BimmerFest BMW Forum banner

cobb S1 aggressive malfunction

2233 Views 10 Replies 8 Participants Last post by  amit1947
OK, So had CObb installed for the past 4 months or so. Been running S1 Agrressive map from day 1. No issues. I was gone for 2 weeks and when I got back drove the car and I say 10min into the drive and as I was hard accelerating from a stop sign, I felt the accelaration was relatiely normal but I think (can prove that) the car went past redline - - it just felt odd at the end of the accelaration band (Pre upshift). Needless to say, i notice the engine sign pop and says malfunction reduce power. Car still drove fine...I panicked. But I continued driving home with no hard accelaration. I parked..An hour later I drive again and malnfunction is no longer showing and car continues to drive fine since. Any ideas people??
1 - 11 of 11 Posts
Plug the accessport into the car and read the codes.
Probably O2 sensors reading airflow that is above the expected limit, so throws car into limp mode. Just turn it off and restart the car. Everything should be cleared. If this persists you can try to swap the O2 sensors and recalibrate them. Usually takes care of it. New sensors are around $150 each.
Same thing happened to me yesterday with my JB4. The CEL light freaked me out too. I was relieved that the CEL did not come back on after I restarted it. I hope this does not recur because it was slower than a Cavalier in limp mode...
I updated to V4.01 maps last night and read the was H30FF. It cleared upon installing V4.01 of Stage 1 Aggressive Stock throttle maps.
The H30FF is a boost leak related code. I can't find the exact definition of it but it's not a huge deal unless you keep getting it. Then you'll need to track down the boost leak code (which can be a pain). I would do a visual check of your charge pipe, DV's and intercooler outlet piping to make sure you didn't pop something off. This is not an uncommon thing when running a tune as more boost will stress the connections and fitting of boost piping.
If car seems to drive fine and no errors are popping you think it is still something I should be looking for from a fault stand point of the things you mention above?
It's never a bad idea to look under the hood of a tuned car every week or so just to check things out. If it does not keep happening then no, don't worry about it but a quick visual inspection is always a good idea.
Since you're running higher boost, you are putting more pressure on the stock components. A boost leak can happen and it's never a bad thing to check your engine compartment to make sure everything is tight. All the things xclone listed are what I would check up on and re tighten if necessary.

You might also want to look into getting an upgraded diverter valve. The stock diverter valve is plastic and as you know, plastic does deteriorate over time. This is the one component that causes boost leaks on these cars esp. if the car is tuned. I would recommend that you check out either the Turbo Smart Diverter Valve or the Turbo Smart Blow off valve options (If you're not a fan of the "wosh" sound from a BoV, then going with the diverter valve upgrade would be ideal).

The Following dyno chart was completed using a 1M, ONLY changing the stock diverter valves to the Turbosmart Diverter Valves. The graph shows the stock diverter valves leak boost, especially down low where it counts. Just by switching them to the Turbosmart Diverter Valves gains in torque are realized throughout the RPM range, with gains of over 25 Ft./Lbs down low.

The following dyno shows manifold pressure, and how just by switching to the Turbosmart Diverter Valves boost pressure is maintained.

IMHO, it's not the OEM diverter valve leaks at LOWER pressure but the spring rate on the aftermarket is harder/firmer, thus at low RPM where the vacuum line only asserted low suction per command by DME, here the aftermarket diverter still fully close (no pressure from the turbo goes out to the exhaust, all air volume goes to the engine), this has been done since the ole Audi turbo tuning (i.e. we use to use 911 diverter valve on Audi 1.8T) for better throttle response feel. Usually bad diverter leaks at high pressure, again IMHO.
Check the Pressure Regulator (also known as Wastegate Solenoid). I had a simliar code and the service department replaced both my pressure regulators because they were not holding boost on the high end.
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.