rustang222

I've searched the forum for a while now and can't seem to find what I'm after so here goes... I've got an 04 with the 5.4. Here is what I've done recently:

- New MC plugs
- All plugs have been re-torqued after original install
- New boots and springs
- Cleaned MAF
- Cleaned Throttle Body

- CEL is currently on for EVAP System leak and I've got a new EVAP line on order to see if that solves the CEL problem but I'm thinking that's a separate issue from what's going on but as always, I could be wrong.

HERE'S WHAT IS GOING ON

When at idle, in drive or park, I have a very obvious stumble in the idle. It seems to be pretty inconsistent and by that I mean, it's not as though it's happening on each motor revolution. However, it does happen multiple times within a span of 5 - 10 seconds.

1. Does this sound like a coil issue or possibly an injector? I've had a friend cycle the injectors with his "fancy" scanner and he told me that they all seem to be functioning fine. He also looked in the truck's "history" and said there were no instances of a misfire. He suggested running some injector cleaner in my next few tanks to see if that helps.

2. Is there any way to diagnose what I believe to be a misfire without actually having the flashing CEL?? I've been driving around with my code reader to try to catch the code if it does happen to trip the light but have had no luck. This has been going on for a few weeks now.

I'd love some thoughts or advice on this.

primalurges

More likely a coil than an injector. However before going nut resolve the EVAP leak as it may all be related.

techrep

iTrader: (1)

agree....solve the EVAP DTC ... i guess you tried a new gas cap already ?

rustang222

Yep. New gas cap didn't solve it. The EVAP line that goes from the valve on the firewall to the intake was in pretty rough shape. It's as though the line is starting to crumble and deteriorate. I'm hoping the new line solves it.

techrep

iTrader: (1)

good deal...may solve your other problem also.. let us know

primalurges

I don't have any EVAP issues yet but my line is also deteriorating pretty bad.

rustang222

I'm sad to report that the new EVAP line didn't solve either problem. So instead of just continuing to guess and throw parts at my truck, I'm planning to take it in on Friday and let the pros take a look at it. I figure a few hundred bucks in diagnostics is money well spent as opposed to my current method.

I'll let you all know what the shop tells me.

VTX1800N1

Did you ever figure this out? I had the same issue and tried several different things. Spark plugs and coils, removing the intake and cleaning the IMRC flaps. Each time it felt like I had solved the problem only for it to come back again. I finally changed both front O2 sensors and I believe this was the final cure. My truck has never run better. No misfire or shake at idle at all. My LTFTs are still out of whack, however. The only cause I can find for that is the cam phasers need to be replaced.

Newfiedan

Check the foam gasket for the air filter tray it has a tendency to come off or disintegrate. Replace it with some foam tape door seal from Walmart.

rustang222

Well.... Kind of. It's a really long story that I should probably share with the community at some point but for now, I'll say that after two new (again) spark plugs, a new (used) ECM, new (used) gas tank, new fuel pump and some new EVAP parts, I'm happy to report that my truck is running very well.

The best part of all of this is, it only cost my $900 at my local dealership. When I have some more time, I'll publish the narrative. It's quite a story...