I've been trying for months and months to track down the cause of this EGR problem. I'm very frustrated with it all, but I really have learned alot about cars and gotten some good experience under the hood. But I still want this problem gone, none the less. Here is a list I typed up. Please offer any advice on what to do next. If you have any questions about anything below, just let me know. I appreciate it

There may be a couple things on this list that have nothing to do with EGR, but I wanted to give all the info I could. Hopefully I haven't forgotten anything...

PROBLEMS/INFO
Code 32 at highway speeds
No usual symptoms of bad EGR operation
Low-backpressure exhaust (EGR problem showed up way afterwards)
Cruise control will not engage at all
Torque converter does lock up
Electric cooling fan not coming on at high temps (if AC is on, fan is on)
Girlfriend insists my speedometer is 7 MPH off, I dunno
High idle (not sure how high, tach is bad)
Usually runs good, but has poor acceleration off idle
I haven’t noticed any detonation
Valve seals need to be replaced
22 MPG average, used to average 24-25 MPG
Possibly running rich, although:
Old spark plugs looked pretty good when replaced

REPLACED
EGR valve (positive backpressure)
EGR solenoid
Vacuum lines (ALL)
IAC valve
TPS
CTS
Thermostat (tried 180 and 195)
PCV valve
PCV hose
PCV breather
Charcoal canister filter
Cap and rotor
Spark plugs
Spark plug wires
Belt

CHECKED
New and old EGR valves (both POS)
EGR solenoid
MAP sensor
Vacuum (good everywhere, but haven’t tested vacuum on road)
Entire AIR system
All electrical connections
Injector spray pattern
Cleaned EGR passages
Cleaned IAC passage

SUSPECTS
Oxygen sensor
Park/Neutral switch
VSS
Timing
ECM

 

Clean the EGR passages...

You mentioned poor off idle response, and then also stated no drivebaility problems.... which is it because it can't be both IF they are related to the EGR.

Clean the EGR passages...

No cruise control might be the switch (common), but if you noticed you had no cruise and a code 32 started appearing at the exact same time - it's PROABALY a vac related issue. No vac to the CC - no CC. No vac to the egr system - no EGR. If the fan and CC problem happened at the same time, start checking your wiring harness for a bad ground, and hold the EGR in a seperate state.

Clean the EGR passages...

How much vac are you getting BEHIND the solenoid when the valve should be open? I see about 60+ KPa for reference purposes. What replacement valve did you use?

Oh, and in case I forget to say it.... Clean the EGR passages...

 

I cleaned the EGR passages several times.

Off idle, but only at WOT, The car is sluggish. It seems bogged down or something.

The cruise control died around the same time the EGR code began showing it's ugly orange face. Sure it could be the switch, they go bad all the time. I checked the vacuum and it was good (cruise and EGR). The vehicle speed sensor must operate correctly in order for the EGR and cruise control to work. This leads me to suspect the VSS has a problem. I get good vacuum from the throttle body to the EGR solenoid (around 20-25" IIRC). When raising the RPM, the solenoid sends a short pulse of vacuum to the EGR valve (again, around 20-25" IIRC). Something has bothered me about this though. Instead of giving continuous pulses (it is a pulse width modulation solenoid) and thus allowing a nearly constant supply of vacuum to the valve, it instead sends that short burst of vacuum and then that's it. The vacuum gauge reads around 20-25" (IIRC ) for a second and them dies off rapidly. What is interesting about this is if I unplug the MAP sensor and do the same thing, the solenoid gives a good solid continuous flow of vacuum to the valve! The valve itself functions properly. I should have gotten the replacement valve from GM but I went ahead and got one from AutoZone. I'm not sure what the brand was.

Again, vacuum is good throughout the whole engine.

The only vacuum problem that I MAY have is with the "Orb of Power" as we like to call it (the sphere used to store extra vacuum for when it's needed, by the cruise control, ect.). It WILL hold vacuum when I feed it with the vacuum pump, but it takes alot of pumping to get it to hold a good amount (~20") of vacuum. I don't know if this is normal or not though. It DOES hold the vacuum once it is in there.

