Rover V8 Spark Plug Oddity

[Hybrid_From_Hell]

Just had a very useful and helpful e-mail from Mr PlugGuru

Interesting reading from the links he has sent me, he has also asked I ring

him Monday, but the bottom line is :

My engine - Valve overlap, sooting of / wetting of plugs on starting

Heat latent and rnage on plug at edges of design

plug working 2x as hard as std (2x spark as now wasted)

Plug firing at 40,000 v vs 9000 std Range Rover coil

Dunking in lakes when Ferkin hot may also "Not Help"

re fouling and plug info :

http://www.aa1car.com/library/sprkplg2.htm

Re EDIS / DIS ignitions and Plugs issues :

http://www.aa1car.com/library/sparkplugs_for_dis.htm

More to come inc suggested plugs to try

Nige

[Boothy]

Without getting into a war can I chip a couple of observations in,

1, What if the secondary coil is centre tapped ??....

2, Following my recent truama and endless problems resolving a very bad missfire a lot of the previous posts makes a lot of possibilties possible,,which doesn't help,,

3, Tommorrow (Sunday) I aim to spend the day datalogging at a play day and will remove a lead, a pair of leads, insulate a lead to a near infinite level (as best as I can) without shocking myself, unlike our forefathers on this forum, who kept me smiling for hours after "burning his whiskers" so to speak on a coil pack,,,,can you remember Nige,,,,

4, Boothys brother, AKA brother Boothy is a 30 years experienced Ford master vehicle technician and when questioned about this subject by myself laughed and replied roughly, " that with wasted spark technology a few oddities occur, one being that a single cylinder missfire due to plug going duff, does and can happen, but if a lead goes H.R. than the pair of cylinders on same coil pack will usually drop out because the return loop has been lost", their usual Ford fix and go answer is to change leads and plugs and it cures it.

The fast fix has beed proven time and time again when customers are paying ridiculous rates for worshop times, we as fiddlers can play all day at our leisure but if you were paying £60 an hour or so you would like the fast fix I'm sure.

Good luck

[ThreeSheds]

Re EDIS / DIS ignitions and Plugs issues :

http://www.aa1car.com/library/sparkplugs_for_dis.htm

In the above link (referring to wasted spark ignition): "Plugs may degrade in as little as 20,000 miles"? That's 4 years for me

Another little thought - if even some of this problem is caused by the reverse polarity arc - then why not swap plugs every few thousand miles? If you did 1-6, 4-7, 5-8 and 2-3, that would even up the wear, wouldn't it ?

[TSD]

1, What if the secondary coil is centre tapped ??....

It depends how the coil is wound. The coils could be wound in the same direction or in opposite direction on the former.

I imagine they are wound in the same direction, and the system is operating almost the same as an isolated transformer. The current through the ground terminal is due only to the imbalance between the 'used' and 'wasted' spark voltages. If you insulate one side, the other plug still fires, using the centre tap as ground return. It is a little less efficient than an isolated coil, because you cannot use the fact that the 'wasted' spark is established at a lower voltage to gain voltage on the 'used' spark side.

(If they were wound in opposite directions, then it would effectively be two small coils firing together in the same polarity. Also radiated and conducted electrical noise woul be increased, which is bad for type approval testing and for all the complex electronics they keep filling cars with.)

4, Boothys brother, AKA brother Boothy is a 30 years experienced Ford master vehicle technician and when questioned about this subject by myself laughed and replied roughly, " that with wasted spark technology a few oddities occur, one being that a single cylinder missfire due to plug going duff, does and can happen, but if a lead goes H.R. than the pair of cylinders on same coil pack will usually drop out because the return loop has been lost", their usual Ford fix and go answer is to change leads and plugs and it cures it.

That's because a misfiring plug is still sparking, just not near any combustible mixture, so the other plug can still fire. An o/c lead breaks the circuit , and no plug can fire, unless the insulation breaks down. The insulation on gen. parts EDIS leads is very good IME.

