out of both sensors.

On Saturday I drove from Tampa to Orlando in ~90 degree weather and was not taking it easy on the drive. First off I noticed the slight oscillation had gone away when getting on the gas. When I got off the highway in Orlando heading to my friend's house I got caught at a few lights and normally the idle would stumble, but it was nice and smooth. Drove around all weekend in Orlando and zero issues with the idle. Same experience on the way back from Orlando to Tampa.

I know the TMAP sensors measure temperature and pressure at the intake so I wouldn't think cleaning them would effect the idle of the car. I would think it would have to do more with the intake and CP. But I did have a TMAP sensor go out on me a while back and while it was on it's way out, my car idled horribly and then finally started stalling when the sensor died.

I was curious to know if anyone else has tried cleaning the TMAP sensors when dealing with a rough idle? (sorry for such a short question and loooong explanaiton!)

Also here are some pics of the work I did on Friday. Also Thanks to Jack_Vang for the CP and BOV and xDrive Mike for the AFE intake.

Before:


After:

And before I get flamed I know the filters are upside down.

[trimtab81]

just ran across your post while doing a search about the TMAP sensors...my 335i like many others has a stumble at idle periodically...I assume you have put a few miles on the car since your original post and I was wondering if cleaning the sensors was a good long term fix...Thanks

[HermanL]

I have the same issue, replaced plugs, coils, injectors, also cleaned TMAP sensor mass airflow sensor throttle body and walnut blast intake valves, no improvement whatsoever, very frustrating.

[BoostedE90]

Originally Posted by trimtab81

just ran across your post while doing a search about the TMAP sensors...my 335i like many others has a stumble at idle periodically...I assume you have put a few miles on the car since your original post and I was wondering if cleaning the sensors was a good long term fix...Thanks

Nope it was only temporary. I would say a few thousand miles and it was back to stumbling. I did nothing to prevent oil from accumulating on the sensors (OCC and/or RB PCV upgrade) so I can definitely see why it came back. I have cleaned them again since with the same result. Also I would imagine over time the accumulation of oil on the sensors (no matter how well or often you clean them) will damage the sensors. So the only solution is to replace them. But replacing them is only going to be a temporary fix until something is done to prevent oil from getting into the intake track.

So my plan is to get an upgrade my FMIC (oil tends to accumulate here), an OCC, RB PCV upgrade, and then walnut shell blast the intake valves. Hopefully that will keep it running well for a long time.

[Jeff@TopGearSolutions]

I bought my 335i with 1.3 miles on it and it didn't have the smoothest idle then either, it's just a characteristic of the car.

There is no real way to pin point what exactly makes for a poor idle.

If you are looking to keep a majority of the oil out of your CP,intake manifold and intercooler you should look into an oil catch can.

Severely poor idle is usually attributed to, injectors failing, fault low pressure or high pressure fuel pumps, gunked up intake valves, vacuum leak/boost leak, old spark plugs, coilpacks on the fritz, or PCV leaks (to name a few LOL).

Some people who are tuned may find resetting adaptations during the change of seasons, hot to cold, or cold to hot might help as it expedites the learning process of the idle with the new temperature changes, other than that if it's not too severe just enjoy your car.

[trimtab81]

Thanks for the feedback...I'm on the fence about the OCC...I'm sure they help, but I've seen too many pics of intake valves still caked up after running a catch can...I've already cleaned my valves @50K, replaced plugs and coil packs (classic misfire)...I may just clean the sensors and see how much it smooths out...should be a quick and easy job.

[Bagelfast]

Try resetting all adaptions aswell

[Gugs]

Originally Posted by 1LUMI

Try resetting all adaptions aswell

This often helps me also when i get the idle stutter.