Thanks

 

Well since you have some of your own ideas that you have yet to fully try, I guess the only other thing I could say if it was a GP Sorensen valve, try ring 29 instead of what ring you used... it's only two bolts and is another idea to throw at you....

Best of luck.

 

I might have to try that, but the 34 I have in there now might not want to come back out. It's a possibility.

What I'm looking for here is for somebody who might know a little more than I do to group some of these things together to track down the cause. For example, I don't have any problems that I know of with the park/neutral safety switch, but if there is something wrong with it the EGR won't work. I DO have a couple problems listed that may be VSS related, and it too has to operate correctly for the EGR to work. So as you can see, I'm following a few leads but so far all roads have led to nowhere. I'm basically looking for help going through what I know so far. Maybe this way we can piece together the puzzle.

How would I chack the VSS, other than checking for supply voltage? I cant "trick" the thing into working without the car moving down the road. Any ideas?

 

That might be hard to find......
Oh hey, if you don't mind If I say something, try jacking up your car by the dif, blocking the front tires (BOTH in BOTH directions - 4 blocks total) put two jack stands under the front of the rear subframe before the LCA's, and two more under the axle sleeves, then lowering the jack to the point that the car rests on all four jack stands with the front tires still make FIRM contact, and then readjust the jack to provide slight positive pressure.

You get five mounting points in the elevated rear, and four blocking points up front. The car won't move on you. Have an assistant turn the key and put it in drive BEFORE you get under (to be sure it doesn't torque a rear mounting point) and then diagnose as in drive, the rear tires will be turning and generating a VSS signal....

I hope you find that guy you're looking for

 

When the ECM commands the EGR it looks for a change at the MAP. Check for any restriction that may cause a slow response to the MAP. If it is TBI remove it and check the passages in the bottom of the TBI unit.

 

The vacuum line running to the MAP sensor is good. The electrical connection at the MAP sensor is good. I tested the MAP sensor and it's good. I plan to rebuild the TBI unit very soon, even though I just did a couple years ago.

 

I rebuilt my TBI Sunday. The PCV passage was completely clogged with black crud. It was about 2AM when I was doing this, so I was tired and didn't even think to check how clogged the EGR passage was. Since the rebuild, the car has run much smoother, the idle has come down a bit, and the car seems to have more power, especially from 30-70MPH. Also, I haven't gotten an EGR code since. I have driven it 200 miles without the code before, but I haven't driven a long distance on the highway since the rebuild. I will do that tomorrow.
I have a vacuum leak in the HVAC controls. I hear a hiss when I turn on the defrost. Also, air comes out of the defrost vents no matter what. The AC can be off, on , at max, anything...and I still get some air from the defrost vent. My windshield is always covered in condensation around that vent I think there is a door that controls vacuum to the vent, I will check that. Is there anything else to check? My cruise control doesn't work either and I wonder if it too is vacuum related.

 

If your cruise control doesn't work and your only getting air through defrost, than it probably is a vacuum problem. They both get vacuum from the same source.


Try tracing the vacuum lines. I'd start with the vacuum reserve canister ("orb of power" as some people call it). The vacuum reserve canister is under driver's side of the car, right under the charcoal canister and in front of the driver's side tire. It stores vacuum for HVAC and cruise. The vacuum line that comes out of the vacuum reserve canister runs up the fender to a vacuum T-fitting right next to the charcoal canister and the horns on the driver's side fender.

One of the vacuum lines on that T-fitting runs right to the cruise control servo next to the radiator on the driver's side. The other vacuum line runs from that T-fitting, up the driver's side fender, turns near the brake booster, runs down the driver's side firewall, and ends right next to the distributor. That vacuum line ends at a small gray vacuum check valve. One line that runs from the vacuum check valve, down the firewall, through a grommet in the firewall, and then to the HVAC doors. The other vacuum line runs from that check valve to a vacuum port on rear passenger side of the intake manifold.


Basically, just check all of those vacuum lines, a leak in pretty much any of them will cause the problem your having.

