Code 43? 90 s10 blazer running bad

Truck has new, remanufactured engine just put in, but is running bad...bogging/losing power when you press on the accelerator (especially at start/low speed), no power, has stalled a few times when engine is cold, etc.

Dealership is getting code 43, knock sensor and wiring are good, so they want to put in a new computer.

1. Does this sound right?
2. Why would the computer go bad all of the sudden when a new engine is put in? (the old engine ran great until water got in the oil at 337K)

Thanks for your help...I've been trying to get this truck working for 3 weeks now and have taken it to 2 other shops that couldn't fix the problem.

Probably not the computer. If the ECM goes bad, often you won't get a trouble code, it doesn't see itself having a problem. Not always of course, but start elsewhere. I'd suspect the connector on the ignition module in distributor first, or a bad module. Move connector around with engine running an listen for difference. Take module out and have it tested at Autozone. Might double check the "timing check connector" to make sure it's been reconnected after having the initial time set. Connector is under dash, passenger side under heater just above the carpet line. Might also actually check that initial timing for correct setting, never know?

Thanks Tom, I'll definitely make sure they check these things out too. In the meantime, they put a used computer in for $70 to see if this solves the problem. It has made a definite power difference if I press the accelerator just a little...there's some real "zip" like you'd expect from a new engine.

However, if you press the accelerator any more, then the bottom drops out and it really bogs until it finally picks up again. It actually stalled twice when I first got the truck back, but the engine was cold. Once it warmed up, no more stalls. No SES light either.

So, when you press the accelerator 10-15%, you've got some power, which levels off after about 2 seconds; 16-50%, it bogs quite a bit; over 50% comes close to stalling, particularly when going up hill.

Could it be weak fuel pump or fuel injector(s), already had a new fuel filter installed? Or just check the ignition module? Timing is set to factory specs because just put a remanufactured engine in that has to be "broken in." Thanks!!!

Check the timings and quit assuming it is set right..

Pull the brown and tan timing wire from the PCM under the dash..

Time the vehicle,

reconnect wire and start.

You are assuming way to much without actuallu checking it.