2JZ-GTE + PowerFC - too rich?

**82MKII** · 25-01-2009, 12:21 AM

Over the last year or so a few people have commented about the black smoke that comes out of my exhaust at the top of each gearchange.
I've done a few test runs and logged the following on my TechEdge WB02. I'm assuming that I start generating smoke when the AFR heads down below 11.
Note that the boost 'hole' is due to the sequential turbos switching from single to twin.
Anyone care to give their opinion?
Am I running too rich on higher boost?

Regards

Peter

**thechuckster** · 25-01-2009, 08:32 AM

you could keep AFR's higher than 12:1

**w0n0matic** · 25-01-2009, 08:47 AM

what is the white scale along the bottom of that graph?
who did your tune?

**richzx** · 25-01-2009, 09:48 AM

I had the same problem when I had a 1J in Mk2 and Haltech E6K, after a lot of stuffing around I found out it was the accelerator pump enrichment. In other words when you put your foot on the acclerator the computer dumps fuel in, just like a carby does sort of like a 650dp holley. I leaned off the accel enrichment and no more smoke. Many tuners do this so that the car doesn't lean out on initial acceleration which is fair enough, but they can take a good thing too far and then heaps of black smoke as you describe. I'm guessing the Power FC has a similar feature???

**3BarSuperstar** · 25-01-2009, 10:57 AM

By the looks of your log you could pull some fuel out from about 4000rpm up at the required boost sites. keep it around 12.0 but make sure you check for pinging.
Maybe go to a dyno to make sure as the knock sensors can get lazy.

**82MKII** · 25-01-2009, 02:07 PM

Thanks for the comments guys.

Originally Posted by w0n0matic

what is the white scale along the bottom of that graph?
who did your tune?

White scale is time (seconds). Xspeed did the tune, BUT, when they tuned it the turbos were configured in true twin mode all the time. I have set it back to sequential twin (I like boost early).

Originally Posted by richzx

I had the same problem when I had a 1J in Mk2 and Haltech E6K, after a lot of stuffing around I found out it was the accelerator pump enrichment. In other words when you put your foot on the acclerator the computer dumps fuel in, just like a carby does sort of like a 650dp holley. I leaned off the accel enrichment and no more smoke. Many tuners do this so that the car doesn't lean out on initial acceleration which is fair enough, but they can take a good thing too far and then heaps of black smoke as you describe. I'm guessing the Power FC has a similar feature???

Yes it does have that feature, however looking at the TPS, it only starts getting really rich a couple of seconds after I nailed it, so I'm not so sure that is it.

Originally Posted by 3BarSuperstar

By the looks of your log you could pull some fuel out from about 4000rpm up at the required boost sites. keep it around 12.0 but make sure you check for pinging.
Maybe go to a dyno to make sure as the knock sensors can get lazy.

I can get access to a Datalogit, so maybe I should record the knock sensors, pull out a bit of fuel and go again, see if the knock gets any worse. It sounds like I should be safe so long as I don't go above 12:1.

Regards

Peter

**JZA70 R** · 26-01-2009, 04:53 PM

You can see well after you lift off the throttle loads of fuel is going in. That would explain the excess fuel on gear change. First thing that pops into mind is a highrpm low load cell is way too rich. easily fixed. However i would want convincing your wideband is ontime in that chart.

second thing that comes to mind is fuel cut on decel, i would try turning the injectors off until low rpm to see if that helps.

also that is a typical xspeed conservative tune. more power to be gained by leaning the last 3rd of that chart up.