01 explorer 5.0 backfire out tail pipe

[Nightbiker07]

lets start off by saying that the 5.0 is in a Ranger, but it is an Explorer drivetrain, and I figure this issue would get more exposure to Explorer guys.

OK, so when I first start the truck up, it runs great for 3-4 minutes (until warm). Pulls strong, no issues to speak of.

After it is warmed up, it begins to run like I am pulling a 4000 pound trailer. No power, and it randomly will misfire and jerk under WOT, and at almost any other throttle positions, (especially low RPM under load) it will misfire, jerk, and often backfire out of the tail pipe several times.


At first, the truck ran better with the MAF unplugged. replaced the MAF. No change.
One of the spark plug wires came loose and burned in half on the header. Took me a while to figure out where the misfire was coming from (dead cylinder #8). New plug wire, new plug, and I saw a minimal improvement. Installed two new MSD coil packs, not much of a difference.

I was thinking that due to the plug wire being severed, maybe the cylinder washed out with fuel and now its low on compression. I havent bothered with a compression check yet because a low compression situation would improve as the engine heated up, and this thing runs great when cold, so I am doubting compression.



Mods
OBX headers
Comp Cams Xtreme Energy Cam
Roller Rocker Conversion
Cat Back Dual Exhaust
SCT X3 tuning
MSD Blaster Coils


I dont think the issue is a tuning issue. The backfiring issue started after the tune was just about finished (we re-tuned with the header installation), and because of the problems, we cant get it dialed in. Nothing the tuner has done with the tune has changed the issue at hand, leading me to believe it is a mechanical problem.

This all started with the plug wire being torched, and now I am tired of throwing $100 parts at it and getting nowhere. Worst part is, I have no Check Engine Light or supporting codes to indicate there is any issue at all.

Does anyone have any ideas where I could start? I was thinking maybe the dead cylinder plugged up a Cat? but it running fine when cold still doesnt really play into that

 

[Turdle]

lets start off by saying that the 5.0 is in a Ranger, but it is an Explorer drivetrain, and I figure this issue would get more exposure to Explorer guys.

OK, so when I first start the truck up, it runs great for 3-4 minutes (until warm). Pulls strong, no issues to speak of.

After it is warmed up, it begins to run like I am pulling a 4000 pound trailer. No power, and it randomly will misfire and jerk under WOT, and at almost any other throttle positions, (especially low RPM under load) it will misfire, jerk, and often backfire out of the tail pipe several times.


At first, the truck ran better with the MAF unplugged. replaced the MAF. No change.
One of the spark plug wires came loose and burned in half on the header. Took me a while to figure out where the misfire was coming from (dead cylinder #8). New plug wire, new plug, and I saw a minimal improvement. Installed two new MSD coil packs, not much of a difference.

I was thinking that due to the plug wire being severed, maybe the cylinder washed out with fuel and now its low on compression. I havent bothered with a compression check yet because a low compression situation would improve as the engine heated up, and this thing runs great when cold, so I am doubting compression.



Mods
OBX headers
Comp Cams Xtreme Energy Cam
Roller Rocker Conversion
Cat Back Dual Exhaust
SCT X3 tuning
MSD Blaster Coils


I dont think the issue is a tuning issue. The backfiring issue started after the tune was just about finished (we re-tuned with the header installation), and because of the problems, we cant get it dialed in. Nothing the tuner has done with the tune has changed the issue at hand, leading me to believe it is a mechanical problem.

This all started with the plug wire being torched, and now I am tired of throwing $100 parts at it and getting nowhere. Worst part is, I have no Check Engine Light or supporting codes to indicate there is any issue at all.

Does anyone have any ideas where I could start? I was thinking maybe the dead cylinder plugged up a Cat? but it running fine when cold still doesnt really play into that

Sounds exactly like the tuning issue I experienced when the tuner sent the wrong vin coded tune file.

Once it was warm it was like it was running on 4 cylinders, sounded like the egr valve was stuck open.

 

[Nightbiker07]

Is there any way to check this without bringing it up to him? we have tried about 7 different datalog tunes and he cant figure out what is going on. And earlier this summer, he datalog tuned this truck without the headers and he had it done after 2 datalogs and it ran great.

I will try running the tune he wrote early this summer, before the header install. truck ran great then, I would think that would rule out a vin # mismatch on the tune.

Although, I never gave him a vin to begin with.

 

[Billy260Z]

Have you checked the Coolant temp sensor ? Because I had a issue like this on a 95 GT I had . After the headers and cam install. The Coolant temp never thru a code . As soon it warm it would just dump fuel and it turned the car into a flame thrower when it back fired !!! I only found when replacing the l intake manifold . I swapped the sensor that was on the new manifold .

 

[Nightbiker07]

Replaced the coolant temp sensor, no change.

Loaded a known good tune, no change.

If I unplug the vacuum line on the EGR, will it keep the EGR closed or open?

 

[Billy260Z]

if the egr is stuck open from a failed diaphragm. unplugging the vacuum source will not correct it .
remove your egr and block it . and fire it up

 

[Nightbiker07]

yes, but if the PCM isnt closing the EGR when the engine comes up to temperature, it would have an effect for sure

I am assuming that unplugging the vacuum line will keep the EGR closed, provided the valve is operating correctly?

