Intermittent engine problem
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Intermittent engine problem
Looking for ideas on how to find and correct an intermittent problem with the engine quitting. No consistency other than engine is at full operating temp, just driving around and the motor quits, will not restart.
Check fuel, good @ 39 lbs, good spark from coil, also tested fuel injectors with node light and had firing signal.
The thing is let the car sit for more than 6 hours and it starts like a champ!
Have gone through everything in the distributor, ICM, rotor, pick-up, all new AC delco parts. Have gone thru all wiring, connectors, inspected for any issues including ECM plug in passenger wheel well. Tested per GM factory manual, TBS, IAC, temp sensor check out ok!
I have simulated the failure in the garage and found some very strange data from Snap-on MT2500 scanner, 3 saved files where the engine died have the same data, RPM- 104 / O2/mv - 996 / Desired idle - 0 / Coolant temp - (-40) yes 40 below / Prom ID - 57869 (actual ID is 3493) / Battery voltage - 0 / VATS problem yes / vehicle speed - one file shows 83 mph other 233 mph.
Now thats really moving while parked in the garage!!!!!
Two other points, engine in closed loop at time of failure. second, engine dies after fans start @ 227 f which seems high.
Engine is ZZ3 crate motor with all original TPI system, everything. No modifications to any wiring, trans, cooling all original except for , hooker emission headers and BBK 52 MM throttle body. Using the original stock fuel injectors I do have a set of new holley LT1 high impedance 30 lbs/hr fuel injectors but have not installed them.
Any ideas are welcome!
Thanks
Check fuel, good @ 39 lbs, good spark from coil, also tested fuel injectors with node light and had firing signal.
The thing is let the car sit for more than 6 hours and it starts like a champ!
Have gone through everything in the distributor, ICM, rotor, pick-up, all new AC delco parts. Have gone thru all wiring, connectors, inspected for any issues including ECM plug in passenger wheel well. Tested per GM factory manual, TBS, IAC, temp sensor check out ok!
I have simulated the failure in the garage and found some very strange data from Snap-on MT2500 scanner, 3 saved files where the engine died have the same data, RPM- 104 / O2/mv - 996 / Desired idle - 0 / Coolant temp - (-40) yes 40 below / Prom ID - 57869 (actual ID is 3493) / Battery voltage - 0 / VATS problem yes / vehicle speed - one file shows 83 mph other 233 mph.
Now thats really moving while parked in the garage!!!!!
Two other points, engine in closed loop at time of failure. second, engine dies after fans start @ 227 f which seems high.
Engine is ZZ3 crate motor with all original TPI system, everything. No modifications to any wiring, trans, cooling all original except for , hooker emission headers and BBK 52 MM throttle body. Using the original stock fuel injectors I do have a set of new holley LT1 high impedance 30 lbs/hr fuel injectors but have not installed them.
Any ideas are welcome!
Thanks
Supreme Member
Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
If It’ll Do 233 Thru The Turns I’ll Buy It !
In spite of the haywire ECM report, you’re either losing fuel or spark.
Wire up a small 12 volt bulb (a side marker bulb works best).
Connect one lead to the coil primary (the ignition module side not the key side) and the other lead to ground.
Make the wires long enuff to bring it into the cockpit.
The next time the engine stalls, crank and observe if the bulb is pulsing.
If you see no pulses while trying to start, the problem is the ignition is cutting out.
If you SEE pulses while trying to start, the problem is fuel.
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I Didn’t Wreck, The Track Moved
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Wire up a small 12 volt bulb (a side marker bulb works best).
Connect one lead to the coil primary (the ignition module side not the key side) and the other lead to ground.
Make the wires long enuff to bring it into the cockpit.
The next time the engine stalls, crank and observe if the bulb is pulsing.
If you see no pulses while trying to start, the problem is the ignition is cutting out.
If you SEE pulses while trying to start, the problem is fuel.
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Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
I Didn’t Wreck, The Track Moved
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Thread Starter
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Joined: Jun 2010
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Re: If It’ll Do 233 Thru The Turns I’ll Buy It !
Thanks for the tip! I have done a similar test with a spark plug had strong spark. Have a fuel gauge connected to the fuel rail, 39 lbs present while cranking. One thing I did not list in original post, scanner list "spark advance" @ 0. Could the ECM retarding spark to the point it will not start?? Just a thought!
Thanks
Thanks
Supreme Member
Joined: Jan 2006
Posts: 3,341
Likes: 10
From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
If It’ll Do 233 Thru The Turns I’ll Buy It !
scanner list "spark advance" @ 0
You can’t trust the info your comp is telling you.
Also, even if the timing was off, you would still hear some cylinders firing, even if the caused the engine to reverse and stall.
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However that’s not the immediate test which can show if the ignition is cutting out due to heat.
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Happy Racing!
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I Hit The Water Barrels Because My Car Was Dirty
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Also, even if the timing was off, you would still hear some cylinders firing, even if the caused the engine to reverse and stall.
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I have done a similar test with a spark plug
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Happy Racing!
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I Hit The Water Barrels Because My Car Was Dirty
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Joined: Sep 2009
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Re: Intermittent engine problem
I'm no expert, but I would guess some sort of circuitry problem with the ecm.. i had a similar issue with mine and replaced the ecm and it was fine... i heard they used some sort of crappy solder on the boards inside? and the solder is seperating at certain temps.. i dunno, i got some sort of run around answer last time i figured mine out... but it did fix it.. have u tried a remanufactured computer yet?
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Car: Firebird Pro/Am
Engine: 5.0 TBI
Transmission: 700r4
Re: Intermittent engine problem
i had a similar problem with my 89 trans am the motor would stall while driving then start back later but what i did not notice at the time was the VATS light was coming on when it happened and what had happend was the VATS computer was going off and on causing the fuel pump to shut off
i also have another solution against what was stated above about timing but i have an old 70' nova that once shut off while pulling into a gas station and when i opened the hood and the distribtor had turned and threw off the timing slightly and would not fire on any cylinders until (a the motor cooled or (b put more power to the battery
but i dont know alot about fuel injection but i hope this helps
i also have another solution against what was stated above about timing but i have an old 70' nova that once shut off while pulling into a gas station and when i opened the hood and the distribtor had turned and threw off the timing slightly and would not fire on any cylinders until (a the motor cooled or (b put more power to the battery
but i dont know alot about fuel injection but i hope this helps
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