I posted a couple of weeks ago about an inconsistency problem. First run was fast, all others were half a second slower (nitrous runs). I have ruled out bottle pressure which was everyone's suggestion.

The local Thunder Racing place in town told me that after my first run of 11.060, the computer was resetting variables to "protect" the car from exceeding certain perameters. His suggestion to test this was to disconnect the battery after the first run, let it sit for a while, reconnect and let the PCM reset, then run again.

Two questions: Does this make sense, and what do you do if it's true? :confused:

 

Hmm, it will learn a little, but I would not think that much. You really do not need to unplug your battery though. You can just pull the PCM fuse. :)

Did you happen to take a log of these runs? I would be happy to take a look at them and see if I can spot anything strange if you like.
Let me know if I can help.
Thanks,

 

Typically when adaptive parameter limits are exceeded, codes are thrown. Not a story I'd expect from TR.

 

Thanks for your input!

I ran again tonight and the same thing happened. All motor runs were very close with 1.75 60', 5.0 330', 7.7 1/8. @ 87mph, 10.2 1000', and 12.25-12.36 quarter @ 109. Three runs.

With nitrous: First run: 1.55 60', 4.7 330', 7.4 1/8 @ 99mph, 9.4 1000', and 11.25 quarter @ 122mph. Not bad considering the heat.

Next three nitrous runs: 1.55 60', 4.7 330', 7.4 1/8 @ 87!!, 9.9 1000', and 11.9 quarter @ 108. Bottle pressure was identical, and weather much cooler.

I could feet the nitrous shut off during the run.

To complicate the issue, after the runs tonight and last week, the car could barely idle, and missed terribly when slowly accelerating. Only way to make it run was to hit it hard. After last week, the car ran poorly for a couple of days and then seemed to smooth out.?????????????????

How's your diagnostic ability? Mine sucks.

 

There are a few things that might be happening here. First, and what I would suspect, you have something cutting your nitrous off during a run, but not your fuel. You might be fouling out your plugs and it would take a day or two for the junk to burn off of your plugs. This would account for the car running poorly for a day or two after the races and then clearing up. Did you happen to notice a nasty cloud of smake behind you when you were running the bad runs on nitrous?

Second, you might be having fuel issues. Do you have a Fuel Pressure Saftey Switch? How about a fuel pressure guage? After a run or two on nitrous really stressing the fuel pump and heating it up, you might be dropping fuel pressure enough to set the safety switch off. This might cause an issue like this also.

Do you have Autotap? If not, I would strongly suggest getting this and taking some logs of some runs. This is an invaluable tool when trying to troubleshoot ANY problems and can mean the life or death of your engine when dealing with nitrous.

Going back old school, try pulling a plug to see if it is fouled(has a bunch of carbon buildup on it). I am really leaning towards this as being your problem.

Let me know if I can help you with analyzing a log file or if you need a copy of Autotap. I will surely help you with either one of those.

Good Luck,

 

Thanks a bunch Chris.
That actually makes sense. Scary!

I see you sell Autotap and LS1 Edit. Which do you like for what I need. Also, these products diagnose problems, but what is available to reset the different variables? You can tell I'm not a mechanic, but I do have really good mechanical friends. If I can't read the logs, they can. But how to fix problems if it's computer generated?

Thanks.

 

First, just a little clarification. We have and use LS1 Edit, but we do not sell it. :)
We do sell autotap though and as I said before, it is an INVALUABLE tool for nitrous tuning and use.
You can get a copy of LS1 Edit and tune your car(change the parameters, fuel curves, timing curves, etc.) from http://www.carputing.com . Just let them know I sent you. :)
I will warn you though, tuning the car via LS1 Edit is NOT EASY in any way! We have hundreds of cars under our belt and there is still PLENTY more to learn. :yesnod:
Unless you you a very good understanding of cars and how they work, I would probably steer clear of this. Get one of your local tuners if you can to tune your car for you. If no one is available in your area, feel free to make an appointment and come down for a tuning session. We have people from all over drive down for us to tune.

Again, good luck. :)

 

Alright, I'm confused. The LS1 Edit is a program for actually editing the computer settings? The autotap is a program for diagnosis of problems? Does that mean that I use the autotap during a run, or any other time, save the results, show them to a good mechanic, and let them fix the problem? Is this the basics or am I still confused?

Does the MAF translator come into this conversation anywhere?

Chris, I think I'm talking to you on another thread about a tranny.


:lol:


[Modified by jpvette, 10:26 PM 4/10/2002]

 

You got it. Nailed it on the head! The MAF-T is nothing compared to a good custom tune. The MAF-T definitly is good for some things though. We do use and sell those also.

I will tell you though, it takes a lot more than an ability to turn wreches in order to tune a car.....