Jumping at low RPMS

[DKH2Hrnt]

Seeing if I could get some help narrowing down the issue I am having with my truck. It is a 2003, 5.4l, just over 100K miles. For a while now the truck has been missing at low rpms, around 1100, but it started to get worse and I can now feel it all the way up to about 2,000 rpm. In the past few days I have been feeling it jump as I pull off from a stop. Now, this morning I felt it start to hiccup as I was sitting at a stop light. The truck doesn't jump at all when in park, but It starts jumping again as soon as I put it in drive. Spark plugs? Coils? Fuel Injectors?

 

[BIG GREEN FORD]

Check engine light on?

 

[Bedrck47]

check for vacuum leaks use a can of spray carb cleaner and spray around the vacuum hose, intake and throttle body if you have a leak you will notice a rise in RPM's

could be plugs. When were they last changed

 

[DKH2Hrnt]

No check engine light. I've had the truck for over a year and a half, and haven't changed the plugs.

 

[Bedrck47]

check for vacuum leaks first.
then change plugs and if you don't install new coils at least replace the boots and use dialectic grease on the wires inside of the boots

 

[Bedrck47]

pay attention to the pcv hose that connects to the back of the throttle body when checking for vacuum leaks

 

[DKH2Hrnt]

Used an entire can of carb cleaner trying to see if I could find a leak, but nothing. I guess the next step is the spark plugs.

 

[Bedrck47]

did you check to see if any codes appear.

 

[DKH2Hrnt]

Would it still throw a code without the check engine light on?

 

[Bedrck47]

it is possible to see a code even if the CEL isn't on

when you first put your key in and turn to run without starting does the CEL come on??

 

[metaldrgn]

So at wide open throttle you aren't really seeing any issues? Just at idle at low/moderate acceleration and it seems like an occasional miss?

If that's the case I personally don't expect plugs/coils to be the cause but I wouldn't rule them out either. The egr valve may be recirculating too much exhaust causing a slight misfire.

 

[metaldrgn]

Duplicate post...

 

[Goats]

So at wide open throttle you aren't really seeing any issues? Just at idle at low/moderate acceleration and it seems like an occasional miss?

If that's the case I personally don't expect plugs/coils to be the cause but I wouldn't rule them out either. The egr valve may be recirculating too much exhaust causing a slight misfire.

If that was the case wouldn't the dpfe senser pick that up. Having saying that it would throw a code.

 

[metaldrgn]

If that was the case wouldn't the dpfe senser pick that up. Having saying that it would throw a code.

Lol, I looked up that part and one of the first things to come up sounds incredibly similar to his problem. That sensor could be the problem. This link is for the Ford Focus but sounds like the same part.

DPFE Sensor and EGR Information - Focus Hacks

Also they mention workarounds you may be able to try before buying parts

 

[DKH2Hrnt]

Would a failed dpfe sensor cause a flashing check engine light? Check engine light came on this morning, then a minute later started flashing. I haven't been able to look into the problem because I had to fix a bunch of other stuff for inspection.

 

[Bedrck47]

did you ever get any codes read

http://www.expeditionforum.com/f42/about-egr-pcv-dpff-evap-iat-tps-maf-23583/#post191356

 

[DKH2Hrnt]

Misfire on #4 cylinder. Of course it couldn't have been one towards the front.

 

[omegalita]

Coils!

 

[DKH2Hrnt]

Took a while, but I was able to switch out the plug and coil on the #4 cyclinder, and now it's running smooth. Hope I never have to do it again. Also seafomed the truck, and my mpg instantly shot up. I was usually getting around 12.3mpg, but now I got 13.8, and that's after my wife drove it!

 

[Goats]

Mine poped the same code tonight