3500 rpm rev limit?

I've got a friend with a 94 4.0 2wd that seems to sputter and pop when it hits 3500 rpm...we tried switching out tons of sensors but no help...it accelerates like a rocket to 3500 rpm. We even switched computers for a bit and now it just seems like it goes to half power when you hit 3500...no more popping and sputtering...anyone with similar problems/solutions?

Do a search for distributor indexing. This is a common symptom of having the indexing off on your distributor.

WOW !!! I NEVER THOUGHT ABOUT THAT. I'll check that tomorrow.

Have you checked the fuel supply? A bad fuel filter or similar problem can act that way.

Distributor is in right. New fuel filter is on...fuel pressure looks good...havent checked the fuel pressure at 3500 rpm though...should be in the 35-40 psi range right?

yellowxj said:

Distributor is in right. New fuel filter is on...fuel pressure looks good...havent checked the fuel pressure at 3500 rpm though...should be in the 35-40 psi range right?

Click to expand...

Should be 31 regulated, 39 unregulated.

Misfire? Bad plugs/wires?

Already put on new plugs and wires. Here's a new twist I noticed the yesterday while test driving...when you get over 3500 rpm...lots of smoke out the back, appears to be transmission fluid on the back hatch...
I drove it about 100 miles checking it out, trying different things, and when I get up over 75-80 mph in overdrive (a hair less than 3000 rpm)...more smoke and oily coverage on the hatch...could the transmission be burning up, an electrical problem in the transmission working through to the engine electrical causing the misfiring/power loss??

Transmission fluid is clean looking, a hair over full, but I've seen worse...

Re: 3500 rpm rev limit?*update*

here's an update. took it to the mechanic who spent many many hours trying to figure it out. Many many tests and rides with extra instruments, talking on tech lines etc. Finally....the crank position sensor(new but evidently not super high quality) was too far away from the tone ring(?)...at rpms above a certain level the sensor signal freaked out being too far away to make accurate readings...computer started dumping fuel in to the system and lost track of spark control...fogging the road with super rich fuel smoke...$368...runs great