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Solved 2004 4.6l started after 2 years having issues after 20 miles

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Stuw

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May 19, 2018
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Year, Model & Trim Level
2004 Explorer XLT 4.6L V8
Progress report:

* replaced EGR valve due to EGR ERR values in forscan. Didn't do anything
* replaced MAF mostly just to prove that it's not the MAF. I know, I know typical parts changer. Didn't do anything
* went to replace spark plugs, spark plug wells filled with coolant. Next step is intake manifold gaskets.
* replaced intake manifold, spark plugs and coil boots runs great now

375000kms

Sat for a long time due to a bad bearing, now fixed.

Trying to get it running again. Drained as much fuel as I could from the fill neck attachment at the gas tank. Had stabilizer in it before. Added some premium and fuel system treatment.

Started and ran amazingly well aside from the rusted out muffler making some weird noise.

Drove it around the block and it was as if she had never been parked.

Took it on the freeway for 10 mins and parked for about 45 mins. On the way back going up an incline on the highway noticed a bit of a tug.

Quickly got worse escalating to very poor throttle response and no power by the time I got home.

Suspected plugged muffler due to rusty condition so I cut a relief hole to bypass muffler. No benefit just loud. Will replace muffler anyways.

Noticed catalytic converters are red hot.

Started throwing p0171 and p0174. Also threw an exhaust code which I can't remember *facepalm*.

Pcv valve is not clogged nor hoses. Pcv valve is actually won't restrict flow either way. The little floater inside just rattles around. Should change it.

Changed fuel filter and ran some exhaust treatment fuel additive.

Still sputters, bogs down if I rev more than a bit. Stalls occasionally when decelerating. Very poor power.

Does it sound at all like it could be bad catalytic converters?

Are my fuel injectors shot?

Where should I start?

It ran so well and just so suddenly declined I really want the old girl to live again.
 



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375000kms

Sat for a long time due to a bad bearing, now fixed.

Trying to get it running again. Drained as much fuel as I could from the fill neck attachment at the gas tank. Had stabilizer in it before. Added some premium and fuel system treatment.

Started and ran amazingly well aside from the rusted out muffler making some weird noise.

Drove it around the block and it was as if she had never been parked.

Took it on the freeway for 10 mins and parked for about 45 mins. On the way back going up an incline on the highway noticed a bit of a tug.

Quickly got worse escalating to very poor throttle response and no power by the time I got home.

Suspected plugged muffler due to rusty condition so I cut a relief hole to bypass muffler. No benefit just loud. Will replace muffler anyways.

Noticed catalytic converters are red hot.

Started throwing p0171 and p0174. Also threw an exhaust code which I can't remember *facepalm*.

Pcv valve is not clogged nor hoses. Pcv valve is actually won't restrict flow either way. The little floater inside just rattles around. Should change it.

Changed fuel filter and ran some exhaust treatment fuel additive.

Still sputters, bogs down if I rev more than a bit. Stalls occasionally when decelerating. Very poor power. Hasn't thrown any lean Codes since I changed the filter.

Does it sound at all like it could be bad catalytic converters?

Are my fuel injectors shot?

Where should I start?

It ran so well and just so suddenly declined I really want the old girl to live again.
It could be a catalytic convertor problem. I was driving my V8 2002 Explorer down the interstate with no problems and instantly is lost power and sounded like the transmission grenaded. Towed it to a transmission shop and they said it was a convertor that failed. A new Y pipe solved the problem. Have you checked the fuel trims?
 






It could be a catalytic convertor problem. I was driving my V8 2002 Explorer down the interstate with no problems and instantly is lost power and sounded like the transmission grenaded. Towed it to a transmission shop and they said it was a convertor that failed. A new Y pipe solved the problem. Have you checked the fuel trims?

I have not checked the fuel trims. I have a pretty basic code reader.

I would have to look up what the levels should be and compare.

I'm about to try removing the upstream O2 sensor and see if it makes a difference. I would honestly just cut the cats out and route the exhaust directly to a new muffler if I had to.

I'll have to search for a write up on reading fuel trims.

Thanks for the info about your catalytic converter story. Once it gets up to temp This thing just starts popping like brap brap brap as soon as you give it more than just a little bit of throttle. But if I find a sweet spot it'll kinda whistle its way up to 50km/h sluggishly. Engine just rocks back and forth during idle and much worse when in gear at temp. Not so bad when cold.
 






I have not checked the fuel trims. I have a pretty basic code reader.

I would have to look up what the levels should be and compare.

