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5.0 engine problems

Hammerhead2015

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City, State
Lebanon, Tennessee
Year, Model & Trim Level
2004 Explorer XLT
I have a 2000 explorer 5.0 with 286,000 on it and having serious issues excelerating it seem to be losing power , backfiring until I let off the throttle, I have changed the cam position sensor, throttle sensor, crank sensor don't no what else to try any help would be greatly appreciated
Maybe O2 sensors? Could potentially be getting a bad reading causing either a lean issue.
 


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Gen2willdo

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1997 Explorer XLT 5.0 AWD
If it is, then you're far better off paying someone to troubleshoot this problem than continuing to replace parts by guesswork. That gets expensive and frustrating very quickly.
Had to have my ecm on my '97 5.0 redone. And I'm pretty decent with wiring, but still needed to chase down errors. $210 later, problem solved. One wire had broken internally. I'd never had found it myself.
 








Mikey195612

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2000 explorer xlt
Had to have my ecm on my '97 5.0 redone. And I'm pretty decent with wiring, but still needed to chase down errors. $210 later, problem solved. One wire had broken internally. I'd never had found it myself.
I
Okay, but it definitely had one at one point and I never saw you say it didn't. If not, I'm curious why no one suggested that?
It had been modified when I bought it ,it has true duels no cats no mufflers a little loud.
 




Tim Ryan

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1940 Ford Tudor Delux
Check your intake manifold VACUUM with a vacuum gauge. If it's low and/or continues to drop as more throttle is increased, I can almost quarantee that your catalytic converter needs a replacement.
 




bpopp

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It had been modified when I bought it ,it has true duels no cats no mufflers a little loud.
I bet. I ran mine without a cat for a few days when I was troubleshooting similar issues. The neighbors were not happy. Here's a thread with similar codes and symptoms. For them it was an issue with the harness.

Check your intake manifold VACUUM with a vacuum gauge. If it's low and/or continues to drop as more throttle is increased, I can almost quarantee that your catalytic converter needs a replacement.

LOL.. there it is..
 




[email protected]

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Alhambra
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2005 V8 XLT
I have a 2000 explorer 5.0 with 286,000 on it and having serious issues excelerating it seem to be losing power , backfiring until I let off the throttle, I have changed the cam position sensor, throttle sensor, crank sensor don't no what else to try any help would be greatly appreciated
Have you considered a plugged converter? Sounds like a breathing problem to me. Just saying...
 








Ziggylilg187

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Osceola
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2000 Mercury Mountaineer
I have a 2000 explorer 5.0 with 286,000 on it and having serious issues excelerating it seem to be losing power , backfiring until I let off the throttle, I have changed the cam position sensor, throttle sensor, crank sensor don't no what else to try any help would be greatly appreciated
Check your vacuum lines. That's what mine was.
 




410Fortune

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B2 "Slightly" Modified
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Backfiring = LEAN
Running fine most times and then struggles when under load = LACK OF FUEL

There have been a few people now in this thread suggest a weak fuel pump, that is how they fixed their 5.0 explorers when they acted similar

I have been around these 5.0's "just a little bit"
It really sounds like a failing fuel pump
I have seen this many times before, I have fixed it many times before. The 98-01 5.0 with the returnless fuel system DOES THIS ALL THE TIME when the pump gets weak

Timing? bent valve? Not if it runs perfectly fine until he puts it under load

Clogged converter, this truck does not have them

New cam sensor may not have been installed perfectly, it could be a tooth off, it could also be a bad part right out of the box. But typically it would not run perfectly smooth at idle if the CPS was a tooth off or out 180
The codes you are getting point to a problem with the cam sensor

Now the codes:
If the truck was in my shop I would take a half an hour and checkout the cam sensor you installed, make sure cyl #1 was at TDC compression stroke when you dropped it in and make SURE it is aligned on the correct tooth on the cam
Then I would check the wiring to the sensor, make sure the pins are clean and seated, harness looks good. A quick continuity check of the wires through the 42 pin plug and to the correct pins on the PCM connector can rule out a problem there.
Check the firing order
Check all wiring, vacuum lines, overall visual inspection of the engine bay
Any coolant seepage around heads?
Visual inspection of the plug wires
How do the spark plugs look? pull a couple and have a look
MAS sensor clean or dirty on the sensor wires
Any leaks in the intake? signs of leaks around the rubber hoses and lines
Signs of leaks around the intake base gaskets, build up of soot, grease dirt
How quickly does the 5.0 start? long crank? points to weak fuel pressure
A properly tuned and running 5.0 should fire immediately on the bump of the starter, yes even with 290K miles

Check fuel pressure cold, then get truck up to temp and drive it monitor fuel pressure when the problem occurs......

