Nissan Patrol 4x4 (Africa)

Hi all,

It's been a while since my last contribution or request but alas.

The issue I have is that after servicing the TB45E (unknown mileage as replaced) after I had an issue with airflow contamination after wrong filter element was inserted .

The engine is modified with a aqua tech compressor (South African product) and intercooler and it necessitated the re-arrangement of the engine bay whereas a Toyota air filter (the cylindrical one) off the LC79 was used.

The issue now is that the engine misfires on cylinder #2 (only this one) and we can't find the reason or remedy.

We did valve clearance, injector swap, spark plug replacement, fuel supply check, ignition timing, injector pulsing signal, vacuum leak checks and all electrical wiring and contacts and compression test. All seem okay.

Now, pretty much wits end and still no cure found.

Is there anyone having experienced similar and could give some idea where to look further?

Thanks for any input in this respect.

I presume it still runs the distributor?

Perhaps putting a timing light on the lead should tell you whether the problem is spark or fuel?

Any news on this?

Will check on distributor, might have a spare one from earlier engine swap.

Running additional tests along those lines.

Sorry if I misled you. I don't think the problem can be the distributor itself (although it could be the cap).

But if you had changed to some other type of ignition system then checking the spark with a timing light doesn't tell the whole story, because if you have a healthy spark but at the wrong time it doesn't help much. If/as you are running the dizzy, then the timing on one cylinder can't really go out without all the others also going out.

Thus, if running a dizzy and a timing light shows spark on that cylinder, then that would immediately mean that the problem has to be fuel delivery (or compression, but you have checked that already).

Peter,
I am running the stock distributor and we are trying with replacement.
Spark is on plug #2 but engine runs on 5 pots.

I have a handful of injectors, but doubt that's the point. Swapped injectors around amongst the cylinders (1 & 2) before and no change.

Yup, elimination process is what we have done but obviously overlooked something.
- Compression - ok
- Injectors - swapped
- Sparks and plugs - fiddled

I am not sure but could a blocked / or partially blocked air flow in the manifold pipe to cyl #2 be a cause.

Story:
Had loss of power during safari trip which turned out to be a compromised air flow sensor housing whereas debris and dirt was sucked up passed the filter as the element was leaving a 20mm gap open.
The paper lable of the filter was torn and sucked into the air channel.
Now we have cleaned the airflow sensor housing, throttle body element and blown out the manifold but form the throttle body side.
If some debris would have passed all the above inclusive the compressor then it could be stuck in the intake pipe (cyl#2).

But that's a long shot and a lot of "ifs" and I can't really say if the motor runs on 5 pots or 5 (+) but it does not on 6.

5+ meaning fueling and sparking but without giving power.

Have you replaced no 2 cylinder's sparkplug lead? Could be a faulty lead.

Here a theory as I am running out of options (and now under time pressure as I should start a safari trip in less than 10 days)

My mechanic today mentioned that the misfire started on the test drive first on cyl #4 then moved to cyl #3 and now persists on cyl #2.
He also mentioned that at some stage used compressed air to clean out the inlet manifold in the process before the compressor was remounted after the bolts repair. (on the support where normally the throttle body is mounted)
Bolt's thread was damaged in the aluminium.

Now, me thinking.
If there would be some debris inside in form of a piece of paper label (similar I found 1000 kms ago in the air flow sensor body) and that made its way through the throttle body and the compressor and then moved around in the inlet manifold, depending on air flow turbulence, now finally lodged firmly in the pipe of cyl #2.
We don't have the normal vacuum in the manifold, but compressed air from the compressor at say 0,8 bar.


What would happen.
1st fuel injection timing is given by the computed airflow reported to the ecu from air flow sensor, so the mixture is optimised.
Now based on my assumption of blockage or partial blockage on cyl #2 the fuel - air mixture is rich, it would over fuel by the missing air volume. (all cylinders get the same injector timing hence fuel volume).

The cylinder would fire but with a less efficient mixture thus "limping" or misfiring.
That is what I think I see, maybe not a totally "dead" function but less than optimal.

Now as said, my theory what is your take.

Any consideration welcome.
Thanks

I would say it is certainly worth stripping the whole intake system and making sure it's clean.

mvcoller wrote: ↑25 May 2023 19:43 Have you replaced no 2 cylinder's sparkplug lead? Could be a faulty lead.

Yup done that, but still no change.