7MGE-Turbo (GTE electronics) EXTREMELY LEAN (16+ AFR's) Above 4000rpms

[Devin LeBlanc]

I just got done finishing my NA-T Setup, I am using GTE computer and wiring harness, 440Cc turbo injectors, stock turbo AFM, Timing at 10 degree's 91 octane gas, Stock turbo at 9 psi Boost, 2.5 inch exhaust with high flow cat, drift motion intercooler and 2.5 inch hard pipes, SAFC Neo for tuning.. Basically if we log AFR's with no correction I am in the 11's 2500-3000, once I hit full boost at 4000 rpm's I spike to 16-17 afr and drop back down into the 14's and 15's under boost.. We were able to correct this while street tuning but by almost maxing out the SAFC Neo's correction up to about 48% and still were at 11.6 AFR (something I don't want to do as it messes with the timing as well..

I have checked the following

Fuel pressure (37PSI at idle) does not move a millimeter on the gauge under WOT full boost
Fuel pressure up VSV is hooked up and working (Tested)
Fuel pump resistor and relay working (idle and cruising is at 8.5-9V) Get on it a little and jumps up to 12.0-12.6V)
Changed AFM's
Changed Throttle position sensors
Checked timing (10 degree's)
Spark plug gap is .30
Changed injector resistor

Also after driving the car sometimes wants to stall when coming to a stop after letting off the throttle, The rpm drops and sometimes dies but mostly it catches it and doesn't die but throttle dips and drops down at idle after driving it.. IF you rev it up and let off the throttle it dips way low 300 rpm usually dies but sometimes gets back up to normal idle speed and then fluctuates.. What could cause this?

Hope do find out what is causing this soon

We are using a LC1 wideband hooked up to a laptop data logging the AFR's, We have tried two sensors both with the same spike at the same time...

I checked codes in the computer and keep getting code 31 (AFM Signal) Short or Open circuit

 

[Devin LeBlanc]

Here are pictures of checking the 5 pins on the AFM plug with a DVOM

E1 (continuity to ground)
VC (5.01V)
KS (5.01V)
THA (5.01V)
E2 (continuity to ground)

Does this sound right?

Thanks

 

[shaeff]

Don't have time to read the whole thing, but is there any correlation between the fuel pump voltage switching and your lean spot?

Have you tried the 12v mod? (it's easy to reverse if you don't need it) Just a suggestion, I'll check back later when I've got some time.

 

[Devin LeBlanc]

Yes I tried just junking FP to B+ and driving it like that still a lean high rpm range... Im dropping the tank right now to swap fuel pumps with one out of a turbo 5 speed car

 

[shaeff]

Ah, good call. I only scanned through earlier. I didn't realize you were still on the stock N/A pump.

 

[Devin LeBlanc]

Fuck im getting really fed up

Fuel pump changed
Fuel pressure regulator changed
AFM changed
Fuel pump resistor and relay working
Fuel pressure staying solid under boost
TPS working properly
Timing checked 10 degree's
Idle at 650rpm


AFR's hold good 14.7 dead on at idle and 14.7-15.0 cruising
Under boost idle to 4000 rpm AFR's are low 11's to high 10's then after passing 4000rpm AFR's jump into the 14's+ and you can hear detonation..

This is stock turbo on 9 psi boost.. Im really stumped.. What's next? Change injectors?

 

[Devin LeBlanc]

Just pulled out the fuel rail and injectors, I checked the ohms on all of them at they are all 3.0-3.1 which is in spec per tsrm.. So none of the injectors are shorted, they still could be clogged.. I will swap another set of injectors

 

[Devin LeBlanc]

Ok, Just got done swapping out the injectors and fuel pressure regulator off another car.. Its getting sickening that I can do it so fast lol

Im a picture whore ill admit it :/

I test drove it and it seems to be fine just need to log the AFR's which I dont have the program on my laptop only my brothers.. need to know how to read it with the LC-1

 

[Nick M]

I just got done finishing my NA-T Setup, I am using GTE computer and wiring harness, 440Cc turbo injectors, stock turbo AFM, Timing at 10 degree's 91 octane gas, Stock turbo at 9 psi Boost, 2.5 inch exhaust with high flow cat, drift motion intercooler and 2.5 inch hard pipes, SAFC Neo for tuning.. Basically if we log AFR's with no correction I am in the 11's 2500-3000, once I hit full boost at 4000 rpm's I spike to 16-17 afr and drop back down into the 14's and 15's under boost.. We were able to correct this while street tuning but by almost maxing out the SAFC Neo's correction up to about 48% and still were at 11.6 AFR (something I don't want to do as it messes with the timing as well..

