Negative LTFT at Idle, KR at WOT

[Duey1083]

Hey everyone,

@Enki I'm creating this thread as per your suggestion.

In March / April, I took it upon myself to walnut blast the intake valves, service / clean the fuel injectors, replaced the injector seals with Overspeeds, replaced the PCV valve in the OEM PCV plate, and installed the DM Stage 1 OCC. I also installed a 3 bar MAP sensor at this time and had the tune revised by Stratified to account for this change; I did this in anticipation of doing a BNR S3 install...not so sure about it anymore, lol.

The car ran fine right after I put it all back together, but over the last couple of weeks I have noticed that the LTFTs have gone to -12.5% to -14.09% during idle. While it idles, I can hear the car constantly adjusting something (maybe the injectors or something)...idle is fairly stable, but AFR sometimes jumps around from high 13s to low 15s (this issue is only intermittent for some reason and wasn't caught in the datalogs). LTFTs are within normal range during partial throttle cruising.

I decided to try a WOT pull in 3rd gear, but had to abort it twice before redline due to high KR (3.69 peak).

I thought the issue might have been that the coupler for the intake to the turbo was loose, so I re-seated it, but the issue has returned. I was extremely careful putting the car back together, following the FSM torque specs and sequences for the fuel rail, intake manifold, and throttle body.

Thank you for reading, and thank you in advance for any help.

 

[Enki]

What I see:

In the idle logs, everything looks fine, but the boost pressure seems off to me for some reason. What is the KOEO value for boost for you?
The only other thing in the idle logs is that you're pulling a fat grip of fuel, which suggests to me you need a MAFCAL.

For the WOT logs, it kinda looks like you either have bad plugs, bad fuel or something else that's causing the combustion event to go out of control; the persistent knock is causing it to richen up a ton, and even that isn't helping with the KR. The step colder plugs alone should be enough to pull out some pump gas KR.

Try putting a gallon or two of E85 in the tank on your next fillup if you can (shouldn't need a retune for just this one tank) to see if it helps the issue at all. If it does, maybe you got shitty gas? As a side note there's a possibility it will be harder to start and run kinda shitty till it comes up to temp; this is because E85 doesn't like step colder plugs, but I wouldn't worry about that too much, since it's just a test and shouldn't really impact normal driving.

 

[Duey1083]

Thank you @Enki

What does KOEO mean?

I thought so too about the boost pressure at idle...should be more vacuum, right?

I had the MAFCAL checked last year before the map revision to account for the 3 bar MAP sensor. The tuner said it was great at that time.

I'll pull the plugs to do a compression test soon and will review them.

As for the gas, I filled up at Shell, which should be good...I do have some e85 kicking around from last year that I could add to the tank.

In Shoutbox you mentioned the purge valve as a possibility. How should I validate that?

 

[Awafrican]

Key on engine off = KOEO

 

[Enki]

KOEO Key On Engine Off. Should let the AP work properly even if the car isn't running; just need to know the boost number in this state, which should tell you if your calibration for the MAP sensor is on point or not. You could also get a decel log (engine braking) which should see really high vacuum numbers.

For the purge valve you could disconnect and plug the hose or just clamp the hose and see if trims change.

I'd be careful using old E85 as it tends to attract water. If it looks like it has separated out into different fluids or is cloudy, don't use it.

 

[Easter Bunny]

KOEO key on engine off

Turn the car all the way on but don't start it

 

[Duey1083]

Okay, thanks guys...appreciate the help.

I'll try that out and see what I get. I'll also try to give the MAF a clean.

EDIT: KOEO boost levels are 0.15 psi...so seems to be okay.

 

[Enki]

Change your air filter as well, if you've not done that in a year or so.

 

[Duey1083]

So quick update...there are no updates, yet.

I was looking at the condition of some of my hoses and vaccum lines. I found that the valve cover breather to the intake was a bit loose and had partially slipped off.

I also noticed a hairline crack in the BPV recirculation hose where it clamps to the BPV. I'll be ordering a replacement from JBR shortly...shipping is expensive to Canada, is there anything else I should purchase with my order while I'm going through all this? I was thinking of replacing the intercooler piping with the JBR stuff, but read mixed reviews.

Next steps:

1) Clean the MAF sensor
2) Clean the air filter
3) Perform compression test
4) Add gallon of e85 and do another WOT datalog
5) Replace BPV recirc hose

If none of those indicate anything, I will send my logs over to Stratified for them to review if anything is amiss in the tune.

