Need help

[Steves LX]

So I have a 89 mustang that I drag race. You can see specifics in my sig. For the last few months the car is hit or miss when I am racing. Sometimes it runs great with no issues at all and sometimes it doesnt. It seems that anytime I have a hard launch or if the tires hit hard between the shifts. The car will die and then take back off. When I say die its like you just turned the key off driving down the highway and turned it back on. You have to lift off the gas pedal when it does this and then put your foot back down and it will take off. I have checked everything and dont know what else to do or what could be causing this. It doesnt matter how much gas I have when this happens. Full tank or a 1/4 tank. It does it. Its just so intermitten when it does. I had it do this twice to me a couple weeks ago on my 2 time trial runs and then during eliminations it never did it again. I've just noticed that it seems to do this when I launch hard or on gear shifts whether its 1-2 or 2-3 or 3-4. It happens more on 1-2 and 2-3 gear changes. I do powershift so it is a little more violent on the car and stuff than just plain jane shifting. I run a tremec 3550, MSD 6AL2 ignition, Walbro 255 high volume fuel pump. The car is fuel injected. I beleive those were the only few things of importance thats not in my sig.

[bobtsgt]

Sounds like what mine was doing last year. Adam pretty much determined it was the MAF flaking out in the higher RPMs. Maybe try cleaning it or swapping it out with someone elses to see if it clears up. Does the car have a recent tune on it?

[Steves LX]

Sounds like what mine was doing last year. Adam pretty much determined it was the MAF flaking out in the higher RPMs. Maybe try cleaning it or swapping it out with someone elses to see if it clears up. Does the car have a recent tune on it?

I did swap that out with Ricky's and nothing changed.

[jlt2006]

I honestly think its a problem between the seat and the steering wheel.:lol:

All joking aside.

You check your MSD box? Connections? Any chance your fuel pump is acting up? You need to get this figured out before the last race.

Good luck.

[adragon72]

Have you checked you tps?

[bobtsgt]

Need to verify the proper voltages with the TPS and MAF to make sure the computer is getting all the proper inputs. I would say datalog it but not sure if you can with those computers.

[mrstang-gt-46]

rev limiter maybe

[Steves LX]

Need to verify the proper voltages with the TPS and MAF to make sure the computer is getting all the proper inputs. I would say datalog it but not sure if you can with those computers.

I agree with you there Bob. I have checked TPS voltage and its all good. I've ran the car with a volt meter hooked up to the MAF and its all good as well. It will not do this on the street or even at the track if the track is crappy. However, if the track is good and the car dead hooks coming out of the hole or it hits the tires super hard on shifts it will do it 98% of the time. But if the track is crappy and the tires spin then it will not do it. It's so intermitten and being a PITA. I could go drive the car to florida and powershift it every opprotunity I have and since the tires wont stick and hit hard it wont do it. But the minute I get to Florida and make apass on a good prepped track. I would be willing to bet you everything I own and then some that it will do its shutoff and come back on deal.

[Stangman]

Man, it's probably ANOTHER A9L computer. You know the trouble you've had in the past. Is your flip chip falling out of the back?

Whatever it is, it sounds electrical. I think the violent launches take their toll on the ECU's and since they don't exactly have the greatest and softest mounting bracket to absorb the blow... I can imagine its jarring the hell out of every computer you throw at it. Unless maybe something is going awry with your computer harness on the outside of the hood? Salt and pepper connectors seeing too much heat? Short in the harness? I don't have any more computers you can test.... you have both of mine and my flip chip/harness

[graysonracin]

could have something to do with the inertia switch in the hatch area, harness to it may have an issue or the switch itself, not likely but worth looking into,ive seen rangers do it before.

[Stangman]

He did have an issue with it a few months ago, but has since eliminated it and connected the wires together. His car was launching too hard for it.

[RIXXX93GT]

Mine did that on 3-4 shifts only when powershifting. I have since pulled the cable for the sct switch off the chip, duct taped the chip into the A9L so no vibration and sent the A9L to have a higher speed crystal installed. No problems after that. I would do the crystal change Steve. Guy at JPC did mine, Chris Fillyaw does them also.

[Stangman]

What's a speed crystal Rick?

[bobtsgt]

I say its time for a F.A.S.T. system lol

[RIXXX93GT]

"It doesn't actually hit a limiter. The computer runs out of processing power and can't handle all of the spark and fuel events so the motor will shut off. It won't turn back on until you release the clutch causing it to restart. " This is a quote from someone else. The crystal is part of the processing system for the EEC, they come in different Hz speeds, this can play a part in how much info your stock computer can handle at higher rpm's. At least thats what I have been led to believe. Steve if your backs against the wall you can always run my computer, lord knows I have no use for it right now.

[INSANEBA]

That sounds like a strong possibility Rick. It deff has to be electrical, maybe a connection to a power for something (MSD) is jarring and cutting power from the launch or shift? Then after you let it settle and restart it, it's fine until it gets another hit? Hate to say it, but wish my problems were from too much hp lol.

[blown96cobra]

I say its time for a F.A.S.T. system lol

Yep. X2. The harness is probably showing it's age and not getting the proper voltage to some of the sensors.

[furiouslyfaster]

Hey Steve did you ever get it figured out I was just curious. Hope ya did