Changing Spark Plugs

Stupot · March 16, 2011

Hi All

My spark plus were last changed about 40,000 miles ago, so...

Lexus Birmingham are selling the genuine iridium spark plugs on eBay. They are selling sets of six, but I contacted them direct and got a set of 8 for £55 which I thought was pretty good.

I've changed spark plugs before on older uncomplicated cars and usually lightly grease the threads of the plug with copper grease and watch out not to over tighten on the aluminium!!

Other than the above, is there anything unusual to look out for when I change the iridium plugs on my Mk4 LS400?

Thanks

Stu

Malc · March 16, 2011

Hi, thought my one's are good for 60,000 miles and at £55 for 8 seems excessively inexpensive !

I'd have expected to pay about double that.

I would think that torque settings would apply........ but I don't know.

Good luck

Malc

Stupot · March 16, 2011

Cheap huh? They arrived today, they are Denso SK20R11 genuine boxed toyota plugs. I thought it was a good deal, they are still available on eBay. The oil filters are on £11 inc postage! I got a couple of those as well. Perhaps Lexus Birmingham are having a clear out?

I'm changing the plugs as some people seem to say 30,000, some 60,000 and some 100,000 between changes, but seeing as it's my new baby, thought I'd give my Lex a treat!

Stu

The-Acre · March 16, 2011

Hi All

My spark plus were last changed about 40,000 miles ago, so...

Lexus Birmingham are selling the genuine iridium spark plugs on ebay. They are selling sets of six, but I contacted them direct and got a set of 8 for £55 which I thought was pretty good.

I've changed spark plugs before on older uncomplicated cars and usually lightly grease the threads of the plug with copper grease and watch out not to over tighten on the aluminium!!

Other than the above, is there anything unusual to look out for when I change the iridium plugs on my Mk4 LS400?

Thanks

Stu

If I was changing my plugs I would certainly be changing HT leads at the same time if they haven't been done in ages.

ManicMark · March 16, 2011

Hi All

My spark plus were last changed about 40,000 miles ago, so...

Lexus Birmingham are selling the genuine iridium spark plugs on ebay. They are selling sets of six, but I contacted them direct and got a set of 8 for £55 which I thought was pretty good.

I've changed spark plugs before on older uncomplicated cars and usually lightly grease the threads of the plug with copper grease and watch out not to over tighten on the aluminium!!

Other than the above, is there anything unusual to look out for when I change the iridium plugs on my Mk4 LS400?

Thanks

Stu

If I was changing my plugs I would certainly be changing HT leads at the same time if they haven't been done in ages.

Hi no ht leads on a mark 4 as they have seperate coil packs.

steve2006 · March 16, 2011

I can't find the Birmingham listings on eBay,could someone link please :D

Stupot · March 16, 2011

Hi Steve

http://shop.ebay.co.uk/?_from=R40&_trksid=p3984.m570.l1313&_nkw=Genuine+Lexus+Spark+Plugs+SK20R11+Iridium&_sacat=See-All-Categories

and

http://cgi.ebay.co.uk/Genuine-Lexus-Oil-Filter-V8-/170604259439?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27b8ce686f#ht_500wt_922

If the listing has ended, contact them direct as you can pay by paypal and they will send them outside of eBay :winky:

John N · March 18, 2011

Changed my plugs on the LS430 a year ago at 60,000 miles, it was a very straight forward job, just had to remove the Battery to get to the rear nearside plug and some bits to get to the offside plugs.

John N

runsgrateasanut · June 30, 2015

Changed my plugs on the LS430 a year ago at 60,000 miles, it was a very straight forward job, just had to remove the battery to get to the rear nearside plug and some bits to get to the offside plugs.

John N

Anyone got a tip how to remove this ****** thing without remvoign the Battery? There's always one thing that own't budge or won't unclip. Looks like I have to open the catch slightly to remove looking at the other one? Hope not to have to remove Battery as my back can't take it.

Thanks

cruisermark · June 30, 2015

Changed my plugs on the LS430 a year ago at 60,000 miles, it was a very straight forward job, just had to remove the battery to get to the rear nearside plug and some bits to get to the offside plugs.

John N

Anyone got a tip how to remove this ****** thing without remvoign the Battery? There's always one thing that own't budge or won't unclip. Looks like I have to open the catch slightly to remove looking at the other one? Hope not to have to remove Battery as my back can't take it.

Thanks

what are we talking about here?

Rupert Dubreaux · June 30, 2015

You shouldn't have to remove the Battery on a Mk2 to change the plugs Stuart .

runsgrateasanut · June 30, 2015

Its the difficult Bank feed line down the RHS of the bay between the engine and Battery.

one is on top and one down the side.