I'm about to try removing the upstream O2 sensor and see if it makes a difference. I would honestly just cut the cats out and route the exhaust directly to a new muffler if I had to.

I'll have to search for a write up on reading fuel trims.

Thanks for the info about your catalytic converter story. Once it gets up to temp This thing just starts popping like brap brap brap as soon as you give it more than just a little bit of throttle. But if I find a sweet spot it'll kinda whistle its way up to 50km/h sluggishly. Engine just rocks back and forth during idle and much worse when in gear at temp. Not so bad when cold.
These two videos are a good place to start.



 






These two videos are a good place to start.




Awesome videos thank you very much.

I will be doing some studying about diagnostics but won't be able to work on the old girl for a couple of weeks.

I will definitely post an update when I have a chance to see what the fuel trims are showing.
 






Alright so after watching a bunch of great videos from SB and Scanner Danner, I got me an OBD Link Ex and ForScan.

Here's what I've got

20240502_162517.jpg


20240502_162843.jpg


20240502_162529.jpg
 






Alright so after watching a bunch of great videos from SB and Scanner Danner, I got me an OBD Link Ex and ForScan.

Here's what I've got

View attachment 452195

View attachment 452196

View attachment 452197

Alright so after watching a bunch of great videos from SB and Scanner Danner, I got me an OBD Link Ex and ForScan.

Here's what I've got

View attachment 452195

View attachment 452196

View attachment 452197
Looks like I've definitely got a problem in bank 1.

Could be a bad MAF maybe along with an intake manifold leak or something extra in bank 1.

To me my 02 sensors look normal. I unplugged a vacuum hose and the engine stalled but the 02 trace responded as it should by going lean.
 






Another set of PIDs

20240502_165818.jpg


20240502_165731.jpg
 






Notice here another oddity that the accelerator needs to be at over 10 percent to get the RPM to respond.
1000013728.jpg
 






It looks to me that whatever is wrong effects both banks since LTFT is pegging at 25% on each. If so, this rules out a bank specific vacuum leak. A smoke test might tell where the problem lies.
 






It looks to me that whatever is wrong effects both banks since LTFT is pegging at 25% on each. If so, this rules out a bank specific vacuum leak. A smoke test might tell where the problem lies.
Definitely something affecting both banks majorly. Does better at higher rpm (while parked). Kinda seems like vacuum doesn't it?

I just noticed that the total trim on bank 1 is 40 while bank 2 is stuck around 25. Definitely more than 1 thing going on unfortunately for me.
 






So what I've found so far:

- Can't be the O2 sensors - the O2 sensors respond to rich and lean induced conditions
- Can't be cats - post cat O2 sensors are a stable voltage when warm.
- Can't be fuel pump - pressures are stable around 38PSI during operation. (Max: 44 / Min:36 )


- Might be an inaccurate MAF? More air going in than is being measured
- Might be dirty or stuck EGR? Might explain poor idle and acceleration, unmetered exhaust leaning out the mixture

Haven't done a proper smoke test. Definitely could be a vacuum issue too.

I kinda just want to throw a MAF at it but I'd hate to do that without a more definitive diagnosis. The MAF appears to respond to rpm by increasing in voltage. I just don't know what the voltage is supposed to be during certain conditions. KOEO voltage is 0.03 which doesn't seem too bad?

I might just have to fold and take it somewhere to get diagnosed.
 






I suggest doing a smoke test to rule out vacuum leaks. This might prevent you from wasting money on unneeded parts.
 






Well due to a lack of a smoke machine and an excess of curiosity and desperation, I wanted to keep tugging on the thread of my EGR valve.

Noticed EGR.Err values both +/- 95 and in between during the episodes of the worst drivability. (Example: Egr command: 89% / EGR Err : -78% and EGR command: 0% / EGR Err: 99%)

These Egr errors were intermittent but coincided with the poor drivability issue so I figured it'd be worth checking out my Egr valve.

Well I stripped half of the threads on the EGR pipe going into the valve and found my EGR valve wasn't full of built up carbon. Actually super clean inside but I couldn't get it to move by prying on the pintle or applying a vacuum to either line.

So now I figure I need a new egr valve and I'm hoping I can get the mostly stripped EGR pipe on the new valve. Might need some exhaust sealant if it won't go. Kicking myself for being so impatient and crossing my fingers I don't need to pull the pipe off of the exhaust manifold because if I strip that then I'm really in for a treat. Exhaust manifold job with over 230 000 miles won't be fun or cheap.

