"mis-Firing" On Cyl 1

[landar]

One of the 'problems' with the LS is that you cannot simply "run it into the ground". It is far too well-built for that to happen. It will destroy you (mentally) with niggling little issues before it gives up the ghost completely. Think about the emotional and time investment you have thus far into this issue as an example. So, you would either need to sell it or fix it.

If the car has people believing it is a new model and in very nice shape, why not invest in fixing the exhaust value issue? You would have to pull the head and have it serviced but it could be worth the experience and trouble in doing so. If it were mine and I were fairly happy with the vehicle, I would have it repaired, doing as much of the work as I could myself. If however, I were tired of the old girl and had the money, I would sell it and get a newer, lower mileage vehicle.

BTW, couple of thoughts on the actual leak. You have 16 intake valves and 16 exhaust valves, right? So perhaps only one of the exhaust valves on cylinder #1 is leaking. Small solace, I know, but something to think about. If you did rework the head, of course you would have all of the valves checked and reseated if need be. I also wonder about removing or maybe loosening the exhaust manifold from the head. You would certainly be able to hear the leak coming right from the exhaust port. You might even be able to see some light if you shined a torch into the spark plug hole and were in a dark garage. Some mechanics even use what they call a "smoke" test injecting smoke into a leaking area and looking for the smoke to exit.

[Mike Floutier]

Hi Landar,

Many thanks for this, I agree with your thoughts about fixing it, I believe it will be worth it.

Regarding the exhaust valve I've no doubt that it's one of the No.1 cylinder exhaust valves and I guess it doesn't really matter which one it is.

In fact I suppose it doesn't really matter which cylinder it is since I'm going to need to do some general dismantling and it's highly likely that all of the valves have deteriorated to a greater or lesser extent.

The next step, it seems to me, in this long diagnostic process (having implicated one or both of the No. 1 cyl. exhaust valves) is to check to see whether the non-closure/sealing of the valve(s) is due to deterioration of the valve OR valve seat recession.

As I think I mentioned, valve seat recession is a common feature with engines run on propane (as mine is - 160,000 miles on propane) so I'm expecting it to be that.

What I'm planning to do next (partly because it's simplest) is to check the valve clearances. As I've not had the valve covers off before I'm planning to do bank 1 first due to easier access.

I was very interested to see these photos on http://www.clublexus...question-3.html which seem to show a variety of wear on the backs of the cams (ie the bit where there should be a gap of 0.3mm at TDC; ie exhaust valve closed). Clearly any metal thats not rubbing against other metal is painted with this golden gunk.

The clear picture painted here is that some valves are closing but some are not, the reason for non-closure seeming to be a lack of clearance. This is what I expect to find when I check my clearances.

So my immediate request is really for assistance by way of any tips for removing the valve covers; especially the bank 2 cover and most especially the dipstick bolts as I can't even feel them let alone see them!!

Ps. I just realised I didn't say why I wanted to distinguish between the differing causes of valve non-closure. If it's valve seat recession, as I'm expecting, then it won't be necessary to take the heads off; simply find an easy way of reinstating the valve clearance.

[curiousB]

The clear picture painted here is that some valves are closing but some are not, the reason for non-closure seeming to be a lack of clearance. This is what I expect to find when I check my clearances.

Isn't the normal wear for values to be they open less as wear sets in? The push points establish the travel and if they wear the valve travels less. So failure to seat wouldn't be wear but damaged valve seat stopping a tight closure.

Instead of a valve job why not buy a used head from a wrecker and install it. That might be a lot cheaper than a trip to the machine shop and new valves and regrinding. If the other bank is still factory original it doesn't make a lot of sense to me to have one bank perfectly new while the other is 200k+ miles on it.

[Mike Floutier]

Hi Curious,

You're right when you say the "normal" wear is for valves to open less; this is bourne out by the replacement shim thicknesses available which err on the thick side (ie.2 - 2.8mm compared with the 2.3mm originals).

However my situation, with running on propane, leads to more wear of the valve seat than the push points - see http://holdenpaedia.oldholden.com/Valve_Seat_Recession.

Changing the heads, in-situ, in a 430 is an enormous job, and given that it would probably be best to do both (as you say) it would be easier to change the engine/transmission completely - however, this would entail the additional removal and refitting of the propane injectors....

Anyway, I've pretty much decided that any immediate repair work would depend on confirmation of valve seat recession (ie. no valve clearance at all - valve cannot close).

Obviously to do this I need to remove the valve cover on the left bank (DS in the US). I've been able to get to all the 9 cover bolts BUT the dip-stick bolts have eluded me.

