no start 87

[jeff eggert]

1987 vette distributer wont talk to ECM wont start unless I advance timing about 20 degrees then I must retard to keep it running esc isnt working it pings under load ,I have replaced ECM, ESC, ignition module, E_PROM, pick up coil, checked all wireing from dist. to ECM, ESC, am getting proper voltages at ECM . timing chain hasent stretched, jumped tooth etc. what is limp home mode? could this be the trouble? am not getting any codes SES light is working .have been trying to repair all summer this is driving me nutts

[c4c5specialist]

HI there,
Unfortunately, your not giving us alot of information.
First, the ignition module is telling the fuel injectors to fire, so that being said, you have the signal to the PCM.
Second, are you sure its the distributor??
Have you checked the resistance on the fuel injectors???
Have you ever had the distributor out of the vehicle??
Why have you replaced all these parts???

The key is to how the vehicle works.
The distributor pickup coil fires 8 signals, per one revolution of the distributor shaft.
That is in relation to 2 revolutions of the crankshaft.
The ignition module reads the signal and then transmits this to the PCM for fuel injector firing.
This is known because of the ability of the engine to run.
If you advance the timing to 20 degrees, that tells us that there could have been a problem when you installed the pickup coil.
The ESC module only reacts when the PCM adds voltage to it.
Even if you remove voltage to it, your engine will still run.
So, with that in mind, please expand on what you were experiencing before you started replacing parts and in what order you did it.
Also, add in voltages on the ignition circuits to the ESC module.
Allthebest, c4c5

[jeff eggert]

sorry it took so long to respond when I registered for this web site my pc got a virus took a wile to repair it .it all started with car running poorly at high rpms got it home and it wouldnt restart got a code for MAF sensor so I replaced it still wouldnt start .I checked for spark had spark,checked fuel pressure at rails ,had pressure ,so it had to be ignition timeing turned distributer and it started have to retard timming to keep it running and it pings under acceleration I did diagnostic tests recomended by ALLDATA .COM all ignition wireing is good, so started replaceing modules, if I rember correctly I first replaced ignition module,then e-prom,ESC and knock sensor, pick up coil ( it doesnt seem to go in but one way and yes I had to remove distributer) ECM ,etc,etc voltages are as follows,dist ref 1.2 ,ESC signal 9.1 , EST1.4, bypass 4.6 all grounds are good. nothing I do seems to help how much information can be retreved with scaning tool TECH-2 or will I be wasting money by takeing car to dealer? I cant realy aford to write blank check to dealer

[c4c5specialist]

Originally Posted by jeff eggert

sorry it took so long to respond when I registered for this web site my pc got a virus took a wile to repair it .it all started with car running poorly at high rpms got it home and it wouldnt restart got a code for MAF sensor so I replaced it still wouldnt start.
CHECK YOUR MAF POWER RELAY AND BURN OFF RELAY. THOSE HAVE BEEN ISSUES ON MAF SENSOR PROBLEMS. THE SENSOR IS RARELY THE PROBLEM.
I checked for spark had spark.
WHAT DID YOU CHECK SPARK WITH? WHAT COLOR WAS THE SPARK?
checked fuel pressure at rails ,had pressure.
WHAT WAS YOUR PRESSURE????
it had to be ignition timeing
HOW DID YOU DETERMINE THAT?
turned distributer and it started have to retard timming to keep it running and it pings under acceleration I did diagnostic tests recomended by ALLDATA .COM
FIRST ALL IS GOOD, HOW DID YOU TEST IT?
HOW DO YOU KNOW THAT THE TIMING IS OFF, IF YOU DIDNT HAVE A PROBLEM BEFORE THE IGNITION PARTS WERE REPLACED, WHY WOULD YOU DETERMINE THAT TIMING IS THE ISSUE????
all ignition wireing is good, so started replaceing modules, if I rember correctly I first replaced ignition module,then e-prom,ESC and knock sensor, pick up coil ( it doesnt seem to go in but one way and yes I had to remove distributer) ECM ,etc,etc voltages are as follows,dist ref 1.2 ,ESC signal 9.1 , EST1.4, bypass 4.6 all grounds are good. nothing I do seems to help how much information can be retreved with scaning tool TECH-2 or will I be wasting money by takeing car to dealer? I cant realy aford to write blank check to dealer

YOU MUST BE CLEARER ABOUT WHAT CIRCUITS YOU TESTED AND WHAT YOU GOT FOR READINGS.
THE TRUTH IS GETTING SOMETHING RUNNING BY TURNING THE DISTRIBUTOR IS USUALLY MASKING YOUR MAJOR PROBLEM BY INCREASING THE HEAT OF THE SPARK, CREATING A SPARK THAT JUMPS FUEL SOAKED SPARKPLUGS.
THAT BEING SAID, YOU NEED TO START AT THE BEGINNING.
1)SET YOUR DISTRIBUTOR TO TOP DEAD CENTER.
2)TEST YOUR FUEL INJECTORS FOR RESISTANCE, 16.5 OHMS RESISTANCE IS WHAT EACH SHOULD BE.
AND THEN POST BACK THE RESULTS.

RESPONSES IN CAPITAL LETTERS.
Allthebest, c4c5

[jeff eggert]

I was able to repair the vette it turned out to be the coil .turns out that a weak spark wont ark under comperession thus when I advanced timing there was less comperession so it would spark .you got me thinking when you asked what color the spark was. thank you verry much for youre help......jeff eggert ...eggertauto@aol.com