I'm having a problem with my engine. While cruising, going over 45MPH then letting it settle, then giving anything but the TINIEST touch on the throttle will cause a TERRIBLE stuttering. I think this can be ruled out as a transmission problem after a few things we did it yesterday.
The first thing we did was replace all 8 spark plugs after we had the computer checked and we were told Cylinder #8 misfired. We also replaced the coil that connects to the top. One thing we noticed was that for the first 4 minutes of driving we had absolutely no problems. The truck was running great, it felt like it had every bit of it's power! Then after that, the thing started stuttering again. Checked what we had just replaced, everything looked like new.
One thing I remember doing after finishing was letting the truck idle for 4-7 minutes before taking it out on a test drive. This makes me wonder if it could be a fuel problem. Does anyone think this could be the result of something that has to do with fuel delivery? Fuel Filter? One of the injectors? I am truely stumped after yesterday. The only explanation that I have for that 4 minutes of wonderful driving is that the truck idled enough fuel towards the engine. Please correct me if I'm wrong... And offer a solution to this problem.
You did good, but if I understand you right, you just changed one COP. With these COP's you have to change all 8 at the same time. What likely occured in those 4 minutes of idling is another COP failed and this will keep happening until you have changed them all. Use dielectric grease on the plugs and boots and some to seal around the top of the boot to keep out moisture. PS: You can get a set of COP's on ebay for about $90, just go there and type in 5.4 coil. A lot better than paying 300- 900 at the Ford dealer!
Hope this helps.
PS: What you can do until you get it fixed, is push in that little button on the gear selector if it is an automatic so it doesn't shift into overdrive. My truck did the same thing, all you are doing is keeping the revs up, because once it shifts into overdrive, the ignition is too weak to pull at that kind of torque.
I'm running into the same problem with my Ford E350 van. It started as a gradual skip, and progressively got worse. I bought a cheap code reader, and it was telling me cylinder #5 was misfiring. I'd erase the computer, and a short time later Cylinder 5 would misfire again, and on a rare occasionally 4 and 8.
I replace the coil on Cyl 5 and there was a huge improvement. However I still get a major shudder at low RPM's as soon at 45-50 miles per hour. I notice it particularly on a slight uphill section of highway around 50 mph.
I cleared the computer and checked again for misfires, but there have been NO misfires. The shudder is very noticable, and I'm down to three suspects.
My primary suspect is the mass air flow sensor, or what ever the sensor is that is located in the round air cleaner case. I was handling the unit while the car was running after replacing the coil and the engine rpm started going up and down while idleing. It continued to go up and down, and then finally cleared up after about 5 minutes. I'm thinking a case of air fuel mixture being too lean causing a buck at low rpm, high speed. This would also be supported by the fact the outside cylinders were reporting misfires, with the exception of cyl 1 (4 -back right, 5 front left, 8 back left)
My other suspect is the EGR which kicks in at highway speed. It could also cause something like this, but I'm not getting any engine light or diagnosis codes.
My third suspect is the transmission lockup torque convertor turning on and off at that speed.
One final clue, if anyone can help, is the van accelerates fine at wide open throttle all the way from zero to 70mph. No issues, it's only at about 20% throttle I see the problem.
Also I"m confused by Gary's statement to replace all 8 coils??? Sure it would work, but replacing the entire motor might fix it too. I would expect to see the computer show me a skip if there was a continued misfire.
Thanks, the first one to die was cylinder #5, front of the motor, drivers side. But just this weekend cylinder 8's coil went, back of the motor, drivers side. By reading the computer I can see which cylinders are misfiring. I'm almost wondering if dielectric grease would save the coils from dying.
The aftermarket coil design is very different than the OEM design. The Ford ones had a resistor at the tip where it hits the plug. The new aftermarkets do not have this resistor and the spring seems to attach right to the top of the plug. When I first installed the aftermarkets I was worried it would impact the radio with static and engine noise which the resistors are there to avoid. But I've not heard any difference. Perhaps the new plugs have the resistance built into them, so it's more work on the coil to overcome two resistors, and that's whats killing them? This job is definitely no fun on a van. I was able to get #5 and 8 in OK, but 6 & 7 look like the fuel injector tubing needs to be removed as I did to replace the plugs.
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