Something isn't right w/ my engine

[IsaacHayes]

Also, are you hitting boost? The MAP is only used in speed density mode, running off the VE tables.. A 1 bar MAP won't read any boost. Until you enable the MAF and tune that, you won't read boost. The MAF reads it by increased the flow of air...

Now if you have a 2 bar MAP and everything scaled for that forget what I just said..

[Schmieder]

You keep saying you have Tuned the VE tables (most VE is pointless but not in all cases)
But have not mentioned much about PE?

If you are going lean under load, are you in PE Mode? have you tuned for PE?

PE is disabled atm, so is the MAF. The fuel trims are tuned in the RPM ranges before the engine leans out, so in a way they are not entirely tuned. But I understand this. I am more so figuring out my issues here.

Now, the VE table is looking good, no real big spikes, ect. The PCM is commanding more fuel in the rpm ranges where the lean out occurs. Even after I adjust the ve table. So no matter what the VE tabler is in the upper rpm range, it still commands more fuel, more fuel, more fuel and the AFR is going into the 15-16 range.

So I will not have a good tune in a way until I fix the fueling issue. I am confident enough it is either the fuel pump or FPR.

I bought a FPR (stock which is fine) and I got a used but known good fuel pump for $10. The fuel pressure gauge I will have later today. For $10, I said WTH, I just got it. I wasted $10 on things far worse in the past.

It will give me some time to figure out what high flow pump will work and what mods I need to do to it.

But all in all, everything I am seeing indicates a lack of fuel in upper rpm ranges. BTW, it is going lean before I hit any boost, so it isn't the map or any boost related issue. This is a fuel delivery issue, I am 98% sure of it.

And the fuel pump makes a gravel, grinding noise after I release fuel pressure and turn the key to prime the system pressure.

The known good pump and FPR goes in today. Wish me luck...lol

Eevr wnoedr why popele can raed graabge so jmbueld up lkie tihs?

EDIT: BTW, now that I got the idle under control, I tried pulling the vac line to the FPR and cap it w/ my finger. I am not getting much of a difference in idle or fueling. And now I can detect a slight gas smell at the FPR vac connector. This is why I bought an FPR. I will put the FPR on first and see what difference it makes.

So the diaphragm may be ruptured and is pushing too much pressure at idle, the PCM adjusts for this and when I give it gas, the adjustment makes the car go lean. This is an idea, not 100% on the workings of the FPR, i just know they are needed for more fuel pressure at WOT conditions. I also know the fuel pump isn't what makes the pressure, it just pushes the fuel, the FPR is responsible for pressures. So a number of things could be wrong with the FPR. It has about 109k miles on it, time for a new one. Especially since I can smell fuel at the FPR. That is where I am lossing pressure for sure. I know I am loosing pressure due to the vapor lock occuring during heat soak. If I had high enough Fuel Pressure, the vapor lock shouldn't happen.

[Schmieder]

Also, are you hitting boost? The MAP is only used in speed density mode, running off the VE tables.. A 1 bar MAP won't read any boost. Until you enable the MAF and tune that, you won't read boost. The MAF reads it by increased the flow of air...

Now if you have a 2 bar MAP and everything scaled for that forget what I just said..

Yes, I understand. But won't the PCM change the fuel trims to compensate the added air? My fuel trims are constantly adding more fuel at a higher rpm where the wideband shows a lean condition occuring. ANd I mean around 3500-4500 rpm where the lean is occuring.

I would think the PCM would learn and the lean condition should fade away over time when the PCM adjusts.

After tuning, I will have the MAF enabled to read the airflow.

[Weatheralls Auto]

....But won't the PCM change the fuel trims to compensate the added air? ......After tuning, I will have the MAF enabled to read the airflow.

How can the Pcm compensate for the added air, if it doesnt know it is getting more?

[3400-95-Modified]

I have not read the entire thread because my brain hurt after reading just a few of the posts, but I'm going to say a few things... You disconnected your MAF so you have no way to measure air accurately. Your ECM is running in speed density mode which is using your VE table all the time, so until you tune that or reconnect your MAF and enable PE then your car will NOT adjust well at all.

Also if you are in the middle of trying to do a VE tune on an OBDII car then why are you complaining about how its running... During this process the car starts out running like TOTAL shit if you are starting with a N/A factory tune. It will take many scans and adjustments of the VE table to get it to just idle properly and not run like crap at part throttle. Then after you do that you'll re-enable PE and the MAF and you'll go right back down to square one and have to tune the MAF table, and then work on your PE once you have the part throttle leveled off.

Tuning takes a lot of time which is why I never got my car consistent or even fast last year, I didn't have the time to get it right and it suffered because of that.

[IsaacHayes]

I did not know the SD VE tables were that crappy on OBDII. I know it is there in case the MAF fails, but I figured from the factory it would be tuned just as good. Now on OBDI where SD is all there is, of course it's tuned well.

You're not hitting boost at 3500-4500 RPM? Not even a little? How is the RPM's getting that high if you are not flogging it or it's under load?

[robertisaar]

I did not know the SD VE tables were that crappy on OBDII. I know it is there in case the MAF fails, but I figured from the factory it would be tuned just as good. Now on OBDI where SD is all there is, of course it's tuned well.

You're not hitting boost at 3500-4500 RPM? Not even a little? How is the RPM's getting that high if you are not flogging it or it's under load?

you would not believe the SD tables on most factory OBD2 tunes....

i've looked at them with tinytuner and it's like someone took spaghetti, threw it against a chart on the wall 10 feet away and that's how they determined the VE number for that cell...

ok, maybe not that bad, but they have a lot of resolution to work with, and they to chose to repeat a LOT of values that could have otherwise been tuned closer...

and i imagine you could get to 3500 without boost, but only if you held it in a lower gear and waited forever to get there with light throttle.

