2004 4.0L Engine Sputtering Problem @ 1000-1200 RPM

[mikeinri]

OK, I'm stumped, and so is the garage...

I have a newly installed remanufactured Jasper engine (long block). Got it back and noticed some hesitation upon light acceleration (maintaining speed on slight incline). After about 115 miles, it flashed the Service Engine Soon light after sputtering quite badly. Pulled off the highway, it was running fine. Did the same thing about 15 minutes later. Runs great at all other speeds, including idling.

Took it back to the shop. Threw a code for #1 misfire. Coil, plugs and wires all checked out OK (those are all about a year old). Supposedly checks out fine for compression. Cleaned the MAF sensor. They ran it and couldn't reproduce the problem, so they had me pick it up, under the theory that the spark plug wire may have been loose.

I took it onto the highway, seemed a bit better but still not quite right. No lights, but rather sluggish at 1000-1200 RPM.

Got it home, and while in park, tried to run the engine at different speeds. Runs great at idle (700-800 RPM), nice and smooth. Runs great at RPMs higher than 1500 RPM. Will NOT hold at 1000 RPM. With my foot solid on the pedal, the tach and engine just bounces up and down between 800 and 1200 RPM, sputtering at times (no new lights).

I had a similar problem with the old engine, but that had bad cassettes and other internal noise, so it never was fully diagnosed (the Ford dealer and local shop couldn't/ wouldn't figure it out, so I ran it for a year until it died).

So, it's possible that something outside of the envelope of the new long block was transferred over, which would probably leave me holding the bag to pay for more diagnosis and repair...

Is it possible that the computer needs to relearn?

I'm already out of pocket for about what the truck is worth, and have been without it for a month. I don't care about that nearly as much as the fact that I feel like I can't trust it, and am out of help professionally around here.

Where do I start???

Mike

 

[mikeinri]

50 views and no clues on a diagnosis plan for an engine that won't hold speed at one specific RPM range?

Mike

 

[mikeinri]

Drove it pretty much all day today. Sputtering keeps happening, but no engine lights. Ran very poorly right after starting a few times. Engine decelleration is the worst, especially when making slight changes on the gas pedal. Very frustrating.

Mike

 

[2000StreetRod]

electronic throttle control?

I think Ford switched to electronic throttle control in 2004. Has that been checked?

 

[mikeinri]

I was wondering about that too. This shop won't have a clue, I'll need to find a better dealer.

Mike

 

[mikeinri]

Spoke with the shop and mechanic stated that he cleared the computer (ECU) to factory. So, I'm thinking that I need updates from Ford, at a minimum. They had nothing but guesses beyond that, and mentioned parts that should throw a code.

Mike

 

[mikeinri]

Got an appointment for Friday at the local dealer (CEL flashed on the way there). They didn't want to touch this in the past, but seemed OK with it now, as it's a Jasper engine. Service manager listed a bunch of things that could be the cause...

Mike

 

[mikeinri]

Semi-update...

Due to a scheduling issue on my end, the dealer service appointment has been postponed until tomorrow.

The truck is still acting up. Sputters when feathering the accelerator at the low end. Flashes the CEL occasionally. Seems to be worse when warm than cold, but I wouldn't swear to that. New change, the CEL came on and stayed on this morning (after flashing previously).

I tried a bottle of HEET dry gas/fuel system cleaner, no change.

Any ideas?

Mike

 

[mikeinri]

OK, new update...

Dealer confirmed Cylinder 1 misfire (codes P0301 and P0174).

They didn't like the look of the spark plug, so those will be replaced. BTW, what's the best brand of spark plug for these engines? Dealer says Motorcraft, non-platinum.

They also believe there is a vacuum leak at the intake manifold. They need to pull it off to check into it further, but at a minimum, it needs an intake gasket kit. They also mentioned possible leaking injector o-rings.

For the items above (not including replacing the actual intake manifold if that's cracked), just under $600 (dealer pricing for the repairs above).

RockAuto and Tasca prices for an intake manifold are just under $300. Just to pick up the truck after this diagnosis, $99...

I called the shop that installed the Jasper engine, and they are going to do the work. Apparently, there were no new intake gaskets supplied as part of the Jasper gasket kit (mind boggling). Scheduled to drop it off over there next Monday...

Mike

Note, edited a few items above after picking up the truck and report from the dealer.

 

[mikeinri]

This saga may be coming to an end...

After spending the weekend all over the internet, reading forums, watching YouTube videos and checking parts diagrams, I brought the truck back to the original shop yesterday. I gave him the report from the dealer, and insisted that he run a smoke test (after everything I researched, I'm stunned that neither this shop nor the dealer did this yet).

The dealer said that they sprayed carb cleaner on the intake manifold junction to the top of the engine, and assumed that the manifold gaskets were bad.

Local shop also said that the intake gaskets were indeed new with the Jasper engine (changed his previous story but showed them to me as well), and that the injector o-rings were also new. I also asked him to replace the intake manifold bolt isolators/spacers, but he insisted they are OK.

When the local shop did the smoke test, they saw smoke coming out of the EGR valve! He said that it makes sense for the carb cleaner test to mistake that for intake gaskets, since the leak was very close to the manifold. No good answer as to why it wouldn't throw an EGR code...

So, I have a new EGR valve, new intake manifold gaskets, and new spark plugs. The local shop cut me some slack on some of the parts and labor (since they should have caught this when they installed the engine, or at least when I brought it back within days of getting it home). Gave me the 500 mile oil change too. Said he's out of ideas if this doesn't fix it (duh...).

Drove it for about 20 miles, and did my own idle testing (slight pressure on the accelerator pedal), and it seems much better so far. Was able to maintain constant idle at 1000, 1200 and 1400 RPM. Seems to idle well on its own. Did have a slight variation when I tried to hold it at 800 or 900 RPM, but nothing like it was before.

Again, I'm not convinced that this is resolved yet (it's been going on for too long, and very intermittent), and I'm hopeful that this was an old problem that carried over from the parts transferred to the Jasper engine, but time will tell...

Main lesson here: Insist on a smoke test!!!!!

I should have insisted on witnessing it, and video taped it as well. If this starts up again, I'll be doing my own smoke test if necessary...

Mike

 

[2000StreetRod]

smoke test reliable

I agree that a smoke test is the only reliable method to detect an intake leak. For most leaks the PCM/IAC valve response is too quick for the engine speed to significantly change when using an aerosol.