STILL trying to figure out a misfire...

[ANVIL]

well my car has been sitting for quite some time now, and i havent been able to DD it since late 2008. spring is here and im determined to get this thing back on the road. ive had a busy winter and finally having more time to try and work on my car again.

heres a thread i made last year about it trying to figure it out:

help-to-get-my-car-running-right-lots-o ... 04-40.html

i havent really done anything since my lasts posts on there.

so basically #6 cylinder isnt firing. things I have tried/checked:

-spark to all cylinders is good
-replaced spark plugs
-swapped coil pack
-swapped ignitor
-double checked all wiring
-compression is 155ish on all cylinders
-tried 2 sets of injectors
-checked all rings and seals on rail/injectors
-same with stock ecu and power FC
-same with z32 MAF and RB25 maf
-replaced CAS

and probably other stuff i cant think of

sometime today or tomorrow i will be double checking the physical timing on the belt/cams but im pretty sure they are on correctly.

ive taken it to a local nissan specialty shop and they either were stumped or just didnt want to take the time to figure it out. im getting to the point where im seriously considering flying someone up here to work on it for me because locally theres almost zero resources for 240/rb here in Alaska. help me out guys, its not much but who ever gives me the solution or something i can paypal $50 bux

[SlowKoop]

Whats plugs are you using? I was having trouble when I when to a cooler plug (bcpr7) I think. Went with old plugs and my miss was gone. Does it feel like there is only a few cylinders working?

[Darius]

So you've physically seen the #6 spark plug wet with fuel to verify that the injector harness is functioning properly?

[Ramius83]

First, please verify that fuel is entering cylinder 6. You need to test the engine with a leak down tester. Compression results don't always prove a good engine. Test the injector plug with a noide light (to prove the ecu is supplying ground to injector to fire when it is supposed to). And did you un-hook the coil pack from the spark plug, insert a good plug into the coil pack, and ground out the spark plug while the engine is running to make sure you are getting spark to cylinder 6???

[Krazykouki]

The more I look at this the more something tells me that something is wrong with the injector wiring, as in something is mixed up. What harness are you using and who did the wiring for you?

I've corrected 2 harness's recently that had injector 4 and 6 mixed up for some odd reason. This would cause a weird misfire. Really sucks that you live in Alaska because you are sooo far away from the majority of the people who can fix this...it's just really really hard to diagnose a car without having the car right in front of me.


What is the Vac at idle?

[ANVIL]

slowkoop - im using NGK V-Power BKR5E-11, also tried a set of HKS Super Fire Racing S30. and yes it definitely feels like all cyl arent working. for cyl #6 i can have the motor running and unplug either the injector or coilpack and there wont be any change in how its running

darius - yes after running awhile and pulling the plug #6 comes out wet. what is the proper way to verify the injector harness wiring?

ramius83 - how exactly is a leakdown test done? i havent done one but i think i can get ahold of a tester, if not i will buy one. also will look into borrowing or buying a noid light as well. and yes i did that test to visually see spark and also have one of those spark tester lights that plug in between the coil and plug.

krazykouki - i dont think the injector harness has been touched since ive had the motor. if you can guide me through a way to test the wiring i will for sure take the time to properly test it. unfortunately i dont recall the vacuum.

im gonna have to get a battery tomorrow because i charged it today and my tester verified the battery is toast after sitting for so long. also gonna try to hunt down a leak down tester and a noid tester. thanks guys for the input so far, hopefully i can get this thing figured out with the help you of guys.

[gawdzilla]

a leakdown test you basically put each cylinder to top dead and replace the spark plug with the leakdown tester. the leakdown forces compressed air into the cylinder and measures the amount of air that leaks past. it can identify bent valves, ringland issues, etc. depending on how much air escapes and where the air is going. search a bit on youtube, i'm sure there are videos of people doing the test.

cylinder 6 never fires? or misses a lot? so you are definitely getting spark, fuel, and air (if leakdown is good). dunno what else it could be. there must be something you are overlooking.

a good way to test the wiring without the noise of a running car is to pull your CAS out. pull all your spark plugs out and make sure all the plug bodies are grounded using a metal pipe or something. then spin the CAS by hand in the correct direction. you will see each of the plugs firing in order. you should also be able to put your hand on each of the injectors and feel them firing in order too.

if this test pans out, the only thing left is mechanical timing or a bad cylinder 6 i'd say.

[l0nestar]

In place of a Noid light, you can use an analogue volt-meter. (The style with a needle, not LCD) It's a quick-n-dirty way when you don't want to wait days / weeks for one, or it's prohibitively expensive.

Use the FSM for the pin-out of the injector harness. Use your Digital multi-meter (with continuity test!) and probe that each pin has continuity and it is going to where it *should* be. Pretty easy on the clip-in sub-harness, but more difficult with the main ECCS plug.

[StricNyne]

this is something a little weird but it worked for some people on SAU, they got the power wire doing to the coils, and placed a relay there. They used the old power as the trigger, said it helped with misfiring by guranteeing the proper voltage was going there, it sounds like your having a bigger problem but its a simple solution that might be beneficial