Code 43

[2500hd4x]

88 K5 w/350. It pulls a code 43 (ESC) on every full throttle run after it warms up. All stock, new tailpipe. It has ~180,000miles on it... I can't hear a knock in the engine, small exhaust leak on drivers side manifold. It wasn't doing the code 43 until I fixed the code 32-(EGR system) then this code started. Before it just ran like crap at idle. Now when the check engine light comes on-it pulls timing, and runs like crap. I have replaced the knock sensor, and the ESC control module on top of the manifold. I have a spare ECM/Prom from my last K5 (87)- I pulled the TBI off of the 87 and put a 600 Holley on it due to too many codes. This one is getting close to the same fate. Where to go next? Any ideas? Any easy way to bypass this code?? Any help is appreciated...

edited for clarity...

 

[1979jimmy350]

the exaust leak could defently cause the problem, also check to see if the wire going to the knock sensor is intact or has a problem. you might want to try a higher octane gas and see if that fixes the problem, if that does you might have a lot of carbon build up in the heads causing the compression ratio to raise

 

[2500hd4x]

also check to see if the wire going to the knock sensor is intact or has a problem. you might want to try a higher octane gas and see if that fixes the problem

The wire from the new knock sensor up to the new module is intact. I know it needed a new knock sensor, the old one was busted at the "tabs" where the wire harness plugged into it and the wire harness kept falling off.

I went to Auto Zone tonight and picked up two bottles of Octane Booster and a new fuel filter. Figured it might be pinging now from starvation of fuel/dirty fuel. It runs pretty hard until it sets the Check Engine light, but even before the light comes on it still surges a little bit occasionally-maybe a fuel filter will help. I have run two bottles of injector cleaner through it in the past few weeks. I have only had this Blazer about three weeks. Put ~ 500 miles on it in that time. I have been running partial tanks-with a bottle of injector cleaner dumped in it up until a few days ago. I filled up with no additives this past week....Maybe thats why its pinging/setting the code (straight 87 octane). I have been trying to work the bugs out of it. It sat up for two years before I bought it so-who knows. Tomorrow night, after work (GRRRR-Im working labor day weekend!!!! ) Im going to make sure its timed right, swap the fuel filter and dump two bottles of Octane boost in and see what happens. Thanks for the input!