I have seen several posts saying having issues with MBC but was wondering if anyone has found a setup that works well.

Currently in 5th gear around 3500 - 4500 RPM on light partial throttle the car will go into limp mode. I talked to someone yesterday that was saying might be an issue with BOV set at 50/50 in combination with the MBC. So I will try to set it to full recirculation this weekend and see if that helps. Anyone else have any ideas to keep it from going into limp mode?

 

maybe to much boost ?

 

yea its maybe to much boost b/c ive had a MBC for like a month and i have a heavy foot and no limp mode its set at 22-23psi

 

i haven't gone into limp mode yet....intake, mbc, exhaust, 23 psi

 

If its a P1235 code, its too much partial throttle boost. Lower your MBC by 1psi and try again. There is a small threshold where it will or won't do it.

Supposedly EcuTeK flashes have cured this. I swapped to ECU boost control before the cure and it works just as well, but with more stable boost control than an MBC. No code.

 

After I got the factory reflash, my car kept going into limp mode even though I set the boost below 20 psi: two codes p1234 and P0223. My theory is that the car was building boost too quickly with MBC. And it's pretty dangerous IMO, because you have around 15 psi around 2,500 rpm with MBC, and when we measured AFR, it was 14 to 1!!! 15 psi @ 14:1 AFR = NEW ENGINE.

Long story short, I took the MBC out. Too much headache. And I got it tuned with Ecutek. Ecutek has 4 maps for boost, and Mike @Road Race Engineering has set my car to peak at 24 and taper it to 17ish at 7,600 rpm. FYI, the boost is 22 psi between 6,000 to 6,500, where it makes peak horsepower.

 

Does this mean that there is a delay in going to open loop fueling? God I hope not. Sti's have that and it is annoying as hell. Older EVO's did not have that. Hopefully that is something ECU flashing can remove although I'm waiting for open source software. $600 for something I can't change or remove myself is a joke.

 

I know this thread has sat for a while but I didn't want to start a new one.

I have been having a helluva time with this damn limp mode, 3rd-4th-5th gear partial throttle, doesn't matter, limp mode is almost automatic. I have had the tuner adjust the boost maps to account for the increase in partial throttle boost and its just not having it... anyone make any progress on this? I don't want to adjust the boost, it is tuned at this boost and I don't want to mess with the tune.

 

Which tune did you receive hel_if_no?

 

X's require that the actual airflow measured Is close to that of the desired air flow as set in the ecu. When there is a significant variation, the ecu assumes that the drive by wire system is not working properly and activates limp mode. The soultion is to measure the actual air flow and remap the targets in the ecu - end of problem. Al