Okay... this might be a retarted question, but I'm going to ask... IF the exhaust was clogged or leaking BADLY would that in return make your fiero have to be 4200RPMS to 65mph ... furthermore... when i let off the accelorator.. the Rpms only drop to about 3900 or 4000.... ::crys:: with gas prices the way they are... I can't afford to have 5 mpg like this is trying to give me.. ...

Most likely other problems as well.. but would this contribute do you think?

PS.. No cat.

Definitly other problems, though I don't know what they might be, someone here will have an idea. Is you exhaust leak right by the engine at teh manifold, and has it been driven this way for many miles?

Idle only dropping to 3900 to 4000?!!! Man alive, sounds like you have a huge vacuum leak somewhere. Ok, what year Duke is this? Check to see if the throttle isn't sticking, check to see that the throttle plate is closing all the way (engine off at idle). Dukes are pretty simple, you have PVC vacuum, brake booster vacuum, couple of small vacuum hoses and that's about it. I really don't think that you could reach 4000 RPMs if you had a clogged exhaust.

What year?

First check the throttle cable to makesure it is returning,check codes as directed in service manual and forum
check for vacuum leak ,first check at E G R.pull egr hose and plug, next check M A P hose check all vacuum hose for split or leak
check T B I to manifold bolts check 2 screws that hold top of T B I to lower half
check manifold to block bolts
look in T B I while running (hmmm4000rpm) at low rpm there should be a steady flow of fuel sort of like surf if to much fuel is spilling out it is injector problem,, if you stop flow from T Bi and it runs better ??
the tps could be installed wrong ,, a common problem or it is sticking check it

It's an 87 if this is the same car he has been asking questions about recently. I forget if it is a 6 or 4 cyl.

It's the 2.5... Yeah this runs really rich, I think the high RPMS may have to do with the fuel/air mixture.. if it runs really rich at idle, at higher speeds maybe its burning that fuel that normally can't be burnt fast enough.. threre for keeping the rpms higher... I don't know.. Vaccum leak is what I originaly thought because thats what everything points to.. however I have yet to find a leak, and I've replaced all of the hoses. Someone is going to have to kill me if I can't solve this one....lol

[This message has been edited by Kyle87 (edited 05-21-2008).]

A 4 cyl and it stays at 4000+ rpms????
Amazing it is still all in one peice. And how the heck do you get it in and out of gear without ripping the dogbone and mounts right off the brackets? I clogged up exhaust usually won't allow it to reach high rpms--at least not very quickly, Won't scavenge out effeciently enough to allow the tb to flow enough air in.

When it's "idling" at 4k rpm, how far open is your throttle plate?

[This message has been edited by maryjane (edited 05-22-2008).]

Ya, we could use info such as...
-were repairs done to the car (besudes vacuum line replacement)? I.E. is it all stock?
-Is it the original engine, or was it swapped in?
-Did it ever run well while you owned it?
-Do you own it or are you fixing it for someone? Maybe they have more details.

It is a very high rpm, even in an auto you would probably wreck the trans fairly soon if driven much dropping it in gear at 4k.

Sorry it took so long to respond, I've been busy with school and such...


The car has -

New - Plugs, wires, Ignition Module, Air filter, PCV valve, Vaccum hoses, Alternator, Fuel injector, Fuel filter, As well as the TBI has been cleaned very well.

Thats what I can think of off the top of my head..

The engine is the original Tech 4 - I am the Owner and of the veh.. It's not an everyday drive, but when I do take it out I like it run well

The car sat for 2 years without use in a field.. I got it for free and have restored most of it, but ever sence I've had it it idles high and lacks power, high rpms. so.... Not sure what else..

I've checked the MAP sensor and IAC.. they seem to be working properly.. I suppose it could be a problem with the TPS sensor.. I'm not sure if I can test it or not..

The transmission I believe is fine, I can feel it shifting into all 3 gears, but I don't know too much about transmissions to be able to "feel" if its shifting right.

HOPE THIS INFO HELPS!

The tranny has a lockup torque converter, it should feel like it shifts into "4th" gear when you're cruising at steady speeds above 45mph. If you're driving along at a steady highway speed and you tap the brake with your left foot while maintaining a steady throttle with your right you should see the RPMs jump up as the converter unlocks, and after a bit you'll see the RPMs drop as it re-engages.

JazzMan