Rusty brain, need help w/FAST

[mosk]

After taking a few years off to devote time to our young son and to rebuild my motor yet again, I finally have my turbocharged Toyota truck back on the road. Or not quite on the road: it seems that lowering the compression ratio by a quarter point or so and changing cams has really altered the motor's VE. This doesn't surprise me, but I seem to have forgotten most of what little I used to know about programming the FAST box, and I'm not really sure where to start.

Does it make sense that a lowered compression ratio and bigger cam would make the motor run leaner than it was? The old maps seem too rich, but I'd like to develop a strategy before I begin messing with them.

I know I suck at EFI tuning, so I do plan on taking it to a professional tuner for a thorough remapping, (is Dan Fodge still in business?) but I'd like to try to get it running a bit better myself first.

Sorry for the rambling post. It's still someting of a shock to actually have a running motor again after almost two years of inactivity, and it seems I've forgotten more about tuning the FAST system than I ever knew.

Thanks,

Jeff

 

[V6 Beast]

Couple things to look at. Do you have wide band o2? Check to see what your target A/F is set at. I am guessing for a nomally aspirated car you want something near 14:1. but don't take my word for it. In my Buick I run 11.2:1. So then look at how much your correction is and adjust the VE so the correction is minimal.

Also check your closed loop parameters.

HTH

Sully

 

[mosk]

Thanks. Actually, it turns out when I set my distributor I was off by a tooth. D'oh! Fixed that and it runs a lot better

I spoke with Dan Fodge and he suggested using the injector size parameter to globally adjust fuel flow until I can get the motor in to him for a retune. Increasing the injector size a few pounds leaned the mixture out a bit so that it actually drives well. The VE table still needs some work, but it drives and idles well. I'm just keeping the boost turned down until we can remap things.

Jeff

 

[Blown86GT]

I am a little confused on the one tooth off problem....I always thought if the distributor was installed incorrectly, you could make up the difference by rotating it till you had the correct timimng. Am I way off base as I am in a similar situation you are in with my car. Its been down for two years and I recently have tried to get it running. However, it is down on power. I see 10 degrees initial BTDC on the balancer with the timing light (its normal setting)...could I be off a tooth still?

Paul

 

[mosk]

Well, keep in mind that this is a turbocharged Toyota 4 cylinder motor. On this motor, the distributor is held in place by a bolt in a slot, and the length of the slot (~1.5") determines the maximum amount of movement you can get on the distributor body relative to the rotor.

In my case with the body cranked to the limits of travel, the inductive pickup was just able to make contact with the reluctor, so it ran, but it ran very poorly. Pulling the distributor and moving the rotor one tooth the other way allowed me to center the pickup on the reluctor, which meant I could finally time the motor.

I don't know if the domestic motors use the same bolt-in-slot hold down mechanism, so I don't know if this is an issue for you.

Jeff