5.4 Hesitation when cold

Reply Subscribe

Thread Tools

Search this Thread

Nov 2, 2007 | 09:16 PM

agblume

Thread Starter

New User

Joined: Nov 2007

Posts: 3

Likes: 0

5.4 Hesitation when cold

First off, I just join this forum and wanted to say hi, It seems there is alot of knowledgeable people on here and maybe one of you can give me some insight. I just purchased a 2002 f-150 supercrew fx4 with the 5.4 It has 62,000 miles on it. I changed the sparkplugs, fuel filter, engine oil, coolant, and everything was fine, but about 2 weeks after i did all this, when i start the truck up and go about 2-4 miles down the road and stop, When i try to accelerate the engine just falls on its face, It shakes and you can hear a miss in the engine around 1200-1500 rpm`s. This will go on for about 4 seconds and then it runs perfect. It happens about 1 of every 5 times i drive it. I scaned the computer for any fault codes and no codes were stored. I took out my IAC and it was very clean, Took a resistance check of it and it was 10 ohms which is good per the service manual. I tried to put some fuel injector cleaner in it and it did nothing. Thanks for any advice you can give me!

Nov 3, 2007 | 06:13 AM

BenS77

Senior User

Joined: Oct 2007

Posts: 133

Likes: 0

From: Jacksboro / Knoxville, TN

I would suspect you have a coil-on-plug going bad.

Nov 4, 2007 | 11:28 AM

rtpalin

Senior User

Joined: Feb 2003

Posts: 155

Likes: 0

From: Edmonton, Alberta

I have had the same problem with my 98 for a few years. I don't think it is the coils unless all of them fail at the same time. Thankfully it only lasts a few seconds. I find if I let the truck warm up for a few minutes the problem does not occur. I have had this happen with a warmed up engine after it has cooled off for 30 minutes.

Rick

Nov 4, 2007 | 01:03 PM

BenS77

Senior User

Joined: Oct 2007

Posts: 133

Likes: 0

From: Jacksboro / Knoxville, TN

Quote:

I don't think it is the coils unless all of them fail at the same time.

Why would they all fail at the same time?

I had a single coil go bad on my 01 Mustang GT and it would do the same thing that you guys describe. No CEL or anything. Horrible shaking, definite misfires, but not all of the time.

I ended up taking it to the dealership and they had to hook up their datalogger to figure out which cylinder. They replaced the COP and plug and it never happened again.

There's not an easy way to test the coils from what I've found. You need some special equipment like an oscilloscope or something like this. Here's another good article on troubleshooting the COP ignition.

Last edited by BenS77; Nov 4, 2007 at 01:05 PM.

Nov 4, 2007 | 06:19 PM

rtpalin

Senior User

Joined: Feb 2003

Posts: 155

Likes: 0

From: Edmonton, Alberta

My truck does not shake like it is missing. It is more like a flat spot. Thats why I figured it isn't the coils. It does not seem to matter how hard I step on the gas, it will not accelerate. If I let off the gas all the way then step on it everything is back to normal.

Rick

Nov 5, 2007 | 11:42 AM

agblume

Thread Starter

New User

Joined: Nov 2007

Posts: 3

Likes: 0

Well here is a update. I took out the IAC and cleaned it...Didn`t seem very dirty but It seems to be running great but this is only the 2nd day of driving it so hope the problem was maybe a piece of carbon on the IAC. I really didn`t think it was a cop cause it would only happen when it was cold and very seldom would it happen...thanks for your reply`s guys

Nov 5, 2007 | 07:04 PM

BenS77

Senior User

Joined: Oct 2007

Posts: 133

Likes: 0

From: Jacksboro / Knoxville, TN

I also had to replace the IAC on my mustang. They aren't too expensive if you have to get a new one. Seems like the dealership charged me $30-40 bucks. Cheaper than a COP.