60 psi on a cold pump is within spec, I bet you find the fuel pressure is lower when its hot......... My $$$ is still on a weak fuel pump or problem in the fuel system causing the LEAN CONDITION

This is the internet, the truck is not in the shop in front of us....so we all have to guess.
Put your BEST guess out here based on the facts in the thread and experience with these engines

He has been chasing this problem, runs fine until warm and then no acceleration under load
He has replaced the crank sensor, no change (a bad crank sensor the truck wont start, no reason to change this)
cam sensor and cam synchronizer, no change
TPS, no change (why would you change the TPS? just test it!)
Cleared codes, they come right back ONCE the problem occurs
Checked fuel pressure cold, 60 psi which IMO is a little WEAK for one of these truck. In spec yes, but when I see 58-60 psi on my gauge, cold truck, on a returnless 5.0 explorer I start to suspect the fuel pump it should be more like 62-68 psi in my experience
 




410Fortune

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Jesus I read the thread you just got a lot of bad advice. The backfire immediately tells me you have unburned fuel in the combustion chamber and it’s firing when it’s not supposed to. A weak fuel pump or a bad alternator is not gonna do that. Sounds like your timing is off honestly. I think you have a mechanical problem not wiring and sensors.

To say that a weak fuel pump will not cause this is lack of experience with these trucks IMO

Unburnt fuel in the combustion chamber due to a timing issue will usually backfire through the exhaust

A lean condition will backfire through the intake

98% of the time a backfire through the intake is a LEAN CONDITION
On a returnless system the truck will run perfectly fine until put under load when you have a weak/failing fuel pump

How many 250K mile 5.0 have jumped time? Like none. I have never seen a gt40 302 lose a timing chain or jump a tooth??? at least not one that still runs fine at idle
Failed cam sensor? maybe....the codes do point to this
5.0 runs perfectly fine most of the time with a bent valve? I doubt it
 




Mikey195612

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To say that a weak fuel pump will not cause this is lack of experience with these trucks IMO

Unburnt fuel in the combustion chamber due to a timing issue will usually backfire through the exhaust

A lean condition will backfire through the intake

98% of the time a backfire through the intake is a LEAN CONDITION
On a returnless system the truck will run perfectly fine until put under load when you have a weak/failing fuel pump

How many 250K mile 5.0 have jumped time? Like none. I have never seen a gt40 302 lose a timing chain or jump a tooth??? at least not one that still runs fine at idle
Failed cam sensor? maybe....the codes do point to this
5.0 runs perfectly fine most of the time with a bent valve? I doubt it
All these answers are great but why does the tach drop to 0 like a loss of power for a second or to then come back?
 




Mikey195612

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All these answers are great but why does the tach drop to 0 like a loss of power for a second or to then come back?
Mean it is like you turned the switch off and then back on.
 




RWAG

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Check all fuel filters especially if problems more likely to occur in hot weather. A partially clogged filter will decrease volume but still show good pressure on a static check. Disconnect and reconnect all associated connectors once or twice to decrease the chances of weak conductivity connection.
 




Explorerpr

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I have a 2000 explorer 5.0 with 286,000 on it and having serious issues excelerating it seem to be losing power , backfiring until I let off the throttle, I have changed the cam position sensor, throttle sensor, crank sensor don't no what else to try any help would be greatly appreciated
Hello. Try to get the readings of the o2 sensors. Use a scanner on the ob2 port. Be sure both sensors are working. Or, unplug both an force the open loop operation. With this you confirm if the problem is a fuel mix issue.
 




fastpakr

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99 4wd - 5.0/4R70W/BW4406
All these answers are great but why does the tach drop to 0 like a loss of power for a second or to then come back?
Have you mentioned that before? That's a very useful detail. Again points to a wiring issue.
 




Mikey195612

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I still need a pin-out on the sensors if anybody has it, I'm going to pull the upper intake this morn to visibly inspect the harness under it.
 




Mikey195612

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I still need a pin-out on the sensors if anybody has it, I'm going to pull the upper intake this morn to visibly inspect the harness under it.
Well I pulled the upper intake for nothing all looks good check the cam sensor wires for continuity all good what next?
 




fastpakr

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If possible, I'd find a way to attach the probes to each end of the wires you're testing and try to bend/flex/wiggle the harness a bit to look for loose connections. An obvious light or speaker associated with the continuity test would be helpful.

This thread has info on the 1996 PCM connector wiring. I haven't found a 2000 yet, but that should at least get you in the ballpark.

Try this one too:
 


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Mikey195612

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I did that yesterday both wires checked good.
 




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