Uneven Idle '98 disco Le

omotemanji

Active member
Oct 7, 2008
26
0
eugene, OR
I have researched alot through all the past threads to answers but i thought someone might have a quick answer to this rather than throwing money at the problem, I thought one of you may have the answer. i have heard anywhere from MAS, plugs, wires, coils, valves, head gasket, and injectors. The truck only has 52000 original miles so i am hoping it is something simple but i gather that it is probably one of the above mentioned causes but i thought one of you long time disco webbers/owners might help me pin it down. I have only had the truck a few weeks but just noticed this problem. There are no lights on at this time aside form an intermittent abs light.
thanks in advance
 

lowwill

Well-known member
Nov 27, 2006
692
0
Hamden CT
Where's the rpm sit at. Mine flux between 750-850 rpm seems normal. I would just tune it up, sea foam it, change fluids to synthedic blends and enjoy. If no cell is on I would not worry to much. Where did you find that rig at with those miles. Have fun now soak up the info.
 

p m

Administrator
Apr 19, 2004
14,606
210
55
La Jolla, CA
www.3rj.org
Idle speed is controlled by IAC valve (solenoid,stepper motor, you name its name). It can get dirty, or gunked up - which I would suspect for a truck with this little mileage in 10+ years. Search for IAC troubleshooting/cleaning/replacement.

There is plenty of other possible causes, of course.
 

omotemanji

Active member
Oct 7, 2008
26
0
eugene, OR
yeah it sits at about 550 when warm and you can watch the tach just kinda vibrate, with little surges. I love the truck and I got the best deal ever $4,800 from some super rich people. i have been running amsoil since I got the truck. I need to get a book but where is that sensor located? I am going to do the plugs and wires and do the seafoam. What does everyone think about lucas on disco's, or should I just use seafoam? I got champions on the plugs because it seem to be a consensus, but generally use ngk. they were cheap so I'm not too concerned right now.
 

omotemanji

Active member
Oct 7, 2008
26
0
eugene, OR
plug wires were real brittle I think they were originals (lucas). One snapped trying pop loose. Any suggestions on plug wires? I can only get borg warner or duralast right now otherwise I have to order, bosch or Karlyn...or buy online and wait. any suggestions on wire sets?
 

p m

Administrator
Apr 19, 2004
14,606
210
55
La Jolla, CA
www.3rj.org
550 is low - it should be around 750-800, IIRC.
IAC valve is on the back of intake manifold - a wiring harness with a 4-wire plug connects to it from the passenger side.
I've no opinion on seafoam.