FAST tuning

Getting closer.. few things that its doing, maybe you’ll can help:

When I let off the gas to stop at a light(don’t let it coast down in gear) it will drop way below idle, say 500rpm, then jump back to idle and then oscillate for a second, then it idles fine. Sometimes when I let off it dies completely. Not sure if it’s a throttle follower problem, or a gain/etc with the idle. I have the gains set at what fast recommended. For reference, my throttle follower is set the same as this:

http://www.fastblackcar.com/camaro/fast/brady.gct

also, take a look at the timing.. seems a bit steep for pump gas, yes? I was thinking more like 25 tops even on 6-7 psi. 9:1

and last one, the throttle seems “lazy” right off idle.. like almost a semi-dead spot. I notice it when I try to blip the gas for down shifts(I have to hit the gas harder than I normally would) and also when doing low RPM shifts around town.. normally you give it a little gas so that the revs match well, but I have to noticeably hit the gas pretty far to do so. When shifting at higher rpm, say 3500 its not nearly as bad for some reason(I assume that’s because the turbo is spooled well, even if its not making boost at low throttle position)

any ideas? FYI, my idle is set a bit diff from the above file. My car idles at 15% tps, so I have the max tps for idle(or whatever that setting is) to 16, per FAST instructions.

I have the same problem with the idle dropping low after higher rpm blasts. Like when I went through the traps it flat stalled on me. I think that was a function of having a manifold leak but Id still like to chase it a little. I dont think it was totally to do it. It all lies in the P and D gain. I have it wrote down at home what each does but forget off the top of my head.

I baselined my program off the same FAST file. lol

Originally posted by aggiez28
ahhhh hah that explains it :p


lol

Jordan I had similar problems with my car. You will have to play with the throttle flower, to get the car to respond the way you want.

As for timing some motors need more some less, every motor is different. My car for example needs 30 degrees on pump were a buddy with similar setup only needs 27.

Yup. same Sh*t here.. It will almost die if you let off right after pushing hard.. if you get it figured out let me know.
Thanks,
STEW

btw, wouldn't the throttle response issue just be enherent to the nature of the lower Compression setup and the turbo?
curious..

yep, every car is different. simple thing to do is to post @ www.turbobuick.com and maybe Craig will chime in. When he was tuning my car he was flipping through screens and changing stuff so fast my head was spinning. I didn't really want to bother him with a bunch of questions since it was a free tune... It's obviously throttle follower and the gain, integral, derivative..


As far as timing goes, I'm running 9.1:1 static compression and I still run that same timing on 15-17# boost on pump gas. I've ran 25# with the same timing on VP 116. :)

Keep the car in the ~11:1 AFR and you can run some timing w/out worrying too much... That's one reason I spent $2k on a fuel system; no worries.


good luck!