Igniter Coil Circuit Problem - Obd-Ll Code P1305

[Mike Floutier]

Hi guys,

My Ls430 has just done 250,000 miles so I decided to change my spark plugs (to cure a seperate misfiring problem) which as you know involves removing the coil packs.

A day or two later I get a P1305 obd-ll code which relates to the no.2 igniter coil along with a "mis-firing" feel - no other codes.

This fault would appear after the car had warmed up and continue. However, after stopping the engine for 5 - 10 minutes the fault would disappear when I restarted BUT reappear after 10 -15 minutes etc etc. But getting worse as time goes on, ie. less good moments.

I tried swapping the coil with one from the other bank but no joy - same problem, same circuit, no. This is good in some ways as it rules out the coil itself but leaves me with the rest of the igniter circuit. Also I checked the plug and it looks ok.

Any suggestions as to how to proceed?

Kind regards,

Mike

Just to update this. I have been checking the ignition wiring and most items seem ok, ie. there is power where there should be power. There is continuity.... The only one that wasn't as I expected was the No. 2 pin on the Coil plug - the one that connects to pin 2 on coil 8 and thence to IF2R at the engine ECU.

Having disconnected the ECU plug this section checked ok for continuity but for shorts it was another matter. Measured from the ECU end there was no shorting at all BUT from the Coil plug there was around 2k ohms. However, this was the same for two other Coil plugs so I didn't consider this significant.

Not sure where to go from here???

Edited January 29, 2011 by Mike Floutier

[steve2006]

The code could be a red herring if you are sure the coil packs are OK,heat is their biggest enemy and does cause them to become thermally sensitive and break down when warm.

Have you checked the CPS and camshaft sensors and their wiring as again particularly the crank sensor they can get the jitters when warmed up.

Ignition timing is controlled by these sensors as they tell the ECU where each cylinder is in the combustion cycle and therefore when to supply the spark,incorrect information could therefore lead to a misfire.

One thing I use is called "Freezer Spray" which is useful for faults like yours,run the engine until the problem occurs then spray the stuff on the suspect components (taking precautions with respect to moving/hot parts) If the problem goes when a specific component is cooled down it would indicate that is the cause.

I still have an oscilloscope which can show the data signals between the ECU,ignitors and coils and gives a visual display which makes it easy to see if something is missing or distorted.

[Mike Floutier]

The code could be a red herring if you are sure the coil packs are OK,heat is their biggest enemy and does cause them to become thermally sensitive and break down when warm.

Have you checked the CPS and camshaft sensors and their wiring as again particularly the crank sensor they can get the jitters when warmed up.

Ignition timing is controlled by these sensors as they tell the ECU where each cylinder is in the combustion cycle and therefore when to supply the spark,incorrect information could therefore lead to a misfire.

One thing I use is called "Freezer Spray" which is useful for faults like yours,run the engine until the problem occurs then spray the stuff on the suspect components (taking precautions with respect to moving/hot parts) If the problem goes when a specific component is cooled down it would indicate that is the cause.

I still have an oscilloscope which can show the data signals between the ECU,ignitors and coils and gives a visual display which makes it easy to see if something is missing or distorted.

Hi Steve,

Thanks for responding.

I guess my initial reaction is that a problem with the CPS and camshaft sensors would show in more general symptoms, ie. the whole area under their jurisdiction, rather than just one coil not firing.

However I'll bear it in mind. I have a more expensive scanner arriving soon from China so hopefully I can get some more data to help with the diagnosis.

Will let you know how it goes.

By the way, can you confirm whether the ECU shuts down the fuel injectors for "non-functioning" cylinders?

Regards,

Mike

PS It also occurred to me that whereas the CPS and camshaft sensors would alter the timing of the igniter signal in this case the obd2 code is reporting that the coil did not fire at all.

Edited January 29, 2011 by Mike Floutier

[Mike Floutier]

Just to confirm that this is solved now.

It was the coil's connector plug that needed cleaning. I hadn't considered this - for some unknown reason - doh!

I guess this sort of code would often attract a replacement coil which may well solve the problem by presenting the connector plug with a shiny new set of contacts - worth remembering!

Many thanks.

Mike

[steve2006]

Glad to hear you sorted it Mike always have a can of Servisol in the workshop.

[Mike Floutier]

Glad to hear you sorted it Mike always have a can of Servisol in the workshop.

Ok, well I thought it was sorted.

Fortunately it stayed sorted just long enough to get through my MOT.

