Ok, so checked every earth strap I can find inc the battery leads at both ends and starter. Checked volts across batt, reading 13.03v, reading at coil 12.3. Checked spark at distributor end of main hit lead and fat blue spark, but faint yellow at spark plug! So did I buy a duff distributor? Also when I bought the car it had the wrong none vented cap fitted. I swapped it for correct cap during effort to re comm her. Could she also have the wrong distributor. Was running ok before, is there a size diff between vented and none vented caps?

 

Caps are the same dimensions.

Lift that cap, look at the carbon brush in the centre post. Is it still there??, they do drop out, wear away, etc. I have been caught with that a couple of times. I also had weak spark at the plugs due to that.

Next catch for me on one. The insulation material of the rotor is crap. The HT from the coil tracks through the rotor to the dizzy shaft and not the spark plug.

I used Echlin cap and rotor whenever I could get them, but still had one with a suspect brass strip that was pitted very slightly right where the carbon brush contacted.

Failing all that, the HT leads could be too high resistance???. I use Magnecor only on the V12, and never had an issue.

 

It's a none gen but new cap. I will lift it on Sunday as I have had enough today, and take a look inside it. I also fitted none gen ht leads but have now changed these to oem spec, problem persists, so while I'm going to lift that distributor cap I may as well change that too for gen item. I will let you know. I checked the vac pipe to Ecu from balance pipe and it holds a vac.

 

It sounds like you are getting too much fuel and too little air, here are few things I would do...
- check air intake for rats, and check air filter is in decent condition
- if car does not idle - add air by unscrewing air bypass screw(one used to set idle speed), this should increase idle.
- check that 'obvious misfire' is actually happening. If plugs are old and foiled/black (sign of too much fuel) replace or at least recondition(heat with torch until red and all black staff burns out). Misfires are tough to prove, and diagnose. Check that cables are good and there are no sparks flying between cables and engine.
- Check that fuel mixture trim on ECU is not 'all the way'(mine was). I turned mine all the way left and then added two clicks.
- Check that black smoke is from too much fuel, and not from oil getting into cylinders (I don't know how :-) by smell? )
- check if all cylinders are firing by disconnecting injector wires and spark plug wires. It should make a difference when you disconnect one. If it does not - something wrong.

I feel you pain, it is difficult to find a problem - but there are clues everywhere. With persistence things always work out.

I got myself a colortune to prove that car runs too rich. At the same time when I thought I had problem that too much gas is thrown into engine - the issue was the opposite - 3 injectors were intermittently not injecting due to bad contact.

Good luck!

 

Thanks. My 15yr old son has never heard her run properly and has never been driven in her. I'm doing it for him really. If I have no luck once weak spark is sorted then I will look into fuel side of things as you suggest.

 

By the way, I am not a big believer into 'weak spark' theory. I am more 'there is is a spark or there is no spark' kind of guy, yellow spark could be due to carbon deposits and not due to weakness. Take cable out of plug thingy and see how long the spark can be. If it's longer than 1/4 inch - it's strong enough.

 

And another thing... fresh fuel sometimes does wonders (if fuel in the gas tank is old).

And one more... coolant temp sensor - that thing can send ECU off big time. If I disconnect mine - engine dies at idle. Check that disconnecting yours has effect. Check connection is good and check resistance with ohmmeter.

 

Ok, refitted new dizzy cap, I just want to mske sure I'm putting A1 where it should go. There is 1 stamped on the cap, it lines up with a mark on the flash shield, so I take it that is where A1 should go? I have the firing order and the order goes anti clockwise, I just want to check my start position is correct. Also, how Is the ecu timed to the engine? I know there is a pick up in the distributor but that only send a common signal? What actually times engine position to injectors? No cam sensors on this model. I have checked my static timing when I was doing the coolant pump, and that was spot on.

 

You have a winner with that 1A marking.

BUT

If the distributor has been out, and NOT put back where it was, that start point may be somewhere else. It matters not in the real world, as long as 2A starts at the right spot.

If the rotor is pointing AT that 1A mark when 1A is at TDC compression stroke, you are good.

The lead sequence is Anti-clockwise.

There is NO sequence to the EFI pulses. They are fired in 4 banks of 3.
1,3,5A 2,4,6A 1,3,5B 2,4,6B are the groups.
It is a "port Injected" engine. So the fuel is injected behind the Inlet valve, and is sucked in as needed. THAT IS SIMPLISTIC for this answer. The ECU has no idea if 1A or 6B is next to fire, so you are correct in your thoughts.

