Won't Idle

[chayes627]

Hello, I have a '96 XLT. Just this morning I started up and just cranks. It will start if I hit the gas but will shut off again after I let off. After starting a few time like that and I slowly let off the gas it will idle at about 300 rpm. Any ideas on what could be causing this? If you need to know anything else let me know. Thanks, Clayton.

 

[bpopp]

Rough idle can be caused by a lot of things. Was it cold? Did the idle get better as the engine warmed up? If so, that's commonly caused by an intake manifold leak. If not, it could be related to fuel, ignition, or a vacuum leak.

Do you have a CEL on? If so, that code can help to diagnose what's going on.

To rule out fuel, use a fuel gauge to test your fuel pressure. 55+ PSI is normal and it should be consistent.

To rule out ignition, check your wires and spark plugs and make sure you have voltage.

A vacuum leak is often the easiest to fix, but sometimes the hardest to track down. I fought with mine for several weeks. Easiest way I found to isolate where my leak was (once I had ruled out everything else), was to plug off all the hoses going in to the intake manifold and see if the idle corrected. When it did, I just used trial and error to figure out which hose was leaking (PCV, Evac, EGR, brake booster, etc.)

 

[chayes627]

I got it fixed, it was the IAC. But what was weird was it happened suddenly. Something like that usually takes some time. All is good now though.

 

[chance942]

Rough idle can be caused by a lot of things. Was it cold? Did the idle get better as the engine warmed up? If so, that's commonly caused by an intake manifold leak. If not, it could be related to fuel, ignition, or a vacuum leak.

Do you have a CEL on? If so, that code can help to diagnose what's going on.

To rule out fuel, use a fuel gauge to test your fuel pressure. 55+ PSI is normal and it should be consistent.

To rule out ignition, check your wires and spark plugs and make sure you have voltage.

A vacuum leak is often the easiest to fix, but sometimes the hardest to track down. I fought with mine for several weeks. Easiest way I found to isolate where my leak was (once I had ruled out everything else), was to plug off all the hoses going in to the intake manifold and see if the idle corrected. When it did, I just used trial and error to figure out which hose was leaking (PCV, Evac, EGR, brake booster, etc.)

Glad to see you got her going good again.

 

[chance942]

I got it fixed, it was the IAC. But what was weird was it happened suddenly. Something like that usually takes some time. All is good now though.

It probably got stuck.Cleaning it might have fixed but since you I guess got another one I guess it's all good.