PLEASE help me figure out this overboost issue.

Discussion in '2.0: LNF' started by spxcro, Jun 4, 2018.

  1. spxcro

    spxcro Junior Member

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    Jun 4, 2018
    Hi. I recently bought my first 'balt. It is a '09 ss/tc with around 160,xxxkms on it. The car is Completely stock (to my knowledge) other then a borla catback and a secondary cat delete I did after buying it.

    About one month after buying the car I started to notice the car over boosting to around 170+ kpa (25ish PSI) and also I strange scraping type noise at high boost levels. The car only does this at WOT. I know that that is waaaay beyond the normal boost levels. Now this was during winter in Canada so temps were around -20 C.

    I was getting a check engine light and a code stating (turbo/supercharger overboost condition). Also the electronic boost/afr/..... gauge (I think its called an RPD??) completely stopped working. I am fairly mechanically inclined and did some trouble shooting and found that my oem MAP sensor (on manifold) was shot. So I replaced it and the car ran great for about to months and my gauge started working again.

    Now this car is just my winter/beater car so once the warm weather came around I took out my summer car and let the cobalt sit on the back burner. About 1 month after parking the car I took it out for a drive and it is overboosting again, even worse then before. I have checked the MAF and MAP (on manifold) sensors and they are fine. I have checked all vacuum lines and they are all good. I have checked for any boost leaks or cracks in charge piping or intercooler and it all seems to be good. I have also checked and can confirm that the wastegate is not stuck and the actuator rod is not bent.

    My last hope is that replacing the TMAP sensor (on charge pipe) will fix my problem and I have ordered the part.

    I have done endless research on this issue and have tried all remedies I have found online and nothing is working. Please, please someone help me.

    Thanks in advance,

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