Injector or distributor cap problem

Mr. Steef

Mr. Steef

^Chris Kastner^
Driver
First its a 91 ka 240sx. Ok so I got my car ran fine and everything was great now the car shakes and idles funny me and one of t he tech's at work tested some things. Compression is 175, 175, 175, 178 basically a 11.9:1. after that we noticed the spark plugs and wires weren't getting full spark (burns around the ceramic/white part of spark plugs). So I changed the wires and plugs with brand new ones. The car was fine right after that. Now The car shakes at idle so we tested the injectors and they all work but the injector on cylinder 3 seems to be clogged or isn't letting fuel into the 3rd cylinder. The injector is moving but no fuel (tested via test light). So im thinking maybe its just a bad injector or something is up with the distributor cap. Help?
 
the tech at work did it for me

found someone else with the same problem fixed by putting in a new injector
 
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Your calculations for compression ratio are incorrect. You would have to know the swept volume compared to the clearance volume, if you did not modify the chamber volume or the piston dish or deck height then its still 9.5:1 which is stock with 179psi cranking compression. Cranking compression will vary depending on ring end gap and its seal to the cylinder wall.
 
240SicknessX said:
Your calculations for compression ratio are incorrect. You would have to know the swept volume compared to the clearance volume, if you did not modify the chamber volume or the piston dish or deck height then its still 9.5:1 which is stock with 179psi cranking compression. Cranking compression will vary depending on ring end gap and its seal to the cylinder wall.
Click to expand...

my friends motor was rebuilt before he got it and was told it has high compression pistons
but we did a compression test today and it was 130 across all 4 cylinders
what would that really make the compression ratio of the pictions?
 
burninskulls091 said:
my friends motor was rebuilt before he got it and was told it has high compression pistons
but we did a compression test today and it was 130 across all 4 cylinders
what would that really make the compression ratio of the pictions?
Click to expand...

you have to measure the size of the chamber from BDC to TDC to find out compression ratio.
 
Well i now know its the injector because i switch the injector from cylinder two to cylinder three and its doing the same thing on cylinder two.
 
burninskulls091 said:
my friends motor was rebuilt before he got it and was told it has high compression pistons
but we did a compression test today and it was 130 across all 4 cylinders
what would that really make the compression ratio of the pictions?
Click to expand...

you sure that you guys didnt miss understand high compression for low compression for turbo charging? cause if you have 130 that would be about right for turbo'n
 
burninskulls091 said:
my friends motor was rebuilt before he got it and was told it has high compression pistons
but we did a compression test today and it was 130 across all 4 cylinders
what would that really make the compression ratio of the pictions?
Click to expand...

Umm, I dont trust compression gauges even if they are brand new. Unless you can verify that its accurate by getting 179psi on a stock ka, then you can trust the actual number the gauge puts out. I check for variance in between the cylinders.

If you get 130 psi across the board, 1, your gauge could be inaccurate, 2, you could have too much ring end gap\ poor cylinder seal, 3, lower compression pistons, test with another gauge to verify if that one is correct.

I would try to find out which pistons it has in the engine. Make sure you have disabled the fuel supply to the engine via fuel pump fuse or CAS disconnect and make sure that the battery is cranking the engine fast enough with all the spark plugs out.
 
Ok so I bought a new injector finally got it in and then car ran fine. Took it for a ride then turned around and started coming back it started shaking again.

Got back popped the hood and unplugged the very first injector nothing changed so then i thought now this injector is bad. Thought about it and then went back to the distributor being the problem. Let the car sit a little while then started it and let it run. The car ran perfectly fine no shaking. Then said ok bye to my friend who's house i was at and the car ran perfectly all the way home no shaking no problems even stopped at the gas station turned the car off then started it about 5 min later. Still no shaking... So tomorrow im going to replace the distributor cap just to make sure I'll update then.
 
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