 

It's not been out, so I'm going to refit leads etc and give her a spin, the new cap I just replaced still had its carbon bush in and there was evidence of slight wear on it so I doubt my bad dizzy cap theory is going to get me anywhere. Will see. Thanks.

 

OK, taken 2 weeks off to sort this B----h. Into week two now, and have gone over everything again, and double checked all your thoughts. She will fire and run, but can't tick over on her own. I have had the fuel rail up and all injectors are kicking out exact same amount of fuel (measured), so this clears the injector wiring and resistor pack? I'm getting Black smoke out of the exhaust. There seems to be a lot of oil in the inlet manifold, with oil weeping out of the butterfly on both sides. Oil is difficult to determine if over full as the dipstick smears, but if it is it's only just over. could i be getting blow back from the exhaust? None cat though? I'm really struggling now. Also put a new battery on, and now the light stays on for a while but flickers a lot before going out? All earth straps look ok and i have added a few more to be sure.

 

I may have discovered my self inflicted issue. Too much oil! What an idiot. Hope i have not damaged anything. Thanks for all assistance provided, i will drain the over fill and report back.

 

Oil drained problem persists. made the mistake of running her in my single garage expecting all to be well. The toxic waste coming out the exhausts sent us running, really nasty stuff. She will not tick over and the smell is just like the odor of the engine oil, i'm guessing contaminated with fuel. Could petrol in the engine oil be causing the symptoms of over fueling?

 

Couple of thoughts.

Does the car have cold start injectors. A seperate injector in each inlet manifold held in place by 2 setscrews?. If so, disconnect them electrically and fuel supply wise, they leak, heaps sometimes.

At the rear of the RH Inlet manifold are various vac hoses. ONE is the vac to the trans modulator. Those modulators do fail, and trans oil is suked up, and serious amounts are sucked up, thus smoking the area, BUT, usually Whitish smoke. Anyway, unplug and cap that vac spigot, just to try, BUT AGAIN, if the alloy Inlet manifolds are oil saturated, that will take many, many hours/days to burn off.

Petrol contaminated oil can cause all sorts of issues, and excessive blow by is one.

Is this "lack of tick over" at cold or hot???

The excessive fuel like smoke is almost like a plugged vac line to the ECU in the boot. Less vac = More fuel, More Vac = Less fuel, SIMPLISTIC explain only. My reasons for going there are simply that the spigot for that line is on the underside of the balance pipe, and any oil in that balance pipe will get into and plug the reliable signal to the ECU MAP sensor.

 

No cold start, i did wonder about the Auto fluid but as you say i have the wrong colour smoke but will check it. Its as though the engine oil is getting sucked in with at that fuel in it and causing a run rich symptom? I suppose i must have contaminated the oil in the early days of trying to get her started, although the oil was new, it must be knackered now. I don't understand the thunderous noise coming out the exhausts though, sound s like something wrong in there too? I will check and complete a comp test too. Thanks.

 

This might be worth trying: Disconnect the crankcase breather system from the B bank air box, and see if that changes anything. If it is engine oil you are burning, it is either coming up the bores, or down the valve stems, or in the breather, or across the head gasket. Disconnect number 10 in this diagram and block the inlet to the airbox off. Clean out the airboxes of oil residue before retrying, and even take out the air filters if they are oil soaked.

 

Has the car sat very long, maybe bad gas. I have had batteries that I charged on my charger and would show that batteries were good when in fact they were not so replaced with new battery and all was good.

 

yes, replaced the juice and put a new battery on it two days ago. The smell of the exhaust has stunk my house out. Smells like the engine oil did when i sucked out the over fill yesterday. Thanks for the help.
I'm going to Try Greg's idea. Interestingly when i bought the car the rubber breather cap that fits over the breather case and attached to the pipe Greg has suggested i remove was lose (refitted now) and the whole engine was covered in a couple of mil of oil slime gunk deposit (all cleaned off now), But it wasn't going in the engine!

 

Good idea, Greg and others know what they are saying, very seasoned Jag mechanics.

 

tried running her without that pipe and the ends blocked off. Can't say i can see a difference, lots of exhaust noise and pressure popping out of the exhaust with loads of un-burnt fuel. Someone mentioned an enrich switch on the ecu, whereabouts is it? Thanks.