1993 4.3 L Misfire and Dieseling

[RichLo]

Yea, definatly not the right term for what your describing, lol. even when an engine diesels after the ignition is turned off it still sounds normal, it just continues to run or stumble a little.

as for a diesel sound, like a loud knocking, that could be pre-ignition due to carbon build up in the combustion chamber or one of those new parts installed incorrectly. as for the carbon build up, you can try doing the seafoam treatment (google it) or running some seafoam in the gas tank for a few fill-ups.

 

[Pete1949]

Yea, definatly not the right term for what your describing, lol. even when an engine diesels after the ignition is turned off it still sounds normal, it just continues to run or stumble a little.

as for a diesel sound, like a loud knocking, that could be pre-ignition due to carbon build up in the combustion chamber or one of those new parts installed incorrectly. as for the carbon build up, you can try doing the seafoam treatment (google it) or running some seafoam in the gas tank for a few fill-ups.

Thanks for the info.

 

[evilunclegrimace]

Have the timing checked to make sure that the base timing is correct and that the ecm is able to advance the timing.

 

[Urambo Tauro]

The dealership already checked timing, but I just noticed that it's not yet clear if they checked the valve timing, or just the ignition timing. I wonder if there's any chance that the timing chain could have slipped a tooth. This truck is a '93... how many miles are on it?

 

[Pete1949]

The dealership already checked timing, but I just noticed that it's not yet clear if they checked the valve timing, or just the ignition timing. I wonder if there's any chance that the timing chain could have slipped a tooth. This truck is a '93... how many miles are on it?

This engine is a Jasper reman with 32 k on it. but has the factory distributor. New throttle body with new injectors about three years old. the injectors were checked and found to be working correctly.

They have only checked ignition timing.

 

[evilunclegrimace]

The dealership already checked timing, but I just noticed that it's not yet clear if they checked the valve timing, or just the ignition timing. I wonder if there's any chance that the timing chain could have slipped a tooth. This truck is a '93... how many miles are on it?

Will you clarify what you mean by checking valve timing? This usually done when the engine is being assembled and the only way to verify that it is correct is to pull the timing chain cover and check the cam gear alignment marks.

 

[Urambo Tauro]

When I asked that question, we didn't yet know that the engine was a recent rebuild. I was still under the impression that it was 25 years old, and probably had a lot of miles on it. And since the water pump had been replaced recently, I figured there was a chance that someone (perhaps the same dealership) might have taken that opportunity to throw a new gasket on the timing cover, while inspecting and replacing the timing chain if necessary.

But at 32,000 miles, this newer engine should have plenty of time before the chain wears out enough to cause any problems.

 

[Pete1949]

Will you clarify what you mean by checking valve timing? This usually done when the engine is being assembled and the only way to verify that it is correct is to pull the timing chain cover and check the cam gear alignment marks.

That procedure has not been performed. I'm going to pull the distributor and check for any play that may cause a possible misfire.