Rogh idle when cold, why?

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Betis
Posts: 109
Joined: Mon Nov 30, 2015 11:17 pm
Your car is a: 1981 Fiat 124 Spider FI

Rogh idle when cold, why?

Post by Betis »

I have a 1981 FI Spider. Had a crack on the boot, I replaced it. Changed the wire pickup and ignition module. I did the timing and adjusted the position of the TPS. When cold it idle rough, like it wants to die, but it does not. Rpms go up and down almost to zero. Once it warms up, It idles perfectly at 1100 or 1200. What could be happening.
Thanks in advance.
Last edited by Betis on Sun Oct 29, 2017 8:21 pm, edited 1 time in total.
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GeorgeT
Posts: 379
Joined: Thu Feb 16, 2012 12:41 pm
Your car is a: 1982 Fiat 124 Spider

Re: Rogh idle when cold, why?

Post by GeorgeT »

Could be the Aux. Air Valve, the Coolant Temp. Sensor or the Cold Start Injector. Get the F.I. Diagnosis Manual and go through the troubleshooting process.
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Betis
Posts: 109
Joined: Mon Nov 30, 2015 11:17 pm
Your car is a: 1981 Fiat 124 Spider FI

Re: Rogh idle when cold, why?

Post by Betis »

Replaced Aux Air Valve and Coolant Temp sensor. And it is still running rough when cold. Any other ideas?
Thanks in advance.
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RRoller123
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Your car is a: 1980 FI SPIDER 2000
Location: SAGAMORE BEACH, MA USA

Re: Rogh idle when cold, why?

Post by RRoller123 »

If the idle is running up and down on its own, it is likely the fault is in the AFM.
'80 FI Spider 2000
'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/STD BED
2002 Edgewater 175CC 80HP 4-Stroke Yamaha
2003 Jaguar XK8
2003 Jaguar XKR
2021 Jayco 22RB
2019 Bianchi Torino Bicycle
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Betis
Posts: 109
Joined: Mon Nov 30, 2015 11:17 pm
Your car is a: 1981 Fiat 124 Spider FI

Re: Rogh idle when cold, why?

Post by Betis »

RRoller123 wrote:If the idle is running up and down on its own, it is likely the fault is in the AFM.
Yes It is running up and down. But only when cold, once it warms up it is perfect. I bought this AFM from fuel injection corp. in California. Just 2 years ago, I know everything is possible but being so recently serviced, one could assume it was good.
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RRoller123
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Posts: 8179
Joined: Sun Nov 13, 2011 2:04 pm
Your car is a: 1980 FI SPIDER 2000
Location: SAGAMORE BEACH, MA USA

Re: Rogh idle when cold, why?

Post by RRoller123 »

Beats me then, I have no idea what could be wrong.
'80 FI Spider 2000
'74 and '79 X1/9 (past)
'75 BMW R75/6
2011 Chevy Malibu (daily driver)
2010 Chevy Silverado 2500HD Ext Cab 4WD/STD BED
2002 Edgewater 175CC 80HP 4-Stroke Yamaha
2003 Jaguar XK8
2003 Jaguar XKR
2021 Jayco 22RB
2019 Bianchi Torino Bicycle
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Betis
Posts: 109
Joined: Mon Nov 30, 2015 11:17 pm
Your car is a: 1981 Fiat 124 Spider FI

Re: Rogh idle when cold, why?

Post by Betis »

I will call them and see. Lets assume that the afm is good. What else could it be?
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Betis
Posts: 109
Joined: Mon Nov 30, 2015 11:17 pm
Your car is a: 1981 Fiat 124 Spider FI

Re: Rogh idle when cold, why?

Post by Betis »

Could a bad O2 sensor be causing this?
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joelittel
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Joined: Tue Mar 08, 2011 6:53 pm
Your car is a: 1980 Spider 2000 FI
Location: Evanston, IL

Re: Rogh idle when cold, why?

Post by joelittel »

I don’t think it’s your O2 sensor.

Do you have Brad Artigue’s guide? He talks about the O2 sensor as well as how to troubleshoot the bosche system.

It would be worth getting if you don’t already have it.
https://www.amazon.com/Maintaining-Ital ... 1517157277

This is another good resource.
http://www.hiperformancestore.com/ljetronic.htm
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