5.0 stutter while cruising.

[Lignite]

I'm running out of ideas, and need help. 1994 Ranger, engine from 1997 EFI 5.0 explorer, remote turbo@5psi.

I've got a miss, or stutter, while cruising at highway speeds (at least thats where it is most noticeable, probably could be there at slow speeds too). Doesn't seem to happen when you get on it, or let off it, just while maintaining.

Another symptom that happens is my air/fuel ratio no longer kicks down (gets richer) when you get on it and push into boost, it just continue to bounce around that 14.5-15.2 or so (used to kick down to 11.5-12 when you got into the boost).

So far I changed fuel pump, changed plugs and found a cracked rubber EGR hose, none of which has changed anything. Anybody got a direction to point me in? I'm apparently in over my head, and thank you in advance for any information.
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[Spdrcer34]

Do you have a custom Tune?

Ryan

 

[Lignite]

Yes, it was tuned by the former owner with a Sniper Special Forces (which I didn't get with truck purchase). Could the tune have been lost and it reverted back to the stock expo tune?

I should have put up some specs, these come to mind: 5.0 out of a 1997 explorer, Garret turbo at abou 5psi, 255lph walbro high pressure fuel pump, 39# injectors, AEM wideband air/fuel gauge.

Could this be an EGR issue? The rubber hose to the EGR was blown for probably 2 months before I realized it, and it blowtorched a hole in my heater box, could a EGR valve/sensor have caused that hose to blow (I have next to no miles on it since I fixed that hose). Perhaps the computer 'learned' a bad habit while that EGR hose was off? Perhaps EGR still isn't working correctly? I'm sorry, I'm just rambling, I just don't know where to look next, and I'm pretty sure I don't trust the dealership around here to know any more than I do (which isn't much).

 

[Turdle]

I cannot believe you are getting no Check engine light illuminated with a egr hose disconnected. List the trouble codes please?

 

[Lignite]

I did just have a buddy check and clear my codes, and my apologies, because I didn't ask him the numbers (I will check if he wrote them down). But I know there were 3, one of which is the missing automatic transmission which is a remnant of the engine swap. Another was a speed sensor (don't know where that came from), and I forget the 3rd one (but think it was EGR related). These were all stored codes, the dash CEL never did come on (though it works, I believe).

Again, my apologies, I will try and get more details out of this by this afternoon, and will also be doing some driving and will see if any more CEL's appear. I'm asking the wife for a code scanner for Christmas, I may need Christmas to come early this year!

 

[Turdle]

switch the key to the on position, check if the CEL light illuminates --

it should. The bulb may be burned out.

 

[Lignite]

Got the pickup back again this afternoon, miss still there, very pronounced in fact, seems like its getting worse over the last few weeks. I forgot to mention the ABS light is on (though I don't think its related). I'm assuming my friends code reader can not read ABS codes(?). CEL lights correctly when I turn the key to start it.


Codes thrown:

po755
po720
p1451

I'm far from an expert, but I'm guessing all three of these are artifacts from the engine swap?

No new codes since those were cleared (probably only 5 miles driven since cleared though). Going to drive it a bit and have him check codes again. My mechanic buddy is leaning towards coil pack, or possibly Cam Position Sensor heading south. Would these be the next thing to try?

Miss is only while maintaining speed, not when accelerating or zero throttle. Seems to starts and idle normally. Air Fuel ratio bounces from 14.6-15.1 (normal at idle), but will NOT richen the mix when I get on it and get into boost (like it used to).

 

[springer275]

fuel filter

It may sound simple, but try replacing the fuel filter. It does not set the sensors off when it is clogged, or possible fuel pump problemn starving the engine.

My ERG valve is bad and it does not cause the 5.0L motor I have to miss, but when I detached it ran terrible, so it is still in waiting for me to replace it, still attached.

 

[Lignite]

I didn't have a fuel filter to put on when I changed out the fuel pump, but I did pull it and blow through it, which seemed free and clean (this could mean nothing). Will put it back on my list to change out, but it really doesn't seem like that could be it, its just not a high RPM or 'smoothness' problem(?).

 

[springer275]

I noticed my 5.0L "coughing" or sputtering which is the best way I can describe it. I only noticed it at 45MPH going through town, not at 65MPH. Not during acceleration or deceleration. It got worse when I ran fuel system cleaner through the explorer which lead me to believe that the fuel filter was plugged.
I had a bunch of work done last week, changed the belt, radiator flush, a bad tensioner pulley changed, and had the fuel filter changed. (I normally do my own work but I have not time this fall) It is running much smoother and not sputtering at 45MPH.

Did you leave the Ranger fuel filter on? Perhaps it is too small for the flow of the 5.0L combined with being old is causing a problem, or when the fuel pump was changed a bunch of dirt was knocked loose in the tank and clogged it up.

Then again, that may not be the problem, though fuel filters are not much more than $10 and would be cheap if it was your problem. I have heard of people using Sea foam to clean up the fuel system, but I have never tried it.

The only other simple items I can think of is a problem with the injectors, or ignition. Your other issues may be related, or not related. The other question is how much of the Ranger did you leave in the engine compartment. The 5.0L requires a very high amp battery, much different than the small V6 motors that they put in the Ranger, and if you left some of the intake air pieces from the old ranger motor, maybe you are not getting the air flow you need.

__________________
2000 Explorer XLT 5.0L AWD
3" Lift Kit

 

[Lignite]

Well engine was running very well a few months ago, so I don't think its an airflow, filter size or battery issue. But I will stick a new filter on, just in case thats it.

 

[springer275]

good luck, sorry for not being more helpful.......

 

[Lignite]

I'm afraid I'm gonna need it! Thanks everyone for the help so far, it is much appreciated, I make a very poor technician, and am going to have a hard time affording taking this to the dealer (who may not know much more), so all of your thoughts and ideas are very helpful.

 

[Lignite]

Well, new fuel filter in, no change. Still has intermittent miss while maintaining a given speed (I think I've determined its there at lower speeds too, just much more noticeable at highway speeds), and air fuel ration will NOT richen when I get into it, like it was tuned (computer flash) to do.

What if Throttle Position Sensor, or perhaps MAF (an aftermarket Lightning MAF in my case) were not reporting to the motor that I kicking her in the guts, and thus it doesn't know it should be dumping more fuel? But wouldn't either of those cause poor running all the time? And how would TPS or MAF cause an intermittent miss, wouldn't it miss all the time?

Still no CEL, and I'm guessing no codes stored (will check again for codes monday or tuesdy). I did have an ABS light on, but that went away when I put my box back on (plugged in tail lights)