Cylinder four wont fire 1991 240sx
 

KA24DE
New distributor, plugs, wires.

Cylinder four will only intermittently spark when not in the head, putting it in it makes no attempt to fire.
I just performed a compression test and all four cylinders are at 175 psi. Moving the wire for cylinder four to cylinder 3, and moving it on the distributor, results in cylinder 3 getting spark. So, the wire is good. Swapping wire three to cylinder four, and on the distributor, results in the exact same thing. Spark when held up against a bolt or something, but nothing when I go to put it on the plug. I'm out of ideas as to what it can be and have had a few people look at it with no success.

Timing has been checked for the hell of it, MAF is working properly, and....that is all that I can currently think of that I have checked.

Re: Cylinder four wont fire 1991 240sx
 

it might be the injector clogged or not working

Re: Cylinder four wont fire 1991 240sx
 

I haven't checked injectors since I couldn't get a consistent spark. I can check them tomorrow and swap 3 and 4.

Re: Cylinder four wont fire 1991 240sx
 

yeah man just keep us posted

Re: Cylinder four wont fire 1991 240sx
 

How do you know that cylinder isn't sparking, and if you know that cylinder isn't sparking then why would the injector be the problem?


So you can remove the spark plug, put the plug wire onto the plug, and nothing happens? Then when you do the same thing with the other cylinders, they work properly? I guess I don't really understand how you're actually testing this.

Re: Cylinder four wont fire 1991 240sx
 

I have taken the plug out and held it against the block, it sparks every once in a while. I'm completely out of ideas and not much of a mechanic ( I have friends help me with this stuff), I'm taking any and all reccomendations (hence the injector idea) as all my common sense ideas have led me nowhere.

I have taken the plugs out with wires attached, held it to to the block and gotten spark on 3/4. The fourth sparks once in a while, and not at a very high interval. I have put a timing light on it, and the light wont light up. I have taken the exact same plug and wire and placed it on cylinder 3 and moved it on the distributor, and I do get spark. The wire and plug are good. I'm confused because this is now a brand new ignition system as far as I know(plugs, wires, distributor cap, button is clean), yet I'm still not getting any spark (consistently).

I have checked fuses and relays, checked resistance on the spark plug wires, made sure plugs were gapped properly.

Re: Cylinder four wont fire 1991 240sx
 

Just an update for anyone that may have this issue. My issue turned out to be ground related. Thanks everyone for the input and private messages, I greatly appreciate the help.

Re: Cylinder four wont fire 1991 240sx
 

Cool, glad you got it fixed.

I'm closing the thread because it's been solved, PM me if you want/need it to stay open.