whistler Posted September 6, 2011 Share Posted September 6, 2011 Hi I noticed a few days ago that there was no change in the idle sound when I disconnected the spark plugs wires at the distributor to cylinders 2 and 4. I had the day off and I've been meaning to check the valve adjustments and replace the spark plugs, so I did both of those hoping that the spark plugs were fouled or something (they weren't, all four old plugs were pretty clean, slightly grey/brown) but disconnecting the plug wires to cylinders 2 and 4 still doesn't change the sound of the idle so I did a compression test on the cylinders. I only ran it once since I was a little worried about running down the battery, but the test came out good. approx 160 on 1 and 3 and 155 on 2 and 4. So I think that probably means that the cylinders/pistons/gaskets aren't catastrophically screwed. When I did the valve adjustment today I cleaned up both of the valve covers and replaced the gaskets and the drivers side cover was noticeably more crusty and dirty inside (I cleaned both covers out pretty well before replacing them) so I'm wondering if maybe the valves are stuck... open I guess? which might also explain the occasional slight backfires I get when I let off the gas from high throttle... but then the compression test should've been crap right? I just don't have enough experience to diagnose yet. Thanks for your thoughts Tom Quote Link to comment Share on other sites More sharing options...
Dj7291993 Posted September 6, 2011 Share Posted September 6, 2011 Did you check for spark from those cylinders? I'd check there first. An engine needs three things to fire: spark, fuel(and air), and compression. You said you have compression, so I would check spark. If a valve was stuck open, your compression test would have failed. Quote Link to comment Share on other sites More sharing options...
whistler Posted September 6, 2011 Author Share Posted September 6, 2011 when I disconnect the spark plug wire there's a spark jumping from the disty cap to the wire. How/what/where else should I check? Thanks Quote Link to comment Share on other sites More sharing options...
81EA81 Posted September 6, 2011 Share Posted September 6, 2011 maby on the spark plug end of the wire. unplug it from the plug and put a screwdriver in it and try to arch it on nearby metal??? Quote Link to comment Share on other sites More sharing options...
Dj7291993 Posted September 6, 2011 Share Posted September 6, 2011 maby on the spark plug end of the wire. unplug it from the plug and put a screwdriver in it and try to arch it on nearby metal??? Yes, you'll want to check this side too. I doesn't happen a lot, but you could have a break in the wire. Although, I doubt it would happen in both, on one side. Check this, but I'd say spark is probably good. Is your car carbureted, or fuel injected? And, if fuel injected, is it single-port (one injector on the throttle body) or multi-port (one injector per cylinder, located in the head or intake runners)? Quote Link to comment Share on other sites More sharing options...
whistler Posted September 7, 2011 Author Share Posted September 7, 2011 the plug wires are brand new, but I suppose that doesn't necessarily rule out that two of the wires are bad, on the same side I'll check it before I go out tonight. It's carbureted. Stock hitachi carb, I haven't been able to find any vacuum leaks, but I haven't replaced all of the vacuum hose yet either. I also need to clean some of the electrical grounds in the engine bay, but I wouldn't think that a grounding issue would only effect two cylinders... thanks for your help Quote Link to comment Share on other sites More sharing options...
Dj7291993 Posted September 7, 2011 Share Posted September 7, 2011 Well, if your wire are new, then that's probably not it. The reason I asked about fuel is, if it was multi port, it's possible that those injectors weren't firing. Since it's carbed, that's not a possibility. You may have your valves stuck closed. Check you timing belts. It is possible for these engines to run with only the drivers side (not well, but possible). Checking it isn't to hard. Just pull the electric fan, and take off the cover (you may need to pull off the fan shroud too, I never put mine back on, so I don't remember). There are a lot of things that can cause a cylinder not to fire, but if they are on the same bank, then you want to look for things they have in common (as I'm sure you know). You could have a restriction in that side's intake or exhaust too, but it seems less likely. Quote Link to comment Share on other sites More sharing options...
whistler Posted September 7, 2011 Author Share Posted September 7, 2011 Well it's an EA81, so it's a pushrod engine and there aren't any timing belts. And it's the passenger side cylinders that seem to be working correctly and the drivers side that seem to not be working. But it actually runs pretty decently, especially now that I have the ignition timing set correctly (t's at about 8.5-9*.) I'm kind've leaning towards the valves being stuck closed idea... because of the relative levels of crud in the valve covers that I mentioned. But I didn't really think that a 4cyl engine would run in a functional way on only two cylinders... and it's definitely functional, I don't have any problem driving 65-75 on the freeway. It just smells like unburnt gasoline (not as bad as when the timing was WAY retarded, but it still smells like it's running rich) and there's no discernible change in idle sound when I disconnect the plug wires for cylinders 2 and 4.:-\ Quote Link to comment Share on other sites More sharing options...
Dj7291993 Posted September 7, 2011 Share Posted September 7, 2011 Well it's an EA81, so it's a pushrod engine and there aren't any timing belts. And it's the passenger side cylinders that seem to be working correctly and the drivers side that seem to not be working. But it actually runs pretty decently, especially now that I have the ignition timing set correctly (t's at about 8.5-9*.) I'm kind've leaning towards the valves being stuck closed idea... because of the relative levels of crud in the valve covers that I mentioned. But I didn't really think that a 4cyl engine would run in a functional way on only two cylinders... and it's definitely functional, I don't have any problem driving 65-75 on the freeway. It just smells like unburnt gasoline (not as bad as when the timing was WAY retarded, but it still smells like it's running rich) and there's no discernible change in idle sound when I disconnect the plug wires for cylinders 2 and 4.:-\ Somehow, I forgot you said ea81 (and cylinders 2 & 4). Just curious, have you removed both at the same time, or just one at a time? I suppose it is possible that those cylinders are dieseling when you pull the wire. Quote Link to comment Share on other sites More sharing options...
whistler Posted September 9, 2011 Author Share Posted September 9, 2011 Well, I pulled the spark plugs and confirmed that they are sparking. Then I played with it a little longer. I'm not sure if the can of sea foam I ran through it unstuck something or partially unblocked something but there is a small change when 2 and 4 are disconnected and a moderate change when both are disconnected. Having both disconnected seems to be about as bad as having either 1 or 3 disconnected. I spent some more time spraying carb cleaner around vacuum lines and replaced two more bits of tubing. Then I ran out of daylight. I'm still not sure why cylinders 2 and 4 don't seem to be firing nearly as strong as 1 and 3. But I am pretty sure that they're firing, whether they were before or not. Nothing particularly conclusive, since it seemed rather unlikely that they were completely non-functional. If anyone has more thoughts I'd appreciate it. I haven't replaced the engine bay "fuel filter" (and it looks somewhat dirty) because the only filters I've been able to find don't have the third port. So i'll try to track down one of those soon, maybe fuel flow still isn't great. Tom Quote Link to comment Share on other sites More sharing options...
Mykeys Toy Posted September 10, 2011 Share Posted September 10, 2011 This all sounds horribly familiar. I had been fighting this for a week or two when we finally decided to pop the valve covers ff and check. http://www.ultimatesubaru.org/forum/showthread.php?t=124901 Hope that solves it for you. Quote Link to comment Share on other sites More sharing options...
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