Potential EGR Issues (Page 1/2)
sjmaye APR 15, 12:26 PM
I have a stock 1988 GT. I don't drive it much at all. Maybe a couple times a year. I have known for a long time that when I get to running highway speed the SES light pops on. Based on prior reading I assumed it was related to the EGR solenoid. Now with the Coronavirus locking me down I decided to get at some of this old business.

I am thinking the EGR solenoid may need to be rebuilt, but before that I wanted to make sure all the lines are going where they should and working as they should. I saw downloaded this diagram from this forum trace all my lines. The reason I question this is that when I restored the car the engine came out and was redone from the ground up. There is a chance I got something wrong. I remember referencing this diagram back then, too. I think I have them right, but I would not rule that out.



What I know-

EGR solenoid - The vacuum tube from the tail of the egr solenoid runs to a metal tube mounted on the firewall. On the other end of this tube a vacuum line is connected that runs to the bottom of the air filter canister. The best I can feel. I cannot see it. I pull this line off while the engine is running. There is no vacuum on it.

EGR solenoid- On the front (facing rear) of the solenoid there are two of those tiny plastic tubes running to a special dual hose rubber connector that slides on to the egr solenoid. While at idle there is no vacuum on either of these hoses. This puzzles me as I would think there should be vacuum on at least one of them if it is connected to the throttle body

At the EGR valve itself there is tiny plastic line going to it. While idling I pulled this off and it had no vacuum on it. I did not expect so at idle, but thought i would mention it.

I would think at least one of these lines would provide vacuum that would be used to actuate the solenoid.

So with that info can someone help me ?
Gall757 APR 15, 12:49 PM
Don't guess about the reason for your SES light; a number is probably stored in memory even if the light is now off. A code 32 will show up over time with the slightest leak in the vacuum lines. If your car has the original plastic vacuum lines, it's time to replace them with metal lines because the plastic ones crack and are nearly impossible to trouble shoot. All the original connectors have to fit tight too.

[This message has been edited by Gall757 (edited 04-15-2020).]

sjmaye APR 15, 02:55 PM

quote
Originally posted by Gall757:

Don't guess about the reason for your SES light; a number is probably stored in memory even if the light is now off. A code 32 will show up over time with the slightest leak in the vacuum lines. If your car has the original plastic vacuum lines, it's time to replace them with metal lines because the plastic ones crack and are nearly impossible to trouble shoot. All the original connectors have to fit tight too.




I was just looking up how to pull the codes. It has been 12 years since I did it last. I also continued searching and found the buddycraig writeup on EGR function. Exactly the description I was looking for.

I will check and confirm codes.
sjmaye APR 15, 03:33 PM
You know.....I think I should have left well enough alone. I found the page showing how to pull the codes. Problem is my ECM won't go in to Diagnostic Mode. I short A and B with a paper clip like I have done in the past and the SES blinks 1 and then stays on. I have tried shorting A and B before and after the ignition is put in to the ON position. Same thing.

Engine runs fine. Maybe I should just pull that pesky SES bulb out. JK. Have you ever heard of a Fiero that would not go in to Diagnostic Mode?

[This message has been edited by sjmaye (edited 04-15-2020).]

Gall757 APR 15, 03:53 PM
The ALDL connector is sometimes installed upside-down. Make sure you are looking at the right pins

.

[This message has been edited by Gall757 (edited 04-15-2020).]

Patrick APR 15, 04:02 PM

quote
Originally posted by sjmaye:

Problem is my ECM won't go in to Diagnostic Mode. I short A and B with a paper clip like I have done in the past and the SES blinks 1 and then stays on.



Something is not right.


quote
Originally posted by sjmaye:

I have tried shorting A and B before and after the ignition is put in to the ON position.



If your ECM wasn't already defective, you may have now damaged it.

From the same code page you linked to...


quote

The trouble codes stored by the ECM can be "read" from the SES-light by switching the ECM to Diagnostic mode. To switch the ECM to Diagnostic mode, two pins on the Assembly Line Diagnostic Link (ALDL) connecter must be jumpered, the ignition turned "ON" and the engine must not be running.




I believe it's important to do those steps in the sequence mentioned.

[This message has been edited by Patrick (edited 04-15-2020).]

theogre APR 15, 06:54 PM
ECM won't report codes etc check the PROM inside of ECM.
Many "Performance Chips" block ECM scan tools and/or storing codes.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

sjmaye APR 16, 05:33 AM
I believe this car to be completely stock. I do not believe any former owners put in any customized chip. Whether the ECM is damaged or not I have no idea. When I pulled the engine and put is back in in 2008. I simply reinstalled everything back as it was. Nothing appeared to be modified. I had no issues at startup, so I don't remember ever having to check codes back then. I can say the car has run good for the last 12 years. I don't drive it much, but it just runs fine even with the SES light turning on at highway speeds.

Thanks for the other view of the ALDL connector. I got that from the factory service manual as well. You are right, the connector orientation gets easily turned around. On my first attempt to pull codes yesterday I shorted AB correctly and turned the key to the ON position. One SES blink then the light stayed on. This confused me because I knew this is how I had done on my other Fiero years ago. I re-read the instructions which were not specific as to whether you short AB before or after the key was turned ON. This time I turned the key to ON and then shorted AB. Got same result. By now I was really confused. I thought I may have gotten ALDL connector turned around in my head. I rechecked the diagram from the factory service manual. Long story short. I ended up shorting FE. Still I got the same result. I looked again and saw what I had done and knew I probably blew something. Nope. Started the car. Everything seems to work just as it did before.

Now, I went in there trying to correct a nuisance and ended up finding this potential ECM issue. Just like an onion. Peel on layer back....
sjmaye APR 16, 02:34 PM
Good news. I went back to the Fiero Factory Service manual and performed the trouble code troubleshooting steps. This time when I shorted AB I thought I was sunk again, but after what felt like a lengthy wait the SES started blinking the codes. I have the dreaded 32 (EGR vacuum control) and also a code 44 (Oxygen sensor - Lean exhaust).

Based on the EGR line diagram the vacuum used to drive the EGR valve is the small line from the throttle body to the double line connector on the EGR solenoid. See red arrows. Is this correct? I checked and above idle I do get vacuum on this vacuum line at the egr solenoid.

Does this lead me to the EGR solenoid probably needs to be rebuilt?

[This message has been edited by sjmaye (edited 04-16-2020).]

Gall757 APR 16, 03:44 PM
I would deal with the code 44 first. As a general rule, fix the higher number codes first, and the others may take care of themselves. As you have seen, the code 32 is not a serious performance issue.