Alright guys, as I said my SES light was on yesterday as I drove it to work. I knew the driver's side O2 was not working.

Anway, when I got back in the car after work and fired it up everything seemed fine until for just a second it acted really stupid, the RPM's fell and it bucked like crazy, did this twice, then it drove just fine all the way home.

I got home and fixed the O2 sensor and fired it up again. I still got an SES light. Code 22, cool no problem. I adjusted the TPS a little and made that go away. I then took it for a spin. I probably drove for 45 miles or so, took at least an hour. Everything ran perfectly, no troubles with anything.

When I got home I washed the car. When I went to start it up it cranked longer than usual and immediately threw a code 36, which is related to the Opti, low resolution pulse.

Now I didn't open the hood when I washed the car, I assure you it didn't get wet. So what's going on here? This opti has less than 1000 miles on it and has not been wet.

If this thing is toast already it re-enforces my belief that the older style was actually superior. It had 76k miles on it, weighed enough to be full of oil, and had been greatly abused and ran perfectly. This new and improved one craps out already? What a waste of time and money. I suppose I'll drive it to work today and see if I can actually make it there.

 

TTT?

I drove it to work today and it still had the code.

It actually threw this code as soon as it started up, and it had to crank longer than usual. It had been firing within half a revolution, since it has set this code it has to turn over several times before it fires.

Otherwise it runs great. Is it possible that just one of the wires going to the opti is damaged somehow? I'd really like that possibility more than having to replace the stupid thing.

 

Code 36 is the Mass Air Flow burn off circuit. Check/replace the relays first if it still acts up look at the MAF unit.

 

That would be just a little impossible. My car is speed density. Apparently the engine codes are different from 91 to 92, makes sense with the LT1 and all.

Nice try though :cheers: I'd love for it to be something so simple.

 

Sorry. My 91 is also speed density but thought that the 92 went back to MAF. My bad.

Just looked it up - 94 went back to MAF. I was only of by two years!


[Modified by Steel Blue 91, 11:53 AM 8/28/2002]

 

Not sure what to tell you as far as those codes go on your model year....but check every connection again and make sure theyre clean and tight.Same for wires,opti,any harness plug etc.Sometimes it is as simple as a loose connection or something.(obvious,I know but just sorta reminding ya)
Also,clear the codes after repair attempts.

Hope its something simple...good luck and keep us posted.
:)

 

Is there a quick way to clear the codes short of disconnecting the battery?

I have to use the paper clip method to retrieve the codes.

 

Do you have a vented Opti? The manual says you can get this code if the vaccum lines are plugged. It says that this code gets thrown if the opti goes 720 degrees without a low res signal.

If it is vented, blow some air through the lines. I did this and the problem disappeared (for a while!).

My guess is that you should start saving up for a new opti. These things never get all the way better, they just tease you by running nice for a little while.

 

Actually I didn't have the vacuum lines tied to anything last night while I was driving. I did re-attach it after it set the code last night.

Maybe, just maybe this is what will happen. I attached the vacuum line but if there was any crud or anything in it, it hadn't cleared because I hadn't run it. Thus when I fired it up this morning it still set the code. Possibly after driving it to work the vent sucked whatever the crap may have been in there out. Perhaps when I go back out in an hour and 12 minutes it won't throw the code.

If not I'll certainly try to blow it out. Do you mean by mouth or via airhose, I have access to both.

 

Your problem is on the High resolution side of the input. If it were on the low side, the car wouldn't run. There is a procedure for chasing this down. The good news it may not be the opti but a ground problem. The bad news it could be the opti or ECM. If you have a Helms, it's listed in book 2 on page 6E3-A- 71. You will need a volt meter too. If you need help, email me.
Good luck


[Modified by ittlfly, 2:20 PM 8/28/2002]

 

I turned the key and it started in all of about half a revolution. So far so good, no SES light. I got on the parkway and nailed it up the onramp, no problems there.

I was headed down the parkway with the cruise set on 70 when it just decided for a few seconds to screw with me. It felt like a misfire on just about every cylinder for a revolution. I know it was more than just a simple misfire because every time it would do it my tach would fall suddenly and then come back. I don't mean fall just a little either, all the way to 0. It missed a little, missed again. I shifted into 5th, and hit the gas, it did it again once or twice and then quit. I put it back in 6th and cruised on home. It never did it again and it never set a code.

Sound like the opti?

I know it's somewhere in the ignition system because of what the tach does.
This is getting real old real fast, I don't exactly have the money to replace a piece of junk distributor that has less than a thousand miles on it and has never been wet.

 

Yep. That's almost exactly how mine behaved (code 36 and everything, except I have an A4) for the 3-4 months before I replaced it. It slowly got worse. I predict erradic idle will be your next symptom.

When the idle got bad enough, I blew it out with a can of air (for cleaning key boards and such). Instantly smoothed the idle.

As a matter of fact, I had both vaccum line plugged into each other for a while.

Contact Sam Smith at Fairway Chevy. 1-800-395-1440
(SamSmith@fairwaychevy.com)

Here's what I got:
non vented opti #10457702 $270.00 complete unit.
Shipping LasVegas to CA, $4.50.


If you've got more time than money, you could try just cleaning the opti. The terminals were corroded on mine (only 7-8K miles). But plan on a complete replacement in the not too distant future.





[Modified by John Row, 5:33 PM 8/28/2002]

 

I've got a plan. A friend of mine has a brand new one at his house that he was going to put on his car. He got it from a local dealer, being that mine is very clean I think he can get it warrantied, he's actually done it before. So I'll just use his and let him warranty mine.

Now I just have to track down another set of water pump gaskets.
:smash: :smash:

I think I could probably change just the opti in an afternoon.

 

Score another one for Jeff Kopp! These things have a 1 year warranty. He'll send me a new one and I'll send him the old one back. Won't get to do it this weekend, but it looks like I have next weekend's project lined up :cheers:

 

Good to hear youre getting a replacement from Jeff K.I seen you said yours had a thousand miles or so,and I kinda wondered if you had the unit over a year or so.Most GM parts get that 12/12 warranty so hang on to those receipts eh?
:)
Keep us posted when the car is done...heck if I ever got an LT1 car,youd probably become my opti mechanic...lol...Id hate to deal with thoise things.
:)

 

Replacing the opti itself isn't that bad anymore. I know what size most of the bolts are so it's getting pretty quick. I don't have to take that much apart either, so I should be able to do it in a day easily.

It's intermitten right now so I'm still going to hop on the dyno this weekend.