You don't need a tuning device at this point. You have one that works much better than the SAFC, and that is the stock readings. Either your car does not see the increased airflow from boost, or you are incapable of delivering the fuel if it does see it. This is assuming you have now changed everthing but nothing changes. And the only constant is your tuning device.

Also after driving the car sometimes wants to stall when coming to a stop after letting off the throttle, The rpm drops and sometimes dies but mostly it catches it and doesn't die but throttle dips and drops down at idle after driving it.. IF you rev it up and let off the throttle it dips way low 300 rpm usually dies but sometimes gets back up to normal idle speed and then fluctuates.. What could cause this?

A lot of erasing the ECM built in memory, such as storing a place to set the idle speed solenoid on an engine. Including one with swapped parts off differnt cars. Or maybe the dashpot is not delaying the closing of the throttle, but the ECM doesn't know that is happening.

The injectors not delivering up to the 440 (Repair manual lists a spec for 15 seconds) could be an issue. Older GE injectors were also low impedance.

 

[Devin LeBlanc]

The stalling and idle problem was the AFM.. The morons before me took the honey comb out (they probably thought it restricted air flow) I changed housings and it idles perfect and never stalls.. The injectors I took out were yellow N/A ones which are low impedance.. I am doing one thing at a time, Thats the thing with doing NA-T working out the small bugs until its setup just right.. I should not have to touch the AFR at this point with a tuning device exactly as you say nick but they are supposed to run rich from the factory which it is up until a certain point... I can gradually get on boost and hit full boost at a lower RPM and the AFR's are just fine its only the high RPM range like its not getting enough fuel

 

[3p141592654]

How are you measuring fuel pressure? It should increase (relative to atmosphere) with boost. If it stays at 37psi while boost is increasing you have not got the FPR reference port hooked up to manifold pressure.

 

[Devin LeBlanc]

got ya, I will put the fuel pressure gauge back on it.. Can I hook it straight up to the vacuum manifold so while it has vacuum it will lower the Fuel pressure and when it has boost it will raise.. Can I take the VSV out of the equation and test fuel pressure then? What should it rise too?

 

[Devin LeBlanc]

Ok, Logged AFR today with new fuel pressure regulator and injectors and same thing.. Lowest AFR under boost was 10.2 and highest was like 14.4 which was at 5000+ RPM's it did not just spike it would creep up as the RPM went up too.. It holds solid AFR until about 4000 then after that creeps up slowly into the 14's

I checked resistance of the injector resistor all in spec, Checked Fuel pump resistor in spec as well.. I have no codes stored in the computer.. I am going to unhook the SAFC where it taps into the AFM wire and see if it changes.. Wondering if it could be a problem with that being hooked up.. I also have another ECU to try its a 5 speed but still runs and drives fine even with the automatic wiring harness and trans.. I will try clamping off the Return hose and see if fuel pressure rises..

I want to run the fuel pump on 12V all the time for one run, I can just jump the two wires that go to the pump resistor right? I jumped them and at idle i am seeing 12.6V at FP through ground on the DVOM..

I also want to add that I have spliced the two knock sensor wires together as this only has one due to it being a N/A Block.. I don't get a code or anything for it so I am sure its working, I also checked continuity through the harness at the KS plug and ECU plug as well as through ground.. Everything checks out good..

Drags are next friday! Ugh want to figure it out..

 

[Devin LeBlanc]

Got it figured out today! It ended up being the SAFC.. I unhooked the wire that taps into the AFM wire and bingo perfect AFR's all the way to redline! I couldn't believe it and after all the diagnosing, well at least it paid off and narrowed it down to that one last thing! Here is the AFR log

Highest AFR ever went under full boost was 11.05 that was when it shifted from 2nd-3rd gear

WOOHOO!

 

[mkIIIman089]

That's a curiously flat trace, last time I saw something like that on my car it wasn't properly regulating fuel pressure.

 

[Devin LeBlanc]

Thats just because the log is zoomed all the way out.. If you zoom in it only changes like .01-.02