tuning fwd perf trimcal

[joefus25]

I have a trimcal i've been playing with for the last few months but i cant seem to get everything right. I keep having problems with knock under boost (above appx. 10 psi) and with a backfire like pop durring in gear downhill decel. I keep playing with fuel pressure and with ign timing as well as the settings on the trimcal itself... but no good results. I was just hoping someone could give me an idea what i might be doing wrong. (87 daytona turbo II)

[giftedmopar]

Is base timing at 12 degrees? What is your fuel pressure at idle? What kind of vacum are you pulling with the car at idle?

Quote:

Originally Posted by joefus25 I have a trimcal i've been playing with for the last few months but i cant seem to get everything right. I keep having problems with knock under boost (above appx. 10 psi) and with a backfire like pop durring in gear downhill decel. I keep playing with fuel pressure and with ign timing as well as the settings on the trimcal itself... but no good results. I was just hoping someone could give me an idea what i might be doing wrong. (87 daytona turbo II)

[MRBOOST]

A good thing to do when troubleshooting with a new cal is to see how it runs with the stock setup, this helps identify whether the problems are in the cal or the car. Have you done that yet?

Quote:

Originally Posted by joefus25 I have a trimcal i've been playing with for the last few months but i cant seem to get everything right. I keep having problems with knock under boost (above appx. 10 psi) and with a backfire like pop durring in gear downhill decel. I keep playing with fuel pressure and with ign timing as well as the settings on the trimcal itself... but no good results. I was just hoping someone could give me an idea what i might be doing wrong. (87 daytona turbo II)

[joefus25]

Yes base timing set at 12 deg, fuel pressure right now is i think 55 psi (vaccume disconnected), i havnt hooked up my guage in a minute but i think i put it back in the same position. Um.. vaccume is around 14"...

[joefus25]

oh ya you could say that i tested my stock setup because it worked good until i put in the trimcal

[GLHNSLHT2]

the backfire on Decel is fuel being added to the cal when off the throttle. Maybe more fuel than stock. Not sure what exhaust setup you have. Mine used to pop something fierce with the 3" straight pipe side exit on it. I turned off all the fuel at anything over 22-23" of vaccum (my car will pull 25" on decel) and it completely eliminated the popping/backfiring.

As for the knock, have you tried retarding the timing in the cal and upping the fuel? Of course it does it across the entire operating range which sucks but if it doesn't get rid of the knock above 10psi you're gonna need it recaled.

[joefus25]

I have a 3" swingvalve and 3inch all the way back, no cat, flow through muffler-and ya it pops pretty fierce sometimes. how did you cut fuel at over certain vaccumes? In the cal i have the timing retarded the -10% setting and fuel at the +10% setting....so hmm maybe need to talk to fwd perf

[giftedmopar]

14 sounds low. Should be almost 20. Check your cam timing. Also, if your not to modded, how does it run with the stock setup?

[joefus25]

ya already checked cam timing, its right on. I thought 14 was low too, i adjusted ign timing for max vaccume, pulled 16" but it was at like 24deg so that is wrong. anyways it ran pretty good stock, minus some sort of miss at idle that i could never figure out. It does it still. beats me.