Solved the problem myself with what I used to use to pull out the Instrument panel on Mercs rather than buy the special pullers. Half a pair of scissors with 3/8ths inch end, bent at 90% angle.. Able to get my hand down by the water pipe and pull toward me the release lever on the plug whilst pulling at it with the other hand. The difficulty is mentioned in this thread, but perhaps later models don't have this problem?

Rupert Dubreaux · June 30, 2015

Are we talking about the wire from the coil that sits down by the Battery , are you also changing the spark plug wires ?

plexus914 · June 30, 2015

Hi....my user manual (model 1997) says 90000 miles for Denso SK20R11 and NGK IFR6A11.

Remove the plugs when the engine is cold. Torque is 17,5Nm!

PS:

60000miles ago spark plugs were changed to NGK IFR6T 11 long life (change intervall is 120000 miles) - checked them few month ago......they still looked like new...=;o)....

runsgrateasanut · June 30, 2015

Indeed we are Rupert.

Always something to slow down progress.(not that I'm very fast in dealing with this sort of thing. Lots of dirt to clean off takes an hour +

First I found my extension to my breaker bar was too short, borrowed one from my mechanic which turns out to be too long for number 1 Spark plug next to expansion tank. doh!

With the exception of number one cylinder the plugs are all Denzo and looking good. Can't imagine they are originals. Cables, not sure?

Numbers 6 and 8 plugs do have a brown ring like rust at base of ceramic. Did I read somewhere this is an arcing problem?

The tip of the coil cable is corroded 1/4 inch on LHS of engine.

Oh and number 7 tube has rust on it - my mechainc said that soemtimes this is caused by water from the Windscreen jet not exiting properly but dribbling down onto the Cover and into the spark plug hole - think he could be right as it is over that tube.

going to check the cables now for resistance - finish job tomorrow, hopefully!

runsgrateasanut · June 30, 2015

Hi....my user manual (model 1997) says 90000 miles for Denso SK20R11 and NGK IFR6A11.

Remove the plugs when the engine is cold. Torque is 17,5Nm!

PS:

60000miles ago spark plugs were changed to NGK IFR6T 11 long life (change intervall is 120000 miles) - checked them few month ago......they still looked like new...=;o)....

The plugs I removed are PK20R11 which in the excellent vutube video of how to change spark plugs the orator mentions that he thought his were originals with this number. Still could have been replaced as they do look very healthy (with the two exceptions). The burn is faultless and so looks like I'll need check elsewhere to discover why my high CO2 emissions.

For interest these are the results of the resistance check and I'd welcome any observations as I'm not au fais with the technical even though my old Dad worked in Radar development , Marconi, Elekluft Bonn and SHAPE after the War. 'Fraid I got Mothers brains bless her!

to LHS Coil 3.88

to RHS Coil 5.00

No 8 10.58

no 6 16.62

No 4 15.16

No 2 4.93

No 7 10.49

no 5 16.15

No 3 14.92

No 1 4.88

Rupert Dubreaux · June 30, 2015

Stuart ,I assume your wire readings are in k Ohm's ,if so they are all within the 25k maximum resistance as specified in the manual . Assuming your air filter is not clogged or exhaust blowing badly , you could try replacing the ECT sensor if you haven't already ,might help with emissions if it is sending the wrong info to the ECU .

Replacing the ECU capacitors made a major difference to my beater Mk2 .

Hope you soon get it all sorted .

plexus914 · July 1, 2015

runsgreatasanut........high CO2?......

Cheapest thing to try first is to change your air filter, get some sort of system cleaner and take the car for a good long run (with engine revs high). This will clear the system of any carbon deposits and will often bring an older car back within the required limits.

PS: I'm wondering if that is some legit stuff - Wheelers Dealers showed Terraclean Fuel System Decarboniser on a Jaguar XK8:

http://www.youtube.com/watch?v=wiViPKIoG68

runsgrateasanut · July 1, 2015

Thanks Rupert I'll have to check where the ECT sensor is placed. I have a set of Capacitors but not too keen to do this job. Re-looking at the vutube on spark plugs, I see that my readings were virtually spot on to original leads when new. These leads have a part binding round them which my new ones don't. Originals? wanted to put in plugs for possible LPG so not a waste of time and money.

Thats an interesting link Plexus may be worth a try. Reminded me of this link to Eric the Car Guy (alias George Clooney) !

I checked my butterfly valve and its pretty clogged so will take off Throttle body and clean.

New Air filter post MOT and using injector cleaner.

