Ok, I'm still having serious running rich/stumbling/hesitation problems with my car. What I know:

The car is fine when cold started. Within a minute of running, the symptoms start to appear.

Symptoms are: Running EXTREMELY rich. I'm talking spitting out of the exhaust tear your eyes up rich. Stumbling/hesitation at low rpm's. When gas is moved at anything more than a slow crawl, car completely cuts out for a split second, then picks right back up. Lower powerband only.

I'm assuming that the stumbling/hesitation is due to the overly rich condition causing a misfire.

The longer the car runs, the worse the problem gets.

Help please!!!!

 

sure, email me ...

Jon AT shoberg.net

 

I'm starting with the assumption that you are using a stock or near stock program/tuning.

In my brief experience the '93 cars are mostly VE tables when it comes to fueling. It look like your idle is about 850mph and the map sensor reading about 60. In my stock bin the VE point for 850/60 started at 72. After 10 sessions of tuning with VE Master I came to a value of 42 for 850/60. This is with a 218/230 'Xtreme grind cam on a 8.5:1 cr.

At this point I would doubt that you could make any mechanical adjustments (fuel pressure, tps, etc...) that would make a meaningful change. You'll probably have to dive into the computer for tuning, just as I did. Perhaps you can find a mail order tune or do as I did, and buy a chip burner.

My first logs started off the same way. Once I got the injector constant changed (24 to 42) and VSS hooked up, the part throttle tuning process was easy.

Have a look at the following blog entries with pictures:
Session 1: http://jon.shoberg.net/archive/000017.html
Session 10: http://jon.shoberg.net/archive/000020.html

You'll notice a larger change in the VE tables. VE Master made the tuning a breeze and the car drives as fine and runs strong. I base this against the part throttle performance of a LS1 car with 224/224 cam, MTI heads, and MTI program that runs 10s. Needelss to say, I'm ditching it all in favor of a FAST.

Just sharing my experiences...

 

Lol, actually, the car is pretty well modded. Heads, 224/230 cam, pretty extensive tuning, albeit the chip in it is a slightly modded version of the initial tune which was DEAD on. It's definitely something mechanical, as I've gone through 6 different tunes and the problem has remained ever-present. It ran perfectly fine on the initial tune btw. Tried again with no resulting luck though.

 

Again, my guess would be that things are for the most part mechanically sound in that you say it starts fine though after a minute of warm up it goes WAY rich. I'd also speculate that the current prom has only adjusted fueling in perhaps mid-range and top end, but fewer adjustments to down low.

If the problem persists and everything is verified to be 100%mechanically I could only recomend getting Xtronics Pocket Programmer, prom eraser, and tunercat. I first tried downloading a couple of downloaded BINs, talked to some mail order programmers, and in the end did just as well as, if not better than mail order on my own. (based on perfromance/idle quality/etc ... when compared to cars running a 'professional' tune).

Definately look under the hood and see if something is going on there. Outside of that, I'd give consideration to looking back into the ECM.

6 tunes ... ran fine on the initial ... now this happens down low ... is it really mechanical?

Good Luck,
J

 

Send a copy of the files over and I'll take a look at them for you. I just got done tuning my 93 383 so I may be able to give you some advice.....

-Rob

 

I'm sure these are probably similiar to the files I saw...and I couldn't see anything in those that looked wrong.
It's too bad someone like injuneer doesn't have the DA3 version...I'm sure he could help out.
Wait...if you download the trial version of any platform of datamaster you get 20 free logs...but can't you view existing logs as much as you want?
Kind of off topic...but it might help.

 

That is correct.