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Very rough idle. New plugs and wires. Pulled each wire off the coilpack and good spark to each wire. When I pull either of the 2 wires on the right side (corresponding to the 2 cylinders on the right side of the engine), no noticeable dip in the idle like expected. Something wrong with these 2 cylinders. Could it be that the timing belt jumped a few teeth on the the right side cam?

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My first thought was that you might have broken a timing belt, but since you said coil pack I'm going to assume you have an EJ series motor with only one timing belt. Check for vacuum leaks, I had a vacuum leak near the intake port (was a port for my vacuum gauge I had forgot about) that caused the same problem. Do a compression check, you could have a blown head gasket between the two cylinders on that side. It wouldn't be an open in the plug or plug wire, since if one side is dead, teh opposite cylinder won't get spark either. Unlikely, but possible, both plugs are fouled.. I'd start with a compression check and go from there. You can rent a compression gauge from most auto parts stores for free, with a refundable deposit.

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Interesting; I have a similar problem with my Brat (EA81 engine). Both cylinders on the drivers side don't contribute to engine power....I can pull both plug wires and the engine runs as before. If I pull just one wire on the passenger side, it dies almost immediately. It also shows up in a failed emissions test----1300 ppm HC at idle, okay at cruise. I've checked compression and it's okay. If there's a vacuum leak, I haven't found it. Car runs a bit rough at idle but runs okay with more rpm. I still get 30 mpg at highway speeds and around 25 when around town.

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Possibly a fuel problem depending on the type of fuel injection, although you didn't name your specific vehicle or model year. Newer SFI F/I uses four separate circuits to fire the injectors sequentially, whereas the previous MPI system used only two circuits to fire the left bank and right bank alternately. If your vehicle employs MPI F/I, one bank may not be receiving fuel. Therefore no change when removing the spark from that bank.

 

It's possible that an injector coil has shorted, or that the driver for that bank has failed, or possibly both. First measure the injector resistance of the good side and compare it against the published spec to get a baseline, then measure the other two. Make sure the injectors are in spec before replacing the driver (to avoid burning out the replacement driver).

 

I'm not sure if the ECU drives the injectors directly, or if there is a separate buffer/driver.

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Well both sides compression test at 150, so I guess that rules out the timing belt or blown head gasket. Got ticking on the stethoscope from all the injectors. Is it feasible to spray starting fluid(carefully) around to check for vacuum leaks? This thing accelerates ok and cruises smoothly, only problem is the really rough idle. At least it's driveable. Maybe take it to a shop have them take a look. They replaced a purge solenoid but didn't connect it properly, hose keeps popping off, I'll get them to fix that. Going to replace the coil because I saw some arcing in the dark.

This is a 91 Legacy, 2.2L MPFI. Going to get a compression tester in a little while. No water in oil or white smoke. Looks like a single fuel line for all cylinders.
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Yes, use starter fluid spray to look for vacuum leaks. Unfortunately, that didn't help me with my Brat engine. One thing I haven't had checked out is the valve adjustment. If one side is adjusted to tightly, it might account for my problem. Have you had the emissions checked? I'll bet it fails big time at idle.

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Yeah, if it's cruising OK, that rules out an injector problem. Checking for vaccum leaks is a great idea. Also you might want to have a look at the EGR (if you've got one) to make sure it's closing completely. If it's sticking open, that'll give a rough idle.

 

As far as the coil arcing goes, it may not necessarily be a critical deal. My last car had the corona type arcing on the coil pack for almost 100k miles, but never seemed to affect the spark reaching the plugs for some reason. The first time I noticed it, I freaked and called the dealer for a price on a coil, but after hearing the price icon10.gif decided to wait for an actual misfire. It never happened, but I did remove the coil and wash contamination off the surface with soapwater and used a little MEK sovent to try and remove any carbon tracking.

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Luckily I just passed emissions in February. It was running better then. Actually this started not long after I had the O2 sensor replaced. Will a faulty EGR give a code? I heard the way to test it is to suck on the tubing to see if it causes a stall, is this true? Off topic: been reading a lot about amsoil being top notch as far as oil and tranny fluid goes. I'm thinking of doing a tranny flush by by running the cooler line into a container, doing 2 qts at a time (takes about 20 seconds).

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Another poster on this site found out the hard way he had a bad new spark plug that caused him considerable time and grief to diagnosis. New plugs can't be bad so....NOT! I realize that having two bad new plugs on the same side would be incredible odds but you may want to try either swapping the plugs to the other side or get two other ones just to eliminate this as a possibility. If this doesn't help then I would check to make sure your injectors are ok. Ohm them out and see if they match the side. Measuring the pulse voltage to them would be good also. This would require a O-scope to look at them. If that is ok then the fuel to the injectors needs to be checked.

 

You stated that you saw sparking so there may be a problem in the high tension voltage lines causing that. Also make sure the grounding is ok for that side of the igntion system.

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Luckily I just passed emissions in February. It was running better then. Actually this started not long after I had the O2 sensor replaced. Will a faulty EGR give a code? I heard the way to test it is to suck on the tubing to see if it causes a stall, is this true?

That would be the proceedure for checking the diaphram which opens the valve to make sure it is not punctured or torn, but my concern was more one of a possible pitting of the valve face and seat or an accumuation of coke on the plunger shaft. Both would prevent full closure resulting in some EGR at idle and there shouldn't be any EGR at idle. You should be able to visually inspect both by removing the EGR valve. Most strong toluene-smelling carb/injector cleaners in a spray can work great for cleaning a crudded-up EGR system. Just don't spray any of the solvent on the diaphram tho.

 

Off topic: been reading a lot about amsoil being top notch as far as oil and tranny fluid goes. I'm thinking of doing a tranny flush by by running the cooler line into a container, doing 2 qts at a time (takes about 20 seconds).

Amsoil's great stuff, but lordy expensive. Unless you're doing extended intervals, you'd be wasting dough ...DOH!!!. IMO the best summer oil for a Sube with some mileage is a 15W-40 fleet oil. Mobil 1 works great in the winter.

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Looks like one of the plug holes is stripped. I posted on another thread. Going to bring it to the guy who helicoiled one for me 6 months ago. I better stay away from changing spark plugs. I never had this problem on any of my other cars.

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I pulled 2 codes from the past history that were fixed already. Someone on this board has an excellent site, tells the codes and how to bring them up(on pre-96 models). I think this Legacy doesn't have an EGR. I'll be happy to get this helicoiled so I could drive to work.

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I had the same thing happen on my EA71 80 wagon-2 cyl not contributing to engine power. Compression, ignition, etc. good. Replaced the plugs to be sure and they were due anyway, no different. So I pondered on a hot august night, with a 12 pak of thinking fluid, WTF could be causing this? I figured some how it had to be no fuel getting to the 2 cyl on the side, so i rigged a little hose to a can of starting fluid and stuck it in a vacuum hose fitting on the dead side of the intake manifold near the cyl head. When I sprayed a hit of fluid, the engine would smooth out, and I even disconnected the 2 good cyls and could run the engine on the 2 bad ones as long as I squirted fuel. Finally traced problem to some big emissions valve about 1/2nch diameter, it was leaking an incredible amount of air into that side of intake manifold. Plugged it and the engine ran smooth.I know that was a carbed engine and the Legacy is FI (I own a legacy now), but it would not hurt to check for vac leaks etc. Good that you have compression all around, that is always my fear when i do a compression test

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