Anyway, what I'm seeing is that if I clean the coil connector AND spray it with electrical switch cleaner (is that what Servisol is?) then I get a few days' cool running before reverting to mis-firing.

However, if I simply clean the connector, it makes no difference, ie. still misses.

I've checked all the continuity and power supply again, this time wiggling the connector each time but all seems fine - this is when it's missing btw.

What I propose to do is obtain a replacement connector and wires and replace the offending item.

I guess I'll have to cut into the "loom" a little which is something new for me but I think it has to be done.

Will let you know how it goes.

Regards,

Mike

[Mike Floutier]

Ok, definitely getting warmer with this.

I noticed a couple of things today (whilst cleaning the coil's connector for the umpteenth time)

1. The connectors have rubber seals everywhere - ok I guess everyone knows this but I didn't - lol!

2. I started reading about dielectric silicone grease.

At first I incorrectly assumed that this grease would help the conduction and thought about getting some - to help stop whatever process is repeatedly causing my coil's connector to stop conducting.

I then discovered that although it's purpose is to maintain conduction, it's actually an insulator. One thing it does is to prevent the current straying, eg. where the coil meets the spark plug. But another thing is that it prevents the ingress of moisture and oxygen/air.

I realised that the rubber seals on my coil's connectors doing the same thing.

A close look at my No. 2 coil's seal showed that it was damaged and ineffectual.

The light is starting to dawn!

Ok, I've ordered a new connector from Lexus and a pot of dielectric silicone grease off eBay.

In the meantime, I've wedged 4 sculpted matchsticks down the other holes on the connector to, hopefully, tighten the connector.

We shall see what tomorrow brings.

[Mike Floutier]

Ok, the story continues.

I got the quote from Lexuspartsdirect for the replacement connector and it's nearly £60. Well I don't know about you but that seemed a lot to me but apparently it's correct, £6 for the connector and £13 each for the four little wires ("repair terminals")

Anyway, what I do is remove the connector, clean it and put it back and it runs ok for 100 miles or so - depending on the weather etc.

Only trouble is that it's the no. 2 coil so I have to remove all the air intake gubbins every time I do this.

So, what I did was to tie a length of string around the connector so that I could wiggle it without having to remove all the air intake bits.

You have to imagine me at a set of temporary traffic lights - there are many around here at present - good old no. 2 coil stops working, Mike jumps out, lifts the bonnet and tugs on his little piece of string. Gives a cheery wave to the car behind - the lights are changing - and hops back in and gets another couple of days trouble-free motoring.

Ok, not really the way you want to continue, especially as a private hire driver.

So, I'm considering a couple of options:-

1. I snip the offending connector off and solder the wires to the coil's terminals - not sure about this, would it possibly damage/unsolder something inside the coil??

2. Try to find some replacement female terminals of the suitable size, forgo a connector completely and simply fill the area with silicone grease.

What do you think?

Kind regards,

Mike

[Ruud]

option 3: Shop around some more and see if someone else has a cheaper connector? :)

[sir john]

Mike..You and your little bit of string take me back a while. As the owner of numerous British cars and LDV vans i never left the house without a swiss army knife, elastic bands, some Aroldite and a piece of string. Fix anything with that lot.

[Mybikesacx500]

Try Benfur, good man for reasonably priced parts, he could perhaps chop a connector out a loom for you

option 3: Shop around some more and see if someone else has a cheaper connector? :)

[Mike Floutier]

Haha, just noticed this thread during search re. my current problem.

It's now 50,000 miles later and I have installed a new piece of string. The latest refinement is that I keep it under tension by running it round one of my propane injectors and then round the power steering fluid tank and tie it off on a suitable point. The course primary tension is achieved by wedging a folded piece of kitchen towel between the string and and the fluid tank. The fine tuning is done with another piece of towel under the string where it passes over the air intake resonator. This not only keeps the string tight but protects it from chaffing on the resonator; something that was a problem with the old piece of string.

[ROYT]

Haha, just noticed this thread during search re. my current problem.

It's now 50,000 miles later and I have installed a new piece of string. The latest refinement is that I keep it under tension by running it round one of my propane injectors and then round the power steering fluid tank and tie it off on a suitable point. The course primary tension is achieved by wedging a folded piece of kitchen towel between the string and and the fluid tank. The fine tuning is done with another piece of towel under the string where it passes over the air intake resonator. This not only keeps the string tight but protects it from chaffing on the resonator; something that was a problem with the old piece of string.

All this high tech repair work on a 430, should have stuck with the old 400 !!