Dead cylinder

[michael]

My friend has a 96 legacy with a dead cylinder. Spark is good, fuel is good. If you pull the injector wires the idle does not change. If you drive without it connected it's much worse than with it connected. Can rings go bad on one cylinder? Any advise is appreciated.

[SoCal LS-L]

Originally Posted by michael

My friend has a 96 legacy with a dead cylinder. Spark is good, fuel is good. If you pull the injector wires the idle does not change. If you drive without it connected it's much worse than with it connected. Can rings go bad on one cylinder? Any advise is appreciated.

Wait a minute, if driving without it connected is much worse than with it connected, its not a dead cylinder. It means the injector is dumping at least some fuel, and it is being burned in the cylinder to at least some degree.

The first thing to do would be to compression check it. It could be a failed head gasket, or a partially clogged injector, or maybe even a valve train problem. The only way to tell is to watch the compression gauge behavior for tell-tale signs of worn rings or a cylinder leak. If its the valves or rings, it probably wont even get to minimum specified compression. If its a HG problem, it will usually get there and immediately drop..... you can open the radiator and see if coolant spurts out concurrently.

[TomsSVX]

Originally Posted by michael

My friend has a 96 legacy with a dead cylinder. Spark is good, fuel is good. If you pull the injector wires the idle does not change. If you drive without it connected it's much worse than with it connected. Can rings go bad on one cylinder? Any advise is appreciated.

Yes they can and often do only fail on one cylinder. Do a compression test (its a 2.2l right?? Its easy) on the offending cylinder and all others as a basis to compare by. if it is in range, replace the injector

Tom

[michael]

Wait a minute, if driving without it connected is much worse than with it connected, its not a dead cylinder. It means the injector is dumping at least some fuel, and it is being burned in the cylinder to at least some degree.

The first thing to do would be to compression check it. It could be a failed head gasket, or a partially clogged injector, or maybe even a valve train problem. The only way to tell is to watch the compression gauge behavior for tell-tale signs of worn rings or a cylinder leak. If its the valves or rings, it probably wont even get to minimum specified compression. If its a HG problem, it will usually get there and immediately drop..... you can open the radiator and see if coolant spurts out concurrently.

Sorry, I should have said half dead cylinder. HG seems good, no bubbles or goo in the oil or water.

Yes they can and often do only fail on one cylinder. Do a compression test (its a 2.2l right?? Its easy) on the offending cylinder and all others as a basis to compare by. if it is in range, replace the injector

Yes it is a 22, The injector has already been replaced. can you give me an idea what the range is on the guage. Neither of us have ever used one. Thanks

[TomsSVX]

Basically all engines will vary. I am not entirely sure what acceptable is for the 2.2l but if you measure all 4 and find one out of whack, that is likely going to be your culprit. Have you checked for spark leak or replaced the plug/wire on that cylinder?

Tom

[SoCal LS-L]

Originally Posted by michael

Sorry, I should have said half dead cylinder. HG seems good, no bubbles or goo in the oil or water.



Yes it is a 22, The injector has already been replaced. can you give me an idea what the range is on the guage. Neither of us have ever used one. Thanks

Do you know the compression ratio? You would multiply that by 18 I believe to get the nominal compression PSI. I think yours is 9.5:1 making that figure 171 PSI. However, like Tom said, you should measure the suspect cylinder against the others to verify a compression problem.

[MadMaxSvx]

I bet that the injector is not suplying enough fuel. A valve that is´nt seatting well can make a cylinder fail also by lowering the C/R.

[michael]

Originally Posted by TomsSVX

Basically all engines will vary. I am not entirely sure what acceptable is for the 2.2l but if you measure all 4 and find one out of whack, that is likely going to be your culprit. Have you checked for spark leak or replaced the plug/wire on that cylinder?

Tom

Plugs and wires were recently replaced with OEM parts. MadMaxSVX, I thought about a valve too, but wouldn't it make a noise of some sort? The injector was replaced so I'm sure it's getting fuel. We compared the plugs and they all looked the same, so I gather there is no lean/rich condition. Thanks for the info everyone.

[MadMaxSvx]

Originally Posted by michael

I thought about a valve too, but wouldn't it make a noise of some sort?

A non seating valve not always makes a noticeable sound,and sometimes the exhaust valve is burned and then compression scapes with the valves making the normal noise. I think the C/R measure is the first thing to check.

[MiataMania]

Compression gauges are cheap...very worthwhile tool to have.


If you know a ball park of where the motor should be its usually a good thing, but run the numbers and if one is more than 10-15% out of range of the others then you have a problem.

[Blacky]

Minimum compression is 147 I believe, same as the 2.5.
I'm dealing with one dead and one almost dead cylinder on my daughters 2.5 Outback. Cyl#1 has 15 lbs and actually fires a bit, #3 has 0 compression. It skipped the timing belt and bent the valves I think.