Let me give you some background to give the full story.

200 miles ago, I am at the track and the first sign of problems are a short hesitation while I am above 4500 RPM twice but no SES.

I go home and am doing other non-engine stuff with it and it dies 3 X at idle but no SES.

So I take it to work for some fun and have the EWP stop working. The car overheats but I catch it before it is in the red very long. Play with the connectors of the EWP and it starts working.

Drive home safely and replace the EWP. Contact CSR and they say to have the ground from the EWP at the battery ground not the frame. I do this.

Car starts up and runs fine at idle for about 10 minutes. I then take it out and get it above 3K RPM. It is then that I get an SES. Pull the code and it is code 36 hi-res failure. Everyone safely thinks opti.

It then sits for a week. I take it out again and get the code 36. Park it and turn off engine. When I go to try and start, it just does not want to fire. Additionally, at this time, the electrical starts doing weird stuff. The tach bounces without me even firing it. The dash lights come on briefly before turning off and the relays in the fusebox start clicking. Turn off ignition and try again. FINALLY it starts after the 4th try. Able to park it in the garage but it then dies at idle.

Question: Should I check the PCM? I don't want to spend 4 hours under my car to change the opti if it still has issues of odd flashing lights, etc.

 

Your symptoms (hard to start and keep running) are typical for missing high resolution pulses. The optical module inside the Opti generates both the high and low resolutions pulses that are sent back to the PCM. I think the tach signal is generated from those pulses.

Not sure about the other symptoms.

WD

 

95 percent its the opti but with the other symptoms it could be something not connected all the way and it looses contact. Maybe you have opti issues and when you changed the ground on the ewp it screwed with the electrical. I would do the opti anyways and also check your wiring but thats my opinion.

 

Hi Res pulse is used only at idle and low rpm. That's where your symptoms are, and that's why it's the opti. Just replace it.

 

Your tach jumping and clicking and lights flickering are from a lack of current from the battery. Most likely from the battery terminals. Remove them and others at the 2 clusters on the passenger inner fender as well as the ground strap from the frame to the engine. Clean them with wire brush or sand paper and put dielectric grease back on them and retighten.

If the problem persists, have someone crank the engine over while you read the voltage across the battery. It should not drop below 11 volts while cranking. If so your battery has an issue. Best to have a supplier load test it.

As far as the 36 High res signal is concerned. It will NOT effect the running of the engine. Says so on page 6E3-A-78 of the GM shop manual. (sorry Engineer and Vader)

The more likely cause is a DTC16 which is the low res signal and it is key to engine running. A DTC16 will NOT set an SES. I guess the one that does not effect the engine will set a DTC so you know you have a problem. As apposed to the one that effects the running of the engine not setting a DTC since the engine will die if the code is active.

Both of these signals are highly dependent on the wiring. Don't forget you have probably 10 feet of wire from the PCM to the OPTI and not 1 not 2 but 6 connectors between them as well. That is if you count all the mates to the 3 joints between them for a total of 6. 1 at the opti (male and female). One about 3 feet further on (male and female) and the last one at the PCM (again male and female). All of which need to be inspected.

Here's what I have seen from others vehicles.

 

Speedy,

Seriously kick-*** answer. Made me do some real thinking and I will do as you suggest.

 

Any chance of getting an update to this problem?????? Since we can't send PM's to you!