Have you looked at the freeze frame data when the DTCs post? You need to know the operating conditions for when the mixture is skewed, ie idle only or higher RPMS or under heavy load, operating temps, etc.

The "spray and listen" method very rarely does anything useful, the computer is usually too fast at making adjustments except in the case of very severe leaks. If your mixture is skewed at idle only, then hook up the scan tool and monitor either STFTs or the upstream O2 voltages while spraying to look for any reaction.

 

I'll see what I can do about getting that done. I appreciate all your help.

 

When it gets high enough to set the codes it's at idle. I'll try spraying and monitoring the STFT and the front 02 today.

 

I did a smoke test and smoke was coming out of the IAC. like the little cap looking thing on it. so should I replace the IAC?

 

Don't want to spoil the puzzle but Makuloco might help.

 

mine is the 2v. And my symptons don't match those.

 

Dang, that's the second time I picked the wrong number of valves.

Your freeze frame will tell you a lot. Gaskets seal better when warm. Codes can get set when the engine is cold. If they are, and you're doing your testing on a warm engine, you won't find the cause.

 

No MIL. just LTFT is around +15 and firm economy is awful

 

If there's no codes then the engine is running "in spec." The O2 sensors are telling the computer what to do to keep the ratios correct, as lean as possible so that all fuel is burned.

I've read that new O2 sensors respond faster than old ones and that new ones can make the engine more efficient. I don't know if it's true or a myth to sell more sensors. Here's an article. https://www.tomorrowstechnician.com/oxygen-sensors/

Good luck.

 

Both banks positive for lean, so, -check everything connected to the throttle body and elbow.

Begin at the air filter, - MAF o-ring (make sure it has one first, and it's damage free), IAT grommet, intake hoses, IAC connection, brake booster, purge valve, PCV assembly and mini tube harness connections (use MEK to seal mini tube vac lines). Make sure the intake is seated properly at the TB and MAF tube.