First of all, I'd like to say hello to everyone...I've been a member of the board but haven't posted because I usually find the help I need doing a search, but it's time for me to break my silence.

I've got an 88 Camaro with the LO3 and it had been throwing Code 32 for a long while, and in turn was cutting off at times while stopped. I followed all the advice on testing the EGR system and came to the conclusion that the vacuum solenoid was bad, but I went ahead and replaced the EGR valve itself because it had a lot of carbon buildup and I wasn't comfortable in attempting to clean it. I also replaced the vacuum lines and then put it all back together only to have it act WORSE than ever before.

It's very hesitant in acceleration and it idles worse than ever before and I'm clueless in what to do about it. A friend of mine who's very affluent with cars simply told me to take it to someone to scan it. Ever since the swap, I've been getting a code 33. At one time, I had a Code 32, 33, and 45 but I erased the memory and now I'm getting only Code 33.

Any advice as to what to do next? Am I overlooking anything? I also took out the IAC valve and gave it a good cleaning, but nothing has improved. Thank you in advance for all your help.

 

Glad to hear about the success with searching.

I'm going to move this from Tech/General Engine to the TBI forum, so they can straighten out any mis-statements I may make.

Code 32 & 33 sound like BAR and MAP sensor problems to me, not EGR. However, I'm going off of general code tables and not those specific to LO3. 45 is O2 sensor rich, which would follow if the other two sensors are wacky.

TBI guys, here's the ball...

 

Code 32 is an EGR fault. IIRC the fault can be:

A. the EGR won't work during cruise (the MAP sensor should "feel" the burp of the EGR when it's turned ON), or

B. the EGR is always (accidentally ON) because of carbon buildup holding the valve slightly open --- this would cause an very unstable idle, or perpetual stalling (in the worst case) because EGR should be off at idle; the engine wouldn't see the EGR turn ON at cruise because it's always (accidentally) on, or

C. the EGR passages are clogged shut, so no matter what the EGR control solenoid does, the MAP never senses the presence of EGR. The clog is probably near the valve itself, it's where the passages are the smallest. Again, the EGR code can be triggered because the MAP never senses the pressure change when EGR is initiated.

All three of the above can trigger a code 32, albeit for different reasons. A bad EGR solenoid (control the vacuum applied to the EGR valve) can also fail to make the EGR work, as will a broken vacuum line to the EGR solenoid.

EGR function, and the reasons for the code 32 are almost always in the FSM (factory service manual) and the diagnostics are something like what I just wrote. IIRC.

A good mechanical cleanout of the flange for the EGR might solve the problem, but you may also need to use some spray cleaner and let it soak to help free up the carbon buildup. I had a Mopar slant6 once and the EGR port at the base of the intake was totally closed from carbon..... so the EGR wasn't functional even though all the hardware was there and working fine. HTH.

 

You can test if the egr passages are shut by pushing on the valve by hand, if it bogs down you're not clogged.

Other than that little tidbit, i'm still stuck with 32 too. There is little else besides going to a shop or doing some data logging to see what's wrong.

 

One of the problems I've had with this new EGR valve is that it's hard to test by pulling up on the diaphram because it's one of those "universal" types that comes with the assorted washers--and the holes on the bottom of the valve are very small and make it difficult for me to pull up on the diaphram.

What I may do tomorrow is take the EGR valve back off and take a look and see if there's a lot of carbon buildup on it already. Would running the motor without the valve on it help clean out any excess carbon buildup? I might try doing that if it won't hurt it.

 

Ok, so I finally got to remove the EGR valve today. It was covered in a lot of carbon, as if it had been on the engine for many years. What could cause such a build up?
I tried revving up the engine several times without the EGR valve on to try and displace the buildup. Could something else be going wrong that I am overlooking? Thanks for all your help thus far and in the future.

 

i had a EGR problem for the longest time until i bought an negative backpressure EGR valve for a tbi truck, since the new valve i havent had any problems.

 

What kind of truck did you order this negative back pressure EGR from casue I hear that headers and catbacks don't have enough back pressure to work with the stock EGR. I think this is my problem.

 

Ok, so I finally got to take the EGR valve back off a few days ago, and came to find the washer was loose but I don't think it had much to do with how it was acting because the car acted the same way with the old EGR valve as with the new one. I'll probably go get an AC Delco valve since I know they're not like the ones you buy at Advance or Autozone.

Also, my old EGR valve is a negative backpressure valve as designated by the N on it. I really wish I could get this fixed, I miss driving my car and I won't have any more off days until New Years Eve.

Anyway, thanks for all your help and ideas, please keep them coming.

 

Ok, so now I'm gonna have to give up and take it to a shop. I don't have a lot of time to do the work myself. I seem to be hurting more than helping. I'll be sure to post the findings tomorrow evening when hopefully my car will be running in all its glory again.

 

Does the EGR affect gas mileage. When the SES light goes on for EGR code 32 I can watch my gas gauge drop even when on the highway at cruise.

 

Yes, it does affect gas mileage. It basically sends some of the exhaust gases back through the motor to try and completely burn off any excess fuel, etc. from the exhaust, IIRC.

 

Well...so much for having the car fixed today. The place I had it dropped off at didn't even have the software to read the codes. News that would've been relevant yesterday. Oh well, I don't know what I'm gonna do as everyone else seems to be busy, and with me at work 9 hours a day, I can't just ask my dad to drop the Camaro off at every place until someone can find the proper software to read the codes. I probably could've told them the codes and they would still be clueless. Anyway, I'll update if anything positive happens. I'm sure it'll be something mindnumbingly simple that I just completely overlooked.

