Ok, this is odd:

I can drive it all day long without the code popping up, but as soon as I turn the AC on it will throw the code within a minute or 2.

Only started doing that this year, no vacuum leaks I can find, EGR valve is working (put a new on on just in case), EGR solenoid also working as it should (bench tested - vacuum applied switch closes).

Any ideals?

(88GT, 3.4l crate engine swap several years ago, auto, AC switched over to 134A 4 years ago).

Edit to add: I will on occasion get a code 44 as well, but I am sure it is related.

[This message has been edited by Mickey_Moose (edited 10-07-2019).]

quote Originally posted by Mickey_Moose: Ok, this is odd: I can drive it all day long without the code popping up, but as soon as I turn the AC on it will throw the code within a minute or 2. Only started doing that this year, no vacuum leaks I can find, EGR valve is working (put a new on on just in case), EGR solenoid also working as it should (bench tested - vacuum applied switch closes). Any ideals? (88GT, 3.4l crate engine swap several years ago, auto, AC switched over to 134A 4 years ago). Edit to add: I will on occasion get a code 44 as well, but I am sure it is related.

So, for those who haven't memorized it, 32 is EGR, and 44 is Lean Exhaust.

It IS possible for the O2 sensor to begin to fail, and not /also/ get a Code 13; however, my thought could be the Vacuum Solenoid. For the life of me, I can't remember where that's located as it's been a decade since I last looked at my Fiero's motor... but I know that typically caused some of the problems for me that you're experiencing now.

quote Originally posted by 82-T/A [At Work]: So, for those who haven't memorized it, 32 is EGR, and 44 is Lean Exhaust. It IS possible for the O2 sensor to begin to fail, and not /also/ get a Code 13; however, my thought could be the Vacuum Solenoid. For the life of me, I can't remember where that's located as it's been a decade since I last looked at my Fiero's motor... but I know that typically caused some of the problems for me that you're experiencing now.

Ok, my bad for not including what the codes are for, thank you for adding that.

Vacuum solenoid - are you referring to the one that controls the EGR valve? What has me stumped is why it only throws the code when the AC is turned on (unless I have a short in the wiring that is drawing down the power to the solenoid)?

You don't have a short, but I bet you have corrosion in a connector. The added load of the A/C may be enough to lower your system voltage. How old is your battery?

quote Originally posted by 82-T/A [At Work]: So, for those who haven't memorized it...

Heh heh, it always irks me when people post just the code number(s)... and then all the rest of us reading the post are forced to go Here to look up what the heck the numbers mean. Such a time waster!

quote Originally posted by Mickey_Moose: Ok, my bad for not including what the codes are for, thank you for adding that.

Just don't do it again, eh!

[This message has been edited by Patrick (edited 10-15-2019).]

AC is a heavy amp draw when the compressor in on.
I would check most wiring in the engine bay including clean/fix all ground points.
See my Cave, Wire Service and rest of section.

Check volts out from alt when engine runs at output on alt AND red wire to Alt side plug then at batter and + block under C500. All should be very =.
Turn on AC, Headlight, etc, and check again. One at a time then more at a time turned on.
Good alt should be ~ 14.7v but iffy wiring can cut that volts big time in a lot of places.
Example: Most Fiero have wiring problems to front then wonder why HL are dim, cooked relays, slow/dead motors, etc. Why? See my Cave, Electric Motors
Front wiring often drops ~ 1v even when everything is good. Just 1 crap connection can easily eat 1-3V more so might get 14.6v in the rear and front only gets 10v or less. Big ones are HL and HL Dimmer switches have crap connection(s) and even they get hot, even cooked, because of contact resistance.

Yes, Check all parts getting vacuum and EGR parts.
Then check O2 sensor and wiring.
Then check exhaust for leaks upstream of O2 sensor.
44 is ECM is ADDING fuel to the max and still have problems trying to get fuel right. (45 does exact opposite Cutting fuel and still think is too rich.)
Vac leaks, exhaust leaks and/or O2 can cause 44.

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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