 

[Nightbiker07]

unplugged the EGR, and thought I hit pay dirt. Took an hour of driving for the problem to resurface. But it came back. and I have a "egr insufficient flow" code with the valve unplugged. but the check engine light doesnt come on, I have to read the trouble codes to see the codes presence. But, the bulb isnt burned out because the light turns on when I turn the car ON (before starting)

It is definitely running far too rich when it starts doing this, as can be seen by the very sooty tail pipes and the fuel economy being about half of what it should be. (its getting 10, it used to be 20+)

I am beginning to suspect a sticking injector or a failing PCM, I am running out of ideas! I suspect the PCM because the CEL will NOT turn on no matter what code is thrown.

 

[boominXplorer]

I had a bad injector in my ranger about 5k mi after my swap. I did a Huuuuuuge burnout and at the end I noticed it wasn't right and let off. I thought I broke a rocker arm from the symptoms but it was just a stuck open injector.

On a 2nd note I've has an sct tune make my truck almost undriveable. It acted like my MAF was unplugged when I hit the gas. Put it back to stock and it was fine. Had to update the tuner and it was good after with the same tune I tried earlier.

 

[Nightbiker07]

I have flashed several different tunes throughout the last few months and weeks hoping it was simply a corrupted flash, but unfortunately this is not the case.

would a stuck injector come and go? the issues do not persist much at an idle, or really under any specific circumstances, which rules out unplugging spark plug wires to hopefully narrow the issue down to a specific cylinder. the only thing that is consistent is that it only happens after the engine is warm.

 

[boominXplorer]

What year pcm are you using? Thought about trying another?

My injector stuck and never got any better. It was drive able but at low rpms it was flooding out and putting extra fuel throughout the intake.

 

[Nightbiker07]

What year pcm are you using? Thought about trying another?

My injector stuck and never got any better. It was drive able but at low rpms it was flooding out and putting extra fuel throughout the intake.

a 2001 mountaineer.

I have a spare PCM. problem is the PATS system will not work on the spare PCM, and the only tune I have with PATS turned off is one of the tunes written with this fuel dumping issue, so the tune could be trash to begin with. And, I will wind up wasting 2 SCT tuner vehicle unlocks if the issue doesnt turn out to be the PCM. I have been saving this particular component as one ov the very last things I try. I am going to run a mountain of fuel injector cleaner through this thing and pray for a result, because throwing $300 worth of injectors at this and hoping for a fix iis getting old....

 

[boominXplorer]

Download Forscan on a laptop and get your self an usb to obd2 cable. Plenty of people have been using it for pats programming and its free. I'd return your current pcm to stock so your tuner is unlocked and try swapping pcms. I fortunately have a scanner that does power balance and pats programming so I've never used it.

 

[Nightbiker07]

Download Forscan on a laptop and get your self an usb to obd2 cable. Plenty of people have been using it for pats programming and its free. I'd return your current pcm to stock so your tuner is unlocked and try swapping pcms. I fortunately have a scanner that does power balance and pats programming so I've never used it.

Awesome! never heard of that tool before. That will fix my "two key" dilemma for this truck.

SCT tuners only let you program 5 separate vehicles. (One at a time)
Changing PCM's will use an "unlock".

 

[boominXplorer]

Don't tune the new pcm before you fire it up. It should run decent even with the cam on stock tune. That way you won't use an unlock if it doesn't fix your issue.

 

[Nightbiker07]

Ordered an obd2-USB cable.

The stock tune runs absolutely terrible with this setup. Running it on the stock tune won't tell me much. With the ability to program the PATS, I will try it for sure. But i don't expect to learn much
The Cam being 4 degrees advanced has something to do with it I think.

 

[boominXplorer]

What cam are you running? I set mine at 0* and other than idle being shaky it ran decent on stock tune. I had a hell of a time getting my pushrods right though.

If you do a search on here of my name and comp cams you'll see my install fun and a video of my truck running on stock tune.

 

[Nightbiker07]

What cam are you running? I set mine at 0* and other than idle being shaky it ran decent on stock tune. I had a hell of a time getting my pushrods right though.

If you do a search on here of my name and comp cams you'll see my install fun and a video of my truck running on stock tune.

running a Comp Cams Xtreme Energy cam. the cam degree wasnt adjustable. i mean, you could change the tooth on the timing chain, but that is extreme change. the "zero" on this cam has everything with the valves happening 4 degrees advanced over a stock cam at zero degreees.

Pushrods were easy, I just finger-tightened the rockers, then turned them 3/4 turn past finger tight and tightened the set screw locks..Converted to adjustable roller rockers, and that made the push-rod adjustment a snap.This cam required a double valve spring set-up though, which required head machining, smaller diameter valve seals and different valve spring locks.

 

[Nightbiker07]

ok so the check engine light finally came on for the EGR being unplugged even though the code has been in the PCM since I unplugged it. first time the check engine light has popped on for ANYTHING being unplugged/disabled since the beginning of summer. Trans now occasionally shifts funny too. I am hoping it is the PCM at this point......not much else it could be.