85 CFI Mustang won't idle

Joe F · 06-28-2001, 09:06 PM

My '85 Mustang has always had a rough idle when hot-started. After a few minutes of driving, it would go away. The last couple of days, it hasn't gone away. Very rough idle, and the motor dies after 10-20 seconds. I have to floor the gas to get it to restart. Lots of hesitation under throttle. I've sprayed the throttle body down with carb cleaner, run a bottle of injector cleaner, and checked for vacuum leaks. EGR valve was replaced 2 years ago. I've heard other guys with CFI engines complain of similar symptoms. Anyone have an idea what the problem could be? Thanks for your help. Joe

84_GT350 · 06-29-2001, 02:43 AM

I had the same problem when my '84 had CFI on it. I'd bet money it's the MAP sensor. If they go out your car starts idling funny and usually dying. Mine would always die at stoplights.

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1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

Joe F · 06-29-2001, 05:21 PM

Thanks for your help. For some reason, it was running fine this morning. Ran terrible at lunch. Ran fine this evening. Does this sound right? Could the MAP sensor work intermittently?

06-28-2001, 09:06 PM	#1
Joe F Registered Member Join Date: Jun 2001 Location: Fuquay, NC, United States Posts: 2	85 CFI Mustang won't idle My '85 Mustang has always had a rough idle when hot-started. After a few minutes of driving, it would go away. The last couple of days, it hasn't gone away. Very rough idle, and the motor dies after 10-20 seconds. I have to floor the gas to get it to restart. Lots of hesitation under throttle. I've sprayed the throttle body down with carb cleaner, run a bottle of injector cleaner, and checked for vacuum leaks. EGR valve was replaced 2 years ago. I've heard other guys with CFI engines complain of similar symptoms. Anyone have an idea what the problem could be? Thanks for your help. Joe

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06-29-2001, 02:43 AM	#2
84_GT350 Registered Member Join Date: Apr 1999 Location: Overland Park, KS, USA Posts: 1,631	I had the same problem when my '84 had CFI on it. I'd bet money it's the MAP sensor. If they go out your car starts idling funny and usually dying. Mine would always die at stoplights. ------------------ 1984 1/2 GT350 (#842 Hatchback w/ T-tops), 302HO, Comp cams Xtreme Energy cam, Carter 625cfm carb, Weiand Stealth intake, MSD distributor, MSD coil, FMS 9mm wires, 1 5/8" MAC unequal shorties, 2 1/2" MAC Prochamber H-pipe, Flowmaster 2 chambers, KYBs, 16"x8" 4 lug Cobra Rs, Falken 245/45ZR16s

06-29-2001, 05:21 PM	#3
Joe F Registered Member Join Date: Jun 2001 Location: Fuquay, NC, United States Posts: 2	Thanks for your help. For some reason, it was running fine this morning. Ran terrible at lunch. Ran fine this evening. Does this sound right? Could the MAP sensor work intermittently?