Misfire help
Thread Starter
|
New User
Joined: Jul 2019
Posts: 4
Likes: 0
Misfire help
2004 Ford F-350 v10. About a year ago had the po303 code and a code indicating a misfire on first 1000 revolutions of motor. At this time I replaced all plugs and coils. Everything was working fine. Now the same codes returned. I decided to swap a few coils and replace plug and injector. The misfire code came back. The truck runs mint with the exception of a slight misfire at start up for about 5 seconds. Power balance test is only completed with engine running so I can’t see what’s happening at initial start up. Any ideas?
Fleet Mechanic
Joined: Jan 2016
Posts: 1,804
Likes: 113
If a injector was leaking down it would flood the cylinder with fuel and cause the miss you are describing. Once the engine started and the flood cleared then all cylinders would fire fine until it set again and soaked the cylinder. Do a leakdown test on the fuel system.
Fleet Mechanic
Joined: Oct 2017
Posts: 1,704
Likes: 164
From: Southwest Ohio
Can be a number of different things: leaking fuel injector, clogged injector, vacuum leak. You can spray some starting fluid or use propane and spray it in different areas around the intake manifold, listen for any rpm changes to find the vacuum leak.
— Dave
— Dave
Thread Starter
|
New User
Joined: Jul 2019
Posts: 4
Likes: 0
Yes. New coils with boots used and dielectric grease. I did replace the number 3 injector. But the miss came back. I was thinking the same about a leaky injector that’s why I replaced it. I will check for vacuum leaks. No lean codes however and fuel trims look great.
Thread
Thread Starter
Forum
Replies
Last Post
