no power at top end?!?!? - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

Rollin · 06-10-2002, 06:34

hello peoples, this is my first post, i got a link to here from posting a question on CAA - www.caraudioaustralia.com so i hope you can help me. i am a 3rd year apprentice mechanic (at holden, sadly, please dont hold it against me) so i have a little clue about how things should work and what makes them do so, but this has me stumped.

my car is a manual 1992 EB XR6 - http://cardomain.com/id/falconxr6 - and it has issues.

when you free-rev it, it hits the limiter no worries, but when in gear and under load ie flat to the floor in second, it will not rev past 4750 rpm. when you pick the next gear, it kind of hesitates before picking up and accelerating again.

the cat is not damaged externally, i have replaced the fuel filter, dizzy cap, rotor, leads, fitted a K&N pod filter, checked the fuel pump flow rate - 300cc in 10 sec, spec is 280cc in 10 sec - reset the computer, fitted a new thermostat (was stuck open) visually checked anything that i think may affect the cars ability to rev.

the middle muffler (before the diff) is a little knocked about from the previous owner using it as a bash plate, and i checked the plugs and noted they were all whiteish (running lean on all cylinders, so i dont think an injector problem) tried to clamp off the return line to check if i had enough fuel pressure but the clamped connections sprayed fuel everywhere so i figured it had enough. i will try to get a pressure gauge on it this week to check a little more scientificly, but is there anything you peoples can think of that would make my car do this?

i just had a thought now that maybe the injectors arent getting enough voltage to open properly, what voltage should they be? 12v at each injector?

sorry for the long post but i tried to give you all as much info as possible, i know that too much is better than not enough - bit like horsepower, hey?

Donut King · 06-10-2002, 06:40

Good to see you managed to post :)

Rough guess on my part but is it possible the clutch is slipping under load or something? I'm probably way off, just a thought that popped into my head

Rollin · 06-10-2002, 06:45

no clutch slip, sorry, the previous owner fitted a heavy duty one 16,000k's ago, it isnt slipping, its definately an engine problem - i need to fix it i almost got beaten by a vt calais today!!!!! oh the shame!!!!

Martin · 06-10-2002, 06:52

My bet would be the accelerator cable, its probably stretched and not allowing the throttle butterfly to open 100%.

Get someone to put their foot flat to the floor on the pedal while you check to see if the throttle linkage opens all the way.

My ED revs out to 5500Rpm no worries.

Rollin · 06-12-2002, 00:32

nope, sorry, checked throttle opening - ok
checked throttle position sensor voltage - ok
i checked fuel pressure when driving - ok
remove exhaust after cat converter and test drive - no change
check intake air sensor voltages - ok
check base timing - ok
check water temp sensor voltages - ok

a have asked 3 TAFE teachers about this and after suggesting several things (which i had already checked) they gave up PLEASE HELP ME I CANT STAND HAVING A CAR THAT WONT REV!!!

xced · 06-12-2002, 01:57

whats the compression like ? for some reason or another its not making the power to rev, check up on the fan clutch, all I can think of...

not much else I can think of, even my XD will spin past that in 3rd or 2nd (too fast to try in 4th)

Bass Crazy · 06-12-2002, 02:07

I had a bad throttle position sensor which caused poor performance, as well as hesitation between gears like you mentioned. Migh be worth checking out.

discokin6 · 06-12-2002, 02:15

hmm..

Take it onto a dyno. there is one thing you havent checked, A/F mix at high revs. Get them to analyze your exhaust gasses on the dyno, see if its leaning out up top. It could be something really simple like a poor fuel flow, clogged fuel filter or something like that..

Martin · 06-12-2002, 07:21

Have you got the computer to do a self test to see what if any codes its showing?

Snake8 · 06-12-2002, 15:45

"remove exhaust after cat converter and test drive - no change"

Sounds like a blocked exhaust to me. Disconnect exhaust before the cat and try it.