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JT ZR-Won
10-22-02, 10:08 AM
My '90 is running a bit on the rich side. I have since added Screamin Demon coil packs. The car needs to have the chip reprogrammed. I heard that if I change the rear end gears to 4:10's later this won't effect the chip reprogramming at all. What about exhaust system? I'm also planning on changing my cat-back exhaust system later as well. I would think this would effect chip performance.

My other question is this: If I supply dyno graghs and air / fuel graphs along with a list of modifications, the person burning the chip doesn't need the entire vehicle do they? Like I mentioned, the main reason for reburning the chip is to fix the air / fuel mixture.

Jay

Hib Halverson
10-22-02, 06:38 PM
How did you determine the engine is rich at WOT?

Is the chip you have not stock or aftermarket. If it's aftermarket, when in the mod. process did you get it, before or after the headers, and, when you first got it, did the engine run correctly as far as AFR goes?

JT ZR-Won
10-23-02, 11:25 AM
Hib, I forgot to mention a few details. I had the car dynoed earlier this year and it put down 342RWHP. I bought the car with the mods already done to it. It already has a custom chip in it that was made for the mods listed in my signature. The chip was burned by Jim Smith and that's about all I know.

As far as the motor running perfectly before the mods, I'm not sure. I can say that it does run real strong now. The only addition to the motor that I have made prior the chip being made is the Sc. De. coils. I threw on a set of drag radials and the car turned a 12.83. Unfortunately that was the only pass I ever made (a couple months ago) due to the rain down here in FL. I'd like to get the chip situation resolved and head back in the cooler weather.

Jay

Hib Halverson
10-25-02, 01:23 AM
Ok.
Jim Smith did the cal., which is good. The car has run a 12.83. The engine has Screamin Demon coils.

But, again, what did you use to determine that it's running rich? Plug readings? O2Ses? Air/fuel ratio measurement? What?

I take it this car is stock except for the coils, the cal and the Drag Radials. Am I right?

Florida is essentually at sea level and with Drag Radials you shouldn't have had a traction problem so I think the car's a tad bit doggy. That could be rich AFR, but with a Jim Smith cal, I'd think that unlikely.

BiZ
10-25-02, 07:39 AM
Hib,

I believe he is determining the rich condition by the a/f readings he got on his trip to the dyno in Feb. I was there and I remember the Dyno operator telling him he was running rich.

Jason

JT ZR-Won
10-25-02, 04:03 PM
Jason has it right. There was a readout on my dyno sheet. The track that night wasn't in very good condition either. Very damp outside due to earlier rain.......but driving an hour and a half to Desoto Dragway I wanted to try and get a couple passes in.

Jay

Hib Halverson
10-26-02, 02:38 PM
Originally posted by BiZ
I believe he is determining the rich condition by the a/f readings he got on his trip to the dyno in Feb. I was there and I remember the Dyno operator telling him he was running rich.

Jason

Ah....
Ok. The car is rich by AFR measurment. The solution is to go back to Jim Smith for further calibration work. The addition of the coils and the 4.10s won't affect that but the change in cat-backs will if the cat-back you change to has less restriction. if the car is just slightly rich, a lower-restriction exhaust might have the AFR being closer to correct. If the car is way rich, the new, lower-restriction cat-back might not lean it enough. Again, Jim Smith is the guy to work with on that.


If I supply dyno graghs and air / fuel graphs along with a list of modifications, the person burning the chip doesn't need the entire vehicle do they?

That should be enough for Smith to get the AFR closer to what you want.

JT ZR-Won
10-27-02, 03:39 PM
Thanks for the info Hib.....my next step is re-doing my cat-back and then the chip. Hopefully that will fix the problem

Jay

Hib Halverson
10-27-02, 03:46 PM
What exhaust do yo have now and what are you going to install?

JT ZR-Won
10-27-02, 05:33 PM
Originally posted by Hib Halverson
What exhaust do yo have now and what are you going to install?

Hib, I'm currently running a full Flowmaster cat-back exhaust. Actually, the system works great and it sounds incredible. However, I'm just looking for a change. I really like the look of the exhaust systems on Chuck Mallett's cars........two large single outlet exhaust tips. It's something different. Another that inspired me is this car here (http://data.corvette.co.uk:8080/ecars/corvette/cala.html)

I like the Supertrapps on this Callaway. I think with a 3" X-pipe into 3" aluminum pipe all the way back to 3" Supertrapps might be the setup I go with. I'm currently looking into different styles of Supertrapps. What are your opinions?

Jay

Hib Halverson
10-28-02, 03:14 PM
No opinion.
Just wondering

JT ZR-Won
10-29-02, 05:08 AM
Originally posted by Hib Halverson
No opinion.
Just wondering

oh

Quasar Z
11-04-02, 12:39 PM
JT,

I know who has the exhaust you want at a price that is incredible. His name is Paul Dehnert and he has a Mallett exhaust that he took off of his ZR-1. I almost bought it but I liked the look of the Tri-Flo exhaust. Contact me off-line for more specifics at mquinn@execpc.com