engine missing during accelration

Reply Subscribe

Thread Tools

Search this Thread

Mar 2, 2010 | 09:23 AM

Schuby

Thread Starter

Senior User

Joined: Feb 2004

Posts: 133

Likes: 0

From: Harriman, TN

engine missing during accelration

ok...this might be a long story, but here goes. I have 2000 F-150 man_tranny 4.6. It has 140,000 mi. It has set for about a month with out been driven. When i drove it it felt like it had a cylinder misfire. In the past i have had water leaks coming from black cowl where it meets the firewall and it did the same thing but much worse, the engine light would come on. As of now the light is not on, but what gets me is that it does it when when im going about 70mph but onlywhen going uphill ( i guess when under more stress??). The only other time it happens is under hard acceleration around 3000rpm range. It runs fine other than that. I put new spark plugs in at 110,000(motorcraft). I used seafoam 2 months ago before the sitting period. Any ideas to what it might be...im thinking of replacing plugs again or possibly new fuel filter.

Mar 2, 2010 | 10:23 AM

SteevenH

Senior User

Joined: Aug 2009

Posts: 304

Likes: 2

Check the #4 COP. It's notorious for getting wet and going bad. Some say you can't do this
but I just did; Have someone sit in the cab and with all the breaks on , put the truck in reverse and bring the rpms up to about 1000
and start disconnecting the COPS. I bet when you get to #4 you won't detect any changes in
how the engine runs. If so , continue disconnecting the COPS . I bet one of them is
bad.

Mar 2, 2010 | 11:03 AM

redwood

Elder User

Joined: Jun 2004

Posts: 747

Likes: 2

From: Pelahatchie, MS

You can also use a code reader and check for pending codes that haven't tripped the check engine light yet...

Mar 2, 2010 | 11:21 AM

SteevenH

Senior User

Joined: Aug 2009

Posts: 304

Likes: 2

I've been told that a code reader with mode 6
might pick up the code but unless your CEL is on , you won't get any codes . I ran into that
problem. Skipping when accelerating but no
CEL , thus no codes .

Mar 2, 2010 | 12:54 PM

redwood

Elder User

Joined: Jun 2004

Posts: 747

Likes: 2

From: Pelahatchie, MS

A couple of weeks ago, mine started missing. It was really bad in overdrive. I drove it like that about 15 miles to the house. No check engine light. I got my code reader, which is JUST a reader, not a scan tool, and hooked it up. I had 2 pending codes. One was for a cylinder #1 misfire, and the other was for a misfire in the first 1000 revolutions at startup. It never tripped the light. The codes were listed on the reader as pending. I replaced the coil on cylinder 1, cleared the codes with the reader, and I haven't had an issue since.

There are many issues where a scan tool will be required to diagnose the problem, but there are many that you can trace using a simple code reader.....

Mar 3, 2010 | 08:57 AM

Schuby

Thread Starter

Senior User

Joined: Feb 2004

Posts: 133

Likes: 0

From: Harriman, TN

ok...I scanned it for codes and it came up with P0300 Random/multiple cyclinder misfire.
Any suggestions on next couse of action???

Mar 3, 2010 | 09:33 AM

redwood

Elder User

Joined: Jun 2004

Posts: 747

Likes: 2

From: Pelahatchie, MS

Have you ever changed all the COPs? Sometimes you can change just the boots and wires on the bottom of the COP that hooks to the plugs and that'll fix it.