I'm kinda resurrecting an old post. Never really got an answer the first time because I was troubleshooting a nasty stalling problem. I am wondering if my 96 F250 with the 7.5efi should go to high idle of about 1100 rpm at first startup for a minute before settling down at about 700 rpm? I also have a 94 Bronco with 5.0 that at first start will high idle for a minute at about 1100 rpm before it settles at about 700.

 

Both my 300 straight 6's rev up to 1500RPM for about a minute on first cold start up, then come down to ~700.


It's normal.

 

OK, so 300's do it and 302's do it. Any 351 or 460 owners wanna join in?

 

A friend of mines EFI 351 does it also. No tach so don't know exactly how high, but it sounds around 1500.

Don't know anyone with an EFI 460 though.

 

All gas cars and trucks do it.
Even all the carburetor gas engines did it from way back until the choke open as they were on what was called a high idle cam.
They also run extra rich while this is going on.

If it does not then you have a problem.

 

Awesome, now I get to troubleshoot again........ Thanks everybody.

 

I know my truck with a 351w idles up to about 1200 at start up and drops back down when its warm. My work truck has an EFI 460 and idles up to about 1400 until its warm.

 

Yep, Mine has always done it too.

 

My truck doesn't do that now that it has a Mustang computer in it, but it did before and yeah that's the way it's supposed to be.

 

I am so glad you said that I was starting to think I had another problem to fix.



Sorry hijack over

 

Reading the Mustang Forum some of the Mustang owners had the no high idle problem and solved it by replacing their Computer.

 

Paul, is it safe to assume that would be a MAF Mustang computer on your 90 F150 HO with mass air flow conversion?

 

Yes that's right, and I'll add that at cold start the motor does have a slightly higher idle speed but it's only something like 800rpm and only for about 20-30 seconds. I can make it do exactly what the truck computer does with my tuner but why.

 

Yup, my 351 does it too. One of these days I'll add an HOA switch for this. I tried it on my truck with some jumper wires and gator clips... electrically driving the idle valve 100% gives me ~1400 RPM which is perfect for when I need to crank up the output from the air compressor. And then I can turn it off and not have it rev so high on a cold start either.

Just have to find a good way to route the wires and a good tie-in point.

 

jimbo285 - What solved your stalling problem ??