91' Mustang cold start problems

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  #1  
Old 12-04-02, 05:55 PM
dalecm
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91' Mustang cold start problems

I have a 91' LX Convertable with the 5.0L engine and manual transmission. It has 115K miles and has seen good care. Recently it won't idle worth a darn on a cold start. I replaced plugs, plug wires, dist. cap and rotor to no avail. Checked the PCV valve and timing. It runs great when warm and starts great when warm also. Any suggestion?
 
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  #2  
Old 12-04-02, 06:25 PM
davidf
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Does it have a carb?If so ,choke or hot air stove pipe system is not right.
 
  #3  
Old 12-04-02, 10:39 PM
knuckles
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All Mustangs have been EFI since 1987.

Check your IAT & ECT sensors as well as your idle air control valve.
 
  #4  
Old 12-05-02, 05:40 AM
Joe_F
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I agree with Knuckles
 
  #5  
Old 12-05-02, 08:53 AM
fordman30
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MUSTANG

My grandma sable was doing the same thing so I put a idle air control valveand it was fix.But, remember to carry your vin# to the dealer so they give you the right one .It is a easy fix 2 bolts out and 1 plug to unplug.10 min tops....have a merry x-mas
 
  #6  
Old 12-05-02, 01:49 PM
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actually, the 86 gt was the first year for multiport injection and computer, the 85's had the 4bbl holley carb and the roller cam.

Anyway, this is a very very very common problem with mustang 5.0's there was a huge discussion on this here:

http://www.corral.net/forums/showthr...threadid=10805

would suggest checking it out, you can run yourself in circles with this one.
 
  #7  
Old 12-06-02, 10:05 AM
Joe_F
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Mid 1984 also had fuel injection in the GT350 special edition model that year. Vin M engine as I recall. My former coworker had one.

Also, 1985 manual tranny equipped were Holley 4 barrel, 1985 autos had CFI to my knowledge.

1986 had Bosch MFI as you stated.

The Holley 4 barrels aren't worth 50 cents. Smokers, leakers, fuel wasters. The fuel injection was a vast improvement
 

Last edited by Joe_F; 12-06-02 at 10:30 AM.
  #8  
Old 12-06-02, 05:18 PM
dalecm
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Thanks

I appreciate all the suggestions. I'll let you know the results as soon as I have time to dig in to it. Should be able to get to it the week of the 9th .

Thanks again`
 
  #9  
Old 12-07-02, 10:00 PM
dalecm
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What is it?

Is the idle air control valve the same thing that the Chiltons manual call the Air Bypass Valve?
 
  #10  
Old 12-07-02, 10:16 PM
Joe_F
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Yes. The bypass term is Ford terminology.
 
  #11  
Old 12-08-02, 12:26 AM
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If you replace the valve you may need the part number off the old one. Take it with you to the parts store.
 
  #12  
Old 12-08-02, 06:00 PM
Joe_F
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Thumbs up

Stevo is correct. It will also help the dealer find it quicker too.
 
  #13  
Old 12-08-02, 09:23 PM
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I had the same thing happen to my 1990 Ford with a 5.0L engine. Not knowing much about EFI, I brought it to the local Ford dealer, who replaced the air bypass valve and that solved the problem. However, I was not too happy after I found out what that valve is and where it is located, because the dealer charged me $ 265 for labor to replace it and $94 for the valve!
 
  #14  
Old 12-20-02, 08:29 AM
dalecm
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Thumbs up Resolution

Well......I finally got the correct part after three trips to the local auto parts store. It did take about five minutes to replace and I paid about $75 for the part. Cold starts are about 95% better. The idle seems a little low, but it runs when cold without having to work the gas pedal constantly.

Thanks everyone
 
  #15  
Old 12-20-02, 08:36 AM
fordman30
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Did the idle air control valve fix the problem ? And you are very welcome...Have a Merry Christmas and New Year
 
  #16  
Old 12-20-02, 08:52 AM
dalecm
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Yes it was the idle air control valve. Sorry I didn't include that info.

Thanks again
 
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