1995 S10 2.2L - Code 32 But...

[whitedavidp]

Didn't have any tranny fluid around so stuck it out with Liquid Wrench. Followed your instructions and, after a long time and a crazy amount of effort, the O2 sensor is out at last. Doesn't even have that many threads! Later I will try to fire it up and see what happens. Hopefully nothing bad. I presume I will get an O2 sensor error of some sort. When I put the thing back in there, what should go on the threads?On my Volvos I use wheel bearing grease - careful not to get any on the sensor. But maybe anti seize is better? Never had any of that stuff. Thanks

[bellaCuba]

Yes, when I install them, I typically use copper anti-seize. I don't like the gray stuff and it doesn't work on the high temp things anyway. If you can't get a hold of copper anti-seize, then go with the grease. That's fine.

[whitedavidp]

Well I am just in from taking a short test drive with the O2 sensor out. All windows open, fire extinguisher at the ready, etc. I did a short loop that included a small hill.

The other day, the engine would simply not rev high enough to be able to climb that hill with any power at all. Today, without the O2 sensor in place, it climbed it just as normal. Obviously more noisy but in terms of power and engine RPM response, it was normal.

From this I feel I must conclude that there is a very high probability that the exhaust system downstream of the cat converter is plugged. I see no other explanation - especially knowing that the original cat converter was said to be 50% disintegrated.

I sure feel that when a muffler shop finds such a condition they should test for such a condition (if they can) or even try to blow out any debris (if they can) as standard procedure. But this one didn't. Oh well.

Now I have to review the theory of operation on the EGR valve. Since this basically sits atop the exhaust system I cannot help but wonder if it can possibly operate properly when there is a high level of back pressure. After all, it seems to be powered by nothing but intake vacuum. I know nothing about this but it seems like there may well be a connection.

Now to find a shop that can install a cat-back exhaust system here on the island where I live. I don't want to drive the car very far so it will likely have to be towed.

Thanks

[bellaCuba]

Originally Posted by whitedavidp

I see no other explanation - especially knowing that the original cat converter was said to be 50% disintegrated.

I sure feel that when a muffler shop finds such a condition they should test for such a condition (if they can) or even try to blow out any debris (if they can) as standard procedure. But this one didn't. Oh well.

I totally agree with your statement. We, as repair techs, should ALWAYS check the work done afterwards anyway. In this particular case, I also agree, the mechanic knew how bad the cat was after removal. In his place I would've gone a step further and check the exhaust for restriction. Even if needed to charge extra (and the "go ahead" from the customer), I would have attempted to have it done right the 1st time. This is what separates good shops from the ones out to make the fastest buck. No care about the quality, just do it to get paid. Grrr. More & more common.

Originally Posted by whitedavidp

Now I have to review the theory of operation on the EGR valve. Since this basically sits atop the exhaust system I cannot help but wonder if it can possibly operate properly when there is a high level of back pressure. After all, it seems to be powered by nothing but intake vacuum. I know nothing about this but it seems like there may well be a connection.

I'm quite sure there is a motor/solenoid to operate the vacuum to the EGR. As far back to the mid 80s, all the S10s have a similar motor/setup. I'll post an image to help guide you. But on the EGR Solenoid, there are ports for the vacuum hose hookups. From the Solenoid, one hose goes to the Throttle body, the other goes to the EGR Valve. The Solenoid is operated by the ECM...

In idle the valve is closed, even on light acceleration it may stay closed. The valve recirculates the exhaust gases into the intake manifold... this is why the manifold can't control the EGR. These valves also need a certain amount of exhaust backpressure to work..

I know I've seen a few videos on their function... there are different types & they work differently. I'm sure a quick search on Youtube will do it.


Great job in testing and very logical way about it.

[whitedavidp]

Thanks again for your help and encouragement! I have read about different EGR valve designs and my Chilton's talks about 3 different ones but I cannot find out if my system is "ported", "negative back pressure", or "linear". My guess at this point is the latter. Either way, even though I got an EGR gasket today I am going to refrain from doing anything with the EGR until I get the exhaust system dealt with. Then I can clear the code and see if it comes back again.

In partial defense of the muffler shop, I have to say that this was all done ad-hoc. My wife just showed up at their door. No appointment, etc. There were folks with appointments standing around waiting while they did the truck. And they did well to force the truck into their schedule. Still, after seeing the condition of the cat converter it seems like it would have made good sense to check and do it all at once. Of course, no warranty that they'd have a cat-back system for the truck in stock anyhow.

I would wonder if there is any way to "save" the existing muffler and pipes? Could the pipe be cut and the cat converter side plugged temporarily and somehow blow out the debris with high pressure air through the cut? The tailpipe is known to be shot so maybe it is best to just replace all. But I do wonder if, once cat converter debris goes downstream, there is anyway to get it out again.

Cheers!

PS, I just remembered that I have a lighted inspection camera that records video on my phone. I bought it on a whim. Maybe I can send it up the tail pipe for a look around?

[bellaCuba]

I was posting these images for another thread, but some may be relevant here too... just for future reference.

image 1, Typical Chevy EGR Solenoid
https://www.dropbox.com/s/rx49erkvfo...26.46.jpg?dl=0

image 2 I'm pointing to the vacuum hose that goes to the EGR Valve
https://www.dropbox.com/s/awda6843an...27.02.jpg?dl=0

image 3 I'm pointing to the vacuum hose that goes to the TBI, to feed the vacuum...
https://www.dropbox.com/s/5ij6hbxhuw...27.13.jpg?dl=0

As far as your last post and possibly using the scope camera, I doubt you'll be able to see much up the tailpipe end because of how the baffles are setup in the muffler... However, maybe using it in the downstream O2 sensor port towards the muffler, you just may find something. As long as the blockage is not in the muffler. *shrugs*

[whitedavidp]

Thanks. You are correct that I did not get very far with the scope camera this morning. Oh well!

I tried to look at those photo links but got 404 errors on all of them.

Cheers

[bellaCuba]

Ahh yes, I just copy & pasted. I verified on the other post but the mere copy/paste method must've screwed it up.. I'll fix it now. Ty

Update, they're fixed

[whitedavidp]

Same has happened to me many times. Thanks for the updates. That engine looks pretty different than mine. But I think I have similar components/mechanisms. Cheers and thanks for all the help.

[bellaCuba]

Oh yeah, mine is a 4.3 s10 blazer, but like you said, many of the components are similar. The s10 series all are quite similarly set up.

[whitedavidp]

got the truck back yesterday from having new muffler and tail pipe installed. runs normally now as I expected. Thanks for all your time and help.

I am still getting the code 32 even after clearing the code the other day. So I guess the EGR system is next on my list. It is always something!

Cheers