I had a 32, and have replaced the egr, and still have an issue. But here's the strange part. After I drive about 5 miles the light comes on. This would be completely normal to expect with an egr issue. That in itself would look like the valve is not opening. I have a new valve, and the vacuum lines are open as far as I can tell so far. However, I also have the opposite problem on occasion. Meaning, every so often I'll go out to start the car and it will die almost immediately if I don't get the rpms up over 1000. That makes it look like the valve is open and not closing at idle! Just now I took it out and drove it a couple miles, and after that little drive it fires right up normally. No rough idle, no low rpm idle, and it doesn't die if I let my foot off the accelerator. Runs totally normal. My experience, limited as it may be, tells me that when something works, then doesn't work, the works again later, that you're dealing with an electrical issue. I know egr solenoids don't often fail, but that's my suspect here. Any other insights? Oh and btw, something else I'm confused about. This solenoid has two vacuum lines. One to the egr, and another ported line to the TB. That line is clear, I was able to blow air through it. The tech article on here says "Most Third Gen. F-bodies use the basic diaphragm EGR valve, but instead of relying on ported vacuum, it relies on vacuum that is allowed to pass through a solenoid." So do I have both? What gives?

 

The code is for the ECM not seeing the EGR operating ; not that the valve itself is actually faulty
It may have nothing to do with the valve operation but is a fault with the wiring or the temp sensor that tells the ECM that the valve is working

Do the code 32 diagnostics

http://www.chevythunder.com/egr_code_32.htm

 

Yeah, I remember you telling me that from before. If I was only getting an engine light that would make more sense, but how does that connect to the fact that sometimes it behaves like it's stuck open, and sometimes closed? (Wether it actually is or not) How would the ECM not seeing the valve change that, and make it show the symptoms of doing one thing one time and another later? And how would taking it out and driving it seem to "fix it" temporarily?

 

Vette,I think we talked about this before too, my egr does not have a temp switch connector. If there is a temp switch, it's somewhere else on the motor. Until it's located, that flow chart will not work for me. The only one I know of is the cts below the throttle body. There's also an electrical connection on the bottom of the plenum between the fpr and egr, but I don't think that's a temp sensor is it?

 

Sorry , gave wrong year info

Your ECM "sees" EGR operation by the change in MAP pressure when it commands EGR operation

 

Ok. Now that makes more sense. Could be a bad map sensor. That was my next suspect. I can test that, I just need to get a hold of a little vacuum pump. Here's one more clue that might mean something to you. When I took the solenoid off, the nozzle where the TB line comes in was closed, I could not blow air through it, but I could the nozzle that runs to the egr. Now, the TB side might be shut sine the car was in closed loop, but if it's staying shut that might explain the code 32. Vacuum is not getting to the egr. What it wouldn't explain is why the car was behaving as if the egr was open at startup, unless the solenoid is working intermittently because it's failing. See, that's what makes me suspect the solenoid. If it was only the map sensor it seems like you'd get the code 32, but might not get the symptoms of an egr that's hung open all the time. I'm also open to the chance of a bad ECM. Just little things now and then have made me suspect that for a while. Lucky for me it's super easy to get to on this car.

 

Don't make this a long list of throwing parts at a problem.

The simple conclusion is that the code condemns a faulty component. In actual fact, the code identifies a problem with the system, which MIGHT include the component, or it could be a variety of other problems, such as wiring, plumbing, corrosion, or even something completely unrelated in another system. If you can afford to replace perfectly good parts with new ones until the problem goes away, that's one way to eventually narrow down the issue. It would really suck if you replaced one of everything, still get a code 32 and then finally found a connector with pin that has a soft spring causing intermittent conact. A logical diagnostic path is the easy way to get where you are going.

 

I couldn't agree more, but here's the problem. The diagnostic flow chart Vette gave me won't help me now because my egr does not have the temp switch connector it describes, the disconnect of which is necessary no matter which way you go on the chart. So if it's not on the egr, where is it? Are we talking about the cts now? What? Also, I know virtually nothing about wiring. So when the chart says "chk green wire for short to ground" I have no idea how to do that. What green wire? I don't have that temp switch connector to begin with! Now I'll grant you, I can learn wiring enough to do a test probably, but I'd still have to know which aspects of the chart apply to my car and which don't. And if there is a short in the wire, where is it? Are we supposed to pull all the wiring out of the car and inspect it? Not practicable, and therein lies the problem.

 

I just did this test of the map sensor.


I did what he said, but got no voltage reading at all from the map at any vacuum setting. I probed it with a paper clip as far in as it would go. I'm no expert on the multimeter either, but I did set it to DC and 12v, what else is there? He says if you get no voltage, then test the hot and ground wires. Ok, how do you do that? Probe and use the multimeter? I hate wiring.

 

Techcorvettecentral says this: "For the 1990-1996 EGR systems the switch was dropped and the ECM would monitor the oxygen sensor reading. The ECM watched for the fuel system to lean out as the valve opened during a predetermined test procedure in the ECM software. This is the way all late model engines monitor EGR operation, if so equipped."

Since my engine (though not a Corvette) falls in this year range, I have no temp switch. Therefore, I cannot use the flow chart linked to this thread, at least most of it. So then how do I do any diagnostics, and which ones apply to me? Just today I went out and started it. It idled roughly and would have died had I not given it gas. After a few seconds of this, it evened out. I can tell you if I take it out for a drive and come back, it will start normally. But if it sits all night, it will cough and sputter at start up. SOMETHING is leaning out the fuel mixture at startup after a few hours of down time.

 

Make sure that ignition is set to run position!
Don't hate wiring - it does a good job of routing signals between sensors and ECM. Back to MAP sensor - Pin B lite-green is a signal back to the ECM sent by MAP sensor, pin C gray wire is +5volt reference voltage, and pin A is a blk - ground return. +5 volt reference is only present when ignition is turned into engine run/start position. Please note wire colors fade over years and get covered by dirt.

//RF

 

Yeah, I had the ignition to the run position. I did everything he says to do in the video. If I had turned it any more the engine would have started. And actually, I turned it one notch and did the test then up the rest of the way--short of starting it--just to check. No voltage either way. The wire colors are still clearly visible. The green is in the middle, so yeah, I knew that was the ECM communication. Maybe I didn't probe it deep enough, but I pushed the clip in as far as it would go. I think this is moot anyway. If the map was bad I'd probably be getting a code 33 along with my 32.

 

And I'll tell you what just infuriates me. For a code 32, manual says "check for a short between terminals B and C or the wires leading to these terminals". AND JUST HOW THE BLEEP DO YOU DO THAT? How do you "check for a short"? I'm a pretty smart guy over all, but there are few things in this world that make me madder quicker than anything involving wiring. I HATE HATE HATE wiring issues, it's like chasing a frig-gin ghost. My dad went to electrical school in the 60's, and while his knowledge may be outdated, he has tried to explain many times, and I still just do not get it. Ok, now that I'm done venting, I have a multimeter, can I use that to check for a short in those terminals, and if so, HOW?