I'm dying here! 01 Explorer is killing me.

[Andy Allen]

'01 Ex. with 250,000 miles. Awesome vehicle until the last year. Runs rough all the time. Replaced intake manifold gaskets (upper and Lower), no vac. leaks, new idle control, engine temp sensor, crankshaft position sensor, new o2 sensors (3), wires/plugs. No smoke from exhaust, compression tests fine. Fuel trims change from extremely lean to extremely rich instantly. Today I plan to remove intake again, and replace all fuel injectors. If no resolution, she's a goner! Oh, fuel pressure is good. Any ideas appreciated

 

[ccm2001]

Try to clean the MAF

 

[boominXplorer]

Any check engine light? How does the engine sound?

 

[Machine090767]

Maybe you need to have an actual professional mechanic check it out.
Throwing parts, money at it and not getting the problem solved doesn't seem to work.

 

[Andy Allen]

Maybe you need to have an actual professional mechanic check it out.
Throwing parts, money at it and not getting the problem solved doesn't seem to work.

Really appreciate your insight and wisdom! Wonder why I went on this forum, could it be that I was hoping for intelligent response? Didn't get it here!

 

[Andy Allen]

Any check engine light? How does the engine sound?

Thank you, your right. Yes to the engine light. No unusual sounds outside of what might be expected from the rough idle. No sounds of internal damage. Codes show bank 1 lean, but as engine temp becomes normal can vary between extremely lean to extremely rich within a few seconds. Seems like some sensor is sending false codes, can't figure out why or from where.

 

[Andy Allen]

Try to clean the MAF

Done . No change.

 

[boominXplorer]

You had the same rough idle before the intake gaskets right? You did change both the bottom O-Rings and the plenum to lower gaskets right? Should if been 6 large O-Rings and 2 rubber gaskets with what looks like 3 connected ovals.

Once the truck is up to temp the o2s will switch back and fourth lean and rich.

 

[96eb96]

Thank you, your right. Yes to the engine light. No unusual sounds outside of what might be expected from the rough idle. No sounds of internal damage. Codes show bank 1 lean, but as engine temp becomes normal can vary between extremely lean to extremely rich within a few seconds. Seems like some sensor is sending false codes, can't figure out why or from where.

Are you talking fuel trim or the 02 sensor graph?
What are your long and short term fuel trims at idle and cruise?

 

[Andy Allen]

Ye

You had the same rough idle before the intake gaskets right? You did change both the bottom O-Rings and the plenum to lower gaskets right? Should if been 6 large O-Rings and 2 rubber gaskets with what looks like 3 connected ovals.

Once the truck is up to temp the o2s will switch back and fourth lean and rich.

Yes to the gaskets. Both upper and lower as you describe. Once you reach operational temp, I can see why they would change back and forth but from extreme of 34 to -11. I don't know a lot about fuel trims but that struck me as a huge range for normal driving conditions.

 

[Andy Allen]

Are you talking fuel trim or the 02 sensor graph?
What are your long and short term fuel trims at idle and cruise?

Yes, it was fuel trims I was commenting on,sorry I didn't make that very clear. Don't have access to those notes right now,but I'll get that posted soon. Any thoughts on clogged or just dirty fuel injectors? I've owned vehicle since 50k. Never done anything other than regular routine maintenance including occasional fuel additive for injectors.

 

[762mm]

My idle got a lot better when I changed the fuel filter the first time at approx. 80,000 miles. The truck used to idle at close to 900-1000 RPM while just stopped at a red light, plus it sounded like the engine was struggling. A new fuel filter fixed it right up; when I removed the old one (original), there was some black goo coming out of it from the side that goes towards the fuel tank (looked like black paint mixed with gas - weird!). After that lesson, I've changed it every 40,000 and never had a problem.

I know you said fuel pressure is good, but if the filter is clogged, the fuel pump may still have some trouble delivering the right amount (volume) of gas on a constant basis. I know a guy who had a Mercury Grand Marquis with rough idle and fuel economy issues and fixed it with a new fuel filter too (on my suggestion). He couldn't believe that a $5 part could make such a difference.

Just a guess... but for $5 worth of parts, it doesn't hurt to try.

 

[Mesozoic]

Yep, dirty fuel filter will cause that problem. Basic preventative maintenance, a fuel filter is like $10.

 

[RandomNerd2000]

Well I'd try the filter, it's the cheapest thing, wouldn't surprise me for it to be clogged. I've found that it gets over looked a lot, and it makes a difference. If you haven't done yours recently, it can't hurt

 

[Andy Allen]

My idle got a lot better when I changed the fuel filter the first time at approx. 80,000 miles. The truck used to idle at close to 900-1000 RPM while just stopped at a red light, plus it sounded like the engine was struggling. A new fuel filter fixed it right up; when I removed the old one (original), there was some black goo coming out of it from the side that goes towards the fuel tank (looked like black paint mixed with gas - weird!). After that lesson, I've changed it every 40,000 and never had a problem.

I know you said fuel pressure is good, but if the filter is clogged, the fuel pump may still have some trouble delivering the right amount (volume) of gas on a constant basis. I know a guy who had a Mercury Grand Marquis with rough idle and fuel economy issues and fixed it with a new fuel filter too (on my suggestion). He couldn't believe that a $5 part could make such a difference.

Just a guess... but for $5 worth of parts, it doesn't hurt to try.

Thanks for the input guys. I really appreciate your efforts, but I changed fuel filter about a month ago ( maybe 500 miles). Hope you all are getting an idea as to why I'm so frustrated. The only thing I haven't addressed is the possibility of severely clogged injectors. Scanner shows 58 lbs. Fuel pressure consistently. Looking more and more like that upper intake is coming off again. Poop!

 

[boominXplorer]

Spray some brake or carb cleaner around the intake while its running and see if the idle changes. Good fuel pressure with a lean code always makes me look for an intake leak. What about the rubber Y under the throttle body, is it in good shape or deteriorating?