firuzrasul

hi,

is that possible? In my Cobra work an ´96 LT1 engine with the ECM from ´93!!!

The problem, may engine dies sometime abruptly!Sometimes it dies after 1 week sometimes after 5 minutes. The LT1 installed in my Cobra Kit dies suddenly after different operation times and temperatures.

Things I checked and replaced:
- Engine ground is perfect
- Battery is o.k., voltage on system is allways 12V
- Ignition Module is replaced
- Opti is replaced
- Coil is replaced
- No codes are indicated ever
- Fuel pump runs after switching on the ignition

Heeeeelp

Cheers from Germany

Andy

Dave_Jones

GM never used a MAF on the '93 LT1. That's a MAP-only ECM. (are you saying you modified it to use a MAF?)

When it dies, can you tell if it dies from a loss of fuel pressure, or a loss of spark?

If fuel pressure is good, but it loses spark first, check the ECM grounds, and coil wire.

Maybe try swapping in another ECM, if you have a spare.

If it loses fuel pressure first, check fuel pump and relay connections.

Did you wire your fuel pump like a stock GM '96 LT1? If so, there is no backup to the fuel pump relay, so a bad/intermittent relay would cause a loss of fuel pressure, as would an intermittent FP relay activation signal from the ECM (i.e. bad ECM or wiring problem)

If you wired your fuel pump like a '92-'95 LT1, you should have an oil pressure switch as a backup to the fuel pump relay, so a bad relay, or even a bad ECM, shouldn't cause a loss of fuel pressure, if the switch is working correctly. (although I hjave seen one of those switches fail intermittently too)

Hope this helps. Good luck!

firuzrasul

i find the problem, it´s not the fuel!
my lt1 works only with map, i have checked this yesterday!
pleas look on following plan.

i see following problem with my ignition on the die!

(8) and (9) is chrashed on 4 volt!

(6) and Ground of my car are crashed too!


(11) + (5) are ok! (9) is ok too, i checked this wire!


and now?

Grumpy

It might be the Optispark dieing. You might try googling for LT1, and see if one of the LT1 boards has any good diganostics on that.

firuzrasul

i have chenged it!!!

;-(

and the same problem!

Grumpy

With a Delco/GM ?.
If it's a Wells, I've had problems with their modules in the past.

Does it restart immediately?, or need time to cool off to restart?.

firuzrasul

sometime i can restart after 1 sec. somtime i need 2 min. !!!

and sometimes i have some realy quick dies between 5 sec. !!!

sorry for my bad english :-)