Recently aquired a nice 93 blazer from my dad, which had the IAC, MAP, EGR, O2 sensor, fuel pump, fuel filter, FPR, Nut Kit, Spider assembly replaced about 10,000 miles back. He had probelems with poor mileage and a "hunting idle". The truck has run great for about a year, until last week.

The motor killed under acceleration from a stoplight while I was on a long highway trip. It would crank but not start. Got towed and at the shop determined there was no spark. We examined the cap and found the center contact had broken off and was loose in the cap. Replace the cap with one that was handy, but it wouldn't start. Put in a module that was handyy and still no starting. The next morning we got a pick-up coil and then there was life. We checked my base timing and it was dead on. However the old "hunting idle" problem had come back. The mechanic and I though it was just the IAC so I left as I needed to get home. As I finished my drive, I started noticing a detonation as I was climbing hills. The more I listened the more I noticed.

I had a friend hook up his scanner and it showed my ignition advancing from 5 deg. and jumping up to 20-25 deg at idle. No CE lights show, but we got a rich reading in the O2 sensor. After driving around the neighborhood for a while we decided to check the plug wires for any arcing. there was alot. Next day I changed the plugs and wires and checked the fuel pressure at the manifold [ok][61].

I though originally I might have gotten a tank of bad gas so I topped of the tank and threw in a can of seafoam. To my surprise I got 26 mpg post distributor repair, the best I ever get is 22.

I was suspicious of the no-name module so I replaced it today with a Delco. I have also cleaned and inspected the IAC,MAP,MAT,EGR with electronic parts cleaner.

The only thing left are the Main CPU or perhaps a leak on the fuel injector system again. I pulled the CPU down and gently tapped it to see if there would be a response, but nothing.


any Ideas out there? I have read 80 pages of old posts trying to eliminate possibilities. This forum is full of great ideas, I just haven't found the last piece of the puzzle yet.

 

BTW its a 4dr 1993 S10 Blazer Tahoe, AT 4x4, 144,00 miles. believe it's a W motor with CPI

 

Check for a vacuum leak.
Cehck the EGR, and check to make sure the cat isn't plugging up.

 

good luck on getting the problem fixed

 

check the gear at the the bottom of the distributor that was my problem
My local mecanic had a hard time dignosing this problem as well