shutdown at WOT

[shobote]

My '89 MTX has never done this before; motor runs and idles great and was just shifting from 1st to 2nd at about 3k, floored the pedal and all of a sudden, total engine shutdown, and since it was in gear, suddenly lurched from around 30mph or so (and luckily no cars were behind me or would have been smasho i.e., no brake lights) Pushed the clutch in, motor caught again, and drove home a few blocks just fine but didn't want to try WOT again; DIdn't feel like fuel starvation since it was so sudden and no noises from fuel pump that has about 25k on it. Am running stock MAF and computer. Don't want to get stranded again (has happened 5 times) and really getting tired of paying for towtrucks and expensive replacement parts; had complete upper 60k with new CPS less than 500 miles ago at Performance Plus and no problems with running til now. Thanks for any guidance, guys.

 

[sideSHO]

I'm thinking an engine ground on this one.When you had the motor all torqued up and then suddenly let off may have cuased the ground to come loose.
I had an 88 ****** GT that had a bad engine ground.That thing would stall out when and whereever it wanted.
Hope this helps

 

[shobote]

Well, the engine was really not torqued up when it killed; slowly/smoothly pulled away in first, shifted just fine into 2nd from about 3k rpm and just as soon as I stabbed the throttle, it died.

 

[Ishodu]

Test your charging system, check your battery, battery cables and connections and go from there.
You should check the codes too!

 

[shobote]

Battery is good; new die hard gold 4 months ago and cables connected good and tight; no corrosion anywhere. I'll check codes and see what's up this weekend.

 

[SHOZ123]

Motor mounts good? Check the DIS for broken or loose connectors.

 

[SHOMA]

Does your tach drop when it happens? Check your codes, Im leaning a bit towards Crank position Sensor here. Even though ithas happened at WOT, it may start happening more frequently, and then not restart.. Does it catch right after doing it, or do you have to pull over and restart?
Good Luck,check the codes first!
Kevin

 

[Dr. Tweak]

Pull dem codes, (instructions on my website, see sig), surely the computer logged something....

 

[shobote]

Have never pulled codes before since never had any problems; will do ths weekend; instructions look great on the website you have the link to; thanks ! I'll check the codes and go from there; BTW, new CPS installed recently so don't think that's the prob. Question; I recently pulled of the 80mm MAF and LPM to go back to stock; do I need to reset the computer, and if so, what is the procedure ?

 

[AutoSHO]

Yes, you need to reset the computer. Pull the negative battery cable for a couple hours.

 

[sdpatt]

A hard shut down like that would indicate a CPS failure. You installed one recently, but did you gap it to .03"? Was the sensor wheel checked for bent shutters?

There is also a possibility that the DIS module has a bad connection. If both the front and rear motor mounts are in bad shape on a 3.0L SHO, there is a chance that the DIS module can contact the roll damper bracket on the strut tower. Check the rear connector for damage and tightness.

 

[shobote]

Think I found the culprit; the MAF sensor connector had a cracked locking tab underneath, and it came out a little from where it would normally seat; applied a hose clamp over it and haven't had any problems during the last 2 sessions of testing at WOT. Make Sense ?

 

[Hack]

If that turns out to not be the problem, I will vote crankshaft position sensor as well. I just had very similiar symptoms and that was the problem.