R manifold + catback = overboost ? :( Topic is solved

Post by **hausmeister** » 10 Jun 2016, 01:03

Hey.
Recently I did some work on my 850 T5R - replaced the rusting catback with tme exhaust and also I swapped in a R exhaust manifold. Now I'm having some issues... before I had the wastegate set to ~3psi which worked fine.
With the new setup the ecu can't really manage the boost any more (it seems), got overboost in high rpm to ~17-18psi. I reduced the wastegate setting to 2.5psi, and now to the factory 1.8 since I still got too much boost.
It mostly only happens when In sport mode where it revs higher.
I think the ecu is still relearning, and the last acceleration I did seemed better, but before that I had fuel cut off a few times. Also power seems to suffer from the higher boost.

I am a bit worried that I did something wrong, but I can't think of what. Turbo is still the same old 15G. Does the Exhaust now flow so much better that the ECU can't cope with it, even with the stock turbo? (I have an IPD tcv installed)
I have to say with 3pi wastegate the response was pretty impressive. Now it is just "meh", but still much better than the original setup.

I also wanted to add a Downpipe and ECU, but hit a snag as I have to source a fitting turbo housing first. So that is on hold for right now.

Post by **hausmeister** » 23 Jun 2016, 11:29

I have reset the ecu again.. maybe it helps. Also the car was using way more fuel... either the o2 sensor got damaged or the ecu weirded out by the changes.
Maybe I will try a manual Boost Controller until I can install the tuned ecu.

Post by **JDS60R** » 23 Jun 2016, 12:07

replace the tcv. especially if its one of those horrible aftermarket aluminum ones. I have a bucket of them that stick - its the type that uses internal orings.

test the wastegate (vacuum and pressure) replace as needed
check MAF
reset computer

Post by **hausmeister** » 25 Jun 2016, 14:17

I think the O2 sensor might have died. Car uses about 1/3 more fuel... not sure what, but something is very wrong

.Except for these 2 issues however it drives fine.
Wanted to replace it anyways, so I'll do that.

I'll try the factory tcv next. I have the one from IPD, so far didn't have issues until right now.

Post by **hausmeister** » 30 Jun 2016, 07:08

The new O2 sensor seems to also have fixed the overboost issue.