FAST up&running! but a couple gremlins still

[S351 R]

Previous ignition problems were solved by going to a '93 TFI Distributor (vice 94-95 remote TFI)

A little throttle blade increase and working the TPS to read 14 instead of previous 16 keeps a steady idle at 950-1000. TPS still maxes out at 90.

- 1st problem: IAC (or something) wont keep up when trying to drop back to idle from higher revs. Takes a little throttle work to keep it from dying then before it re-stabilizes.

- 2nd bigger problem: Anything above 1500 rpms sends the stock tach swinging sporadically as high as 3000 when FAST dashboard RPMs are much more stable (and lower). Although the engine is not as sporadic as the stock tach, the engine doesnt sound real happy and hunts & seeks when trying to keep 1900 RPM or so. Throttle input to rev above 1500 doesnt really match the rate of engine adjustment (ie throttle changes have an inconsistant effect on raising engine revs. Below 1500 rpms all seems ok.

- 3rd problem: Fuel pump primes fine and seems to be working fine while running (steady FP), but dashboard still shows "0". Is this a big deal to fix or a harmless glitch? Fan seems ok and shows "1" when on.

Sorry so long, but any input is appreciated.
Kirk

 

[tazgn]

For the IAC problem (as I had too), you just need to increase the P and/or D trims. I don't remember exactly which table this is called, but it's just 3 values in the table. The P and D trims determine how fast the IAC motor moves and how far it moves in each step of movement. I played with how the term for how fast it moves and the car never dies any more. As for the Fuel pump/fan I don't think those values will mean a thing for driveability or functunality in you application. As for problem #2, I don't really have an answer.... Sorry.

Derrick

 

[S351 R]

thanks for the input, got plenty of tuning fun ahead of me.

Been calling around about the Tach problem and nobody seems to know either.

Not sure whether FAST is somehow altering signal that affects the "Coil -" (tach gets signal from that wire according to diagram); or if and in-line tach "resistor"? is bad; or if there is really misfire going on.

Kirk

 

[bobc455]

For the IAC, I like to adjust the throttle blades so that the car idles with no IAC necessary- the IAC only kicks in for cold start, etc. Mine is set up to hold my idle about 800RPM in neutral, then it drops to about 700 when I put it in gear. I have the idle speed set at 680 in FAST, and once in a while the IAC will jump up a bit, from 10 to 11 or 12 when the idle waivers a smidge.

Can't help much on the tach situation, except that on my car I used to have a problem when my tach lead ran too near my coil.

-Bob Cunningham
bobc@gnttype.org

 

[S351 R]

Thanks Bob, and I think you're on to something with the proximity of the coil to the Module and interference.

What might be the best way to give extra "shielding" to those wires that are closer to each other than they were with the old distributor.

I also wonder if sync'ing the distributor timing to the FAST timing (with a timing light @ 2k rpms) will fix things.