'01 V8 EB bogging at WOT

[Joe Dirt]

I'm cross posting this into the stock forum... Maybe nix the one in the modified forum? Everything is stock... Sorry!

Ok, so anyway, one of the guys that works at the place next door came over because he saw my Explorer in the parking lot. He's having a hard time trying to figure this out.

He recently replaced his upper intake after cracking it (with a new stock one) when trying to tighten down the coil pack bracket. He had the fuel rail off also. There are no fuel leaks though. (I don't know why he took it off)

Afterwards, when the truck runs, it seems to accelerate just fine if you're under, say, 75% throttle. Seems to be normal zip. If you floor it, it kicks down the trans, the RPM's hit the kickdown level, (about 3k?) stay right there and the truck doesn't accelerate, totally bogged down. If you back off the throttle a little, it shifts back down and goes. From where I drove it, it doesn't have a problem going highway speeds or anything, it's just that it only seems to have access to "most" of the throttle.

Checked the accel cable, kickdown cable, both are fine. Butterfly is open at full throttle. Everything is plugged in. He said that when he put the vac lines back on, he used a tree (red/green/white) from a '97 Ex, everything fit except that he had to pull the '97 rubber end that pushes onto the intake and put the one from the 2001 on there because the '97 wouldn't fit the intake tube. The FPR and EGR are hooked up to vacuum. When I had the scanner hooked to it, the throttle position was showing high enough that it should go. It seems more like it's bogged, not getting either fuel or air.

Anyone have thoughts?

 

[koda2000]

if it were a carb'd engine i'd say fuel starvation. as it's injected, it could be fuel or air related. has he cleaned the MAF? has he replaced the fuel filter? what does the fuel pressure look like?

 

[Joe Dirt]

I need to talk to him again tomorrow, er, today...

Fuel filter was replaced about a year ago he said, MAF had not yet been cleaned but I'm taking the cleaner with me to work tomorrow so I can spray it, along with the fuel pressure gauge. I think I may be missing the insert though, to fit the schrader valve though...

It's odd though. When you floor it, it downshifts, and the rpm stays at about 3k. If you feather the throttle off even a tiny bit, it will start accelerating. It's almost like it could be a trans issue. Low fluid maybe? I didn't even think to check that today.

It's weird- the old seat-of-pants thing where your car feels like it accelerates better at 3/4 throttle than it does when it's floored- it's like that at 3/4 throttle- it pulls all the way up the speedo. It runs great, no codes. It's only when you give it that last 1/4 throttle that it loses it. It will hold that rpm and will not move. It's weird...

 

[Abbondanza]

What happens when you punch it when it's in park? Do the RPMs rocket up or same issue? If they rocket up, I have to say yes the trans is involved in the issue. If not a direct mechanical problem then somehow the way the computer is interacting with it, almost like it was upshifting and not downshifting. If the engine races up when in park and wot, then the only thing that would stop the same rpm boost when in gear is too high of a gear, you would think.

 

[Joe Dirt]

I'll have to try that. It just seems odd that a miniscule drop in throttle position allows the truck to "catch" and start accelerating. I know when I checked the trans fluid yesterday, it was barely on the bottom of the stick, and might in fact have been just from scraping the residual fluid off the inside of the tube when I pulled it out to check it that even put it there in the first place.

I did test the TPS with a multimeter, and had the obligatory .96 on one wire, and ran to near 5 with the other at full throttle, so I don't suspect that.

Since he did the upper intake gasket, could a leak in that gasket cause this? He mentioned this morning that the first time he put it on and torqued it there was a vac line caught between the upper and lower intake. So, he loosened it, removed the line, and re torqued it. Also did get a replacement vac line, so that wouldn't be the issue unless there are issues with that vac tree that might cause this. FPR and EGR vac lines are hooked up fine.

What about the PCV? The thing is loose- what if it pops out of the grommet? Could a PCV that happens to be hanging out of the lower intake cause this?

He isn't coming in until this afternoon, so Id' love to have some route to travel when he shows up since we won't have tons of time.

It's just super stumpy that if you were to drive this truck up to 75% throttle, you would think it's mint.