Hi ,newbie to forum.1989 S10 Blazer 4.3L, code Z,
TBI, EST Dist.I thought I was fighting a fuel problem til I hooked up timing light. What happens is,,,Starts and idles,shows 12 degrees timing,if I barely crack throttle it will rev up but if I open throttle even a little faster the timing timing drops to 0 degrees. So all I can get while driving is barely above idle before the engine lays down. Any help would be apreciated,Pop's

 

No codes except when I run tests. Man,it a bugger when ya have a problem a no codes post!!!! I'm a thinkin maybe Dist pick-up? Pop's

 

Have you checked your base timing? You need to disconnect the vacuum advance and the timing wire inside the truck to check/set the base timing.

 

Yes I have set the base time at 0 degrees , the ECM then advances the timing about 12 degrees. This Distributor doesnt have vacuum advance.Thanks for the reply,Pop's

 

There are a few different distributor setups for your year according to my references. Just to clarify, you set base timing after disconnecting the timing connector under the passenger side dash inside the truck, correct?

If so, have you inspected the pickup coil? Done any testing on it (resistance should be 500-1500ohms)? How about the knock sensor? If the detonation is detected the ignition module in the distributor will retard timing.

 

Yes,I set base timing with EST wire in cab disconnected. I took ICM out of distributor took it to A-Z had it tested (ran it 5 times) it checked good.I'll check ohms on pick-up. The only check I've read about on Knock sensor is to pull wire off check for voltage (5 Volts).I havent done this yet,is this correct way to check Knock sensor???? Thanks Pop's

 

It seems like the ECM is kicking out the EST completely.I pulled the connector off the ESC module did some checks,engine off swich on:
B= 12volts
C=.o2 volts
D=good ground
E=108.2 with meter set on 200k
Maybe Gimpy well chime in and clear me up.
Thanks Pop's

 

I ordered a new dist from skip white performance. While I had it out I put in a new knock sensor.Dont know which one fixed it but Blazer is a runnin again.Pop's

 

hwy man, u might want to try just swapping out the HEI module from the new one just to check if its that. i've got a faulty one and its not throwing a code anymore, which is odd. the HEI is the piece with 6 little prodes coming out of it inder the cap. sounds like a nice truck!

 

I took the icm to AZ and ran a check 5 times and it pass every time,I was thinking it might be the pickup bad. I got the complete Dist for about the same $'s as a pickup would costand didnt have to tear it apart!!!! Thanks for the reply Pop's