Thread: P0171 Code LTFT Maxed @ Idle

Once I moved and "seated" the filler neck better it stopped. As for the vacuum leak, I will have to redo about 5 inches worth of line at the nipple under my snout along with a T. Then I should be golden. I'll take a couple pics and a video.

Well I tightened up all the vacuum connections I had under the snout, at the FPR, and at the MAP... Car does better, but still sometimes pegs at 16.4, but doesn't stay. I unhooked the battery for a few hours and still. LTFT's are better, but not fixed at idle... Think I still got a vacuum leak in that area...

But I hitting 10psi boost now LOL

I'm thinking if my injectors are tuned in correctly, and everything is in sync I should only be squirting as much fuel that's needed... So if unmetered air coming in from somewhere it will show lean condition in return adding more fuel hence the +16.4 and not -16.4? My thinking, could be wrong...

If this is the case, why doesn't it run bad? Maybe it is I just can't tell... AND if it's this bad, why as SOON as I give it a little gas it straightens out and I'm within +/- 3-5 and 0 @ WOT...

Plus my fuel mileage is crap.. I average 14.5 MPG....

Well..... Guess I'll have over the winter to think and wonder about these stupid fuel trims LOL, my trans is just about gone. Found that out today the fun way. I swapped my 3.4 pulley for a 3.2 and took it for a ride. Weird my fuel trims acted better with the 3.2. VERY strange!!! But anyway, I went WOT from a 40 - 45 mph roll, trans down shifted, whined like most of us do when we break something, 0 KR, LTFT's were locked on 0 through the whole pull. Before I knew it I was at 103 - 104 and ready to upshift when I had MAJOR slippage and bounced off the rev limiter. Now I hear a slight nail on chalk board sound and a rattle when in gear. All is fine in park. Car still drives, but if I give it any throttle beyond babying it the trans lags and slips. So I'll store the car over the winter, save up for my TEP Trans, HPTuners, either an intercooler or Nitrous (maybe both), and get ready to play next year.

I'm surprised how much of a difference the 3.2 is over my 3.4... Makes me wonder about my tune. John said it's a safe tune, does this mean safe for a 3.4 and just right for a 3.2??? I dunno, but dayum!!! LOL

It is!! I'm scratching my head, but until next year I put my 3.4 back on. As for the screen, I don't have one with the N* setup so that's out.. Very weird...

I figured the trans would last me a year or so. It's a 160K+ stock GT trans that I've beat on for years so I kinda figured it would go. It's not completely gone, I'll drive the car a little more tomorrow and baby it to see how it does. My car club does a couple Christmas Parades here and I was hoping to ride with them. We'll see. I'd love to build my trans, but motors I can do transmissions I wouldn't know where to start.. Would save me a lot rebuilding it but yeah I have NO idea!!! LOL

I don't understand the whole KR thing to be honest. I'm surprised mine didn't knock with the 3.4, but I assumed the tune was washing it with fuel to make it safe. My buddy has a stock 97 GTP and he never knocks. He's tried and gotten like 1.2 under a heavy pull uphill.. Might be mileage related?? My motor I got had 17K on the clock when the car was wrecked. My buddies motor only has 70K and has been babied before him and he rarely gets on it. KR is puzzling, like these fuel trims.

Thinking about it, can carbon buildup cause KR? Carbon buildup on the piston tops, combustion chambers, or on the valves cause hot spots? Something I did that I have not heard of anyone else doing was I wire brushed the top of my pistons cleaning them. They weren't very dirty, but there was some build up on them... I'm just thinking of obsurd stuff out loud.. LOL I could be the beer talking to right now..

I'd like to find a GTP trans core since mine's a GT to build, but there are NONE around here.. I keep an eye on carpart.com and ehh.

I'm out on the fairly clean place, no garage just a large carport so that plays into the climate control as well. FFS.. LOL I'd greatly appreciate it though!!! We'll see what we can do after I figure out what all I need to buy and see where I stand.

Your sig doesn't show but I found them!! lol with rockers, headers, and the reptile tune you should be good!!! Have you tried a stock PCM or were you getting KR bad before the tune? I'd message Bill and bang heads together. He's the man and has helped me quite a bit over messages and text. I'm leaning toward your LTFT's leaning out or carbon build up causing hot spots.

Guys we are wanting to have a GP meet in Tn soon, are any of you interested in coming?

Where at?? I'm game, if I can make it.. LOL

Just to add to this, it may help. I have been chasing this code for a year and a half now until the other day, thought it was vacuum lines, fuel pressure problems, exhaust leaks, gasket issues. It would be at 16.4 idle and as soon as i tapped the gas it would go to 0. I would get the CEL on and off. No one here has checked there boost bypass valve. Mine was leaking from underneath where the actuator pole goes into the plunger of the boost valve. I sprayed carb cleaner in there and it pulled it right in. I new right there that was my vacuum leak. Now this did not show up at all when we smoked the motor. Installed new valve and now car idles at 0.8

Did you guys get this resolved? I am seeing 16.4 LTFT as soon as I take my foot off the gas. Running an XP cam and seeing about 15 in/Hg of vacuum at idle and about 13 at highway cruise.

I think my vacuum numbers look OK but I am going to check for leaks this weekend.

I gave up on it actually, I blew my trans the car was parked for about 6 months. Now that I'm back on the road I still have the same issue. 16.4 at idle then at 1% throttle and higher my LTFT's go to 0... I'll check my BBV and see if that's it. I even redid all my vacuum lines when I installed the motor back in with the new trans...

I'm going through the same thing on the other side of the coin, I get way negative LTFTs. I've done different injectors, checked fuel pressure, check FPR, all passes with flying colors.

Mine turned out to be a vacuum leak... egr block off plate...

all good now

I think mines in the header cross over pipe.

Try seafoaming it and watch for smoke, I found mine leaking that way.