Intermittent boost issues
Intermittent boost issues
Hey Guys,
This is a 2009 Cobalt ss with just a hahn intake. Occasionally I will only get ~6 psi of boost (varies a bit by gear but around that.) While other times i get full boost with no issues. It's like a 50/50 coinflip on whether I get full boost or not. Doesn't seem like a boost leak as I think if it was bad enough to only be 6 psi It would be a full time thing- not just randomly. I do have a full set of zzp charge pipes/intercooler/forge BPV/trifecta tune to put in but I wanted to get things straightened out first before I modded. Any Ideas? I already replaced that boost control solenoid as I figured that was a low hanging fruit to try - no luck. Any ideas?
Thanks
This is a 2009 Cobalt ss with just a hahn intake. Occasionally I will only get ~6 psi of boost (varies a bit by gear but around that.) While other times i get full boost with no issues. It's like a 50/50 coinflip on whether I get full boost or not. Doesn't seem like a boost leak as I think if it was bad enough to only be 6 psi It would be a full time thing- not just randomly. I do have a full set of zzp charge pipes/intercooler/forge BPV/trifecta tune to put in but I wanted to get things straightened out first before I modded. Any Ideas? I already replaced that boost control solenoid as I figured that was a low hanging fruit to try - no luck. Any ideas?
Thanks
One other thing to note- cold starts often result in the car stalling unless I give it gas at 3k+ RPMs for 30 seconds or so. After the car warms up it will be fine wont stall etc. No pending codes or anything.. Help 
Last edited by Magz_rule; May 10, 2019 at 04:12 PM. Reason: spelling
Do you have the GMS Upgrade (Stage 1) by chance? I had a similar issue with mine and I had the lower TMAP sensor connections soldered to 100% fix the issue. I believe it was shorting out (intermittently) near the AC Compressor, but I'm not 100% sure.
There is a lot of good info here: http://chevyhhr.net/forums/showthread.php?t=33012
Also, here is a checklist I found from Bill Duncan , GM HPVO engineer (Part of team for Turbo upgrade kit (GMS1)
1. It is most likely the connections to the lower [TMAP sensor] (in the intercooler tube by the AC) that need to be fixed.
2. Check for a wire rub through at or near the AC compressor
3. Check to see the sensor is sitting flat
4. check to see the o-ring is properly installed and not cracked (It should be blue).
5. Check for a system leak.
Good luck! Matt
There is a lot of good info here: http://chevyhhr.net/forums/showthread.php?t=33012
Also, here is a checklist I found from Bill Duncan , GM HPVO engineer (Part of team for Turbo upgrade kit (GMS1)
1. It is most likely the connections to the lower [TMAP sensor] (in the intercooler tube by the AC) that need to be fixed.
2. Check for a wire rub through at or near the AC compressor
3. Check to see the sensor is sitting flat
4. check to see the o-ring is properly installed and not cracked (It should be blue).
5. Check for a system leak.
Good luck! Matt
Do you have the GMS Upgrade (Stage 1) by chance? I had a similar issue with mine and I had the lower TMAP sensor connections soldered to 100% fix the issue. I believe it was shorting out (intermittently) near the AC Compressor, but I'm not 100% sure.
There is a lot of good info here: http://chevyhhr.net/forums/showthread.php?t=33012
Also, here is a checklist I found from Bill Duncan , GM HPVO engineer (Part of team for Turbo upgrade kit (GMS1)
1. It is most likely the connections to the lower [TMAP sensor] (in the intercooler tube by the AC) that need to be fixed.
2. Check for a wire rub through at or near the AC compressor
3. Check to see the sensor is sitting flat
4. check to see the o-ring is properly installed and not cracked (It should be blue).
5. Check for a system leak.
Good luck! Matt
There is a lot of good info here: http://chevyhhr.net/forums/showthread.php?t=33012
Also, here is a checklist I found from Bill Duncan , GM HPVO engineer (Part of team for Turbo upgrade kit (GMS1)
1. It is most likely the connections to the lower [TMAP sensor] (in the intercooler tube by the AC) that need to be fixed.
2. Check for a wire rub through at or near the AC compressor
3. Check to see the sensor is sitting flat
4. check to see the o-ring is properly installed and not cracked (It should be blue).
5. Check for a system leak.
Good luck! Matt
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