I know 94eddie is saying I told ya so, and I still haven't smoke tested it but after a couple weeks of work I think my next plan is to buy a half decent smoke machine just for the peace of mind about vacuum leaks.

I did put a vacuum gauge on the intake where the brake booster hooks up and my readings were around 15mmhg at idle dropping maybe an inch as the idle wavered. A snap throttle test at idle brought that vacuum down to around 8 inches and up to 22 before settling back around 14/15 inches - current altitude around 2200 feet above sea level. . Sustained throttle wouldn't produce 0 pressure but dropped to around 6 or 7 inches. More confirmation to me that it's not an exhaust clogging issue.

I noticed that whoever had the truck before me did the intake manifold replacement as my current manifold has the aluminum coolant channel and modified alternator bracket. Probably due to a leak before.

My next plan is:

1. New egr valve (hopefully not a new egr pipe)

2. Smoke test

3. Replace my spark plugs (I've put over 62000 miles on them since I got the truck), check resistance on my coils and wires.

4. Inspect my fuel injectors. (My high fuel trims under load, especially on bank 2, tell me I might actually have an injection problem) might as well while I'm doing the plugs. Don't have a scanner that does a balance test, might get one of those injector pulse testers.

5. If none of those things work then it's gotta be a MAF or TPS

And on with my mission to get this thing on the road again. Too many memories and too much to prove to the wife to let it go now!
 






375000kms

Sat for a long time due to a bad bearing, now fixed.

Trying to get it running again. Drained as much fuel as I could from the fill neck attachment at the gas tank. Had stabilizer in it before. Added some premium and fuel system treatment.

Started and ran amazingly well aside from the rusted out muffler making some weird noise.

Drove it around the block and it was as if she had never been parked.

Took it on the freeway for 10 mins and parked for about 45 mins. On the way back going up an incline on the highway noticed a bit of a tug.

Quickly got worse escalating to very poor throttle response and no power by the time I got home.

Suspected plugged muffler due to rusty condition so I cut a relief hole to bypass muffler. No benefit just loud. Will replace muffler anyways.

Noticed catalytic converters are red hot.

Started throwing p0171 and p0174. Also threw an exhaust code which I can't remember *facepalm*.
When I worked on a Ranger 6cyl. of that vintage having a bad injector dumping fuel, the engine went into limp mode. Theory is when catalytic converter damage is imminent ECM says shut down time derating power. Glowing red is the clue.
 






When I worked on a Ranger 6cyl. of that vintage that had a bad injector dumping fuel, the engine went into limp mode. Theory is when catalytic converter damage is imminent ECM says shut down time derating power. Glowing red is the clue.
What did the ranger drive like under limp mode? Was it intermittent or did it stay in limp after it was triggered?
 






What did the ranger drive like under limp mode? Was it intermittent or did it stay in limp after it was triggered?
The owner said it could not get out of its' own way.
Not sure as it was a few years ago, fairly certain the MIL was blinking at the time.
 






Alright so new EGR valve didn't improve drivability. I loaded a MAF in the parts cannon too and that didn't help.

So next step for me was to take a look at the spark plugs because hey that might be it right. Running out of options at this point.

Spark plug wells 1, 6, 7 and 8 so far are filled with coolant. Spark plugs look fine from bank 2. Got bank 2 plugs out but I figure I need to do the intake manifold gaskets or else this is going to happen again.

as far as I can tell, when it sat for 2 years the gasket leaked and filled the spark plug wells with coolant. The dust piled up from rodent activity and time so it hid the evidence.

While cleaning out the spark plug wells I noticed yellow discoloration around the gasket edge on bank 2. Near cylinders 6 and 7.

The spark plugs from bank 2 didnt look too bad but definitely over 100000km on them.

Ford store opens tomorrow so I'll grab new spark plugs, coil boots and manifold gaskets and let you know how that goes. Kinda happy to finally be on to something.

20240601_214100.jpg


20240601_214027.jpg


20240601_152005.jpg


20240602_131705.jpg
 






If you have an air compressor, you should thoroughly blow all the debris from the spark pug wells before removing the old plugs and installing the new ones. Also, thoroughly clean the coils and lube the plug contact.
 



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If you have an air compressor, you should thoroughly blow all the debris from the spark pug wells before removing the old plugs and installing the new ones. Also, thoroughly clean the coils and lube the plug contact.
Thanks Eddie. What a pain in the butt scooping coolant and sand out of the spark plug wells without a proper air compressor is! Any suggestions for what cleaner to use on the coils?
 






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