random misfire - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

singlecamslam · 03-30-2014, 11:48 AM

95 stock auto s14 just developed a misfire. Its random i know this because when i hook up a timing light the spark goes nuts, on any cylinder. What i tried so far:
new cap rotor
different distributor
timing is fine
wires are fine

The misfire is very random, car will run good than it will start acting up and wont stop for a while. Any ideas?

Kingtal0n · 03-30-2014, 04:07 PM

put the interior back in it...

haha. ok so, a misfire huh. Lets see. You need to figure out which cylinder(s). It is probably just one cylinder. Which narrows down your search quite a bit.

could just be a spark plug.

singlecamslam · 03-30-2014, 04:15 PM

I stated that the misfire is random, meaning in all cylinders, i hooked up a timing light to each cylinder and the light goes crazy, meaning the spark is very inconsistant.

Kingtal0n · 03-30-2014, 04:25 PM

check your computer (plug/wiring/tightness of bolt) check your grounds. Replace the computer.

could be related to, the distributor, grounds, computer, wiring.

Or you have managed to use the wrong brand(type of) spark plug / wire.

singlecamslam · 04-08-2014, 11:40 AM

Alright, Tried a different ecu no luck. Cleaned the MAF same issue. Plugs and wires are fine. Anymore ideas? The car is 100% stock, i'll be looking at the grounds next, as far as i know theres not that many. Its very random and comes and goes. Mostly misfires though fouling the plugs right away..

eek · 04-08-2014, 05:12 PM

What type of plugs are you running? Gapped correctly? You sure your knock sensor isn't going bad? Pretty common on these old cars for the knock to go bad.

singlecamslam · 04-09-2014, 11:55 PM

Tried a different knock sensor today, pain in the ass work for nothing same problem. Going to try some new plugs. Throw some idea out.

eek · 04-10-2014, 12:35 AM

Main causes of engine misfires - loss of spark, unbalanced air/fuel ratio, faulty fuel injector and a loss of compression.

I'm not trying to have you just change random parts, have you tried checking to see if your ecu is throwing any codes?

I had the similar weird issue on a bone stock 98 ka24de. Car drove fine but kept throwing misfire cel code. I brought it to several shops and even 2 different dealerships. They could not figure out what was wrong. After 3 months for my unique situation the CEL just went away and never came back.

Shit plugs can cause misfires (hopefully its not like bosch +4 plugs). Test the injectors, run a fuel injector cleaner.

Driftwire · 04-10-2014, 05:02 AM

Are you using BKR6E plugs

03-30-2014, 11:48 AM	#1
singlecamslam Post Whore! Join Date: Apr 2008 Location: Norcal Posts: 2,534 Trader Rating: (10) Feedback Score: 10 reviews	random misfire 95 stock auto s14 just developed a misfire. Its random i know this because when i hook up a timing light the spark goes nuts, on any cylinder. What i tried so far: new cap rotor different distributor timing is fine wires are fine The misfire is very random, car will run good than it will start acting up and wont stop for a while. Any ideas? __________________ Nothing says racecar like a stock car with no interior.

03-30-2014, 04:07 PM	#2
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	put the interior back in it... haha. ok so, a misfire huh. Lets see. You need to figure out which cylinder(s). It is probably just one cylinder. Which narrows down your search quite a bit. could just be a spark plug. __________________ 5.3/4l80e/turbo 240sx playthrough: tinyurl.com/4l80er

03-30-2014, 04:15 PM	#3
singlecamslam Post Whore! Join Date: Apr 2008 Location: Norcal Posts: 2,534 Trader Rating: (10) Feedback Score: 10 reviews	I stated that the misfire is random, meaning in all cylinders, i hooked up a timing light to each cylinder and the light goes crazy, meaning the spark is very inconsistant. __________________ Nothing says racecar like a stock car with no interior.

03-30-2014, 04:25 PM	#4
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	check your computer (plug/wiring/tightness of bolt) check your grounds. Replace the computer. could be related to, the distributor, grounds, computer, wiring. Or you have managed to use the wrong brand(type of) spark plug / wire. __________________ 5.3/4l80e/turbo 240sx playthrough: tinyurl.com/4l80er

04-08-2014, 11:40 AM	#5
singlecamslam Post Whore! Join Date: Apr 2008 Location: Norcal Posts: 2,534 Trader Rating: (10) Feedback Score: 10 reviews	Alright, Tried a different ecu no luck. Cleaned the MAF same issue. Plugs and wires are fine. Anymore ideas? The car is 100% stock, i'll be looking at the grounds next, as far as i know theres not that many. Its very random and comes and goes. Mostly misfires though fouling the plugs right away.. __________________ Nothing says racecar like a stock car with no interior.

04-08-2014, 05:12 PM	#6
eek Zilvia FREAK! Join Date: Feb 2004 Location: California Age: 43 Posts: 1,025 Trader Rating: (29) Feedback Score: 29 reviews	What type of plugs are you running? Gapped correctly? You sure your knock sensor isn't going bad? Pretty common on these old cars for the knock to go bad.

04-09-2014, 11:55 PM	#7
singlecamslam Post Whore! Join Date: Apr 2008 Location: Norcal Posts: 2,534 Trader Rating: (10) Feedback Score: 10 reviews	Tried a different knock sensor today, pain in the ass work for nothing same problem. Going to try some new plugs. Throw some idea out. __________________ Nothing says racecar like a stock car with no interior.

04-10-2014, 12:35 AM	#8
eek Zilvia FREAK! Join Date: Feb 2004 Location: California Age: 43 Posts: 1,025 Trader Rating: (29) Feedback Score: 29 reviews	Main causes of engine misfires - loss of spark, unbalanced air/fuel ratio, faulty fuel injector and a loss of compression. I'm not trying to have you just change random parts, have you tried checking to see if your ecu is throwing any codes? I had the similar weird issue on a bone stock 98 ka24de. Car drove fine but kept throwing misfire cel code. I brought it to several shops and even 2 different dealerships. They could not figure out what was wrong. After 3 months for my unique situation the CEL just went away and never came back. Shit plugs can cause misfires (hopefully its not like bosch +4 plugs). Test the injectors, run a fuel injector cleaner.