Clay Assassin

Troubleshooting the EGR system, code 32 on a '89
Idiot light only comes on while highway driving.
I know how the system works, but I get a little confused on the laungage in the descriptions.

Anyway, stuck a mirror in there to see, and applied 16" vac to the egr.
I expected this thing to really move to the open position. It appeard to just flutter a little. it opened, but not a whole lot. And maybe didnt stay open.

Is this thing supposed to open wide, or just a tad?

Thanks

mikey whipreck

The EGR valve should open a noticeable amount and not move when you apply vacuum and are looking at it. If it doesn't, the diaphragm in it is probably leaking.

That said...

I dont think that is causing your code 32. On my '85 I believe the only part of the EGR system that can cause a code to be thrown is the temp switch itself. On mine, the temp switch is stuck into the side of the valve. I do not know what your's looks like.

If you do some digging in the archives, I believe you should find the EGR troubleshooting flowcharts from the FSM (if you don't already have one).

SunCr

Check vacuum source - from under the throttle body to the solenoid, teed off to the Charcoal Canister. Mine likes to come apart at the T.

65Z01

I'm not sure how far the EGR Valve should open but after you apply vacuum the EGR Temp Sw (on the EGR Tube) should close due to hot gasses flowing through the EGR Tube. This is not happening after the ECM calls for EGR and that is why the code 32 is being set.

From your test I would suspect that the EGR Valve needs to be replaced.

Clay Assassin

I could just go buy an egr, or, I could buy a tee and some rubber hose, and tee my gauge into the egr/vacuum source.

That way, if i'm loosing vacuum when attached to the egr, I would know it was leaking by the reading.

I'm just worried im missing something. I am not sure how to ground the gry wire on the egr solenoid to activate it and test the solenoid. Anybody done this?

I could probably test the temp switch with a multimeter, but honestly, electronics are not my bag and I am far from my skill set with this stuff.

65Z01

You should be able to (carefully, the hard vac line is brittle) pry the connector off the EGR Sol to jumper. Then jumper the Pnk/Blk wire to the EGR Sol connector and ground the Brn wire contact at the EGR Sol connector. If you can trace the Brn wire to where it's accessable, you could (carefully) cut away some insulation and ground if for the test.

The hardest part of replacing the EGR Valve is getting a wrench onto those two bolts as there are star washers under them. I use a small box-end wrench and some lever to crack them loose.

Clay Assassin

busted the hard vac line already....
I'll try to test it tonight.

Thanks!!!

65Z01

You may be able to patch that line with some rubber vac tubing; I picked up a new one from my local Chevy dealer a few years ago.

C4boy

A bad EGR valve will not throw a trouble code. If you can reach the valve, one simple way to test it is this. Push up on the diaphragm from underneath and hold your finger over the nipple. The diaphragm should stay up until you release the vacuum by removing your finger. If the diaphragm won't hold, the valve is bad.

If you have to throw parts at the problem and have trouble diagnosing it, I'd replace the EGR temp. switch. If you see that the porcelean is cracked where the wire fits into the switch, it's probably the culprit. They're only about $10-15 bucks.

Clay Assassin

A bad egr wont through a trouble code?

My manual says if the egr fails to open, and the ECM is calling for egr, the tempertaure dignosis switch will remain open (cold) and result in code 32. Its right on the page before the trouble decision tree.

Are the later models different?

mikey whipreck

Don't forget, what throws that code is what the ECM sees as happening, which may be different then what actually is happening. On my '85, I had a bad solenoid and a bad valve, but I was not getting a code 32. I have a different EGR system then yours, however.

65Z01

Yes you have a different EGR setup (temp sw on the EGR Valve) but don't forget that the ECM will NOT call for EGR during cruize unless the coolant temp is above 175deg F. So a "stuck shut" system would not throw a code with low coolant temp.

Clay Assassin

Ah, now we are getting someplace. I only get the light when I'm cruising down the highway for several minutes. How sure are you on the 175°F? As soon as my temp gauge hit 160° yesterday, the light came on. If I goose the gas peddle for a few seconds, the light goes out a few seconds after I let off the gas. Manual says the light will go out of the switch changes position. I ws thinking perhaps after racing the engine, and stopping the vacuum might shoot up to 20". (Thats what happens on my blown 2001). So maybe the extra vac is enough to pop the valve a little and heat the switch?

One more clue: This problem just started after a drive shaft rebuild where I had to drop the exhaust. A previous top engine cleaning revealed an exhaust leak on that side. When I dropped the exhaust, I replaced the stud causing the problem, and bolted it up tight.
The insulation around the switch is kinda ratty.
The manual speaks of grounding the diagnositc lead on the solenoid.

Anybody know where this lead is and what it looks like?
I didnt get a chance to check the switch last night. I will put a multimeter on it tonight and see if its open. Then I'll try to put vac on the EGR and see if I can get the valve open enough to close the switch.
My guess is the valve wont open enough.

Thanks for the help guys. Maybe I will figure this out with your help.

patsfan

I get this code after cruising down the highway @ a steady speed ( like if I have cruise on or if I just keep it @ 70 for 5 or 10 mins ) . I was told that it would happen when I gutted my cats and the only way to get rid of it was to reprog the chip . Did U gut your cats while the exhaust was down or ever gut them ?

Good-luck I'm sure you'll find your demon
PatsFan

Clay Assassin

Still stock all the way through.

gutting the cats reduce backpressure? Maybe disrupt the flow back through the egr tube?

Slalom4me

Hmmm, symptoms sound familiar...

Anything of value here? Code 32 - Should I really care?

.

Clay Assassin

Ordered a new switch just in case. 12 bucks.

Ill give it a hard look tonight. It has always appeared to be fine when I have looked at it, but I have not checked to see what kind of shape it's in.

Slalom4me

Once again, I overlooked giving credit to Gordon Killebrew for
this tip. It appears in either Vol 1 or 2 of his 'Top 50 Questions'
booklets and it worked for me.

Gordon Killebrew's "For Your Car" I purchased several items from
Mr. Killebrew and had a very helpful exchange with him when I
made use of his telephone assistance service.

.

C4boy

Clay, the EGR valve itself is a mechanical component and does not send or receive anything to/from the ECM. It only holds or releases vacuum. The EGR temperature sensor and the EGR vacuum solenoid have wires which do feed the ECM, and can set off a trouble code. The solenoid is an electro-mechanical part, since it has an electrical component as well as a diaphragm. The ECM never knows if the EGR valve is actually working and can't get a trouble code from just the valve.

The temperature sensor reads the temperature of the exhaust gasses and feeds that info to the ECM. Once warmed up, the ECM turns the EGR solenoid on and off as needed. All the solenoid does is apply or block vacuum to the EGR valve when told to do so by the ECM.

Since your light only comes on while highway driving, that's the reason I suspect the temp switch. The EGR "diagnostic switch" that the service manual mentions is nothing more than the connection of where the egr temp sensor wire connects to another wire, located behind the distributor (took me 3 days to figure that one out). It looks like a bullet connector.

89vert

The only time a defective temp switch will throw a code is on cold start up. I would throw a code 32 on cold start up, replace the temp switch and code is gone at cold start up. The SES will still come on and off while cruising down the highway. I will have the mainfold off this winter and will replace the EGR valve then. This all started after removing the converters. I think I read somewhere that when the light goes on and off it is throwing the code because its looking for flow thru the EGR valve and not seeing it.