 

I'm having the same problem.. but with my Camaro... 2.8L EFI... I get the light while driving.. it varies.. can be from 5 miles out to as much as 80.... The shop said it was just the EGR and disconnected it.... well now I saw that the plastic line to it is all cracked up... how expensive/hard is it to replace? I also watch the gauge go down... Would love to get this fixed.. but VERY limited finances... I've driven with it like this for the last 5 or so months.. I suppose I can wait another 4 or 5 till summer kicks in and I can get a closer look.

 

KnightConvoy,

OK, first, did you replace the vacuum solenoid? You said you figured out it was bad but you didn't say if you replaced it or not. Next, I don't trust those universal EGR valves. I went through some similar headaches trying to find a direct-replacement EGR valve instead of the universals in which you have to install orifices, washers, or whatever those things are. The dealership is the best place to go for a direct replacement AC-Delco EGR valve (that's where I ended up getting mine), if you do decide to get a new one (you mentioned it earlier).

You mentioned that now you are getting a code 33, which is not for the EGR valve at all. It's for the MAP sensor, this is the info I get for a code 33:

Code 33: MAP sensor- Leaking or restricted vacuum hoses; poor electrical connection, open or short in circuit; defective MAP sensor; defective ECM

The MAP (manifold absolute pressure) sensor is located on the top lip of the firewall on the passenger side. It's located above the transmission dipstick and in between the motor and the big black AC box. It has one vacuum line attached to it and 3 wires. Check the wiring for burns, cracks, or shorts, and double-check that the MAP sensor vacuum line is good and is hooked up to the back of the TBI unit and the MAP sensor.

 

As far as "reading the codes" is concerned, can't you do that manually by turning the ignition ON and then shorting the right pins on the ALDL connector, and then watching/recording the flashing lights on the dash? Why do you need a shop, or a code readers/scanner to do it?

I'm sure the detailed instructions are here on TGO if you search. I usually just look them up in the FSM, but not everyone has one.

And FWIW, EGR isn't there to burn fuel that wasn't burned on the first pass thru the engine. It's there to purposefully recirculate a little of the combustion product back into the intake to (A) lower the subsequent combustion temps, and (B) allow a very lean mixture to be burned without fear of detonation. EGR is also used only during street/highway cruising. It's not used at idle and it's not used at WOT.

Detonation = explosion of the mixture, which you don't want because it subjects the piston/rod/crank to a high-impulse shock loading. Instead, you want the mixture to be burned so that the loading on the engine is smooth (no shocks).

As far as lowering the combustion temps (I know that sounds odd, adding hot exhaust to lower the burn temp), it's done to prevent the formation of nitrogen oxides (NOX) so it's done mostly for emission reduction... and I'll leave the details of how to the chemists.

So EGR lowers emissions AND allows lean burn to occur. so the fuel economy can be improved.

Cams with "high enough" overlap don't need an externally-fed EGR because they always retain some of the exhaust in the cylinder, by pushing some of it out into the intake ports where it then gets fed back into the engine. "High enough" in GM terms, means a cam that has as much, or more overlap, than the production LT4 cam that was used on the 96 Corvette, and a handful of LT4-equipped Camaros. Those engines had no EGR because they had self-EGR (via cam). That would suggest that EGR can be safely deleted after a cam swap (when using a cam with enough overlap), and still satify a snifffer test so long as the engine is otherwise well tuned. FWIW, HTH.

 

Thanks for clarifying about what EGR does, kdrolt, I couldn't fully remember at the time.

You're right, it's listed how to in the FAQ page, but it sounds to me like they were trying to hook up an actual scan tool to it to check the engine while it's running, since he stated they didn't have the "software" (sounds like a Snap-On scan tool to me). I think most mechanics these days have forgotten, or never learned about the "paper clip code reader" .

 

Thanks for all the input guys. I know how to read the codes myself, but no one I know around here is really willing to help, they all say "take it to a shop" claiming that their scanners might pick up something that I missed. Even when I call shops and tell them what's going on, all they tell me is they'd have to scan it--even if I give them the codes and such.

As for replacing the solenoid, I did so. I also took back that universal EGR valve and got a good AC-Delco replacement, but nothing changed as far as performance, it was still lagging heavily and suffering. All the vacuum lines were replaced as well.

I didn't even think to check the vacuum line going to the MAP sensor, I've been so concerned with what I may or may not have done wrong with my EGR valve and solenoid replacement I've totally overlooked what could have been right in front of me.

Again, thanks for the help, I really appreciate it and I'll let you know what I find.

 

Knight....

do check the vacuum line as you posted......

but you also said that your one size fitzall new EGR piece was very sootywhen you removed it.

Remove the EGR valve and gasket and probe the passages in the intake manifold with a stiff wire to a depth of at least 4". These two passages should be rather clean and free to pass gasses. if there is caked on carbon closing off one or both passages you will need a hammer and chisel.

$$ to bannas you have clogged EGR ports......to do an effective cleaning the manifold shud come off of the car.

Do this first then well go to the EGR solenoid system.

 

Well, the answer was literally right in front of me. The problem was the vacuum line being disconnected from the MAP sensor, which in turn made it run super-rich and throw the code 45. It's things like this that really make you go and then you realize you've got to replace the spark plugs due to that one little line being disconnected while I still tried driving it.

Thanks for all your help guys