Nissan Patrol 4x4 (Africa)

I have no idea where to put this thread because the fault could be in any category so Mr Moderator please help out...

I have a confusing misfire. Even more confusing because as I've gone along with fault finding the misfire has decreased in severity.

The morning after having filled up both tanks I went off in the car and after about 1-2km I got a bad misfire.
There is no Check Engine light and no fault codes

Because of having just filled up I suspected dirty fuel. So I changed the fuel filter, drained and flushed the tanks. Still misfire.
Replaced the fuel pump. Still misfire
I did the PCV valve and checked all vacuum lines. Still a misfire
I fixed a crack in the inlet duct just next to the clamp at the inlet manifold. Still misfire.
Disconnect battery to re-set the ECU. Still misfire
Cleaned the MAF sensor. Still misfire

The misfire is not immediate, it comes in after a couple of minutes.
It seems to be less severe than previously (or I could just be getting accustomed to it or haven't driven as far during my test drives)
There are patches here and there in the rev range when it revs clean.

Any suggestions where to look next?

When I open the fuel filler caps there is pressure or vacuum being released. Is that normal for the patrol or could I have a breather blockage somewhere perhaps?

There should not be pressure or vacuum in the tanks.

However, in my opinion a misfire is unlikely to be caused by anything in the fuel system. Fuel system issues would lead to either starvation or running rich.

Misfires are most likely a symptom of an ignition system problem. I would be looking at plugs, plug leads, coils and that kind of thing.

I would go with Peter's suggestion. Maybe spark plugs first. If you pull off the plug leads one by one can you isolate a cylinder? Or I guess disconnect the coil packs rather!

Have you washed your engine recently? I picked up a misfire about 2 weeks after I washed the engine. Water got into 2 of the plugs and caused a misfire.

spike sometimes when you stand in a dark garrage at night you can see the spark problem

New member, experiencing same problem. Did a trip from Cape to Kunene, on way back intermittent misfire started in Windhoek, first started as an intermittent miss while idling with some loss of power when accelerating. Windhoek Nissan could not find any fault code. Took the chance and drove back to SA, miss cleared at Rehoboth, no problem until back in George where problem started again. Changed all plugs, problem still present. Nissan George could also not find a fault code. Logic dictates next step is finding a coil fault, other possibilities O2 sensor, vacuum leak, injector etc. I do not want to throw parts at the problem, saw a video on you tube, Diagnose Dan in Netherlands. He has the test equipment to immediately isolate the problem.

Does any member know if there is someone in the garden route area that has electronic diagnostic equipment?

Tomc wrote: ↑23 Nov 2021 14:03 New member, experiencing same problem. Did a trip from Cape to Kunene, on way back intermittent misfire started in Windhoek, first started as an intermittent miss while idling with some loss of power when accelerating. Windhoek Nissan could not find any fault code. Took the chance and drove back to SA, miss cleared at Rehoboth, no problem until back in George where problem started again. Changed all plugs, problem still present. Nissan George could also not find a fault code. Logic dictates next step is finding a coil fault, other possibilities O2 sensor, vacuum leak, injector etc. I do not want to throw parts at the problem, saw a video on you tube, Diagnose Dan in Netherlands. He has the test equipment to immediately isolate the problem.

Does any member know if there is someone in the garden route area that has electronic diagnostic equipment?

I would try Dr Quincy in George Industrial.

Thanks, tried him, he unfortunately does not have an ignition analyser. He installed the latest Unichip in the Patrol 5 months ago, dropped my consumption from 24l/100 to 17.2l/100

Took Patrol to Nispro in George this morning, his diagnostic tool detected coils breaking up on cylinders 2 and 4. Vehicle approaching 200000km, this is apparently when you can expect coil problems.

Reporting back to close off the thread

The short answer....I fixed the misfire problem but I rectified so many things that I can't put my finger on which specifically caused the actual misfire fault.

When I bought the patrol I took a calculated risk knowing it had some potentially dodgy aspects, and shortly thereafter I also discovered that it had been submerged at some stage, but working on it now I discovered some serious backyard mechanic botched jobs. So it was kinda good luck that I had this persistent misfire because it got me off my ass to start getting involved mechanically and thus able to discover "hidden" issues and get them sorted

"And thanks again Tinus for always being keen to help)