Timing 95 4.3 W PCM

I can't seem to find the "shunt wire" to discuonect so that I can set the timing on my engine. Under hood? by PCM under the glove box? Please Help!

So here is my situation, I have 1995 Blazer with a 4.3 L, Vin W engine with CPI and standard distributor engine. The computor is located below the glove box inside the cab. I replaced the engine with a stock reman motor. I set the engine to TDC on the #1 cylinder and installed the distributor to so that the rotor is pointing to the # 1 plug wire. It started up no problems, but per the new engine install instruction I need to set the timing first thing. The engine has a wandering idle speed. Per the Chiltons manual "The timing systems must be bypassed prior to checking the ignition timing. Locate the single tan wire with black stripe that's conected to the distributor and unplug the connector. Don't unplug the harness connector from the distributor." This is the wire I can't seem to find. My distributor has two connectors comming from it. One has two wires that go to the coil and the other connector's wires appears to go directly into a larger wire harness. I am struggling to find this wire that disables the computer control of the timing.

Sorry for such a brief post the firist time, I am new to this fourm.

Any help would be appricated,

Thanks

If you have the "W" engine and PCM, there may not be an EST bypass connector. With that type system (Enhanced Distributor Ignition, or EDI) the distributor incluides a cam position sensor beneath the rotor. The only thing you need to do is verify that this CMP is in phase with the crankshaft. If the CMP is not "on" when the #1 cylinder is in the TDC position, the spark timing may be erratic and the "Check Engine" light may be on.

Blue Bowtie may be right, but just to make sure, its located on the passenger side kick panel, under the dash, passenger side, behind the carpet. Pull the carpet off a little, and if you have one its there.

If you have a vertical (spark plug wires connect to the top of the distributor cap) its most likely you have the older HEI system, and there is a bypass wire to set base timing. Good Luck!

blazes makes an excellent point to simplify this - If the cap is the older style, you likely have HEI and an EST bypass. I'm not sure what year the break point was for the enhanced distributors.

Thanks for the help. I do have the HEI ignition with the EST bypass. The connector was located attached to a wire bundle going into the ECU. (Tan wire with black stripe) I had previously opened the panel on the passanger side below the glove box where my ECU is at. When I followed the wire bundle from the ECU towards where it goes into the firewall, I found it. Not sure if I would have be able to get to it by pulling back the carpet as the wire bundle comming out of the ECU was heading up behind the glove box.

Anyway, when I unplugged it and started the engine the SES light came on and the idle was steady. I adjusted the timing, but needed to remove part of the stock air box so I could see the balancer and timing mark on the timing chain cover. When I reconnected the EST bypass, the SES light went away. Yea!!

I found this diagram which also helped me to understand what to look for.


http://img358.imageshack.us/img358/1705/timingconnectorpz9.gif

Should I reset the ECU (computer) by disconnecting the battary for 10 minutes or am I good to go seeing that the SES light went out?

Thanks again.

John

If you have the computer on the passenger front tire well in the engine compartment, you can't time the engine.

Should I reset the ECU (computer) by disconnecting the battary for 10 minutes or am I good to go seeing that the SES light went out?

Thanks again.

John

Good thread fellas.

I wouldn't try a reset, looks like you're ok now.

Yes, always clear the computer after setting the timing.