my 5.8 jumps and sputters randomly during acceleration and during almost every WOT upshift past about 4000 rpm. I have no Check engine light on.

pulled codes, the only codes i got were EGR not closing properly and a transmission code (TCC lockup- i have a manual switch on dash)

I tested fuel pressure hot and cold and they were within spec.

I also put a vacuum tester on the engine and there are no leaks, or bad valves or anything.

I replaced the fuel filter.

I swapped a known good MAP sensor from another truck of mine.

The EGR, EVP, and EGR tube were replaced two years ago.

Last year i replaced the IAC and TPS

Last year i also replaced the plugs, wires, cap, rotor, coil with all MSD parts (minus the motorcraft plugs).


Basically, it starts popping and sputtering like crazy when at WOT merging onto the highway. And randomly when giving it any more gas than what is needed to maintain speed. Sometimes it does it after it is warm, sometimes it does it immediately during a cold start. It will also miss at idle sometimes. Every once in a while i will get a good strong WOT 5000 rpm upshift and its fine.

last week i was towing about 7500 lbs, and as soon as it got warm it ran like that the entire time unless my foot was off the gas. it sounded like it was running on 5 or 6 cylinders the whole time while running extremely rich. had absolutely no power.

WHENEVER IT ACTS UP LIKE THIS IT IS JERKING BACK AND FORTH BETWEEN REGULAR POWER AND THE "RUNNING ON 5 CYLINDERS" FEELING. you can always smell the rich exhaust.

i dont know what to do next. my next thought was a full tune up. coil, cap, rotor, plugs, and wires.

could it be the egr? it is only two years old. i have headers with straight pipes and no cats so if it is the egr i will block off the port on the shorty headers and make a sheet metal piece and seal the hole on the intake manifold side.

let me know what you all think.

 

Have you checked the timing? you might be needing to set the timing right (anywhere around 10-14 BTDC should work, remember to disconnect the SPOUT). Also, check the firing order, one missplaced sparkplug cable could easily cause this condition.

 

would the timing need to be set even if it has never been messed with? the distributor is not loose and has not moved i checked that. the firing order is also correct.

i pulled a plug and took a picure of what it looks like. to me it looks like sometimes its been really lean and sometimes its been really rich.

http://img188.imagevenue.com/img.php..._122_260lo.jpg

 

You need a tune up dude.....classic signs of an engine miss....dont skip over the basics....plugs wires

 

Cap and rotor

 

while your tuning it up check your throttle body gasket, if a piece of it has fallen away or its broken appart in any way and leaking, it can cause surging.

 

As i said, check the timing, if you have "never messed" with it how would you know if it's actually rights? some things, even the ones bolted, move at least a little over the course of time. It would not surprise me that the only screw that holds the distributor in position moved at least a little (even beyond of the acceptable ranges or the ECU).

Maybe try and Seafoam the engine? that could help and it won't hurt anyway.

 

seafoam will clean up anything, good *****

 

i would suspect timeing but also i suspect fuel pressure. reason i say that is when you checked it you where probably sitting still. if you could check the pressure while driving i think you would see it drop. this will cause poping and bucking not to mention lean/rich condtion sporatically. Make sure you dont have the #7 & 8 plug wires touching at all. these are known to crossfire and also create similar symptoms.

 

I agree with Kem on possible cross firing. Check you firing order because on mine the #6 then #5 fire sequentially so I separated them. Also, have you pulled the CM, continuous memory codes for driving history?

 

I chased a miss for a long time.. it was stupid Ford Racing plug wires that were absolute junk (with little warranty to boot!). Intermediate, all the time, then intermediate.. The broken wires are now replaced with the stock wires that I thought were no good and the truck is running like a dream.

Thing is, balance test wasn't showing anything. I think the wires were grounding out somewhere on the block, but only occasionally.. plugs would foul due to weak spark, then clean up under certain conditions. I blamed EGR because it was worst when EGR was in full open, but I think the weak spark would only show itself and cause the miss when EGR was open, possibly needing stronger spark and then fouling the plugs? My theories are all over the place and I have dozens, I doubt I'll ever know why..

Just, all your new parts need to be looked at before other stuff. I've spent MUCH more time troubleshooting problems caused by new parts on this truck than I have on old original parts.

 

hi all- it really bothers me when i read a thread and the the guy with the problem never announces the final outcome so im trying to go back through and and finalize all my posts-

i fixed it and it runs like a dream, ErrorS you were right it was the crappy ford racing plug wires and old plugs. new accel wires and motorcraft plugs did the trick!

thanks to all for your help

 

Ahh, guys, I'm not an idiot, that was Autocorrect making me say stupid stuff (intermediate instead of intermittent)

glad it worked out screaminford, spread the word about the Ford Racing wires, I've been seeing it all over the place. I can understand a bad batch going around, even quality manufacturers mess up sometimes, but it would be nice if they backed them up with a better warranty.

 

Yeah .....what this guy said in the begininng ......seriously, thanks for following up......and letting us know what it was. Reps on the way for that !

 

New to the thread but I can't figure this one out... So I have a 1995 f150 351w five speed 4x4... Everything was working great when I did the motor swap and now I can't seem to figure out what the problem is.... The truck starts up and idles like its suppose to, when you put it in gear and start to take off its real jumpy and has no power... And can't seem to find the problem... Any advice would be great thanks!!