SOHC Won't rev above 4k

[gijoecam]

I've got a buddy that is on the road and he just called me... He's got an '02 Ranger with the 4.0 SOHC and a manual trans. He said that it won't rev above 4000 rpms in any gear or neutral. It's not throwing a code, and otherwise running fine, just runs out of steam at 4K. It doesn't sound like it's hitting an electronic limiter, not missing, sputtering, or stumbling at all. It just won't rev.

Aside from the basics (air filter clogged, fuel filter plugged), any other ideas? The only other thing that comes to mind is a bad TPS, but I think that would cause other driveability issues too.

Thanks, gang!

 

[btexpress]

What the bleep is he doing over 4K? And for how long? In neutral this is the rev limiter, to protect from engine damage. While driving, don't know why anyone would maintain any rpms over 4K with a sohc motor. ...........

 

[gijoecam]

What the bleep is he doing over 4K? And for how long? In neutral this is the rev limiter, to protect from engine damage. While driving, don't know why anyone would maintain any rpms over 4K with a sohc motor. ...........

Gee, I dunno... merging? Maybe towing uphill? Maybe merging on an uphill on ramp while towing his camper? Why does it matter?

On an engine whose redline is 6k, 4k isn't really pushing it, and with a manual trans on an '02, there's no rev limiter aside from redline. He's been able to freely rev it to redline for the last 150,000 miles... now, all of a sudden, he can't, and I'm at a loss for possible causes, so I'm turning to the experts... Anyone?

 

[btexpress]

Gee, I dunno... merging? Maybe towing uphill? Maybe merging on an uphill on ramp while towing his camper? Why does it matter?

On an engine whose redline is 6k, 4k isn't really pushing it, and with a manual trans on an '02, there's no rev limiter aside from redline. He's been able to freely rev it to redline for the last 150,000 miles... now, all of a sudden, he can't, and I'm at a loss for possible causes, so I'm turning to the experts... Anyone?

OK, I'll stay out of this one then.......but there is a rev limiter in neutral, or Park with an automatic, you cannot rev a Ford past somewhere between 3500 and 4000 in neutral or park.

 

[gijoecam]

OK, I'll stay out of this one then.......but there is a rev limiter in neutral, or Park with an automatic, you cannot rev a Ford past somewhere between 3500 and 4000 in neutral or park.

On the EXPLORERS, from '02-up with the automatic transmission and the 'by-wire' throttle, yes, there is a limiter. That may also be the case with the automatic-equipped Rangers. I can't say for sure. However, we're trying to deal with a RANGER with a plain ol' cable throttle and a manual transmission on which the rev limiter is not set artificially low.

At any rate, a rev limiter of any sort would not explain the inability to rev beyond 4k when in gear and accelerating.

 

[rwenzing]

How about a plugged cat or muffler? That could keep it from revving.

 

[ThePhoenix]

i thought something was wrong when I couldnt rev past 4k....but then I read....

 

[dmac0923]

my 02 ranger SOCH 4.0 automatic 4x4 has a rev limiter in park at about 3500 RPM

 

[steventadams]

my 02 ranger SOCH 4.0 automatic 4x4 has a rev limiter in park at about 3500 RPM

We are talkin about a manual here.... There is no rev-limiter on the manual and it should be able to get to redline.

 

[budwich]

maybe try posting in the 2002 plus side of the forum where people might be more familiar with that "age".

 

[gijoecam]

I stuck it here thinking that his Ranger's drivetrain more closely resembles our Explorer's than the '02-up Explorer's.

Oh, and before I forget, I mis-heard him when I talked to him the first time... It'll rev to redline in neutral, but won't go any faster than 4K under load in any gear but first... Sounded to me like the engine is starving for fuel. The question was, 'Why?'

Turned out it was the fuel filter. My two thoughts were the fuel filter (cheap, simple, and quick to change) and the TPS. He data-logged the TPS, and there were no flat-spots or dead-spots in it, so we ruled that out. However, the injector pules-width was maxed-out even though it wasn't going any faster. That clearly pointed to a fuel supply issue, and the filter is the first thing to check. He said that the gunk that came out of it was horrible!! But the replacement filter now lets him bark the tires hitting second (which he hasn't been able to do in years!). He's thrilled!

Thanks for the help!

-Joe