aj_40_9

Ok, I looked through the forum and found several hits on this topic but nothing really seemed to match my situation. I recently got the car back from the dealer who did extensive head work and im now showing the P0172, and P0170. I understand the code but the only problem is that it's not showing any signs of problems that I can tell. The first one popped up when I was taking off, it didn't die it just stuttered a bit and bam, check engine light. Other then that it runs like a champ, once I cancel the code it takes a couple of days for it to show back up. I would take it back to the guy who just did the work but it's 2 states away. Is this an O2 going bad or should I not even waist my time and money and take it to a dealer. Thanks for your time.

Billman250

Its not a bad o2. The car is running rich, for a WIDE RANGE OF REASONS.

aj_40_9

So to the dealer then.

vbb

Is the car completely stock? If not, what mods do you have?

aj_40_9

AEM Intake, I just recently fixed the vacuum lines fixing that code. Yesterday I was driving it around to see if it would do anything funky and I found at times when leaving an intersection it would try to lurch to the point I would have to engage the clutch and try to re-engage. I'm assuming that's not normal, I apologize for not be more descriptive. I've only owned the car for a few months and one of those it sat in a shop. So as for as normal operations go in this car I don't know because this is my first time owning anything this advanced.

vbb

Yeah, you shouldn't be running rich, especially with only an intake for mods. The hesitating/lurching thing is a little strange. Have you tried clearing the CEL and waiting to see how long it takes to come back on? Is your car doing anything else odd besides the lurching forward?

aj_40_9

Yes, i've cleared it a couple times to see if I could get a different code to surface. It usually takes a full day to a day and a half to show back up. I took it into the shop yesterday and they're leaning towards bad valve timing, but nothing solid yet. I should know more Monday.

aj_40_9

Update, Apparently the valve timing was way off. The technician also said it's very possible that when the head was decked they took too much off which is leaving the timing chain loose enough to throw the cams off? The tech also said the o2 sensor is reading that the engine is running lean and it progressively runs richer and richer until it throws the code. He didn't think that it was the real contributor to the code. He also stated that the TPS could be reading out wrong as well. Both were running within normal voltage range so he wasn't convinced that they were the main contributors. One thing is for sure and consistent the code is progressive. The fuel starts out normal and gradually pushes itself to the point it's running too rich. They said tomorrow they're bringing another technician in to drive it around with the laptop record the data and analyze it. Billman250 what are your thoughts on this.

aj_40_9

Update, The cars valve spacing was pretty screwy but the real culprit was the fuel regulator. It was pushing 80psi and not sending much back to the tank. Changed it out and it runs like a top.