zgrawcock

Hi guys, I am finally at a loss with my 09 HHR SS and I am really hoping someone else has experienced my problem and fixed it or some of the better experts can point me in the right direction. I am not entirely inexperienced I have worked on a built cars before but am running out of options on mine. It is 09 HHR SS 5 speed manual and what my issue is it seems like less than 2.5k rpm doesn't matter of gear but I was once in awhile getting lean and car would kinda jerk stutter then gets rich and runs fine again but is only at very low rpms. But it is becoming more frequent and I would like to get it fixed before it causes bigger issues. mainly seems to happen at less than 30 percent throttle as well. I drive the car little aggressively I never have an issue only low town rpm and throttle percentages. I am leaning towards the throttle body going bad or maybe the injector rail. I have replaced everything else. over last month I have replaced MAF, both 3 bar maps, both o2 sensors, the hpfp and diaphragm side of the pump and the throttle pedal. Car is fully built externally and tuned, all internals are stock. I can write a mod list if someone thinks it would help but didn't want to write useless list in most cases. Another reason I am leaning towards the throttle body is about 5 or 6 weeks back I started getting issues with car going into limp mode (engine power reduced message) along with a p0122 Throttle position a circuit low and I cleaned and relearned the throttle body along with changing the pedal out. seemed like it helped but did not fix the problem. I don't want to keep throwing parts at it and hoping it will solve the issue and its getting quiet expensive at this point. I have checked for boost leaks, there are none, BPV is fine, I have good fuel pressure on both sides of the hpfp, checked the evap solenoid which is fine, and have replaced the list about as far as sensors etc so I know they are good also sea foam the intake periodically to try keep valves clean but have good compression so I don't think that would be it and also idles great with no hard starts but doesnt matter the temp outside, I have no fuel or afr problems anywhere in the rpm range if I drive it at 50 percent or more throttle it is only less than 2.5k and I would say roughly less than 30 percent throttle in any gear but doesn't do it all the time, it is getting more frequent but not all the time and afr will swing from 12.0 to about 16.8 17.0 and jerking hesitation like doesn't want to run and no codes. Like I said next step is throttle body unless some one out there has another idea that I am missing and then I guess will be getting opel upgraded rail if that doesn't fix it. only other thing I had thought of was maybe plugs but figure would start missing at harder pulls if they were going bad (have roughly 20k on them NGK iridium's) Anyway sorry for the novel but wanted to be as clear and detailed as I could. Thanks guys

63 Nova SS

iTrader: (3)

Sadly sea foam isn't going to help you keep the valves clean, and if you've never cleaned them, that's not a bad idea. Has your tuner checked over the tune to make sure your fuel trims are ok? I doubt your injectors have gone bad so I wouldn't look there especially if they keep up at fuller throttle levels.

zgrawcock

I know the sea foam threw the gas tank wont help being it is direct injected but still try to spray down in the inside of the intake manifold when car is hot try keep stuff broke up. But yes you are correct that is something I should probably do just to be safe and see. be good weekend project I suppose.

ECaulk

iTrader: (6)

If it's not the throttle body going bad, then it's the tune causing the issues. Try resetting the fuel trims and see if the issue lessens (if you don't have a scan tool/interceptor just unplug the battery for 5mins)

zgrawcock

Yes I do have interceptor that is how I have been trying to catch it. I will give that a shot tonight before work. Thanks.

zgrawcock

I wanted to report back in case anyone else came across similar symptoms with there car. I ended up taking the intake manifold off to replace the throttle body and as im sure most people will know the valves were disgusting. A lot more so than I had expected. So I cleaned them up completely and the intake manifold as well. I also hooked the throttle body back up to find that between approx. 5 to 40% throttle the motor for the blade was like stuttering, twitching wouldn't hold a constant position even with the pedal held steady. So I believe this was the reason I was having my issue, but I do know that some of the parts I replaced were wore out contributing to it and the valves were definitely not help matters at all. But that replaced with some new gaskets and spacers along with clean valves I got my throttle response back and it holds a good afr all the way through the pedal range with no more jerkiness. Thank you guess for the help and suggestions.