[Weatheralls Auto]

VE is for when Maf fails, does not really need much tuning.

I believe he is getting some boost, and without the Maf it is going lean.

I see burnt pistons in the future.

[robertisaar]

VE is for when Maf fails, does not really need much tuning.

I believe he is getting some boost, and without the Maf it is going lean.

I see burnt pistons in the future.

as long as the MAP sensor isn't getting maxed out at ~105kPa, he should be fine. if it hits that or goes above, then yes he's getting boost and the MAP would only show the maximum amount of kPa that it is capable of reading...

we need a datalog... STAT!

[Weatheralls Auto]

I do not have HPT (export scan log when happening in Cvs)

But In his long run (did not state any running issues)
I see a TP of approx 38-40%
O2 reading of 004mw
and a Map of 99 to 101

must be getting boost I would think for map to be staying 99 and only 38-42 TPS ?
and the 4mv O2 is not good.

PLUG MAF back in and do a log

[DefEddie]

Put the new FPR on,sounds like that is the issue.
If you pop off the vacuum line and smell gas that is an indication of the diaghpram leaking.
And the pump grinding is probrably a bad bearing in the pump,which would affect flow/volume.
Can't wait till you get the new stuff in and see what happens!
Keep us apprised.

[IsaacHayes]

Yeah, I agree, 30% TPS and 99-100 kpa is not a N/A situation.. Unless you had like a 80mm TB or something on there..

My 3100 couldn't even get to 100 kpa even with large manifolds/plenum etc until I went to the larger TB. I think 97 kpa was the max I got.

Time to enable the MAF and go from there. SD isn't going to help you if the MAF fails with boost anyway...

Unless you want to throw a 2 bar on there and re-scale everything......... which might not be a bad idea so that if the MAF did fail you'd be saved...
Hell some LS1 guys run in SD mode solely and disable the MAF for good...

[Schmieder]

In process of getting pump in tank. I had the shop do it for me since I couldn't jack the car up onto my jack stands high enough.

If I could do it right (lifted high enough) I would do it, but it needs to be done right so my local shop is doing it for me, I know the tech well and I get good deals there. I put the FPR in and there is some better drivability, but still leaning a little.

After some careful consideration, I'm going to get the VE in close as I can and scale the stock chart in the out of bound areas and get the MAF up ASAP. I CAN get mt fuel trims to hit near zero. But they were altering due to the bad fuel pressures.

Oh yeah, shop said fuel pressure was really low and bleed off quickly at shut down. Bad check valve in pump?

Sooo, the MAF will be enabled when I get it back after a one last time VE tune with a GOOD pump, lol.

Who ever said they see burnt pistons soon, no way. I don't run it lean, I just know it is going there. I back off at 16.5. It generally stays 14.5-14.3 on easy drive logging. Few times the o2's jump to extreme lean but that was at lower rpm, low load and very quick. I think now I was pushing it but I wasn't really pushing it. It will be ok. Now I know my boundries and won't go there again.

With good pump I will have a stable VE table. Then it is time to tune the MAF. I might get a 2-bar MAP and scale values as was said here. That would be best in the long run.

As promised, I will have videos when she is tuned up. I have a quality musicians microphone ($200 mic) that i will use to capture the true sound in video. And no cheesy back ground tracks either. Just the roaring allure of boost over a raging 3100 and my hair on fire.....lol

[Schmieder]

Put the new FPR on,sounds like that is the issue.
If you pop off the vacuum line and smell gas that is an indication of the diaghpram leaking.
And the pump grinding is probrably a bad bearing in the pump,which would affect flow/volume.
Can't wait till you get the new stuff in and see what happens!
Keep us apprised.

And that seems to be the big issue I am having. Not enough fuel at higher rpm's and vapor lock during heat soak. It is vapor locking cause pressure is dropping way too quick which would otherwise prevent vaporization of the fuel.

I believe I now have the problem under control and will be resolved tomorrow when i pick up the car.

And I told the tech, do not go and drive it around for fun, it isn't tuned and if you do, you will be replacing my block. So, no joy rides, got it?...lol

[Schmieder]

Yeah, I agree, 30% TPS and 99-100 kpa is not a N/A situation.. Unless you had like a 80mm TB or something on there..

My 3100 couldn't even get to 100 kpa even with large manifolds/plenum etc until I went to the larger TB. I think 97 kpa was the max I got.

Time to enable the MAF and go from there. SD isn't going to help you if the MAF fails with boost anyway...

Unless you want to throw a 2 bar on there and re-scale everything......... which might not be a bad idea so that if the MAF did fail you'd be saved...
Hell some LS1 guys run in SD mode solely and disable the MAF for good...

When I said I wasn't hitting boost yet, I meant no psi readings above 0. But yeah, the kpa readings are def from the turbo as it does begin to spool up. Sorry for the mix up.

Oh and the logs I posted, the really lean readings from the O2's (4mv) is when it misfires. I wasn't driving it that lean, thats just crazy.

I should have the car back today. I really wish I could've done the fuel pump myself, oh well. At least the shop I use I know the techs well and they do great work.

edit: Would any GM 2-bar map sensor work? Do the 3800 supercharged use a 2-bar map and would they work for my app? Cause if so, I could probably get a 2bar cheap.