91 c1500 stutter on acceleration

[badass66ss]

ChevLoRay, it seems as these trucks are getting older with more miles, mechanical issues must be taken into consideration. Unfortunately, poor maintenance by the previous owner is most likely the cause of all of the issues we have found. Hopefully with some help we will find the final problem with the timing control. ChevyTech has definietly been a lot of help to users of this forum and we all appreciate it!!

[ChevyTech]

Thanks for vote of confidence and kind words guys.

The timing control (Electronic spark timing) you ask about could definitely be causing problems.

That fact that it runs better with the timing that far over advanced is a sign of a spark control system retarding the timing.

Knocks, rattles, ticking, clanking, what ever you have making noise, on, in, or bolted to the engine, should be considered as having the potential to cause the timing to get retarded by the system.

The Knock sensor contains a piezoelectric crystal which causes a voltage to be produced. Loose components on or in the engine can cause the knock sensor to create a voltage and the system may interpret this as pinging. The system will back off the timing to try to stop what it thinks is pinging.

Loose torque converter bolts can cause a false knock signal to be detected.

If there are very excessive knock counts the system should set a code 43.

[badass66ss]

It is not throwing any cel at all. everything on the motor is tight. We have not had the tranny out so I'm not sure about the Torque Converter bolts, but the tranny was replaced some time before I bought the truck. The knock sensor has been replaced as noted much earlier in this discussion. Other than loose components causing a "knock", is there anything else that could cause the timing to retard like this? Do you think the ECM could be bad again? I read somewhere that the battery should be disconnected each time you plug in/unplug the bypass wire. Is this correct? Could this short out the ECM? Thanks again for your help!!!