explorer won't rev

hi ther i have a ford explorer 1998 4.0 v6
had the car from auction then find out it's ruf at idle and won't rev past 3000rpm
code read it all clear
cheaked for blocked intake and exhaust all good
dont know what's happening
got a teck cd off ebay just waiting now
eney idears
please help thanks darby

it wont rev past 3k in gear or in park? if in park thats normal. there is a rev limiter so it is not over reved in park, now if this is while its in gear its a totally diffrent story.

no rev

when she's in park nutral or drive

Check the obvious first. Does the throttle open fully? Are the floor mats in the way? You can take out some slack from the throttle cable with cable ties by the pedal. Check the TPS for correct operation. Check the fuel filter.

Disco the batt, reset the PCM, how many miles? (plugged cat?)

i am a mercanic and have tryed most things
it stuggle's at idle as down too overfueling whaen reved it picks up nicely till 2500rpm and flat out at 3000rpm more thottle just make's more induction noise
i have a snapon code reader and can't find fault's /disconnected battery to reset pcm / disconnected exhausts front of cat's / good compession / mas and cam + crank sensors all good

try cleaning the iac and maf....there are threads on here that show how to do each, not hard at all

should still rev if maf or iac were playing up
but i have cleaned iac and changed the maf

Could be the FPR is stuck closed (Fuel Pressure Relief Valve). This would cause excessive pressure and maybe flooding the engine.

Intake O Rings

Rough idle is a sympton of the intake o rings letting air in after the throtle butterfly, could be a limited opperating stratergy due to exhaust oxegen/ mixture wrong see posts on the O ring call back problem.( needs O rings made from different material) How do the timming chains sound on cold start up) just done mine it runs like clockwork now

Dick

Check that the accelerator pedal is not hanging off the firewall. My pedal dropped off while driving a few years ago. Had to have my mechanic redo the Ford dealer repair because the bracket was bending again and I could not get full engine response.
Cheers!

no my pedal is fine geting full trottle today had the inlet manifold off and cheaked all gaskets all fine not sure if it is the pcm or the gearbox controler
do they rev limit in park and nutrual ???
got a cd on the way hope its got the info i want
thanks darby

darby said:

no my pedal is fine geting full trottle today had the inlet manifold off and cheaked all gaskets all fine not sure if it is the pcm or the gearbox controler
do they rev limit in park and nutrual ???
got a cd on the way hope its got the info i want
thanks darby

Click to expand...

As said above yes they rev limit in park and neutral, if you have an auto tranny

it is an auto tranny my code reader can see all gear selections but i don't know what contols it rev limiting ?
but she's still crap at idle which take's me off the idear
when cold will not idle and has not alot of inlet mainifold vacum whitch get's better as it warm's up but even then you can't lock the brake's
strange i know but she looks a nice motor and i want to go have a good drive to see what i think of it
it is doing about 40 mph at the mo all gears seam to work
i don't know ?

Sounds like the inlet manifold 'O' rings are leaking or you have some other vacuum leak. I found on mine that the upper inlet manifold came loose which caused all sorts of idle issues.

Sounds to me like the PCM took a dump.
I have not seen a OBD-II (EEC-V) computer take a dump yet, but I have seen a really similar situation to what you describe happen a few times on EEC-IV computers.
We had a 93 Explorer, would fall flat on its facce over 2800 RPM, no matter what. Codes came back all clear.
Tried everyything. Swapped computers, ran perfect.
Junk yard computer was $60, still runs perfect to this day.


Also which 4.0L V6 is this? OHV or SOHC? (sohc = timing?)

I was having a similar problem except at 2500rpm. My mechanic told me it was the crankshaft postion sensor and I am going to pick up my X and let you know.

looked at the inlet o rings looked fine getting some new one's fit to make sure
have thought that the ecu may have gone down about £170 big risk but may have to do it to be sure
ive had the crankshaft sensor of it has resitsance and when something steel pasted over sensor it trigers but i dont know sepc reading's
got a cd comeing for that i hope
it is the sohv timeing chain's do they slip no noises off it
just a bit of tappet noise
thanks darby

SOHV = ? Overhead valve (pushrod engine)
or SOHC, single overhead cam

I don't think they sell the OHV in Europe. The SOHC is a European motor.