So next thing to do is a compression test, and then an injector leak down test...
edit: if it's just loss of power to #4 coil, it'll be somewhere in the engine loom...
This car will be the death of me but before i set fire to it i'd like to move it on. Car was running rough so replaced the cam and crank angle sensors which is a common failure on these cars, didnt fix it so while checking the coils i found that cylinder 4 isnt firing. Swapped coils around and no difference so replaced the spark plug although they are only 2 years old,seems to be no power to the coil which is odd as there are no visible breaks in the wiring loom although i'd need to undo the tape and tubing to check the whole length. Using Datascan II on my phone brought up no error codes which is weird.
Last edited by loanrangiel; 29-03-22 at 08:55 PM.
Look Here -> |
So next thing to do is a compression test, and then an injector leak down test...
edit: if it's just loss of power to #4 coil, it'll be somewhere in the engine loom...
Last edited by wotnot; 29-03-22 at 10:08 PM.
its a lot of work to pull the wiring harness apart , personally i would run another wire direct from the ECU to the coil and see if that fixes it.
lsemmens (30-03-22)
Depends....he said 'no power to coil'...I know that's a bit grey (because the coils are ground switched), but if he's talking missing 12v at coil #4 terminal 1...we're talking maybe 60cm of loom ontop of the engine...this is easy, and if I were a betting man, my first hunch would be the soldered splice between coils 3&4 ....(big black dots are soldered splices on nissans)
If it's switched ground from ECU (coil #4 terminal 3), then just a continuity check will find it....and if bad, then what you suggest is on the cards =)
loanrangiel (30-03-22)
Had a chance to look at this again on the weekend, unpicked the loom section that runs across the top of the motor and all the wiring joins look good. Couldn't find my workshop manual on disc at the time for the wiring diagram but downloaded a new copy, the diagram shows a ground, signal and power running to each coil so i'll be checking continuity on each.
I can get a used harness for about $60 if i cant find a break anywhere but i have ready of a failing ECU giving issues like this.
wotnot (04-05-22)
let us know what you find , its probably a break somewhere or a miscrimped connector . Ive even seen connectors which lost their grip on pins over time , causing intermittent opens.
wotnot (04-05-22)
Yeah, commonly referred to as 'pin fretting' ; I own a nissan of the same vintage, I replaced every (engine) connector under the bonnet 5-10years ago ; it's why I got it cheap (hard to start, misfires, intermittent engine power, bad fuel economy)...works 100% now.
Even if it is the ECU, there's a good chance it's as simple as replacing a driver (the older stuff can be reworked easily)....keep us posted =)
loanrangiel (06-05-22)
The only joins ive seen so far are the earth wires for each coil, the the power and signal appear to run all the way to the ECU in one continuous wire.
If that's the case then i suspect the earth is to blame although strange that its only one coil affected, more diagnoses tomorrow.
Quick test;
loanrangiel (09-05-22)
Getting 0 - 0.1V on the signal wire and 14.34V on the power wire, swapped coils around just to be certain and no change so its definitely somewhere in the wiring.
Where did you take those measurements?...at ECU or at coil connector?
Also...how are you discerning the misfire/nofire at #4?
VroomVroom (12-05-22)
Bookmarks