81 Turbo Monte won't run on computer

[dhattey]

Hello all

I am reviving an 81 Monte Carlo T-Top Turbo with automatic tranny. It didn't run when I got it (barn find), opened up top of engine and everything looked great, turbo is tight and spins freely, only bad parts I found were the EGR solenoid (anyone have one?) and the knock sensor (connection was broken off sensor, replaced it with a shiny new $104 replacement). New gaskets, wires, plugs, caps, rotors, rebuild on carb. Now the problem:

If I disconnect the 4 wire connecter from the distributor, it starts great, timing is right on 15 degrees, and it runs weak but it runs down the road. Plumbed a test vacuum/pressure guage into the passenger compartment and its getting up to around 0psi but no real boost - attributed that to the lack of computer control and spark advance.

But if I hook up the 4 wire connector it immediately retards the timing fully (off the scale, can't even see the mark) and it bucks, snorts, even backfires through carb occasionally. Takes a lot of nursing of throttle to even keep it running. Scared to try to even get it into drive with it running this bad!

ECM is not throwing any codes - repeats "12" over and over as long as test connector is jumpered.

I started another thread looking for where the ESC is so I can ohm out the connection to the knock sensor and run through the diagnostic procedure in the shop manual.

I don't know if the car ran when parked, but its in great shape - the interior cleaned up great and the paint even took a shine.

Any ideas? Anyone see this before?
thanks
Dave

[charlief1]

It almost sounds like you've got the distributor in the wrong place. Check the timing with the esc and remember you have to short out the aldl to time it properly. Just plug into the diagnostic plug and time it.

[dhattey]

I thought timing was set with 4 pin ESC to Distributor disconnected to put HEI module in control. I hadn't heard of jumpering ALDL - do you leave the ESC connected in that case?
thanks

[charlief1]

The computer sets the timing but the esc retards the system in the event of knock. I may have the wrong procedure but I think that is the right way to set the timing. Either way you have to short the esc to set the timing and set it first then the esc and computer take over.

[SloGN]

ok what i would do is try unplugging the knock sensor and see how it runs witht he 4 pin harness connected to the dist.


if that don't yeild and good results try locating the ESC module (should be located on the pass inner fender) unplug it and see how it starts running.


The esc module is what commands the ign timing to retard when it get a knock signal for the knock sensor.

The ecm may be apart of that too i i don't think on the early models.



HTH

pat broughton

[Freddie's Buick]

Originally Posted by dhattey

I thought timing was set with 4 pin ESC to Distributor disconnected to put HEI module in control. I hadn't heard of jumpering ALDL - do you leave the ESC connected in that case?
thanks

It's the EST, (Electronic Spark Timing), 4-pin terminal one unplugs at the distributor, not the ESC terminal on the distributor.

You can then time the vehicle by shining the timing light onto the timing marks on the pully.

Jumpering the ALDL inside the vehicle, below the radio bezel is just to diagnose the ECM, (Electronic Control Module computer), for codes.