The V7 1UZ

[Danger Mouse]

Should really start a diagnostic thread, as it's not the plug lead like I thought.

Symptoms: Misfire, dropping down a cylinder then clearing, finally dropping to 7 cylinders permanently after messing about with the leads (hence why I suspected that).

Multimeter seemed to confirm, but after testing 2 known good leads, I realised the multimeter wasn't working correctly.

Still running on 7, but occasionally with a loud ticking from what ever cylinder isn't firing, but that seems to go away, come back, go away etc...

I'll continue on the electrical gremlin hunt (will check the plugs and dizzy cap next) but anything else to test?

 

[Danger Mouse]

Curiouser and curiouser...

So thought I'd dig the supposed dead lead out of the trash and test that, just to confirm I was incorrect (both good leads tested and are indeed good)... dead lead is dead. Yet it's still running on 7.

Only thing I can think of is as it was running home on 7 it has fouled the plug on the dead cylinder and it's now the plug not firing.

Either that or there's another dead lead somewhere, but I tested every other one on the weekend.

 

[Zuffen]

These do foul plugs and they sure don't like clearing themselves so try swapping in a new plug.

The clicking you refer to is interesting.

Is it clicking when it's running on 7 cylinders?

I would expect a quiet clicking when the injector fires, which would mean it would be running on all 8.

Do everything in a logical and single order.

Replace the spark plug, in fact replace them all with new ones. I know it isn't cheap but they could all need it anyway.

See if that fixes it.

If not I'd check the condition of the rotors and caps on the basis you have the leads checked and you're sure they're OK.

Another option is to run the engine in a dark garage and see if any shorting is going on between leads or leads/earth. These have long leads that go some funny places.

 

[Danger Mouse]

The clicking/tapping is random. It sometimes did it while running on 7 sometimes not. Wasn't doing it a few minutes ago though...

So put a clean plug in, the old one was black and covered in soot and gunk, so quite possibly fouled. Seems to run on 8 now, but need to take it for a run to make sure. If it is, I'll replace the rest of the plugs when the new leads turn up.

Cheers for the help!

 

[Danger Mouse]

Oh this is getting annoying... so it's back to missing and randomly dropping from 8 to 7, then going back up to 8.

Been working on my bathroom today, so haven't had time to spend on the ute, but will hopefully be able to look at it tomorrow.

 

[V8hilux]

Is your distributor cap alright?

 

[Danger Mouse]

I'll be looking at exactly that tomorrow, along with pulling all the plugs to check for fouling and retesting the leads for continuity.

Oh the fun...

 

[Danger Mouse]

New dizzy cap didn't solve anything. Still waiting for the new leads and plugs from the States, but trying to find the issue while I wait.

Runs better, but here's the odd thing. I start from cold and she runs sweet as for about 5 minutes, then the miss starts creeping in and gets worse until it drops down to 7.

Coil packing up when it starts getting warm perhaps?

Annoying thing is I really miss driving it, just want to go for a blat.

 

[krayn]

A faulty injector could be fouling the spark plug or possibly one valve has a tight clearance and when it warms up the valve gets left open??? Possibly an idea to check valve clearance..

 

[Danger Mouse]

Wouldn't think valve clearance, the last time I took it for a decent drive it would randomly clear and run sweet for a few minutes. Reckon it's electrical but just trying to figure out what.

 

[Danger Mouse]

What are the symptoms of a dodgy ECU? Been reading a few threads on here and a couple mentioned dropping coils, dodgy grounds and the like, not a million miles from my issues.

I did have some poor wiring issues when I got the ute, the air filter was sitting on the main loom and had worn through the insulation (MAF assembly was reading a negative voltage when I was tracing the loom and looking for poor earths). Just thinking it could be more than that and I'm actually experiencing dodgy ECU issues...

...ok I'm mainly guessing, wish I was a better mechanic...

 

[Danger Mouse]

So took it for a long run, it pops a bit on idle but generally it's actually running pretty sweet, occasional cough and splutter, but significantly better than last weekend.

That would indicate I'm in the right area, plugs, leads dizzy cap etc. Will see how it runs when the plugs and leads turn up from the 'States (way cheaper but takes a while for stuff to turn up).