 

I have checked all those vacuum lines. Last week I replaced the check valve you mentioned. I am suspicious of the "orb of power" though. When I connect a vacuum pump to it, I have to pump and pump and pump before the vacuum reading indicates that it is holding decent vacuum. It takes alot of pumping to get it to 20-25". Once there, it holds the vacuum if I remember correctly. As far as the cruise control is concerned, I think it is probably the switch. Before it quit working completely, I could get it to work by first tilting the steering wheel up and then setting the cruise button. That sounds like an electrical problem or a bad switch to me, but you never know with these aging thirdgens

 

That's how mine is, as well.

 

I drove 600 miles on the highway without getting an EGR code. Tonight, I drove 10 miles to Wal-Mart and halfway there I get that SES light. I parked at Wal-Mart and checked for the code...32 AGAIN! Will it ever end?

 

Man bro Im having the same problem My car runs really good and i just got a GM EGR Valve and it comes on just like you. Its really pissing me off. I have headers, would that cause a code 32?

 

I'm sorry you're having the same problem. It really is from hell isn't it? Headers could cause a loss in backpressure and make EGR not function properly. I have a 3" Hooker cat-back with a pipe in place of the cat, so I'm sure I have lost some backpressure too. BUT, my EGR problem started 2 years after having the exhaust done. I'm lost on this EGR crap.

 

Me too. This started way before my header swap. I dont know what it is at all. Is there different styles of EGR's out there?

 

Black Widow: '91RS305TBI correct? Vin E correct? Page 2E2-C7-1 of the '91 Camaro Service Manual states under the title Negative Backpressure EGR Valve, 1st paragraph beginning sentence: The EGR valve used on this engine is a negative(NEGATIVE) backpressure valve.
As information, EGR only operates at Hwy cruise speeds, normal operating temperature. The ECM uses the following sensors to regulate the EGR solenoid: Coolant Temperature Sensor (CTS)
Manifold Air Temperature Sensor (MAT) Throttle Position Sensor (TPS) P/N Switch.
During cold operation and at Idle, the solenoid circuit is not grounded by the ECM. This blocks vacuum to the Egr valve.
Vacuum hose is cheap, get the size to the EGR valve, put in a tee and run a lenght to somewhere inside to observe vacuum when the SES light comes on. Its momentary and quick, so pay attention and have some one with you for safety. Get an idea, observation etc. I assume you have the forthought to require a GM EGR, requires no washer quess.
120 miles east of Albany, always could use help too! What say ye?

 

Hey black widow, I just noticed that you are from Albany. Lets get together and get that thing straightend out.

I am moving this week to the north end of Lee co. but next week should have some time. I also have an 89 bird (tbi) that I am stripping so we could have some doner parts for testing.

 

once you guys figure out what the problem is let me know so i can fix this too. I would really appriciate it big time guys. I just cant figure this stupid thing out.

 

Hey! Somebody else here is from Albany! Don't you just hate this town?
Thanks for offering help Big AL91 and Kyle Folds. It would be good to get together and work on these things. I live in Radium Springs near Putney.
Some of the TBI cars came from the factory with negative backpressure EGR valves and some came with positive backpressure valves. Mine, as far as I know, came with the positive. The positive that was on there worked for the first 4 years I had the car. I'm thinking about switching to the negative, but I'm hesitant to do so because something would still be wrong with something somewhere as to make the positive backpressure valve not work anymore. I'm going to drive the car with a vacuum gauge hooked up soon, I just haven't gotten around to doing it yet. Does anybody think that having bad valve seals could cause the EGR problem? I've never done valve seals myself before, but I would like to try soon. Is it pretty easy?

 

I note your quote on factory installed postive or negative EGR Valves. Didn't know that the Manual to be incorrect in this subject. Had some other checks that you might try, but since your EGR is a difference and I tend to be by the book, better not. If the valve seals have a reference to the EGR operation, must have reason beyond doubt. Good Luck!

