Hello Forum! I sure hope some can give me a clue here: Have a 99 E350 Super. 5.4L Trition. What's going on is the engine is acting like it has no power especially at low RPM it actually jerks and makes whole van shutter. If you mash on the gas, it will stop shaking but just doesn't take off like it should. And the gas mileage is beyond terrible. My 1st thought was clogged CAT Conv because it doesnt seem to be pushing enough air out the tailpipe. But today I took it off and you can see light thru it. Though I don't know if that tells the tale. I know the SES light works, so I would think a misfire would make it light up? So I am sort of stuck between fuel pressure or restricted exhaust. I'd appreciate any input.

 

has there been any recent maintenance performed? perhaps it needs a new fuel filter? I am new to the vans but have had the 5.4 for a few years now. Strange that its not throwing codes...

 

No recent maint. Actually just bought this 5 mos ago. And drive it very little. BUT, this has progressed since I got it. I know the SES light works because the EGR valve died on it the day I got it. Your right, it is wierd. I really thought it was a driveline/suspension issue, but you can put it in neutral while driving and its all good.

 

another idea is to check your mass air flow sensor and air temp sensor near the throttle body. they could be dirty and gunked up.

 

OK I can give that a shot. I planned on doing a basic tuneup/maint to the engine, though I am a bit scared about the spark plug issues I've heard about. Will have a look at those.

 

the spark plug issues I hear about concern the 3V 5.4 where they break off during removal or blow out of the heads. you have a 2v so the only issue there may be getting to them.

 

Yeah it does look like a challege to remove them.

 

I had a similar problem.
Check to see if that year has upstream and downstream CATs. Even if the downstream one is good, the upstream ones may be cloggy.
My '02 5.4 had one on each exh.man. and one downstream. I replaced the downstream and removed the 2 on the manifolds. It ran like a champ for almost a year, now it is having other issues.

 

Seriously 3 CAT's? I guess I will pull the doghouse off and look to see. Can you tell what the heck they look like or will they be obvious? Thanks for the tip, never heard of such a thing.

 

Probably only have one Cat on an e-350 - they were classified as heavy duty and only were required the downstream cat (California emissions might be different)

Since you said putting it in neutral made things better - I wonder if your problems aren't in the transmission. If you only had one gear or the torque converter has failed and locked up you might have similar symptoms without the engine throwing a code.

Just an idea...

 

I mentioned neutral because I thought I had a driveline issue-suspension, u joints, etc. But the van is running rough at idle and even very slow speeds. I'm leaning towards an engine issue though I will certainly give the trans a bit more attention. Thanks

 

Wouldn't be the first time I've mis-read a post...

If you had a push-rod V8, I'd say the timing chain has jumped on it. I'm not familiar enough yet with the overhead cam engines to say whether or not that was a possibility.

 

I haven't had much chance to mess with it due to 3 other messed up vehicles. But I think I will start with plugs, MAF, etc. And see what happens. Tritons are new to me too. So guess I am gonna get my lessons the hard way.

 

Check it for codes, the MAF will throw a code, plugs are so difficult that I paid the dealer to do mine, I didn't want a stripped one, a 97,000 mine was stalling a few times after starting it, plugs solved it. Now you could see about getting the injectors cleaned, they run a strong solution straight into the injection rail, turn off the fuel pump and run the engine on the cleaner alone, had it done after I bought it at 73,000 but had codes due to faulty sensors too, I got quite a bit of power after.
BTW you have a pre cat up toward the manifolds, and a cat down stream on both sides, bringing the tally to 4, my 99 E-350 5.4 ext is setup this way.

 

Wow Maples - that's a world different that the set up with the v-10. I've got straight pipes back to a central cat then to the muffler. Go figure...