My '99 Legacy GT has rough idle and hesitation when started, but the problem seems to go away after the first minute or two and it doesn't happen everytime. I checked the wires at the coil and the #1 post on the coil was somewhat corroded. I cleaned it up and there seems to be enough left to get a connection. The spark plug wire was a little rough also. I'm not getting any check engine light but I think I'll change the wires anyway. I'm wondering if I should replace the ignition coil also????? Please advise.

Well if those are still the original wires they could probably use a change. If you look at it in the dark when starting do you see any sparks or anything in there anywhere around the coil or wires, or if you spray some water on it do you see any sparks? If yes those items could probably use replacement. If you replace coil and/or plugs, coat the insides of the boots with good silicone dielectric grease to keep the moisture out of there. Maybe plugs are due for replacement too?

 

Is the issue any different on a warm/hot start vs. cold start, or when it's wet out/dry out/high humidity?

Definetly noticable on warm/hot starts. Hasn't been wet in a long time. I lost about 10% of the #1 coil post to corrosion. Will replace wires and check for spark on coil. May get a used coil, what coils are compatable with a '99 EJ25 DOHC manual???

I have a coil off a 98 2.5 that will work fine. I'm in the springs. Lmdew@hotmail.com How's $30 Larry

Hm, well hot/warm start problems from what I see in other threads could be the ECT engine coolant temperature sensor going (I guess causing bad air/fuel mixture on startup until o2 sensor is up to temp).

Now, why wouldn't Red's ECL be on if his motor is acting up so badly? Obviously he has at least one cylinder MISFIRING. And I gotta belive a dodgy ECT sensor would be a great reason to light the CEL. Sounds like there may be deeper problems here.

I have my doubts about changing the coil to solve this problem. What about the plugs? Have they been changed? That would be my first choice over the wires and coil in my book. Cleaning the EGR valve may help also. A intake manifold leak may be present when the engine is cold is another possibility I think.

 

As far as the CEL light is concerned, does it turn on when turning the key from OFF to ON? If not, then something is wrong.

Dodgy ECT sensor won't light the CEL if the ECU can't tell something is wrong with it such as open or short circuit or resistance outside parameters; the thing might just be grossly inacurrate; it's pretty much just a thermistor as far as I can tell.