Odd misfire, HELP

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myfirstl322

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Hoots mon...
Hello,:) i hope there is someone who can help me with a problem on my 4.4 (Bmw engine ), i have had it 8months with no engine issues, anyway, it just developed this misfire on number 8. :(
I have renewed the plugs and swapped the coils to no avail.
It is Lpg converted and the misfire is present on both fuels, although worse on Lpg, which i expect is because Lpg is a lower cetane rating ?

My basic diagnostic skills are stretched with this as i am getting a 12v reading from all coils, but number 8 still misfiring and leaving soot deposit on plug which i would guess is ignition fault.....

An important consideration is that it seems to run perfectly from cold, but around the point, or maybe exactly at point of fast idle( electronic choke) changing to normal it misfires..?

I would really appreciate some expert pointers as to what may be the problem... Thank you very much in advance for any help, this is my first post. P.s. New pcv valve and the FOUR hoses renewed recently, rocker gaskets need doing, but there is no oil in spark plug wells.... the misfire comes like a switch ??? The worst thing is it started as i was going to airport to collect the guy who agreed to buy it, totally gutted for him and myself.
 
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Hi Hippo,
Local 4x4 specialist with dedicated diagnostic checked it and he suggested injector wiring problem, but can't look at it for a week as he is busy. Basically his machine says '' misfire number 8 '', lambas all check out ok. Do you think it could be loom? Maybe i could try bypassing main loom with a temporary one to that cylinder from as near the ECU as possible after tracing wires .... at least to eliminate a possible break up in the feed,,,, is this the way forward? this issue is a bit strange, at least for my wee brain because it is evident on both petrol AND Lpg so my thoughts are it is not fuelling but ignition related???? Many thanks for any info...:)
 
You could try the method you suggested

I hear about a few TD6 L322's that have had misfires caused by a broken loom to the injectors

Not heard the same thing with the petrol engines
But it's worth a try
 
Thanks again Hippo...
Get this, a strange thing happened today whilst i was at my local garage getting my other car MOT'd, while tester was doing my ticket i picked up a mechanical suppliers catalogue and briefly thumbed through it, and my eyes fell upon an ECU test and repair section by some industry expert....

There wasn't a L322 Ecu listed , but ALL Bmw Ecu's referenced stated that they all suffer from ' ignition supply signal failings '...... considering that mine has a Bmw engine i think i may have my Ecu tested, at least to eliminate it........ it only costs about £50 to have it tested.... please stop me if this seems wrong ?

P.s. The Bmw Ecu's were mostly 'MOTRONIC',, not sure if my Range Rover has this brand or not ???

Really need to sell this soon so again i ask anybody who may be able to assist to please do so.. i live near Inverness btw....Cheers
 
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The injectors are supplied with +12v with the ignition on and are fired by connecting 0v via the ecu. I've got the pin outs somewhere for the Motronic ecu if you are going to have a go and try jumpering the offending coil. Pm me if your interestd.
 
Hello REWMER, :)

appreciate your input....

Not quite sure exactly what you mean regarding 'your pins'...
I know you mean Ecu pins but are you suggesting a DIY Ecu repair?
Not sure if i'm up to that unless it's an obvious dry solder problem.


I gather the Ecu does the ignition switching...
 
Hi. My bad ! just looked for the document and its gone! Any way I lifted the following from an X5 manual - same engine and ecu....., it should not be too much of a problem identifing the the wiring. You may be able to jumper a lead from the coil to the ecu plug if you make up a lead with fine probe end. Looking at the ecu with the flat side down the coil connections are the last plug on the right. pin number 2 you need for coil 8



But ...........

First off - check you have power at the coil with the ignition on, then check the 0v for continuity and then lastly the signal wire.

You have three wires on the coil - Green +12v, Brown 0V and the signal to the ecu which is black initially which then changes to black with a blue trace at the ecu end.

No need to take the battery off.
 
Hi all,
going to try 'jumpering' from #2 pinout at Ecu to number 8 ignition coil, at least to eliminate a loom fault... #2 pinout is for #8 coil i believe so fingers crossed...

i will let you know the outcome asap, Thanks again everyone for their input.

My hope is a loom fault but my hunch is an Ecu fault as i mentioned earlier the MOTRONIC Ecu's are prone to ignition output faults..
 
Ok guys,
a certain part of my anatomy is now misfiring so i will book it into a diagnostic specialist.... Will let you knowthe outcomeasap..Cheers....Parp sry
 
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