Thread: P0171 Code LTFT Maxed @ Idle

Originally Posted by dbextreme

It's a mystery to most of us so far... LOL Mine is progressively getting worse so I know it's a vacuum leak. I can actually hear a hissing sound now between the number 3 and 5 injector so I'm leaning toward my supercharger gasket (even though I spray carb cleaner and propane and NOTHING). As long as I give my car gas, it's fine.. As soon as I let off the gas it rumbles and pops (backfire but not like an actual backfire) then it will smooth out.. Very weird. But my fog machine was shipped today (I used the free super saver shipping.. :-/) so I'll get it middle of next week. I hope to see the fog coming out from under the supercharger where I hear the hissing and NOT a cracked housing or LIM. I'm eager to get this fixed so I can drop pulley some more..

Check your EGR tube and all your vacuum lines. But if it only happens at OP temp, that is odd.. sounds like something tune related, or part related and the heat opens a crack more?? Dunno... Hopefully once we find what's up with our, it will give more options to others.

I'll post pics and videos once I start playing with it. What I have to do is:

1. smoke test the car
2. replace rear valve cover gaskets (stupid zzp gaskets)
3. replace the 2 2.25 clamps on my cross over pipe with two 2.25" band clamps I now have
4. hopefully replace the supercharger gasket and fix my P0171 code lol
5. install my new tips... Ready to get my car's azz looking better...

Yeah I don't have EGR or evap. All gone. On friday I did a few really minor quick things to try and resolve it.
-Moved my IAT sensor. This was zip tied directly to the throttle body. I decided to move it a bit closer to the air filter. Probably did nothing but seemed like a good idea.
-I trimmed some of my vac lines, aka cut the tips and re-put them on. I also added zip ties to all connecting spots.
-Probably a silly thing but a likely spot for me as well to have a vac leak is the supercharger gasket as its sealed to a very old SS Intercooler core, so I carefully ran a line of rtv around where they connect (without taking the supercharger off)... Probably didnt do anything but I figured why not...

Weirdly enough, with just doing that stuff I haven't had the issue since. I havent driven it much since though. The real test will be after I drive it for awhile on a hot day. Pretty stoaked if its resolved currently though...

No luck her yet either guys. I'm gonna try New band clamps also. I ruled my tune out because when I disconnected the pcm and reconnected the fuel trims were fine for like 5mins.

I wouldn't jump the gun, the first 5minutes the PCM was in open loop.
Once it went in to closed loop it went nuts again right?
It still may or may not be the pcm.

O ok well how do I rule out the tune?

Lol, that's a hard one. I can't answer it. I've got a PCM on the way from reptile to see if it fixes my problem.
I'll update as soon as I get it.

Yea I still need to get some band clamps for the crossover.

Nice, I hope it works out for you. I'm gonna try band clamps on the crossover and I may try rtv under the snout where it leaked before.

How'd the fog machine work?

Go to lowes and get a 3.5"rubber Pcv cap.

Not sure. But they make 4"as well.

Yeah mines still screwed up. Seemed to take a lot longer for the problem to arise though. After I sat in some traffic for awhile and drove it for a total of about 25 mins on a fairly warm day (80s) it got to full temp and was there for awhile before the problem came back. Once again 16.4 idle when it was all heatsoaked. Of course this morning since it was cooler and I have a short commute to work (~10 mins), it ran great.

Something is expanding or something when it gets hot enough and causing an issue. I dont know what it is though. :C

Yea I'm still losing my mined with this code. It use to go to zero at wot now it locks in at 10 I'm just scared somethings gonna give.