As title states im having bit of a misfire issue. I suspect the fuel injectors as the problem. I have new fuel pump, filter and coolant temp sensor. I know the manual says that the ohm readings should be at 11 ohms. I took a reading of each injector. cylinder 1 = 12.1, 2 = 11.7, 3 = 11.9, 4 = 13.1 The engine was warmed up while taking the readings. would that make a differnce when checking the ohms? Are my ohms readings to high? Thanks!

just took a reading on the spare injectors i have. all 4 reads 11.3 ohmsso it probably the injectors

Start your car. As its running go down line and unlug the spark plug wires. As you unplug, then plug back in, listen to hear if you can remove one, and it doesnt idle worse. Once you find that cylinder, thats the bad injector.

^ correct

I think the heat does effect it because it will expand and will change slightly. It just shouldnt be like way above what its supposed to be. You can also listen to injectors by putting a screwdriver on the injector and listen for clicking, that being the solinoid. No click no good

today i went to the junk yard and pulled 4 injectors that all read 11.5 ohms . I installed all 4 injectors and still having a problem. the cars idle is good but it just has a misfires here and there when sitting at a light. I changed the fuel filter to the z32 filter. cleaned the MAF, spark plugs, cap and rotor. I tested the ignition coil for the hell of it too. it tested out ok. so i tested the coolant sensor. the manual says when warmed up it should be around .30 ohms. my is reading .22 ohms. so i went do and bought a new one. the damn problem continues! it reads .22 ohms too. so i dont know what else to check.... but i did jerry rig it though. i went down to radio shack and bought a .68 ohm resistor. i put that in place of the coolant sensor and bam! no more misfire! but thats not the fix though....
Modified by NISSAN240SX12 at 10:28 PM 7/13/2009

maybe your wires leading to the sensor is bad also check your grounds

I removed the resistor because i dont want to be driving around with it in there. as everyday passes the car is getting worse. I performed a compression test and came out with 150 on cylinders 1,2,4 and 120 on cylinder 3. I keep hearing that 150 is good but then i hear its bad..... I guess to me im thinking that this is my problem. I just rebuilt this engine last year and it only has 10 thousand miles on it. I grabbed a vacuum gauge and hooked it up to the engine. I'm pulling 20 hvac at idle. the needle is steady. any ideas anyone? thanks for anyhelp!

i have the same problem

so i did another compression test but i was looking to see if i actually had a bad exhaust valve or weak rings. i put a little bit of oil in cylinder 3 and the compression went up to 180 so that tells me i have bad rings.... that no good news. so i get to tear down the engine one more time and replace cylinder 3 piston rings.

ok i have my engine apart now with the pistons out. everything seems to be going smooth so far. i have the new pistons rings from NPR. I just thought of another thing about my low compression readings. I had the engine bored out .020" last year during the last rebuild. Would that cause me to have lower compression readings? I wouldn't think it would cause that to be a dramatic change. Cause i should be at around 175 psi with new rings and all and i used a felpro headgasket which is the OEM replacement. i did some searching here but didn[t really find a solid anwser. Thanks everyone!