WILL NOT IDLE

Clean out the idle air control valve and see what happens. This guide can help

https://www.2carpros.com/articles/stall-at-idle

Please run down this guide and report back.

Thanks that was it and The Mustang is now running great again, thank you

Willie, Memphis Tn.

I tried starting my car (GT model) and it would not turn over. I disconnected the positive cable and checked it with a multi-meter and it read 12.8v. I let it sit for a few minutes and tried again and it struggled but started. When it started, it was not as thunderous as usual. (I have straight pipes). When it started up, it felt different so I checked the rpm . I was sitting around 500 rpm. It usually idles around 2000-2500. I have no idea what is going on.
Help!
Mack

500 rpm is a bit low, that engine should idle around 650-700 rpm once warmed up, around 1000 when cold and it drops pretty fast as it warms up.

When was the last time the engine was serviced? The no crank sounds like dirty connections. Go over those and clean them at both ends. A fuel pressure test would be a good thing. If the converters were removed that isn't going to help the engine as it monitors them to determine how to map the fuel and spark.

It was serviced about two months ago just for a check up. I also had the oil changed about the same time. The positive connector was a little dirty and I cleaned it off. How do I go about a fuel pressure test? It ran just fine yesterday and earlier today. Just the last time I started it this afternoon was when it started. Is that usually how something like this happens? Just starts doing it all of a sudden?
Also, thank you for the quick reply.

I just started my car again, and the idle was correct at around 1000. Any reason why this would suddenly start working again like it should?

Loose or dirty wiring connection would be the most likely reason if it "fixed" itself. The issue is finding it when it is an intermittent problem. You mention cleaning the positive connector. If you removed it to clean it, that could have reset the ECM so it now idles correctly. I would clean every connector by opening it, spraying some contact cleaner and re-seating it, look for corrosion or loose pins. Then wait and see if it does it again.

And that is how some issues occur, you turn the key and the battery voltage hits a marginal connection or component and it stops functioning. Other issues are simply caused by wear and time.

will idle like a kitten purring at low idle. will not idle high with out loosing power. Have tried several approaches. Please help. Thanks Jeff

scan for codes and check fuel pressure with a gauge first autoparts rent it

Did that change filter cleaned injectors checked emission control valve had compression test done on exhaust changed coil pack two spark plug wires checked all plugs changed fuel out with 100% gas plus lucus plus sea foam. I'm at my wits end. This is my daughters car and you can imagine the pressure. I appreciate all the help you have given me.
Thank you
JC Chapman

if you fuel pressure is not with in the 30-45 psi with key on engine off then you have a weak pump or a regulator problem. try cleaning throttle plate on both sides and iac hole with choke cleaner as well as checking for a vacuum leak.

When coming out of first gear acceleration is low. When rpms pick up it runs fine. No other problems with other gears just the initial acceleration at first gear. Also when I idle the car or it is parked and the ac is on I can smell something sweet coming from the vents which I'm guessing is antifreeze. Help please.

if you can smell something sweet out of vents it's probably a heater core leak check pass floor for being wet. other than that scan for codes and check fuel pressure with a gauge auto parts rent it.

idel pradlam hild and low

[quote:b2f5231874="ANGEL CARTAGENA"]Engine problem
1991 Ford Mustang V8 Two Wheel Drive Automatic 126000 miles
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idel prablam hild and low[/quote:b2f5231874]

Engine Performance problem
1991 Ford Mustang V8 Two Wheel Drive Automatic
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the car revs up an down at idle an then shuts down when put into gear

id start by removing throttle body and clean it with carb cleaner .and id install a new idle control valve all with new gaskets including gaskets on tb.check all vacc hoses round tb to see if any r bad broken to mushy soft or unplugged.good luck