Diagnose this!!
Diagnose this!! This may be long winded, but the more info the better!!
93 LT1 as follows:
HOTT cam kit, Painless wiring harness. ECM is tuned from Street and Performance, for the cam and 1.6 RR's, EGR removed, VATS removed.
The history:
Bought this engine from a coworker. He pulled it out of an el camino he sold minus the engine. I have put it in a 1986 short wide chevy truck. The previous owner had the ECM programmed, and also sent it back again before i bought it to test the tune again. Im assuming he had issues with it running also.
The ISSUE:
When i finished the install, the truck ran ok, but it had a hesitation when getting in the throttle. Also it shuttered pretty heavily from a dead stop. So I bought a 2800 stall for the 700R4. This seemed to help it out, but it is still not perfect.
After about 1 week, it stopped running at all. Found out that the OPTI plug was corroded and actually had a pin left in the plug when i pulled it off. So The previous owner had a box of parts i got with the engine. I threw on another OPTI, is was used. Fired right up. Still had the hesitation from about 2,000 RPM up to around 3200 RPM.
At this point i started replacing what i thought could be wrong. Here is the list of items i have sinced replaced :
(all parts were bought new)
coil, ignition control module, NGK platinum plus plugs, MAP sensor, MSD pro billet OPTI, fuel pump (AC Delco).
This got it running back to where i was before. I was sure the MSD opti was the fix, but it was still hesitating.
I did notice when driving around 40-50mph you can feel the engine hesitate for about 5 seconds, then actually feel and hear the engine pick up, and throttle responce is great. This keep repeating in cycles, but it wasnt bad enough for me not to drive it.
Now this morning i went to pull it out of the driveway, and it will start up then die. start up, then die. Start up, try to die off, the engine picks up, then dies. it wont keep an idle without me feathering the pedal. If i punch the go go pedal, it gulps air and dies, doesnt even try to correct itself.
I should also note that there are no codes being thrown, nor has there even been a code thrown.
I then tested the TPS, and it ran up smooth to 4 Volts. MY meter doesnt show decimals, so i am assuming that it was ok. The 5 volt signal reference is present also.
I then tested the IAC. It tested out ok also. I tried unplugging one of the O2 sensors, but it still wont hold an idle. I then rechecked all the grounds, anfd they are clean and tight.
So thats where i am... where do i need to look next?!?! Try tuning it with some one else? Is it possible that the ECM is shot?
Also, the transmission doesnt have an electrical sending unit, its only cable. Could this cause the computer to be all screwed up from not having a speedo reference?
93 LT1 as follows:
HOTT cam kit, Painless wiring harness. ECM is tuned from Street and Performance, for the cam and 1.6 RR's, EGR removed, VATS removed.
The history:
Bought this engine from a coworker. He pulled it out of an el camino he sold minus the engine. I have put it in a 1986 short wide chevy truck. The previous owner had the ECM programmed, and also sent it back again before i bought it to test the tune again. Im assuming he had issues with it running also.
The ISSUE:
When i finished the install, the truck ran ok, but it had a hesitation when getting in the throttle. Also it shuttered pretty heavily from a dead stop. So I bought a 2800 stall for the 700R4. This seemed to help it out, but it is still not perfect.
After about 1 week, it stopped running at all. Found out that the OPTI plug was corroded and actually had a pin left in the plug when i pulled it off. So The previous owner had a box of parts i got with the engine. I threw on another OPTI, is was used. Fired right up. Still had the hesitation from about 2,000 RPM up to around 3200 RPM.
At this point i started replacing what i thought could be wrong. Here is the list of items i have sinced replaced :
(all parts were bought new)
coil, ignition control module, NGK platinum plus plugs, MAP sensor, MSD pro billet OPTI, fuel pump (AC Delco).
This got it running back to where i was before. I was sure the MSD opti was the fix, but it was still hesitating.
I did notice when driving around 40-50mph you can feel the engine hesitate for about 5 seconds, then actually feel and hear the engine pick up, and throttle responce is great. This keep repeating in cycles, but it wasnt bad enough for me not to drive it.
Now this morning i went to pull it out of the driveway, and it will start up then die. start up, then die. Start up, try to die off, the engine picks up, then dies. it wont keep an idle without me feathering the pedal. If i punch the go go pedal, it gulps air and dies, doesnt even try to correct itself.
I should also note that there are no codes being thrown, nor has there even been a code thrown.
I then tested the TPS, and it ran up smooth to 4 Volts. MY meter doesnt show decimals, so i am assuming that it was ok. The 5 volt signal reference is present also.
I then tested the IAC. It tested out ok also. I tried unplugging one of the O2 sensors, but it still wont hold an idle. I then rechecked all the grounds, anfd they are clean and tight.
So thats where i am... where do i need to look next?!?! Try tuning it with some one else? Is it possible that the ECM is shot?
Also, the transmission doesnt have an electrical sending unit, its only cable. Could this cause the computer to be all screwed up from not having a speedo reference?
Last edited by hazyredeyes; Mar 3, 2007 at 07:57 AM.
