Iroc_Z28

here is my problem it is with a 89 350tbi it is like the timing wont advance and retard..i was looking on the block for a knock sensor and found it but is has no wire running to it and i couldnt find anything that looks like it should go to it...also someone told me to check my electronic spark control module..where is this item located and what does it look like.....here is what all i have done so far it has new plugs, wires, fuel pump, fuel filter , new cap and rotor button and none of these items has helped...thanks for your help

Damon

If the knock sensor is not connected the ECM should throw a code and light the check engine light. If that's not happening you have to figure out why first. Even if the knock sensor is not connected and you have a check engine light the timing will still advance under ECM control, but it will be a very weak advance curve since you will be running in "limp home" mode.

The ESC on my brother's 87 was located near the power brake booster inside the engine compartment. This is a different module than the ignition module which is located inside the distributor.

Stoopalini

Here is a good graphical breakdown of the TBI's component layout.

Hope it helps. I got it from http://www.goingfaster.com/spo/spo_t...y_central.html



Thomas.

Stoopalini

DOH! I just realized you have a 350, and not the LO3 ........ oh well, maybe it will help you a little anyway?

Thomas.

RyanSS

what could be the cause of the SES light not coming on when the knock sensor is unplugged?

Iroc_Z28

really i dont know what would keep the light from coming on...but i know the light works...i just had one mechanic tell me it was the esc ....i really have no idea what is wrong with it but i have replaced everything except that and i have had the timing checked twice and it has been right both times..

Nitroburn

This might be a long shot but it happened to me. I was getting code 42 (ESC) and like youself, my timing was not advancing at all. I purchased and replace the ESC module but that didn't fix the problem and I still go the code (so I put the old on back on).

I then purchased a new ignition module (the one that goes in the distributor). Hooked the new one up....car would not fire at all!!!! Put the old module back it, it started. However, it did not throw the code and the advance was working properly!?!?!?!?

Come to find out, there is two wires from the pickup coil which plugs into the ignition module (green and yellow). These two wire are susposed to be in a plastic plug housing. Mine were not. When I hooked the wires back up the ignition module, I reversed them. Problem solved.

Check your wires going from the pickup to the module. If they are in the plastic plug, then you should be ok as it will only plug onto the module one way. If you just have the bare terminals going to the module, the green wire (as it is one mine) should be on the OUTSIDE pin of the module when mounted.

Mike