ZackCousineau

Please help! Im scratching my head on this one guys. im having an issue with the blow off and wastegate control.. a little back story..
so I recently bought this 2010 cobalt LNF with a Trifecta 23 psi tune already tuned to the car. Ive been driving the car for months now and ive only had occational issues with the tune "going stupid" to where it reverts to the factory tune until I cycle the ignition. that aside, I noticed a couple things that lead me to think that the valve seats were warped causing lower compression but not low enough to really show any performance issues. (cyl. 1-4 about 110psi +/- 5psi) my dad had a LNF sitting in the basement so I tried reverting the car back to the stock tune before replacing the engine to ensure that the new engine isn't getting pushed too hard with a potentially bad tune.. well, immediately the idle was smoother and the car sounded overall much healthier, until I went to give it a test drive... i then noticed that the wastegate and blowoff controls were all out of whack.. only about 6psi of boost, and the blowoff diaphragm was fluttering, as if the blowoff solenoid wasn't accuating.. I babied it home and on the drive I noticed that the air/fuel ratio was "backwards." while first pressing the gas peddle the car will studder, the a/f ratio will peg at 18.1 and when its under a load the a/f ratio is goes all the way down to 12.1, and while engine breaking the a/f ration is at 10.1.. so I then decided to replace the engine with another LNF out of a 2012 regal. I was able to use the same harness from my cobalt and I was able to just "plug n play." I put the engine in hoping that the issues would straiten themselves out (thinking its maybe an aftermarket b/o valve, etc..). well, the new engine does sound healthier but I am still having the same issues.. everything is routed properly and everything is tight. (already boost leak checked)
if anyone has any idea on what could be going on pleaseeeee help.. I honestly feel like it a tune issue because this issue started ass soon as I reverted it back to stock. I want my car back and running right. at this point im scratching my head because all solenoids work via scan tools but don't while driving/running..

exninja

iTrader: (1)

how did you revert the ecm to factory? dealer flash or new ecm?

ZackCousineau

Dealer flash via MDI and SPS through GM. Im a tech at a GM dealer

exninja

iTrader: (1)

do the map sensors match the config (just thinking of something simple)? could there be something residual in the ecm from the trifecta tune? i'd suggest trying a different ecm but i'm sure you've thought of that and it's pricey if you don't have a spare around.

ZackCousineau

I really wanna stay away from buying a new ecu. I have a feeling the program downloaded to the car wrong or something like that.. I just wanted to pick some other brains to see if anyone else has encountered this issue.

ZackCousineau

the crappy thing about that is that GM wont let me reinstall it because it sees that the current update is already there. is there a way to "hard reset" it, where it removes any software that it can so I can reprogram it??

63 Nova SS

iTrader: (3)

I know there has been issues in the past trying to get a trifecta tune off an ecu. Are the map sensors working correctly? Is there some way that it's reading your gas peddle inverted- full throttle is reading idle?

ZackCousineau

That would make sense. (residual tune being left from the trifecta.) because ass soon as I de-tuned the car it started acting goofy.. is there a way to do like a "global reset" to the ECM itself?? I want to avoid buying another ECM if at all possible. im prob gonna try disconnecting the battery agin and touching the two battery leads together (not while its hooked to the batt lol) to drain any residual energy, then ill let it sit overnight disconnected. I don't think itll work but wth, right?

exninja

iTrader: (1)

what map sensors are in the car? be sure to double-check that, I could see issues pop up like you're seeing.

ZackCousineau

I have one Bosch MAP sensor on the lower charge pipe, and an ACDelco one on the intake

exninja

iTrader: (1)

not 100% on what the top one is, but those map sensors are not the correct ones for the "stock" tune. the LNF upgrade package thinger (from GM) was new map sensors and a tune. you'll want to download the upgrade tune, then see how it runs. also you'll want to double check that IM sensor.

ZackCousineau

The lower charger pipe sensor is a four wire bosch sensor with only three wire running into it. it also has a small jumper harness to make it work with the factory engine harness. what type of sensor do I need for the lower charge pipe if im going back to stock tune?? the one on the manifold is a factory one I know that for sure.

exninja

iTrader: (1)

the one in the intake isn't the one that the car came with. It's been replaced at some point. The question is whether it's a 2.5bar or 3.0bar. The lower one definitely looks like a 3.0bar. I don't know why they'd have a 2.5bar and a 3.0bar on the same car. You should be able to look up which sensors you need at your parts department, or rockauto.