Car Repair Maggots: Help Me Help Myself

[Odin]

Having a bit of trouble want to diagnose it before I try to fix it.

So Grease Monkeys start your engines.

98 Subaru Forester (Les-Mobile)

AT IDLE: The car stays at correct RPM then starts to shudder, goes up to just around 750 rpm drops to below 500 rpm. Does this over and over again. If I give it power the car shudders/engine shudders, as though it is trying to give it power but can't. At high RPM it doesn't seem to actually give me full power and anything less results in shuddering. Held at a low rpm with no power I don't see any issues.

I THINK:

That it is the distributer, as awhile ago I checked the plug wires and one of the nodes coming off the distributer was corroded. I wire brushed the node and replaced the plug wires. It fixed the problem for a little bit but I still don't think I was getting full power as though I was running on a blown cylander. Also while it was corroded, the guy that checked on my car got sparked by a spark from the corroded node (not by touching) so I don't think it was working well.

SOLUTION: currently it is replace distributor.... unless someone has another idea.

NOTE: I have recently replaced the Air filter, oil filter, changed the oil. ALSO the car can make it from point a to b... but for how long.

[Haus]

You got it. Seems to be a somewhat common problem. I have replaced mine 4 times so far in 185,000 miles on the '98 Impreza. Subaru calls it an 'Ignition Coil Pack' and they usually run around $60 at the dealer. Also, you probably already know this, but check the plugs while you're at it. My corroded nodes have also been accompanied by corresponding corroded plugs.

[DaveTV]

I would also post here

[Blatant]

tps maybe, shitty gas. Try ultimate subaru or nasioc.

[lemon boy]

if you're replacing the d-cap you might as well go ahead and do the plug wires as well (and the plugs really).

[Aldo]

do the plugs first!

[Sensisnow]

Like everyone else said, change the plugs, wires, and coil pack. If that doesn't fix it then check the Throttle Position Sensor and/or the Idle Air Control Valve.

[runethechamp]

Yes, start with the easy stuff. PLugs first, then wires, distributor. Also make sure the timing is correct. And a faulty tps can give you results like this as well.

Just as an example, my timing was way off when I did my smog check a little while ago. I adjusted it to normal, but then the truck (4runner) ran like crap with no power and hesitation all the time. I have yet to confirm this, but it seems like my tps sensor is either bad or badly adjusted.

[fez]

is the check engine light on?
sounds like an egr valve (or some part of the emission controls) to me.
maybe see if a local shop will scan the codes for you and tell you what it says, some will for a small charge.

[300hp]

www.nasioc.com will have all the subaru info you could need. Is your Raging Lesbo Moblie a 2.2L or the 2.5? The problem at I idle is usually the result of a vaccum line that has a tear in it or has become dislodged and your car's ECU is struggling to learn around it. Check all the rubber lines, spray soapy water on them when the car is just warming up to check for leaks if you have to.
As was also metioned before, the Coil packs become loose or go bad. Change all your plugs to copper tipped plugs in the proper heat range (they're cheap) I know plugs on a boxer motor suck, but it shouldn't take you long with the battery removed. take hte washer fluid bottle out for some extra clearance as well. Be sure you screw the coil packs back in snug after you put the new plugs in.
I'd say if you do both of the above, you should be able to fix the problem. On my WRX, it was having serious problems hunting for idle after I did work to it. I tore a vac line wiht my pliers and that was indeed the problem.
H.

[Odin]

Thanks guys. When I had the corrosion I changed the plug wires, however I didn't even look at the plugs. I will try that first. The check engine light DOES come on. However, I would like to try plugs/coil first.

[crashnburn'd]

The check engine light DOES come on.

Take it to a shop and have them tell you what code made the light come on, if the light is on, it's silly to try to diagnose it by yourself. Some places will charge, but others won't. I know nothing about Subarus, but I've had cars with bad O2 sensors do pretty much what you're describing.

[Aldo]

Take it to a shop and have them tell you what code made the light come on, if the light is on, it's silly to try to diagnose it by yourself. Some places will charge, but others won't. I know nothing about Subarus, but I've had cars with bad O2 sensors do pretty much what you're describing.

It'll say misfire. You haven't changed the plugs, I'd give a hearty ole' internet reccomendation to do the plugs first. You may find an offensively gummed up plug left over from when you had a faulty wire.

Although with that said, you'll probabaly have to have the codes read anyway in the process of resetting the light.

[assgasorgrass]

Bad ignition coils. Happened in my 98 Outback. Shitty idling, hesitation when accelerating. Both coils were fried, corroded. Replaced coils, wires and plugs. Runs mucho bettero. Still has a leaking PS unit, the crank seals just went again, 3rd time in one year. All with 71K.

[midget]

check engine light = take it in to see what code is thrown. autozone will do this for free.

[warthog]

Before you take the plugs out, find a Chiltons or some other guide(doesn't have to be the one for your car- they all have this guide in them). They always have a section that shows different levels of fouled plugs. Those spark plugs will usually tell the tale, as long as you know what to look for.