1988 fiero formula idling at 2k rpm and rad fan stuck on (Page 1/3)
cartercarbaficionado APR 22, 10:25 PM
finally had time and money to throw at this so I replaced all the sensors on the engine and threw a new distributor in. runs alot better but still won't idle below 2000 rpm and it's not drivable with the radiator fan stuck on, it's not the fan relay or temp switch (I think? it's hard to tell since I don't have a manual to tell me where the 2nd switch is) someone said it might be the ac compressor switch but it isn't the one on the dash so I'm a little lost, also typical overheating issues but im pretty sure that won't be an issue once it stops sticking it's fan on at 60 mph
Patrick APR 22, 11:23 PM

quote
Originally posted by cartercarbaficionado:

...also typical overheating issues but im pretty sure that won't be an issue once it stops sticking it's fan on at 60 mph



If your Fiero has "typical overheating issues" with the fan stuck on, what makes you think overheating "won't be an issue" with the fan not stuck on? If you bought this Fiero in its present condition, and the engine actually is overheating, it's possible the previous owner jury-rigged the fan to be on all the time to try and hide a cooling issue.

IMO, the 2000 RPM idle speed is something more critical at this point than the fan. You need to find the vacuum leak.
cartercarbaficionado APR 23, 01:50 AM
the overheating really only became an issue with that fan stuck on, also was working correctly when the vehicle was bought just not sure what failed yet, also not sure where the leak would even be since I personally have removed all the vaccum lines and capped them off except the map sensor line and the egr line, i did do headgaskets not too long ago (as in I haven't even been able to drive the thing because it had a thermonuclear meltdown with its old distributor pickup and coil while parked) it did do this type of thing before but would stop if I messed with the tps but it would also shut off so probably not great (new one went in with a new connector wired In and soldered properly) so at least it's not a bouncy idle anymore, buddy things it might be the egr line but it's a stainless one that's only a few years old

[This message has been edited by cartercarbaficionado (edited 04-23-2024).]

1985 Fiero GT APR 23, 09:09 AM

quote
Originally posted by cartercarbaficionado:

the overheating really only became an issue with that fan stuck on, also was working correctly when the vehicle was bought just not sure what failed yet, also not sure where the leak would even be since I personally have removed all the vaccum lines and capped them off except the map sensor line and the egr line, i did do headgaskets not too long ago (as in I haven't even been able to drive the thing because it had a thermonuclear meltdown with its old distributor pickup and coil while parked) it did do this type of thing before but would stop if I messed with the tps but it would also shut off so probably not great (new one went in with a new connector wired In and soldered properly) so at least it's not a bouncy idle anymore, buddy things it might be the egr line but it's a stainless one that's only a few years old




Do you not have vacuum brakes anymore? I would hope you didn't cap that off haha, the most common vacuum leak is the EGR tube, especially if you've removed and reinstalled it, it is likely cracked. Have you checked your coolant level? Like Patrick said, you are not overheating because your fan is stuck on. Is the fan on all the time the ignition is on, engine on or off? Or is it only on when the engine is running, does it turn on immediately upon startup, or take a few seconds before turning on?
theogre APR 23, 10:06 AM
Yup, fan On & still "over heats" Is Not cause by "rad fan stuck on."

Engine Is Not Over heated running @ 200° to ~ 230°F no matter what claim here & elsewhere. Pushing > ~ 235°F is starting to be over heated.

Fan is On because:
Engine is really Over Heating.
Some Wiring Problems Forcing the Fan On.
Someone "played tricks" Force the Fan On like Either a switch you flip/push or Low Temp Switch in the engine from RD etc.

Engine that is Over Heating to Boil Over can be many things.
Like Many Simply Do Not Follow Fiero Coolant Fill Directions can easily over heat the engine.

See https://web.archive.org/web...erocave/coolfill.htm & rest of section.

------------------
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

Vintage-Nut APR 23, 11:04 AM

quote
cartercarbaficionado
...it's hard to tell since I don't have a manual....



If I was you, purchase a printed factory service manual to troubleshoot your Fiero issues.

PDF Copies of GM, Haynes and Chilton's
https://fieroinfo.com/manuals/

--------------------------------------------------------------------------

I agree with Patrick and solve the high idle speed first.

---Double Check on ALL the Vacuum Lines---





IF you're SURE that you don't have any vacuum leaks, and still have a high idle;

The second step is to replace the engine coolant temperature sensor for the ECM (GM 25036979 for V6)

------------------
Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

82-T/A [At Work] APR 23, 12:31 PM

quote
Originally posted by Vintage-Nut:

PDF Copies of GM, Haynes and Chilton's
https://fieroinfo.com/manuals/



Can I ask a dumb question? Is it legal to have these manuals in PDF form and offer them up as free downloads? I'm not judging, I'm just curious because I wouldn't mind backing them up as well. I just know you can still buy the paper manuals (the service manuals are usually $80), but sometimes a company will release the rights to something to help the community. I'm just curious...


Thanks!
Vintage-Nut APR 23, 03:03 PM

quote
Bing Copilot

Fieroinfo.com hosts a collection of Fiero manuals directly on their website.

Please note that while fieroinfo.com provides access to these manuals, it’s essential to verify the legal rights associated with their distribution and usage.

If you have any specific concerns about the legality of these manuals, I recommend seeking legal advice or contacting the website directly for clarification.
cartercarbaficionado APR 23, 05:44 PM

quote
Originally posted by 1985 Fiero GT:


Do you not have vacuum brakes anymore? I would hope you didn't cap that off haha, the most common vacuum leak is the EGR tube, especially if you've removed and reinstalled it, it is likely cracked. Have you checked your coolant level? Like Patrick said, you are not overheating because your fan is stuck on. Is the fan on all the time the ignition is on, engine on or off? Or is it only on when the engine is running, does it turn on immediately upon startup, or take a few seconds before turning on?



it is a new egr tube allegedly and i did reinstall it during headgaskets but it was going this behavior before then anyways, coolant level is fine and I've bled the system correctly, I'm only overheating at speed since my rad fan is spinning slower than the air is coming in (gt bumper on a formula also doesn't help my case considering the missing lower dam) it's on all the time with the key on engine status doesn't matter no clicks are heard
cartercarbaficionado APR 23, 05:48 PM

quote
Originally posted by theogre:

Yup, fan On & still "over heats" Is Not cause by "rad fan stuck on."

Engine Is Not Over heated running @ 200° to ~ 230°F no matter what claim here & elsewhere. Pushing > ~ 235°F is starting to be over heated.

Fan is On because:
Engine is really Over Heating.
Some Wiring Problems Forcing the Fan On.
Someone "played tricks" Force the Fan On like Either a switch you flip/push or Low Temp Switch in the engine from RD etc.

Engine that is Over Heating to Boil Over can be many things.
Like Many Simply Do Not Follow Fiero Coolant Fill Directions can easily over heat the engine.

See https://web.archive.org/web...erocave/coolfill.htm & rest of section.



it got new headgaskets because during a drive the temp gauge suddenly went to 0 and the coolant was violently boiling for over 10 minutes, also the fan only started doing this somewhat recently meaning its a wiring or switch issue. but no one wants to actually tell me which switch on the ac compressor is the one to control the fan which is the last thing it could be since I've checked everything else and the relay has a signal stuck on