I have a 96 Subaru Impreza which recently had an engine clean with a pressure hose. Now in low rev's (anything below about 3K) it seems to misfire, at least that's what I think is happening. As you take off, the car jerks and sputters, and has a low popping sound which I think is only in one cylinder. Sounds a little like the car is running out of fuel even though it is receiving plenty. Any Ideas?

Try removing each spark plug wire, one at a time, and wiping it down with WD-40. This should displace any moisture in the pores of the wire. Spray the coil with WD-40, also. Coat the ends of the spark plug wires with dielectric grease.

If the problem persists, replace the spark plugs, coil, and spark plug wires. Cleaning a modern-day engine with a garden hose is dangerous. It's easy to short out the ECM, alternator, and key sensors. It's safest to spot clean the engine by hand. Similarly, jump starting a battery is also dangerous.

Thanks for your help. I discovered an excess of water sitting around the spark plugs. I managed to soak this up and remove the plugs, give them a dry, and replace them. This seemed to do the trick.

Wiping the wires with WD-40 and spraying the coil also seemed to help get it running a little smoother. I'll probably replace them all soon anyway as it doesn't appear to have been done in a while but for now it seems to be going OK.

I was pretty careful about the cleaning job. It was a small high pressure kit I used, not a typical garden hose or pressure cleaner. I also removed the battery (to remove any current) and covered the alternator, ECM, all sensors, fuses and some of the wiring. I also used an air compressor to remove excess water after cleaning and gave it plenty of time to dry properly before I even thought about starting it again.

I think next time I'll still just spot clean now that it's pretty clean all over. Save myself some of the trouble. Thanks for your help