 

[Awafrican]

JBR hoses for tmic are good, no issues personally I wouldn't run them for Fmic but others do without issue

 

[Duey1083]

So I ordered JBR BPV recirc hose and intercooler hoses, as well as the JBR thermal insulating intake manifold and throttle body gaskets.

I'm starting to suspect a leak from the throttle body...i had issues torquing the throttle body to the intake manifold.

EDIT: what is the best way to clean the threads that are drilled into the block? If I pull the intake manifold off again, I would like the clean them out to remove any oily residue that may be throwing my torque readings off.

 

[Awafrican]

Hit it with some break cleaner then some compressed air will clean out the threads nicely

 

[Cfoldone]

Also run a tap to clean up threads too.

 

[Duey1083]

So I ran a compression test on the engine and it all checks out okay:

Comp 1: 169
Comp 2: 170
Comp 3: 172
Comp 4: 167

I've uploaded some pics of the spark plugs as well...they look a little sooty, but i also only took the car for a short drive around the neighborhood before doing the compression test.

I'm cautiously optimistic, but my LTFTs at idle are around -5.47% to -6.25%; approximately 70 miles since I last reset the ECU.

Troubleshooting done to date:

Cleaned MAF and air filter
Foil taped the BPV recirc hose (waiting for new JBR to replace it)
Re-secured the valve cover breather line to the intake (found it loose)
Re-secured the coupler from the intake to the turbo inlet
Checked and re-gapped plugs to 0.028"

As mentioned, trims appear to be improved; however, it may still be too early to tell. I'll keep driving it around casually for a few more miles. I'll then try another WOT run once I have the new recirc hose installed.

 

[Duey1083]

So I rechecked the PCV and OCC setup. The PCV retainer ring was secure, all hose clamps were tight and secure also. The check valve arrows point towards the intake manifold.

While I have the car on jack stands, I was thinking I could snoop check the test pipe I installed last year to check for leaks.

@Enki, should I just be disconnecting the line from the purge valve and then plugging it with my hand to see what it does to my trims? Or does it need to be disconnected while driving around a bit to diagnose it?

I'm starting to run out of things to check now, without removing and reinstalling the intake manifold and throttle body. Oddly enough, my LTFTs started to dip again to -10.16% yesterday and when I left the car idling, they started improving again to -7.03%. It has been about 120 miles since the ECU was last reset, so maybe it's still relearning?

 

[Enki]

Yeah you can thumb it at idle to see if the engine changes sounds with it on vs off. You could also just pinch the line.

Also you can't really trust idle trims since so many variables can change trims and at idle it's basically magnified 100x.

 

[Duey1083]

Yeah you can thumb it at idle to see if the engine changes sounds with it on vs off. You could also just pinch the line.

Also you can't really trust idle trims since so many variables can change trims and at idle it's basically magnified 100x.

I removed the hose and put my thumb on the end and no difference between it connected to the purge valve or being plugged by hand.

So I think the purge valve is good.

I think I will just drive it around like normal for now and install the JBR BPV recirc hose when I get it, and try a WOT pull then.

Other than that, I'll reach out to Stratified to see of they can find anything wrong.

 

[Duey1083]

@Enki / @Awafrican, I was doing some reading on the forums, and I was wondering if I should also explore the pressure relief and spill valves as a potential culprit? I also read that seals within the HPFP could be a cause of rich LTFT at idle issues...and as noted by @Enki, my car is running pig rich during WOT runs as well.

What function does the spill valve on the HPFP perform? I'll read the thread regarding the HPFP tear down, clean and rebuild.

At this point, I don't think this is a vacuum leak. I also don't believe this is a MAF sensor issue as there is no obvious behaviour and I checked to ensure the calibration was the same by comparing it to last year's WOT runs. The voltages and g/s correlate with last year's run.

 

[Enki]

You'd be fine with stock seals; it's what I use and no issues there. The only way seals can cause an issue is if they leak enough to flood your oil with fuel, in which case, you have vastly more serious issues than running rich at idle.

 

[Duey1083]

As a bit of an aside to my thread, @Awafrican, part of my recent mods was to relocate the ECU to the top of the fuse box as I found it had been rubbing on the intake.

I'm having some issues with the relocation due to the cables, which are bound by the white plastic protector.

Am I okay to remove that shield? Pretty nervous about damaging the wiring harness and wasn't sure if that is required. It is putting strain on the positive battery cable though.

EDIT: uploaded picture.