Hello everyone,
Im a 19 year old college student with a 92 classic. I have done all the work to my rig by myself with the help of my dad but I need some serious help now. Some background - We have done alot to this classic. Most recently we rebuilt the top end, putting brand new fuel injectors in it (which i got for about 300 for the set, lemme know if you want the contact) put Hedman headers on it, new steering shaft to clear the headers, OME HD kit among others. The problem is this... since the rebuild and headers the truck has a really rough idle. When approaching a stop, or sitting idle it jumps from 300-800 rpm, almost like its trying to cut off. We put a new ignition coil and cap, rotor, plugs, wires and idle pentiometer and it still does it. It does it more often when the air conditioning or power source like the cd player and subs, headlights are on. If anyone has any advice please let me know.

There is also a second problem that might be more common. The truck has developed an awful metal squealing/screeching sound. Its like an engine or body mount has failed and there is metal to metal contact. Please any help is welcome.

Thanks,
Thomas Riley

Whats your fuel pressure? how about the filter? did you change that?

sounds like it's the idle control valve on the back of the plenum.

look for the black blob on the black of the plenum- take it out and you might find its gunked with carbon and other crap. Give it a damn good clean and then connect it up- you should find at idle and with a/c and other stuff on that it is open a little bit (or a lot if cold) but when engine is running hard it starts to close. did you make sure you put the right injectors in- they were two sorts for the Rover v8- an early and a later and either will fit into the same heads.

do you have any more info on the squeeling- when it happens? is it all the time? are you sure it's not just a squeeling fan belt?

Most recently we rebuilt the top end, putting brand new fuel injectors in it (which i got for about 300 for the set, lemme know if you want the contact)

The problem is this... since the rebuild and headers the truck has a really rough idle. When approaching a stop, or sitting idle it jumps from 300-800 rpm, almost like its trying to cut off.

There is also a second problem that might be more common. The truck has developed an awful metal squealing/screeching sound. Its like an engine or body mount has failed and there is metal to metal contact. Please any help is welcome.

Thanks,
Thomas Riley


1: That price for injectors is about right, if not slightly high.

2: The idle variation is likely due to one of two things. Idle Air Control Valve fouled with carbon, or a vacuum leak. If the problem didn't occur until after the top-end work, I'd look for vacuum leaks around the upper plenum (ask me about the time I removed a plenum deicer on a GEMS engine and didn't realiz hte bolt holes went all the way through the casting and reuslted in a huge vacuum leak-sometimes it's best to admit these msitakes rather than have them brought up at inopportune times:flipoff2: )

3: The sound, does it do it at all times, or only when the engine/suspension is moving aorund?

PT

Is the idle control valve different than the pentiometer? we replaced that along with the stepper motor. Im not sure if either of those have anything to do with it. We attempted to change the fuel filter, but it is entirely rusted and couldnt get it off, we set it aside. The fuel pump was replaced with a used one.

Atlantic British lists the complete set of fuel injectors for $600, i thought 300 was a good price for the ones i got.

And the wretched noise. Its only when the truck is moving. There is a vibration that occurs at about 25 mph when accelerating.. and slightly when decelerating. Its like something with the driveshaft is shaking, but Ive also heard it will vibrate with a down cylinder or bad spark plug. Im not sure, I just want my car back, so if there is any help please let me know.

Thank you all that put stuff up,

Thomas Riley

The potentiometer is the throttle position sensor, the stepper motor is the idle air control valve. If you replaced the IAC, pull it out and look for crud inside the mating surfaces, it can interfere with the seating of the valve.

As for the squeak/noise, take a look at the universal joints.

PT