Rupert Dubreaux · July 1, 2015

Stuart if you haven't located the ECT sensor yet ,it is behind the top coil ,and underneath the plastic bridge piece that carries your nice new plug wires between the two banks , they usually have a green plug on them . This part is quite important as a reliable engine temperature reference is needed by the ECU for fuel trims etc .

Although after market ones are available and maybe ok it is safest to source an OEM part from Toyota ,you will need a deep socket to remove and replace ,cannot remember the size offhand .

Those curly black binding pieces on your original leads are positioned at stress points on the leads to help guide them and prevent fractures ,they are easily removed and can be reused on your new wires to serve the same function .

Always a good idea to clean the throttle body if it is looking coked up .

If you dont feel competent with a soldering iron and don't have access to a decent fairly high wattage soldering station with a small tipped iron then don't attempt the ECU caps replacement . You might be able to find a computer repair wizz kid or old style TV or audio repair shop that still employs some service people ,to do the job for a fee .

Unfortunately with today's throw away society these people are becoming as rare as old LS's .

Rupert Dubreaux · July 1, 2015

Stuart you could try the ripple test as detailed in this link from the US site

http://www.clublexus.com/forums/ls400/715345-how-to-check-your-ecu-without-removing-it-from-car-by-yamae.html

to check if your ECU caps are ok ,it is fairly easy and will show if yours are ok or need replacing .

The capacitor can be obtained from somewhere like Maplins if you don't have any lying around .

runsgrateasanut · July 1, 2015

Many thanks for the interesting info Rupert and others.

I transferred the curly bindings.

The Lead set were slightly longer than originals (Prospark - better than too short!) which leaves you with a dilemma where to stuff the excess and hope the Covers will go on without a problem and not rub. Took a while to fit the Filler side and discovered in addition to several missing screws, that the upper rubber strip was missing from the panel. Transferred the lower from throttle side as ingress of oil and water possibly on that side due to this. . Hate it when parts have gone astray. Screws on order, rubber? that will have to wait.

Postponed carb cleaning until tomorrow. Purchased gasket looks on small side (via Rock Auto who I have used for some years.) May be OK - hope so. Unfortunately, the Cleaned and spray painted throttle spare I have, turns out to be for a Mk 111 and is not the same. Vacuum pipe goes into the side, near the bolts. Not on mine. Is messing with the cruise control wire and other parts likely to create problems? I prefer to take TB off to clean.

Ps I have a small solder station and the Caps courtesy of a senior member. Will check the ECT and also perhaps the MAF sensor after the TB clean. Fingers crossed that the spagetti of cables was put on correctly. I will know tomorrow.

Rupert Dubreaux · July 3, 2015

Glad to here you have it back together and running ok .

Did the gasket fit ok ,agree Rock Auto are a good source for spares ,even with shipping they can be cheaper than over here.

For the soldering you need 50/60watt from your station ,use a small tipped iron if you can working space is limited . With the old caps out use a large stainless pin ,heat it up as you gently push it through the leg holes in the circuit board to clear them of solder . Those like a small hat pin with plastic bit on the end are best for this , solder sucker and braid were not very effective for removing Japanese solder .

runsgrateasanut · July 3, 2015

Many thanks again for useful tips. I'll be copying and pasting them for future reference.

I hadn't quite finished the job when I wrote my last post. Started the car and was hearing a strange whispering noise and checked under the bonnet and clearly the cup of water would have been spilling over.

Stripped back and found no 1 cylinder cable was in two parts. (At least I hadn't wrongly wired them) Being the shortest cable really puzzling.The oil cap side was difficult getting the cover back on. Why they had to place one of the coils down the side of the engine heaven knows, but it made trying to ensure that the coil cable did not get snagged extremely difficult. Clearly No 1. cable must have got snagged and I snapped it. It couldn't have touched the Cam Cog I feel sure.

Started the car and only a slight ripple on the water and I think less exhaust visible even at cold.Great news on emissions hopefully. It will get a run shortly and see how it performs.

BTW the ECT sensor - is this also known as the IACV idle control valve? I've seen it mentioned as being in the spot behind the coil pack?

Rupert Dubreaux · July 3, 2015

No they are not the same item the IACV is bolted on the front of the intake plenum ,to the right of the coil looking from the front just behind the plug wire bridge it has some hoses attached and what looks like a large black plastic cap .

They do need cleaning sometimes , and can cause idling issues if the valve gets coked up .

It can be a bit of PITA getting all the new wires to fit nicely like the originals ,the Denso set I fitted recently to my Mk3 came with a spare coil lead and medium length plug lead ,probably anticipating the possible snagging scenario .