Hi everyone, Ive got a 4.2 in my truck that stumbles and feels like it's going to die when you give it gas from a stop. It doesn't do it all the time, and does not put check engine light, or show any codes. plugs/wires/coilpack/DPFE have been replaced. MAF, IAC were cleaned. Fuel filter is new, fuel pressure is good, Vacuum is good. Truck is scary to pull out into traffic with. Any Ideas? Thanks!

 

Try Techron in the gas to clean the injectors. Pull the throttle body and clean it.

 

Thanks glc. I already cleaned the throttle body when i did the MAF sensor, and ran Lucas injector cleaner through it

 

Without a code, this can be tough to nail down. However, never assume that new parts that you installed are good. Even though you cleaned them, you can't assume the IAC and MAF are good. The EGR valve itself could be sticking. The EGR vacuum solenoid may be bad. Some of these things can be tested with a reasonable assortment of tools and test equipment and a factory service manual. It could be the TPS.

 

I had the same thing happen to me, replaced plugs AND wires, and it went away completely...

The hesitation was ONLY from a stop, ran fine the rest of the time, I thought it was the tranny or something in the driveline, but it was the plugs and/or wires. I did it at about 150k miles.

 

Idle has gotten rougher too. the truck sits a lot. I put new motorcraft plugs and techron in it. Maybe that will help.

 

If you have never done plug wires, you should have done them too. Go motorcraft wires, they are expensive as hell, but worth it. I tried aftermarket wires and they sucked.

 

Motorcraft wires are not that expensive if you order them from Rock Auto.

MOTORCRAFT Part # WR6110 {#3L3Z12259AB, WR6080}


$35.79

 

Wow, wish I would have known that when I did mine. I just changed my plugs again a couple weekends ago but didnt do the wires this time, runs better but if I knew I could get them for that price I would have done the wires again.

 

I had a similar problem with my Windstar and it was the plenum gasket leaking vacuum. If you have a scantool that does live data try looking at the maf data while its running as I have seen those cause problems like that in other non-ford vehicles.

 

After plug wires if not fixed look at the electrical power end for the cables.

 

That should drop lean codes, though, correct? I know when my '03 was running rough, I didn't get a CEL for anything ignition-related, but I figured replacing factory-issue plugs/wires/coil pack in a truck with 145k miles or so was a prudent course of action.

The intake leak in my case came just a bit later.

 

The guys thread above U just replaced his injectors for the same problem U have. A thought.

 

When my plenum gaskets and isolator bolts needed replacing, I got a IMRC stuck code, not a lean code.

 

Did the plenum gaskets/isolaters (P0174 code lean). fixed the IMRC links at the same time because the bushings were gone and rods out. got no IMRC codes though...
Plugs and wires are new motorcraft parts, Ran Techron thru the motor, fuel pressure is in spec. At this point, I think the gas in the tank may be bad (Goddamn E10 gasohol).
The truck sits a lot and the gas may have seperated or gone moldy or whatever the crap does.
How do I drain the tank on this truck?