Timing Issues....Need Help

[readymix]

Here is the situation. Fresh Rebuild on an 87 350 TBI. Has less than 2 hours on the motor so far.

When we set the baseline timing it goes perfect. Right at 0deg. Then i plug in the timing connector and recheck the timing and it will advance when the engine is revved up a little.

We shut the engine off and then restart it and it all goes to crap from here. As soon as it starts the timing is retarded about 16deg BTDC. If we unplug the timing connector it will reset to 0deg

What should we replace. I have spare parts available for this if i take them off of my truck. I just know that someone has an advanced (not Haynes) version of the ESC troubleshooting guide.

I'll put up pics of the motor later

 

[1-ton]

As soon as it starts the timing is retarded about 16deg BTDC. If we unplug the timing connector it will reset to 0deg

That is a wierd one. The only thing I can suggest is to disconect the the negative battery terminal for about five minutes (to reset the ECM), and then take the truck out for a drive, so that the ECM will adjust itself to the needs of the truck's engine.

 

[readymix]

Tried that last night. I will go do it again though. I will be outside all day on this i think.

 

[3 on the tree]

Does your rig have a knock sensor??? If so, I would replace it and see if that is the culprit.

 

[dyeager535]

Saw a post on another board where the timing was at insane numbers, (it was an injected Camaro) turned out to be the pickup coil IIRC.

Only need to pull the ECM fuse to reset the ECM, and it takes about 20 seconds.

 

[1-ton]

Only need to pull the ECM fuse to reset the ECM, and it takes about 20 seconds.

And you will not have to reset your radio preset buttons, and clock.

 

[readymix]

I was thinkning about the knock sensor. I looked through the haynes and the T/S procedure for the KS does not pan out. I tested it on the other truck and came up with the same readings. Any insight?

Also we have eliminated the ESC.

 

[dyeager535]

Eliminated ESC as a culprit, or removed it?

 

[Thunder]

I am thinking pick up coil or maby distributor module. ECM uses both to set the timing.
Clear the ECM. Start it. And check for codes. Dont un plug the timing bypass because it will throw a 42. That is the code to look for if the pick up coil is bad.

 

[readymix]

dyeager535

Eliminated ESC as a culprit. We took the one out of my truck.​

Thunder

I am going to also swap the Coils. What exactly is the Distro-Module??? I am not familiar with that term although i probably already know what you are referring to....just under a different name.​

 

[Thunder]

Black box in the dist. AKA Electronic Spark control module. (ESC)

 

[readymix]

Thanks. Already covered that.

The ESC on this truck is mounted to a bracked right next to the TPS and IAC though. No in the Distro...?

 

[Thunder]

OOps sorry (old age is catching up to me) I ment the EST module in the dist. Yes the ESC is the square thin module by the TPS It works with the knock sensor to retard timing. They are usually pretty reliable tho and dont go out very often. failure is usually associated with a code 43.

 

[readymix]

Cool, I will go swap out the EST Module then. Be back later with any updates.

 

[Thunder]

While you are in there. If you have a ohm meeter check the two leads that come off the pick up coil. Should be 500-1500 ohms between them. If out of range the pickup coil is bad