High ilde problem 1985 Fiero V6

Tiny
ROLO97739
  • MEMBER
  • 1985 PONTIAC FIERO
  • 110,000 MILES
My son just got a 1985 fiero with the v6 and it has a high idle about 2500 rpms when it's cold and about 1300 when it warms up the egr tub is gone Where it bolts to the the plenum there is a steel plate blocking the port. Im not sure but lets say the egr tub was bad and making it idle high and if I removed it like the previous owner did and plated off the port where it bolts to the plenum would'nt that stop the high idle. If this is true I was wondering if there is anything else that be causing it to have a high idle or do I have to replace the egr tube befor I can go any further.

Thank You





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Sunday, November 6th, 2011 AT 7:43 PM

19 Replies

Tiny
FIXITMR
  • MEMBER
Could be a vacuum leak check all vac hoses. IAC could be bad/dirty. That's multi port injection, right?
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Sunday, November 6th, 2011 AT 8:03 PM
Tiny
ROLO97739
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Im not sure if it's multi port or not would that make a difreance
on what I need to do. Heres a pic of the engine maybe you can tell from the pic if it is or not.I did check for vacuum leaks but and cant find any but Im not sure if Im missing any.

Thank You for your help

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Monday, November 7th, 2011 AT 12:29 AM
Tiny
FIXITMR
  • MEMBER
Yes, it's multiport. Unplug IAC and see what happens. Car should stall since that's what controls idle.
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Monday, November 7th, 2011 AT 1:00 AM
Tiny
ROLO97739
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Hi fixitmr
first of all I want to thank you for all your help.I tried what you said and unpluged the old IAV and it kept running so I replaced the IAC with a new one and drove it for about 5 mile at 50 MPH and now the idle is about 3000 rpms and it won't drop down at all and if I unplug the new one it keeps running so that made it worst.I was hopping you have some more input that could help. Is there a chance that the wireing or plug for the IAC could be bad and if so can it be tested. Also on the right hand side throttle body on the outher side of the throttle cable there are two little parts that you can push down and it bogs out the moter now I can push it down and nothing happens heres a pic of the part Im talking about. Thank You
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Monday, November 7th, 2011 AT 6:19 PM
Tiny
FIXITMR
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Were there any instructions with new IAC? Did you disconnect battery? That looks like TPS which if reading wrong at rest can throw off computer as to setting idle. Also are you sure butterfly is ABSOLUTELY shut when relaxed?
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Tuesday, November 8th, 2011 AT 3:04 AM
Tiny
ROLO97739
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Yes the butterfly is shut and I did disconnect the battery. Since the last time we talked I have removed the plenum upper & lower. Checkt all vac lines and cleaned throttle body and replaced all gaskets I don't think I have any vacuum leak every thing looks good. When I start it the ldie is still 3000 rpm I also can unolug both plugs from the throttle body and the car will stay running.I also wanted to know if the speedometer does'nt work because this one don.T could that make this happen. Also could you tell me is the speedometer work with a cable or electronicly well Im lost any input what to try next would be graet. Thank You again for all your help
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Thursday, November 10th, 2011 AT 2:21 AM
Tiny
FIXITMR
  • MEMBER
So the car was acquired in this condition? Anyway, take the IAC out and block the hole and start and see what happens. Also tuy blocking the throttle body opening. Cant run without air!
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Thursday, November 10th, 2011 AT 2:59 AM
Tiny
ROLO97739
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When I block the TB engine will stall when I plug the IAC hole it works the same. Going to pick up a new TPS
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Thursday, November 10th, 2011 AT 2:08 PM
Tiny
ROLO97739
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My bad if I put my finger in the hole where the AIC goes in I can move my finger in or out and make the idle go up or down I can make it run good with my finger.
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Thursday, November 10th, 2011 AT 5:22 PM
Tiny
FIXITMR
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So looks like the IAC is the problem. It's not setting itself properly for some reason. You might plug it in while it's still out of manifold and turn key on and watch it function. Even start motor with finger while you watch it's functions.
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Friday, November 11th, 2011 AT 3:20 AM
Tiny
ROLO97739
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I have another queston what can make the trmostat do this the old one looked just like this one this is a new I put it in last night.
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Friday, November 11th, 2011 AT 6:57 PM
Tiny
FIXITMR
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Wow, that is weird! Surprised there is room in cavity for such a contortion!
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Friday, November 11th, 2011 AT 11:40 PM
Tiny
FIXITMR
  • MEMBER
What brand is it? Maybe a straten out with a tweak to the outside would prevent he buckle? This happens to people more often then 1 would think! Blame on yuri geller! The reccommended brand is stant. The part number for a Stant SuperStat 195 F thermostat for a Fiero is 45819
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Friday, November 11th, 2011 AT 11:46 PM
Tiny
ROLO97739
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Regaurding back to your replie on November 10th. Yes the AIC is working properly with my finger in the hole I can regulate the air flow and make the AIC open & close. I agree that something is programing it wrong, Could it be because my Spedometer's not working and it's telling the computer that Im not going 40 mph therfore not programming it right.
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Sunday, November 13th, 2011 AT 7:16 PM
Tiny
FIXITMR
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Is that fiero a GT?
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Monday, November 14th, 2011 AT 6:15 AM
Tiny
ROLO97739
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No It's a SE
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Monday, November 14th, 2011 AT 12:24 PM
Tiny
FIXITMR
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Are you sayin the speedo dont work? check this out. http://www.fieros.de/en/articles/speedo.html
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Tuesday, November 15th, 2011 AT 6:34 AM
Tiny
ROLO97739
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Ok now I got the speedo working right it was the speed sensor but I still have a high idle about 1200 to 1300 rpm and it now has a 4th gear I didn't know it had so It's getting better the only thing I can think of is that maybe the cold idle sensor is not working right. Is there anything else that I could be missing that could this?

Thank You
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Sunday, November 20th, 2011 AT 2:26 PM
Tiny
FIXITMR
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You could try pulling plug from coolant temp sensor and see if it effects ide? Maybe somebody performance chipped the computer(if that's possible)and that's where the programming is off for idle?
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Sunday, November 20th, 2011 AT 6:08 PM

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