Rough Idle 94 GC 4L 6 cyl
 

hi,

My 94 GC idles really rough , 4L 6 cyl.
I rev her up above 1000 rpm and its smooooooooth.
Only rough when idling.

Just replaced the fuel pump thinking that would fix it, but it didnt.
any suggestions?

Gato

Re: Rough Idle 94 GC 4L 6 cyl
 

Hey Gato, welcome to the board!

rough idle problems can be caused by a few things, the Idle Air Control Valve being clogged up (its the square blocky bit, with a round sensor on the throttle body) or the Mass Absolute Pressure sensor which is connected with a hose from the intake manifold to the actual sensor on the firewall

my MAP hose got broken when i had cleaned up some leaves under my hood, ended up fixing it with a straw and some electrical tape until i could run out and get some hose.

but these are what you should be looking for, next step would be checking plugs and ignition issues

Re: Rough Idle 94 GC 4L 6 cyl
 

When was the last time you changed your fuel filter? Also try putting in some injector cleaner for the next couple of fill up.. Do the cheaper corrections first.

Re: Rough Idle 94 GC 4L 6 cyl
 

Have you cleaned the throttle body lately?

Re: Rough Idle 94 GC 4L 6 cyl
 

I just replaced the fuel filter when I had to change out the fuel pump.
Couple weeks before that I ran seafoam through the gas tank , starting to wonder if that
kill my fuel pump.

Gato

Re: Rough Idle 94 GC 4L 6 cyl
 

Not sure how to be honest.

Re: Rough Idle 94 GC 4L 6 cyl
 

I'll poke around under the hood, thanks for the suggestions.

Gato

Re: Rough Idle 94 GC 4L 6 cyl
 

What is seafoam ??

Re: Rough Idle 94 GC 4L 6 cyl
 

When I first heard about seafoam I was the same.

http://www.seafoamsales.com/how-to-use-our-products.html

You can run this through your tank and it'll clean injectors and other stuff.
You can run this through your intake manifold.
Had a friend that had a subaru with a noisy engine, he ran some seafoam through it
and it was quite afterwards.
Stuff is amazing.

Gato

Re: Rough Idle 94 GC 4L 6 cyl
 

yeah that stuff is worth its weight in gold i tells ya (and is getting to be about as expensive!)

but its pure petroleum, its not going to mess up your fuel filter, its got the viscosity of gasoline, it basically loosens up the varnish (which could clog the fliter, if it free'd up enough of it!) its good for cleaning the carbon off the valves, free's sticky lifters cleans injectors... i pretty much use this stuff on EVERYTHING, in the oil, in the gas and in the air intake (pour it in from the brake booster hose usually, got the deep creep for spraying in the throttle body)

but id check those sensors, thats what its sounding like to me, or a vacuum line.