My only questions at this stage are: 1. Do you really need to remove the dip-stick bolts to get the cover off? and, if yes, 2. How do you get these bolts off; from above or below? - Any tips would be gratefully received as it's this dip-stick bit that is the real hurdle at present.

Many thanks!

[landar]

I just checked the dipstick bolt on my '02 LS430 and it appears to be a 10mm by feel. If you use a small mirror, you can see the bolt just to one side of the oil dipstick bracket which is 'L' shaped. The bolt is forward of the bracket, that is, toward the firewall (cabin area). This would all have to be done by 'feel' from the topside. It does look like it would help to pull the under-engine cover and look from the bottom.

However, this is all a moot point, I believe. The dipstick attaches onto the head and not the cover so you really do not need to remove it, save for one thing...the oil dipstick tube is in-line with one of the cover bolts and blocking direct access. But I think you could flex (or slightly bend) the dipstick tube and access the cover bolt. Especially true with the aid of a swivel socket (lets you take a different angle at a bolt).

[Mike Floutier]

Thanks Landar, that's encouraging, I've been able to get a swivel headed socket onto the cover bolt you mention so that's not a problem, I'm just waiting for a ratchet tool to arrive as otherwise the bolts would take forever to remove.

Will let you know how it goes.

Thanks again!

[landar]

One thing that I am really curious about Mike... have you ever calculated how much money you have 'saved' by running gas over petrol?

[Mike Floutier]

Hi Landar, Oh yes, it's one of the reasons I'm persevering with these exhaust valves. Based on $1.60 to the £1, it cost me around $4,000 to convert the 430 to propane and my annual fuel saving is around $5,000.

I converted it when I bought it for $11,000 in October 2008. My first year or so was fairly slow business-wise as I'd only just started the car service, so let's assume the savings paid for the conversion by March 2010. Since then I've probably just about paid for the car through the subsequent savings on fuel.

What I'd really like to do, now it's all clear profit, is to save enough to pay for the replacement car, the only question is, should it be a 430 or a 460, but that's another story.

If you really want to know how beneficial propane is, it's worth considering that, in practice, I actually paid cash for the current 430 from the savings I made running my previous car, a Ford Scorpio; that is having already covered it's purchase price and propane conversion cost. So you see why I'm keen to sort this out.

Anyway, thanks to your encouragement, I invested in a universal joint type socket connector which seems ideal for working on these well concealed bolts. Even with this I finally gave up accessing the dip-stick guide bolt from above and took your suggestion to go below. Having removed the under engine cover and the left side under engine cover I was able to get my trusty new U-J socket onto said bolt (using multiple extensions as it was a long way up).

The bolt felt like just another 10mm bolt but it turned out to be a 12mm, worth noting. Also, although the manual mentions bolts for each of the dip-stick guides, the one bolt beems to fix a single bracket that is attached to both; which is good news.

Ok, I've just got to wait for a quiet sunny day and I can check these valve clearances, will let you know how it goes.

Thanks again! I'd never tackle this stuff without you guys.

[curiousB]

Isn't it easier to determine an exhaust valve leak by your leakdown test anyway? A visible indication isn't as telling.

This chart shows where both sets of valves should be fully closed a leak test at the sparkplug would tell if they are leaking. If the exhaust is the culprit it will leak to the exhaust pipe and you should hear it there, Intake would be at intake manifold, rings would be via the dip stick.

I'm not sure what you gain by checking valve clearance other than what you know today. I believe you've confirmed the valve leaks. It was your intuition from the start. You are running on 7.5 cylinders.

I'm a little surprised you don't have an emissions code popping in the car. If the valve is that gone I would suspect unspent fuel is leaking by the valve and burning in the exhaust manifold/ catalytic converter. Might be interesting to look at the LT and ST fuel trims in the ECU to see if it correlates to this at all.

[landar]

I "think" Mike's strategy is to pull the valve cover and confirm if the issue is valve seat recession or a 'burnt'(damaged) valve. If recession, there will be little or no clearance when the valve is fully closed. And he will re-shim the offending valve(s) using a smaller (thinner) shim to allow the exhaust valve to again fully touch the seat. Granted, it is somewhat of a band-aid solution but may buy him a few more miles.

If a damaged valve, the head needs to come off. Or sell it. Make it someone else's headache. ;)

[Mike Floutier]

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.

[Laurance]

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/upload/service/diagnostic-trouble-code-table.pdf

Symptoms:

-Engine Light ON (or Service Engine Soon Warning Light)

- Lack/loss of power

- Hard start

- Engine hesitation

[curiousB]

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.

[Mike Floutier]

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.

[landar]

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.

[Mike Floutier]

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?

[Mike Floutier]

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?

[landar]

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.