LTFT spikes to +16/other times perfectly fine

[PWNED]

I have been going in circles with this issue of my LTFT hitting +16 at times. Other times it is perfectly fine. I have sprayed brake clean and poured water on every vacuum line, gasket or rtv seal and trims will not change (usually -3-10 ltft at idle) Yes its rich but whatever. I even replaced my #1 o2 sensor with a genuine GM part. I have also replaced my BBV due to the findings of the orange diaphragm having a minor tear with no change. I have never kept an eye on my trims this much since my IC install at the beginning of this month. I want to say that I have watched my wideband dip into the 11's/12s (cruise/part throttle/idle) before my IC install so I believe this is an issue that has been on going. The car has no real issues with pulls. It does pull decent for what it is with no hesitation ever. At idle my fuel pressure is 45psi. At 2500 rpm it is at 44. When I got wot it will hit 62. Prime is 54 and will drop to 40 and rise back to 48. I have not tested fuel pressure when my issue happens due to the fact it is sporadic.

[PWNED]

And the tune

[PWNED]

Today I removed the band clamp around my crossover and found a very minor leak (minor soot buildup) So I rtved the entire area where the pipe slips into and re installed the clamp. As well as rtving my map sensor just incase it was cracked and acted up due to heat. Nope.....nothing changed.

I am at a loss to an extent. I am thinking there must be some table I don't know of that is making me lean. It will happen around 4000-5000hz at light throttle in cruise for the most part. But...not all the time. I even added 1% of fuel to 3500-5000hz and it didn't change.


I am stock fuel pump. Maybe 100K on it? I am not sure as it was a used drop in. Maybe its getting hot and weak at cruise?? But it has no issue pumping out at WOT. When I first got the car 2 years ago it had an ebay 255 walboro and every now and then after driving and coming to a stop the car would die but would start right back up like nothing happened. Ended up being a bad pump so I ditched it for a stocker at the time.

[Russ K]

Why is your IFR table messed up? And your MAF table is lower than stock till 8000 Hz.

Russ Kemp

[PWNED]

Why is your IFR table messed up? And your MAF table is lower than stock till 8000 Hz.

Russ Kemp

How is the IFR screwed up? I am running 42.5 injectors (same table for 8 years by pervious owner). I remember making a thread over a year ago and I was sent on my way as it was ok by other members.

I am running an lq4 maf. He never input an lq4 table and just modified off the stock. So I did the same to get my WOT afr's/most tirms in check (same table for 8 years (for the most part/ I have modified it a bit over the past 2)

I did remember that the stoich was set to 14.1 by the pervious owner. I switched it back to 14.7 and no change.

Today's maf table as I had to modify it to get my wot afr's in check due to the stoich change.

Here is the problem yet again.

I am thinking it is heat sensitive.

[Russ K]

How is the IFR screwed up? I am running 42.5 injectors (same table for 8 years by pervious owner). I remember making a thread over a year ago and I was sent on my way as it was ok by other members.

Take another look at your IFR table in 2d, it looks like a side ways Z.

Russ Kemp

[PWNED]

Holy SHIT.......how in the hell does this happen!?

How can I get this in check???

Do you think this is the culprit?? I am literally speechless right now......besides pissed.


---Side note---

When I had my gtp I had my stock injectors sent out to fuel injector connection to be made into 48's (I believe that was the name/ this was years ago)
I supplied my stock IFR table and they spit me back this table ( I labeled it S1x for reference)

Now this is how it should basically look??? In the pictures attached.



Reference to what I have for an injector on my Regal now if needed.

http://shop.zzperformance.com/store/...jectors-6.aspx

http://www.hptuners.com/forum/showth...ectors-support

[PWNED]

Here is a stock File. How can I modify off this IFR table? I have looked at a few other tune's on the repository and have different slopes to them (for 42.5's). I am lost on why this is.

I did stumble scross someone saying multipy the stock IFR table by 1.25. Where did this value come from? Is it ok to use?

[PWNED]

Well unfortunately the IFR change did not help. The car decided to act up the other day and today. What am I missing? Could the maf be at fault? Or fuel pump? I did hear a noticeable tick from the engine area today only when standing in front of the car. The crossover pipe has been re sealed with rtv and band clamped weeks ago. I did not see any soot anywhere. It might just be the nature of the headers though. It does seem like the 02 got lazy or it saw something?

[PWNED]

Bringing back from the dead. Car has had a VE tune, new fuel pump, valve cover breather and will still act up.....at a total loss!! I even moved the 02 sensor close to the front header and no avail...at thos point I disconnect the 02 sensor to cut the BS out and am now tuning it as it should. What gives?!

[ZeroBoostBuick]

So you disconnected/disengaged the MAF and tuned the VE table. Correct ??? And once you had the VE pretty good you re-engaged the MAF and the fuel trims went to shit ???

[PWNED]

The fuel trims went to shit before and after the VE tune. No change at all. I have been chasing this for years. The issue is random for the most part every day. I posted on the 3800 forum and come to find out my issue was me having no rear 02 sensor. I never knew this but there must have been a certain year that GM added something. Basically the pcm dumps fuel to see how the cat responds which in terms the #2 oxygen sensor sees it and says hey stop. Well I removed mine and never knew this. A few weeks ago when I brang the thread back from the dead I added the #2 sensor back and the car has not acted up one bit. It has been years and this was the fix. HPT has no option to eliminate the pcm from doing the said above. The only way to tune it out is tiny tuner or DHP which are very scarce. The easy fix is just add the sensor back.

[5FDP]

01+ computers have cat diag that HPT can't disable.

[507]

Good to see everything work out. Congratulations. VE tuning on the 3800 platform is a delicate subject.

[Ghostnotes]

Had an 05 GTP with the same issue after doing header work. I do remember finding the fix on 3800 forum.