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2G Car won't rev over 4k at full throttle

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Ryukashi

Probationary Member
4
0
Feb 15, 2013
Karlsruhe, Europe
Hi,


I know there are other Threads for this topic and I've read them but unfortunalty none could help me find a solution.
The problem as mentioned in the title is that the car won't rev over 4k under full throttle. While standing and without a gear the car will rev to 6k but also not till redline. While driving and giving only about 23% throttle the car revs over 4k but as soon as I give it more throttle it feels like it hits the rev limiter and black smoke comes from the exhaust.
One additinal problem is that if I make a moderate pull and instead of changeing into the next gear I keep my foot on the clutch pedal the rpm's will drop to zero and the engine stops. I've also changed the boost settings from 1bar to 1.6 bar but that didn't make any difference

I've checked the following:
- switched MAF
- switchend Intake Pipe
- switched Idel Control Switch
- switched Power transistor
- new Spark Plugs (NGK BPR7ES)
- new Spark Plug Wires (NGK)
- switched ignition coil
- wired fuel pressure sensor directly to intake manifold
- boost leak test with 2 bar (a very small amount of air leaves through the screw to adjust idle)
- tested Injectors
- Speed Sensor is plugged
- FuelFlow increases with boost

My Setup:

- Walbro 255
- FIC 650 Injectors
- FP 68 HTA
- ECMLinkv3
- cxracing Intercooler Kit
- Ferrea Valves
- Kiggly Racing Valve Springs
- Stock MAF
The car is a 1997 GST

Any more ideas would be great :)
 
If you still have a catalytic converter on the car, I would drop the downpipe and take a cruise.
 
Sounds to me like it's going rich.
Do you have a wideband o2, if so what's it reading when it does it?
Have you done a boost leak test?
Is your car tuned for the 650cc injectors?
You've got ECMLink, capture a log of it happening and attach it to your next post.
 
Hi,

I'll check the catalytic converter but the car still makes power. If the catalytic converter is clogged it should at least affect acceleration?

Totally forgot the Log, sorry. It's attached to this post. Yes I have a wideband and it's around 10.5 AFR.
I also forgot to mention that I've also switched the Camshaft Sensor. And yes I did a boost leak test as mentioned in my first post.
 

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I had sorta the same issue.... run pig rich, absolutely no power after 4k but seemed fine under vacuum/cruise.... tested injectors with ohm readings and they were in spec. Replaced damn near everything. Wire's , plugs, fuel filter, resistor pack ect. I also had FIC 650's. Had a set of 450's. Installed 450's to pull my 650's to clean them. Got all my power back above 4k and running strong. After I cleaned the 650's I put them back in the car, setup my ecu for the 650's and ran great! Two weeks later back to no power after 4k! The FIC injector kept failing only in the #1 cylinder twice! Got the stockers in now and no more problems since. I think they would just get heat soaked and that one injector would fail. So try swapping back to 450's to see if that's your problem....
 
Thanks for all the replies so far. I think I've found the problem. The problem first occured when I was tuning wbfactor to be around 0% in ECMLink. To do that I raised the mafcomp sliders.
Well it seems like they are way off because my wideband isn't accurate (never really dropped below 10.5-10.0). I lowered the maf comp sliders significantly to around 9% and now I'm able to rev over 4000k again.
It's still not perfect but way better than before.
 
That's a known problem with tuning using a AEM UEGO wideband, unfortunately they don't always log accurately. The AFR reading displayed on the gauge is good (assuming a working o2 sensor) but the logged AFR value doesn't always agree with what's displayed on the gauge throughout the pull.

Here's a video I created a few years ago that might help you get it logging accurately and make tuning a bit easier with it, if you're interested... The video is of my old setup running Speed Density but using the MAFComp sliders is exactly the same, you'd just move the slider up/down to richen/lean the mixture to force it to idle at your target WOT AFR.

You must be logged in to view this image or video.
 
Hi,
My Setup:
- Stock MAF
The car is a 1997 GST

There is absolutely no reason a 2G car with a stock 2G MAF would need over 30% airflow compensation. You either have a massive boost leak, or as you already suspect, your wideband is not accurate.
 
That's exactly right, 10:1 is the richest AFR that can be displayed on the UEGO. So, if the gauge is displaying 10:1 while you're WOT you could be popping and backfiring actually running a 8.5:1 AFR and not even know it.
 
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