1994 Sunbird LE 2.0L 4 cyl

Was running fine, did a good bit of freeway driving yesterday with no noticeable issues except the occasional random misfire at low RPM. Just enough to put it on my "tune up at some point" list, nowhere near "this is going to get nasty very soon" level. On the way home last night, I stopped for about an hour and a half to visit some friends, got back to the car, it started fine, ran pretty well, (cold weather and enough time to cool off, so a little rough was expected) and the "check oil" light came on. Checked the oil, and it was at the bottom of the "ok" range on the dipstick. Had some in the trunk, so I got it back up to the top of the range and took off again. Maybe five minutes of 30-45 MPH driving later, I went to get on the highway, and suddenly it got really rough with an obvious power loss. Roadside fiddling determined that pulling the #1 plug wire made no change whatsoever in the idle, so presumably #1 is just dragging now.

Got enough spark to shock the heck out of me when I pulled the wire, but again, no change at all in the rough idle. Pulling any other wire pretty much kills the engine, regardless of whether #1 is plugged in or not. Replaced the spark plug, then swapped them around to make sure I didn't just have a stroke of really bad luck and put DOA one in there. Some carbon fouling on all the plugs, but not bad considering they were probably in there for 60-100k miles before I got the car.
I can smell a little gas when I pull the plug out, but of course, no way to know for sure whether it's getting a good fuel/air mix that way.

This one is the one with a specific coil pack that's $500-700, so no way I'm going to change that as a troubleshooting step on a car that I only paid $500 for. I can go back to Craigslist and find another $500 beater that runs as well as it did for the last month, but if there's a $50-100 option, I'd like to keep it running for a couple months while I save up for something in better shape, and hopefully sell it to some other guy who just needs a beater to get around for a while. (With full disclosure of its remaining problems, of course. Sometimes "It gets down the road right now. No promises about tomorrow." is worth $350 to someone.)

A Compression test may be in order, try some Seafoam for a tankfull to see if it clears up in the meantime.

Doug in P.R.


92 Pontiac Sunbird LE, 2.0, AT, Red / Black with Grey 155K miles. Hurricane Maria Survivor ! ( It takes a licking and keeps on ticking ! ).....in Salinas, Puerto Rico!

Well, no compression to speak of on #1. Got a little on a retest, but nowhere near what it should have. Did a piston soak on it, and it didn't leak down, so it looks like the rings aren't too horrible. My guess at this point is going to be a slow exhaust valve that isn't fully closing in the time it should be, but that does get fully closed within a second or two. Presumably, if I started the compression test on the intake stroke with the exhaust valve having had time to close, that would account for getting some pressure, but none if it was started at a time when the exhaust valve was already open, no matter how many times the crank turned.

Got a borescope and a few other things on the way. Hoping to spend a couple hours going through all possibilities Saturday.

Worn out Cam lopes or rockers?

Doug in P.R.


92 Pontiac Sunbird LE, 2.0, AT, Red / Black with Grey 155K miles. Hurricane Maria Survivor ! ( It takes a licking and keeps on ticking ! ).....in Salinas, Puerto Rico!

92Sunbird PuertoRico wrote:Worn out Cam lopes or rockers?

Don't have a factory spec to go by, but the lobes for that cylinder match the others.

Found a junkyard with a couple of pulled complete heads for it about 3 hours away. If I can find someone with a reason to go down there so I can catch a ride, I may grab one of those and swap it out at some point. Not my favorite plan, (Would be about $225 by the time I add on a full set of gaskets and a timing belt since I don't like putting one of unknown age back on, and $225 is a big chunk of getting a different $500-750 beater.) but it's a possibility.