Care to elaborate?

 

If I was to diagnose the problem by studying that small clip of your log then Id say you have a rich condition. The PCM has tried and failed to correct the problem which is why you see the 108 Lterm and 96 Sterm.. those are the max fuel corrections.

Have you installed an AFPR or larger injectors w/o a new chip?

 

Nope, havent touched either. COuld this be from an exhaust leak maybe? Because I have one at the manifold.

 

Exhaust leak works the opposite way. BLMs will spike instead of drop off like you are seeing. I kinda wonder if your MAP sensor or intake temp sensor are bad since you have a 93 those 2 are essential for fuel calculations.

 

I see. I just dont get why it happens after 15 or so minutes, well after closed loop. Could a bad map or intake temp sensor act like this?

 

Weird question....what does your voltage guage read or do when it does what you described related to poor performance.

 

The last scan while this was happening showed 12.9 volts and I think the gauge was coresponding. New battery as well.

 

Also, if the opti was going bad, I would tend to think you'd see really high integrator spikes as the O2s see fresh air (unburned mixture has high O2 content...just like a pre-O2 exhaust leak).

But I'd be willing to say that code 36 means you need to replace your entire opti.

 

WHat is the hissing sound I hear when it idles once the problem starts. I just took the car out, ran fine then slight hesitation then it got progressively worse. As I idled in park in my driveway the idle was very erratic, then a hissing sound would come on, real loud, sounded like coming from drivers side, maybe 30 secs, then stop. The idle would get a bit better and then decline and the hiss would come back. What is this? It only happens when the car runs poorly, never close to startup.

 

I think what you're hearing is the air rushing past the IAC. With the intake ducts in place the sound will seem to come from the air filter area. If you remove the elbow and let it idle while the trouble is occurring, that would make it easy to tell if the sound was coming from the IAC passage.

If it is that, mine has been doing that same thing. On mine I was able to figure out it always misfired right before that would start happening. I think it ends up doing that as the computer changes the IAC position in response to the change in vacuum due to the misfire. While trying to figure out my problem I actually unplugged the IAC as it was running, it stopped the surges and strange noises and made the miss easier to realize.

I think that's due to the miss, so I am fixing that and we'll see if it fixes the rest. Should know tomorrow in my case, hopefully.

 

I know you've been at this problem for a while and I can guess it's gotten about two miles past frustrating, so I've got something for you to try.

Earlier you mentioned you received a code 36, signaling potential problems with the optical sensor. Mine did not throw any codes, but it seems your problem is more severe than mine. One thing I noticed while monitoring live sensor data is that I occaisionally got a ridiculous RPM readings when it was acting up. "Actual RPM" did stuff like go from 650rpm to a supposed 4350rpm a half second later, then back, while idling. That could also explain why the tachometer would twitch like it wanted to jump up. So that's why I'm in the middle of an opti change. From the wiring diagrams I can find the PCM determines RPM from the optical sensor.

You have an AutoXray scanner, I would put it on live monitor while the problem is occurring and just keep watching the actual RPM reading. I too have an AutoXray and think I wasn't able to see this happen too easily as those scanners update only every half second, so it could easily miss this happening, as the PCM might see 8 other readings per second that the autoxray might miss.

Tomorrow I should find out if the opti solved it, and will let you know.

 

I checked all the wires and harneses connected to the opti and they look all right, at least to me. Im thinking about just ordering an opti...

 

Well, if you are having the exact same issue as me I may have good news. New opti is in, and if it still has the problem it's not noticable so far. Before I began disassembly it would begin misbehaving in less than 20 minutes on a hot day. After finishing the opti I just ran it for 75 minutes and the problem hasn't occurred. (oh yeah, it's a hot day)

I also noticed it idles smoother, and is more responsive to the the throttle. Exhaust tone seems a bit sharper too. No signs of erronious RPM readings either. I will continue testing, but looking good so far.

 

Congratulations, Im glad you got your problem all sorted out! Our problems seem a little different, mainly mine seems more severe in that after the problem occurs, the car is almost incapable of driving within minutes. Regardless I think Im going to call up Dal and ****** up an opti tomorow. Did you change the waterpump too? If so what'd you get?

 

1 hour test drive during rush hour, with some spots here and there to open her up a little, definately a little stronger. No problems. I am real jumpy still worried it might reappear, even the slight change in rpm with the a/c cycling on and off makes me nearly panic for a moment.

Yeah, I think yours is the same basic thing just more severe. Mine the car didn't even throw a code, it didn't seem to care.

I did put on a new water pump too. I was going to just get a reman from the local parts store, but it looked less like reman than it looked used. They had a brand new one in stock so I took it instead. Wish I had known beforehand, I could have gotten a new GM WP for the price I paid for this unknown brand. ($133)