Went to the track... highly disappointed, and found a major problem.

D

Doward

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Jan 11, 2006
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Stock 1988 Supra, what I *THOUGHT* was good running condition (no misfiring, runs cleanly, no codes, all maintained, etc)

Then I ran the 1320.

The numbers don't lie

18.35 @ 75.75
18.02 @ 75.66
18.07 @ 73.79
17.81 @ 75.98

I was like WTF - DO I HAVE A BOOST LEAK OR WHAT? I idle @ 21inches @ 600rpm, so that makes me want to rule out any kind of leakage. BOV works fine, I tested it.

Hooked up the ZT-2.

I idle @ 12.2 AFR.
I staged 5psi @ 13.0 AFR
I launched, and my 13.0 AFR quickly dropped to 10.2 AFR, and flatlined @ 9.8 AFR.

Something is causing my car to run rich as hell, obviously.

I cruise 15 inches of vacuum, again, 11.9-12.1 AFR.

So I have something CONSISTANTLY making me rich.

I noticed that the screw on my old AFM housing was completely out, allowing the most air to bypass the AFM. The current one is almost completely in... ok, maybe there is a problem, I'm going to test that shit out TONIGHT.

I do have a question - if someone put a high flow fuel pump in, but DID NOT bypass the J-tube... approximately how much richer than stock would that make it run? Further, would the restriction cause a build up of fuel pressure, causing high rpms to be even further rich?

I do not have a fuel pressure gauge at this time (obviously on the list of things to get, now!)

I freaking got out ran by a riced out Integra. :3d_frown: This can not be allowed!
 
D

Doward

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Jan 11, 2006
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Doesn't matter... on the way home, anything from 40% to 70% I never rise above 12.2:1 AFR... of course, if I run the rpms up over like 2500, and let off the throttle, I jump up to 21:1 AFR, but hey - the TCCS is supposed to cut the injectors over 1600rpm when 0% throttle, right?
 
D

Doward

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Jan 11, 2006
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IJ, I'm using the new Bosch LSU 4.2 (I believe, lol) Widebad... it's not dead, nor is it fouled...

I pulled the spark plugs while @ the track to verify - I'll post pics in a little bit (doing the AFM swap currently... I had a spare body (the one that was on the car) with an adjustable screw in it)
 
D

Doward

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Jan 11, 2006
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Yes, I'm using the simulated narrowband output... the stock TCCS is throwing no codes from it. I could check for crosscounts, if need be?
 
D

Doward

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Jan 11, 2006
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JJ, how long must the car swing in the rich area, during closed loop, to throw a code?

IJ, I'm going to bypass that J Tube tomorrow... I assume no bad would come of it, if it were bypassed with a stock fuel pump, assuming the stock FPR is working, correct? The JTube is just a fail safe mechanism?
 
D

Doward

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Jan 11, 2006
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Also, just a quick clarification - when I FIRST crank up the car (warm), I register 14.6-14.8.... the second I blip the throttle, I roll down to 13.6 area, and if I go get on it, I never come above 12.5 again.
 
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D

Doward

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Will find out in just a second.... ended up just drilling out the damn plug over the screw, but I haven't touched it yet.... Give me a good 10-15 minutes to check out Vf, and I'll let you all know.... assuming, of course, I find out how to check Vf when I do my search ;)
 
M

MKIIINA

Destroyer of Turbos
Mar 30, 2005
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those af's are pretty normal. i when i was stock and my bros car also we dyno'd about there for a/fs (maybe a touch richer as it just bottomed out the wb at 10:1 under WOT) get an afpr and back it down a few psi and see what happens. our cars run pig rich!

ninja edit: that adjustment screw, when backed out, will make you run leaner as it lets more air past the sensor thats unmetered. closing the passage will richen you up more!
 
D

Doward

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Vf, immediately after cranking the car after sitting for about 1.5 hours, was sitting @ .778, and slowly dropped to .743, then abruptly jumped to 1.007, and hovered between 1.007 and 1.009. If I free-rev'd the motor by hand, Vf would dive to around .8, then swing back up to 1.007-1.009 area.

WB02 is reading 12.7-13.0 during this time.

*edit* JJ, you're saying opening that passage under it won't allow unmetered air around the sensor, thereby slightly leaning out the mixture?

*edit2* Going to check crosscounts....
 
D

Doward

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Jan 11, 2006
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Uh... ok, I checked the crosscounts, same way as the Vf... LOL... It would move maybe 4-5 times in 10 seconds when idling, but if I rev'd the motor at all, it would jump around maybe 3-4 times per second, then settle back down the throttle was held still - didn't matter if it was idle, or holding 2800rpm.

*EDIT*

Unscrewed that AFM screw out as far as I could, before actually removing it - now idles @ 13.0-13.2 afr, Vf flips between 1.004 and 1.005

Now, for something odd.. Free rev'd, it'll increase RPM speed, decell FC kicks in, and it sits around 14.7-15.0 for approx 3/4 of a second, and over the course of the next 20 seconds, I watch it fall slowly and rather evenly back down to 13.2-13.0 AFR.

Also, Jtube is stock and unmodified, currently ;) Thinking of drilling that hole out, if nothing else comes up :(
 
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jetjock

jetjock

creepy-ass cracka
Jul 11, 2005
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Redacted per Title 18 USC Section 798
Yeah, there ya go. Vf is subtracting fuel and the sensor is still cross counting. That's why no codes. It's back to why you're rich. You ought to remove the J tube first and go from there. You may need to tweak the fuel pressure but remove the restriction first. That said there are other things that'll cause the loop to be shifted rich or lean. The slightly shifted ones are sometimes a bugger to find too.

The AFM screw will only adjust idle mixture to a great extent an N/A car with a metering flap type AFM. When the flap is almost closed the air is forced to go through the unmetered chamber because the flap presents an obstruction. As the flap opens there is less and less resistance to air flow through the main chamber so there is less impetus for the air to flow through the unmetered one. Now how much restriction does a Karman AFM have? Even at idle? The screw will tweak it slightly but not by much. At least not the stock screw.

So says the TCCS training manual. Add to that I have yet to see a Karman change output very much when the screw is messed with and that's using a frequency counter on it's output and 5 gas analyzer up the pipe. It's also why the screw's factory setting is coded into N/A AFMs but not the Karmans.
 
D

Doward

Banned
Jan 11, 2006
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Yeah, it didn't seem to make much of a difference, but I had to try :) I'll go unbolt that damn J tube right now, drill that bitch of a restriction out, and see what happens :)
 
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