 

Do you have the digital E.G.R. valve controlled by the E.C.M.? If you do, then you need to focus on the coolant temperature sensor, throttle position sensor and the manifold absolute pressure sensor. These feed the E.C.M. the information it needs to control E.G.R. valve operation. If you don't have the digital E.G.R. valve, then you have an E.G.R. valve that depends on manifold vacuum and negative exhaust back-pressure to control valve operation. The spurts of vacuum operation you mentioned earlier is normal. These spurts control the amount of gas that's recirculated. During cold operation and at idle the E.C.M. should be grounding the solenoid to prevent vacuum from reaching the E.G.R. valve. I need you to give me a little more info before I can really try to help you out.

1. Does the engine run rough or stall?
2. Does the engine surge when you're driving down the road?
3. Does it ever just stall?
4. Are you experiencing over-heating problems or just running hot?
5. Does the car seem to be slower than it was before?
6. Have you checked the intake manifold for leaks and to make sure the bolts are tight?
7. Is your catalytic converter even slightly clogged?
8. Have you done an emissions test to see if you're within acceptable limits?
9. Did you change the O2 sensor?

This will help out a lot. I'll keep an eye out for your next post.

 

1. No
2. No
3. No
4. Only after driving for a while and then going through a drive-thru or something.
5. Only while the SES light is lit
6. Checked
7. No cat
8. No emissions testing in south Georgia
9. A while back, I'm going to checge it again soon It might be contaminated from all the smoke (valve seals).

Thanks

 

:Ramair21; No expert, IMHO headers start o2 code problems in Injected models. And, according to all the info I have, that is a ' 91 Camaro Manual and Haynes ' 82- ' 92 Repair Manual, all call for a Negative EGR. If you are stock related, you can verify the EGR via the VIN No. All ' 90 and later model with 3.1 V6s are equipped with Digtal EGR Valves and only the most with genious attitudes can diagnose and I'll leave that portion to those to help.Two things one must know when troubleshooting EGR problems. 1. Does EGR Valve do its job if it operates alone?
Idle, almost normal temperature, lift the EGR Diaphram with fingers manually and if the Idle stumbles or stops, good. If not, take it off and clean, clean, intake and valve. If operating ok manually, 2. How many in. of vacuum occur at the EGR vacuum side of the EGR Solenoid? The Book states at least 10, say 12 or more. OK say, next would be sure the Solenoid is mounted properly, no binding or leaks(use a hose next to ear) finally get a resistance check on the coil, must be at least 20 ohms. Good Start IMHO. Good Luck!

 

Thanks Big AL Im going to check it out. i havent got a o2 code yet but the o2 is a stupid bosh one. Should i change it out? All so i know for sure i have a negative backpressue egr. When i push the EGR valve up when the car is running no change at all in the engine. I should clean out my intake manifold then huh?

 

O2, RIP! The EGR Diaphram per say is a softy material surrounded by a skeletal metal frame, pull on frame for checks. Clean out intake, probably, exhaust gas hole clogged, (tip) might be. We are still talking stock here and that nothing has been done to overcome inoperative EGR at some other point. Good Luck!

 

The question ramair21, is did you check the valve's movement when the car was at normal operating temperature? If you did, then you probably need to clean the passages as suggested earlier. Failure to do so will likely result in spark knock (read as detonation that will cause the timing to be retarded) and overheating. Hope that helps you out. Post again if you have to.

 

Thats the thing, I did check the valve movement when the car is a operating temp. I dont get over heating but sometimes i do get a knock, my timming is advanced 6*. It seems to come on when im doing about 0-70MPH anything over that it doesnt come on.

 

cut all that bullcrap out of your car already, damn leeching egr system.

 

Clean the passages then.

 

Yes, you can wipe this EGR stuff out, reprogram chip etc, and wonder every time the engine burps if its got something to do with wipe outs. Your choice. Personally, IMHO, gas now at $2.50 avg a gal in SE Ga, must be a $1 more in NY. According to that learned (limited), this failure of the EGR costs 3-5 miles to a gal, depending driving edificate. And besides, I try to master stupid things and if failure comes , will keep trying on these forums til a Master is found! Thanks for the input and Good Luck!
The Masters are on here, if you have a desire to learn more about the o2 sensors, find an overlooked item in the FQA articles under I believe " what everyone should know" Got an A/M o2, beware, again IMHO.