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"mis-Firing" On Cyl 1


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#61 Mike Floutier

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Posted 11 April 2012 - 03:16 PM

Yes Landar, all correct, and that was my strategy. I finally got the valve cover bolts undone BUT I could only raise the cover an inch or so - I couldn't figure out how to get it completely out and with time running out, rain forecast and concerns about damaging the gasket I re-assembled it all.

It was quite exciting to actually get to see the cam-shafts etc. and after 300,000 miles to see that it all looked nice and clean BUT sooo frustrating not to be able to check the clearances.

I may well have another go at getting the cover fully off again at the next suitable opportunity but in the meantime I'll continue to drive around the problem as best I can to avoid damage to CAT.

I have had one or two Heath Robinson ideas which I may run past you guys in due course because, on balance, I tend to agree that the cost of any proper valve work might not be economic.

Will let you know how it goes.

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#62 Laurance

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Posted 12 April 2012 - 01:23 AM

Hi all,

I have a 2002 LS430 which is just coming up to 300,000 miles.

I had it converted to run on propane around 150,000 miles ago. I have been using an upper cylinder lubrication system but this was not working for around 30,000 miles, on and off.

Recently I started getting a flashing Engine Light along with a P0301 code (mis-fire on cyl 1). This would happen ONLY when the engine was completely cold AND under load - eg. pulling uphill at low revs. Any combination of flat/downhill terrain AND/OR engine warmup and the "fault" would clear.

As the weeks have gone on (I do around 1,000 miles per week) it has got worse; ie. "fault" is more easily precipitated and takes longer to clear AND can sometimes appear WITH a warm engine under load (only very occasionally).

I monitor the fuel consumption quite carefully and I am not seeing any significant increase.

The physical "mis-fire" sensation is only noticeable when stationary, in drive, at idle. To give an idea, on a scale of "1 > 10", if removing the coil lead for 1 cylinder was a "10", then this feeling is around "3 or 4".

I should clarify that although the flashing engine light and P0301 codes are only occasional, the feeling of mis-firing is constant.

There are no other codes.

Around 50,000 miles ago I had a very strange problem with misfire codes on most of the cylinders in No. 1's bank. This would happen on gasoline BUT not on propane and completely cleared up following change of spark plugs and air filter and has been fine ever since.


The present problem is the same whether running on gasoline or propane - each system has it's own dedicated injectors.

So far I have swapped the cyl 1 ignition coil with it's neighbor to rule that out AND I have replaced the cyl 1 spark plug - no difference.


I'm not sure what could be the problem OR what I can try next.

Any ideas would be gratefully received.

Kind regards,

Mike


P0301 means "Cylinder 1 Misfire Detected"
Possible causes
- Faulty spark plug 1
- Faulty ignition coil 1
- Ignition coil 1 harness is open or shorted
- Ignition coil 1 poor electrical connection
- Clogged or faulty fuel injector 1
- Injector 1 harness is open or shorted
- Injector 1 poor electrical connection
- Improper spark plug 1
- Insufficient cylinder 1 compression
- Incorrect fuel pressure
- Intake air leak
learn more at: http://www.uobd2.com...-code-table.pdf

Symptoms:
-Engine Light ON (or Service Engine Soon Warning Light)
- Lack/loss of power
- Hard start
- Engine hesitation

#63 curiousB

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Posted 12 April 2012 - 09:54 AM

This is a pretty long thread with many twists and turns. It is pretty clear there is a problem with one or two exhaust valves on cylinder #1 and that it is likely to do with propane fuel which is more common in the UK.

The car is in good shape but with many miles it makes for tough choices on economic viability of various repairs. A new engine is out of the question and a rebuild of the head is likely borderline on a cost-benefit basis. Maybe a salvage yard head swap might be ok but its a big undertaking.

At this stage the OP is hoping to find uniform valve seat wear such that readjusting the valve shim can result in a better closure of the valve. Its a long shot but given the cost of other options its probably worth a look see.

#64 Mike Floutier

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Posted 14 April 2012 - 05:30 AM

Thanks Laurence, I appreciate your input.

The main thing I need help with at this stage is removing the DS (PS in UK) valve cover. I can get it an inch or so up BUT can't get it out completely, hence I can't check the valve clearances.

Would love to hear from someone who's done it.

#65 landar

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Posted 14 April 2012 - 09:27 AM

Thanks Laurence, I appreciate your input.

The main thing I need help with at this stage is removing the DS (PS in UK) valve cover. I can get it an inch or so up BUT can't get it out completely, hence I can't check the valve clearances.

Would love to hear from someone who's done it.

Mike, there are 9 bolts around the perimeter of the cover so if you remove those and the COP's (coil on plug) from each spark plug, you should be good to go. I really believe that you are just feeling the resistance of the spark plug tube gaskets in the cover. You would need to pry up evenly around all sides to get the cover to slide up each of the four tubes. I think it is just binding on the old, hardened tube gaskets.

#66 Mike Floutier

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Posted 17 April 2012 - 05:48 AM

Thanks Landar, I'm able to get it up an inch or so, the plug hole gaskets are all clear of the tubes. The problem is that however I move it around its fouling on something.

I'm concerned not to force it for fear of damaging the cover gasket which looks in perfect condition - no leaks when I replaced the cover (phew!)

Have you removed this cover? If so do you remember how you manoeuvred it out?

#67 Mike Floutier

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Posted 17 April 2012 - 05:49 AM

Thanks Landar, I'm able to get it up an inch or so, the plug hole gaskets are all clear of the tubes. The problem is that however I move it around its fouling on something.

I'm concerned not to force it for fear of damaging the cover gasket which looks in perfect condition - no leaks when I replaced the cover (phew!)

Have you removed this cover? If so do you remember how you manoeuvred it out?

#68 landar

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Posted 17 April 2012 - 08:01 PM

I have not personally removed the valve cover on my LS430 but I have removed valve covers on many other cars. I saw the post on Club Lexus showing the valve covers removed and no mention of difficulty in removal. You have checked very carefully for some sort of harness or bracket being tethered to the cover? Usually you can tell where something is being held down by prying up on one side or another and noting the point of most resistance.

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