Kage.
Member
- Joined
- July 22, 2014
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- 29
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- STL area
- Year, Model & Trim Level
- '99 Mounty V8
I stuck this post here as I think I am out of the realm of the “Stock” portion of this forum:
I’ve got the build listed on my website (MidwestNomads) and over on Pirate 4x4 if you want the full on details of the build.
In a nutshell, the motor is the only part that hasn’t been touched during the build (185k mile 5.0). From the 5 gear swap on out, everything else has been touched. At this point I don’t know if the 5 gear swap might have caused part of the issue, but I kind of doubt it.
The issue I have been fighting pretty much since the inception of this build is a random “Miss Fire” for the lack of better term. I’ll randomly get what either feels like a momentary dead miss, or quick completely loss of power. A “skip” if you will. The frustrating part is that while I can typically get it to occur at partial throttle while highway cruising, It can happen at any time, any engine condition, and have a variable duration (it’ll miss once and be done, or it can do it for 15 miles straight). It does seem to do it more when ambient temps get above 80°F, but it’ll still do it when it is cooler outside as well.
I have data logged this thing to death looking for some sort of pattern and I have kept coming up empty handed. Whatever the issue is, the PCM does not appear to know about it. Or at least, it doesn’t know how to report it.
Lots of parts have been changed out while trying to chase this thing down. When you look at the list below, it’ll appear that I was just shot gunning parts at it, but there was a method to the madness and it actually created a better running motor, but the miss persists. So far the list of replaced parts is:
Fuel Pump (I have good fuel pressure)
Fuel Filter
Injectors
Plugs (2 times, with two different brands, same results)
Wires (2 times, with two different brands, same results)
Coil Packs
Cam Position Sensor
IAC
TPS
MAF
EGR solenoid
DPFE (and the hoses that go to it)
ERG cleaned and checked out good
No vacuum leaks to be found
Wiring harness appears to be in good shape as far as I can tell
When pulling plugs to inspect the cylinders, I’m not finding any irregularities. There isn’t a cylinder missing more than the others, and all the plugs look to be normal every time I pull them.
Compression is good and even across all the cylinders. I don’t recall what the numbers were off hand, but they were within spec according to the FSM I have.
So yeah, I’m completely stumped here after chasing this around for a long dang time. The only thing left to throw at it is a crank position sensor (crank pulley spins true by the way), but I have some serious doubts that’s going to fix it either at this point.
Searching around online shows that lots of Fords (including the V8 powered Exlopers) have random misfires that nobody seems to be able to find. This is a tad bid discouraging and I’m really hoping that I’m just missing something obvious here.
I’ve got the build listed on my website (MidwestNomads) and over on Pirate 4x4 if you want the full on details of the build.
In a nutshell, the motor is the only part that hasn’t been touched during the build (185k mile 5.0). From the 5 gear swap on out, everything else has been touched. At this point I don’t know if the 5 gear swap might have caused part of the issue, but I kind of doubt it.
The issue I have been fighting pretty much since the inception of this build is a random “Miss Fire” for the lack of better term. I’ll randomly get what either feels like a momentary dead miss, or quick completely loss of power. A “skip” if you will. The frustrating part is that while I can typically get it to occur at partial throttle while highway cruising, It can happen at any time, any engine condition, and have a variable duration (it’ll miss once and be done, or it can do it for 15 miles straight). It does seem to do it more when ambient temps get above 80°F, but it’ll still do it when it is cooler outside as well.
I have data logged this thing to death looking for some sort of pattern and I have kept coming up empty handed. Whatever the issue is, the PCM does not appear to know about it. Or at least, it doesn’t know how to report it.
Lots of parts have been changed out while trying to chase this thing down. When you look at the list below, it’ll appear that I was just shot gunning parts at it, but there was a method to the madness and it actually created a better running motor, but the miss persists. So far the list of replaced parts is:
Fuel Pump (I have good fuel pressure)
Fuel Filter
Injectors
Plugs (2 times, with two different brands, same results)
Wires (2 times, with two different brands, same results)
Coil Packs
Cam Position Sensor
IAC
TPS
MAF
EGR solenoid
DPFE (and the hoses that go to it)
ERG cleaned and checked out good
No vacuum leaks to be found
Wiring harness appears to be in good shape as far as I can tell
When pulling plugs to inspect the cylinders, I’m not finding any irregularities. There isn’t a cylinder missing more than the others, and all the plugs look to be normal every time I pull them.
Compression is good and even across all the cylinders. I don’t recall what the numbers were off hand, but they were within spec according to the FSM I have.
So yeah, I’m completely stumped here after chasing this around for a long dang time. The only thing left to throw at it is a crank position sensor (crank pulley spins true by the way), but I have some serious doubts that’s going to fix it either at this point.
Searching around online shows that lots of Fords (including the V8 powered Exlopers) have random misfires that nobody seems to be able to find. This is a tad bid discouraging and I’m really hoping that I’m just missing something obvious here.