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Dead cylinder

884 Views 3 Replies 2 Participants Last post by  ghnl
Well, it appears to be anyway. Ok, the dirt, it ran great till suddenly it went to three cylinders while driving, thinking it was the injectors I sent them to Cruzin Performance, Great work by the way, I put them in and it still runs on only three, and as before its still the the #3 cylinder, it does fire on that cylinder but when I pull the plug wire while running there's no change in idle, it does it during idle and while reving. Changed plugs, switched plug wires, inspected cap and no change.
Could the timing tabs somehow moved or something like that?
I guess my next step is to do a comp. test and hope its not a valve. ???
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Check the connector to the fuel injector. Make sure it is on tight. Look inside the connector and make sure the terminals haven't slipped out of position.

What does the spark plug look like after it's been run a little while? Wet & smells like gasoline? That'd say the injector is firing but fuel is not getting ignited.

Have you checked valve clearances? Peek in via the spark plug hole and verify that the valves are opening & closing.

Could be a minute crack in the distributor cap affecting the post for #3.

How old are the plug wires? I had a problem once (with old wires) of 'cross-fire'. Ignition wires running parallel can induce current in the other wire leading to misfires. Try removing the wire to #3 from the wire holder at the front of the cam cover and temporarily routing it away from the other wires.

A compression test (and leak down test) would help let you know if the problem is inside the engine or not.

edited to add: always check for intake air leaks and vacuum leaks. Sometimes they can leak in such a way as to affect one cylinder more than the others. Also check the plenum to intake boots (short hoses).
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Well, it's not good, I dida comp. test and here's th results; #[email protected], #[email protected], #[email protected], #[email protected] so I put a little oil in cylinder #4 and got 135 and with #3 still at ZERO, I didn't bother doing 1 and 2, by then I was just too disgusted at the results:(. So, by now it doesn't matter if it's a burnt valve or head gasket, either way the head needs to come off, I'll go out later and re test # 1 & 2 with a little oil to see if there's any change, there may me but I hope not much 'cause I don't want to go too far into the motor.
OR,,,,,I could try to sell it!!!!
That's too bad. It does sound like the head will need to come off.

If you want to diagnosis it further before taking anything apart consider a leak down test. My eL-cheapo version is to just use an air hose that screws into the spark plug hole to apply pressure to the cylinder. The piston must be at TDC with the valves closed -be careful ! - the engine can suddenly turn when the air pressure is applied. With the air hose thus attached, listen at the exhaust pipe, the intake, the sump (oil fill cap) and look for bubbles in the radiator. It is normal to hear some hissing past the rings but not elsewhere.

A real leak down tester has a pair of pressure gauges. One measures input air, the other reads how well the cylinder will hold pressure and gives you a reading in percentage.

One thing to do before tearing anything down is to check valve clearances. But if anything has drastically changed to cause no compression in #3 it seems like the head is going to have to come off anyway...
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