[lawwailok]

my car has been on E50 for about a year and recent months i went back to E30 cuz i didn't want to kill my newly LPFP too quick. so last week driving normally and merging onto freeway from a carpool light. CEL came on while trying to pick up speed, checked code, 30FF.
then i switched to OTS stock map and tried to do a few WOT, 30FF again. so went home, checked all the possible connections and vacuum lines, couldn't find anything at all. since i had an appointment the next day at the dealer to fix my oil pan gasket leak, might as well flash back to stock rom and hopefully to trigger that code and hope dealer can do smoke test and able to find something. but don't matter how hard i drive, i couldn't get that 30FF show up again.
so i PM Ken @wedgeperformance and asked for some opinion. i gave Ken the history of the car and what has been replaced. after a few PM exchanged and i picked up the car from dealer, was told that smoke test couldn't find any leak and my SA and tech couldn't duplicate the code either, Ken narrowed down to the last possibility - TMAP sensor. he suggested to give it a good cleaning since a dirty sensor will not read high voltage on higher boost map and will trigger CEL. so i picked up a new sensor while picking up the car. went home, swapped out to the new sensor (since the old one has been cleaned at least once or twice already), the old one was super oily and the electron inside the sensor was so dirty and it was pure black color vs the new one i picked up from dealer is yellow color.
pumped back E50 to the tank and flashed it back to E50 map to test it and see if any more 30FF will show. car has a much smoother idle, and better response, and did quite a good amount of WOT and no more CEL or 30FF.

i guess Ken nailed it right, it was the TMAP sensor causing the problem. when i had the old sensor, car wasn't as responsive and boost wasn't as stable. he explained to me that if it is stock boost level, even with a dirty sensor the voltage is not high enough to trigger anything. but once the boost is over stock level, if the sensor is dirty or covered with a lot of oil, it may not be able to handle higher voltage as boost level increases. i'll keep an eye on it this week and do more testing to make sure 30FF is not coming back.

i don't have a tune from Ken, im on PTF but he is such a very helpful member even i PM him the symptom, he would response very quick and try to help me to solve the problem. i wouldn't think of tmap sensor can be boost related! a big thank you to such a very helpful guy on the forum!

[Jklad]

Great info. Was it the tmap on the cp, or the one on the intake mani?

[Jnat]

Great to see members that are in the know and helpful at the same time@!

[WedgePerformance]

I think everyone by now knows our cars have a lot of oil which travels through our intake system. I think it's great we have E85 today and our cars are making a lot of power. But gone are the days of methanol injection which helps to keep the TMAP sensors clean. If you're not spraying, you have a higher chance of oil soaking your sensors. As OP found, this causes a lot of issues with your car which can lead you down the wrong path trying to diagnose a 30FF or ruff idle replacing plugs, coils, and injectors.

Two things I highly recommend.

1. BMS Oil Catch Can

2. RB Turbo Upgraded PCV Valve

It's the best @ $200 dollars you will spend for the heath of your car.

[lawwailok]

Originally Posted by Jklad

Great info. Was it the tmap on the cp, or the one on the intake mani?

it's the one on the CP

[Boost'n E92]

Originally Posted by lawwailok

it's the one on the CP

Glad I saw this thread and your post Eric, I was getting the engine malfunction yesterday at the track (sac raceway) the first time I went out to the track all was good, was running e30 and ran 12.9 as my fastest, second time out at the track is when I got the 30ff and funny thing is I put a bms occ between my trips there to the track, and I went to the dark side and got me a jb4 g5 last week to try out, and it was being temperamental yesterday at the track, first run I was like this car is slow, with cobb I was 12.8 and my first run was 13.5, 13.7, 13.8, then I decided to check where my map was and it was on 3 which is for meth, I was running map 5 all the time, then the car kept kicking to map 4 which oem like performance, did map changes twice after 2 runs it was kicking it to map 4 could this be because of the so called boost leak the 30ff? I was only able to get one good run after about the 5th run I ran a 12.8, I was like ok now it running right, then next run again it dropped it to map 4, I looked at the vacuum lines and checked out good, I think I need to tighten my cuplers on the fmic a little and check my tmap, and clean it or replace it, I am now at 82k on the car, how much was the tmap at the dealer?

[chepy24]

this is why i love the forums!! im gonna clean mine for the hell of it this weekend now lol

[GoRomeo]

Originally Posted by WedgePerformance

I think everyone by now knows our cars have a lot of oil which travels through our intake system. I think it's great we have E85 today and our cars are making a lot of power. But gone are the days of methanol injection which helps to keep the TMAP sensors clean. If you're not spraying, you have a higher chance of oil soaking your sensors. As OP found, this causes a lot of issues with your car which can lead you down the wrong path trying to diagnose a 30FF or ruff idle replacing plugs, coils, and injectors.

Two things I highly recommend.

1. BMS Oil Catch Can

2. RB Turbo Upgraded PCV Valve

It's the best @ $200 dollars you will spend for the heath of your car.

10yr. Old thread got to love it Bringing this from the dead. Great information. Knowledge is Power!