Vacuum Leak?
 

Guys, I've been doing a lot of my own diagnosis and think I have the issue with my box cornered, but would love to get some advice to make sure I'm on the right track.

Had 1130 and 1128 codes since I bought the car. Thought for sure it was AOS, had the white smoke and everything. AOS replaced, codes came back. The car does this odd thing at a cold startup that sounds like it's going to stall. The only way I can describe it is when the car is on "choke" it runs fine, and then when it switches to run after startup, it bucks, rpm idle bounces like its going to stall for maybe 10 seconds, then it corrects itself and runs fine. Gas mileage seems low, so I know its running rich, and the codes confirm this. I pulled the plug on the MAF and started it and the same idle issue happened with the MAF disconnected so I don't think its an MAF issue. I did clean the MAF and did a new air filter recently and the codes came back after driving it about 100 miles.

Thoughts on this? I'm going to take it to my indy to get it leak tested, but I'm hoping I'm on the right track and not just throwing money away for nothing. 2002 Base Tip if that matters to anyone. Thanks in advance for the advice.

P1128 and P1130:

These codes indicate that the O2 sensors on each bank have reached their enrichment limits; possible causes:

• Intake is leaking
• Fuel pressure is too low
• Injectors are carbonized or otherwise contaminated
• Fuel delivery volume is low

I appreciate the response. I had originally heard that they usually related to either an AOS, MAF or Vacuum Leak of some kind. I'm guessing it's a continuation of an intake leak as that is what was repaired (supposedly) right before I bought the car which was causing it to not pass Smog Test in CA. I don't think the fuel pressure is an issue. Injectors are new to me, but haven't heard much of that in my searching. Any other advice or suggestions you can offer based on the idle issue at startup? My wife is ready to kill me with the constant CEL issues and I really don't want to be throwing parts at the car if I don't need to.

Have you measured the fuel pressure??

What are the MAF readings? If they are below spec, then it's likely a vacuum leak. If they are up to spec, then suspect a fuel delivery problem. Check the fuel pressure and fuel delivery values.

I am troubleshooting these same two codes. I did a smoke test (with my homemade machine) and found two leaks in the intake system. One is at the rubber boots that connect the intake manifolds, and the other is in the brake booster vacuum hose (the curved part of the hose, right next to the air filter housing). I hope this would help with your problem.

For me those same codes where the result of the hose between AOS and Throttle body not seating right, vacuum leak. I had cleaned the Throttle body so I did remove that hose. The clipping system, while a great exercise in over engineering, may have been better served with hose clamps

Good Luck

Guys, just updating this with some additional info. I'll be taking it to my Indy likely first week of April to have everything leak tested. I'm pretty sure if it was a fuel delivery problem I'd have more issues than the momentary startup bucking. I will advise him of possible causes, but he was a Audi/Porsche dealership guy for years so I'm sure he knows what to look for.

I will update this with the eventual solution. Thanks for all your help.