Dave

[jonket]

Here in Iceland they say that we should only use Champion or Bosch sparkplugs.

Seems like the NGK spark plugs get wet in the Rover V8 engine for an unknown reason.

[missingsid]

Oi BBC

You been overdosing on those telephatic tablets again bl**dy druggie ?

Yep, having had a VERY long Conv with a Plug Guru (no, not that sort

he has said the following

1. Heat range - with a block now 4.5 heat soak is huge, suggested an oil cooler - which was on the cards

2. Plugs are prob working outside the "Approved" Ranges - esp when Red hot plug cermaic shoved in Rocker cover deep ice cold water

3. Gap set at .6 is again at the max for this plug, but would be OK for road use with 40,000 output, but not 1 and 2 added

4. Changing plug temp rnage may cause starting issues but has suggested a alternative, written down here somewhere but way off what I have now

5. Aviod C Plugs (ie BPC etc) as reduces cooling dump via surface area

6. No 6 - Monty Python gag, showing me age

7. Don't bother cleaning, the plug prob is a combo of Cam, fuel fouling on start, Heat and warm up

8. avioding cold starts and short journeys and deep ponds will help

9. Cam causing washing on start up due to Valve overlap, suggested raised start up numbers to reduce the lower RPMs

10. Fit a diesel* - so I shot him, .............even if he was helpful

Nige

* may have made this up

Hi Nige,

This is not a criticism as I love your LR and the work you have put into it, but when you you describe your engine spec surely it is the least likely for anything except a race car or comp safari motor, why put it in a slow off road motor? Wouldn't you would be better with an LS engine or something that has loads of torque and is really simply tuned?

NO NOT a DIESEL.

Marc.

[Hybrid_From_Hell]

Marc,

No offence taken

Yep, it was an ex comp race motor, fitted with Flapper technology, jag injectors,

adjustable Lucas ECU, jag AFM and was a real PITA to get to run on the road,

where as as a comp motor it normally sat at 5000+ rpm

Megasquirt has literally transformed it, there are a number on

the forum who have been out in it with me last was Will W for the day,

he can confirm that if you didn't know any better

you'd just think it was a Big V8, none of the quirks

that were there pre MS remain

The other key reason to purcahse was it was very very cheap,

I doubt I would get LS1 heads for the money paid,

ok, I had to rebuild it, and the rings were outrageuos money,

but it is still a cheap £££ vs BHP

I think the valve overlap adds to the plug problem,

but EDIS + Water diving Rover V8s Plus ford coil packs output

near 5x the output v, plus wasted spark x2 sparks may find

that a standard V8 + Megasquirt may get through plugs quicker

than expected, a conversation I have recently had with Mr Boothy

sort of maybe confirms this

If it was as it was when I first fitted it then I think it would have since been removed,

it was overly fussy, and driving in heavy traffic was a nightmare, as

it would flood due to the crude overfuelling mods (strate of the art when done)

not suiting road use vs comp racing, MS has changed all that,

I now actually have a docile motor, drivable, bags of grunt thats actaully

ok fuel wise too, until you boot it, then it is erm "Quite Quick"

Nige

[TSD]

Nige,

Don't describe the old modded ECU as 'state of the art'... I've got coffee all over the monitor now

[Hybrid_From_Hell]

:rofl:

Fair point

Not often you see the words "Lucas" and "State of the Art" in the same sentence

More like prob when it was 1st built with all its Lucar*e trickery the owner let

out a little squeal each time it was used, when I owned it some years later

I too let out a little squeal every time I used it, but not for the same reason

Nige

[Hybrid_From_Hell]

Heads up

Being a pedantic old bugger, I wnated to be sure I had "Got" the misfire,

so I removed Plug No 1 on the V8 and placed each of the old plugs in turn,

3 plugs later I found the misfiring plug, did the others and they seemed ok

Sat and studied the misfiring plug.

On seriously close examination I think I may have discovered the issue

as the phrase goes "It just came apart in me hands guv - 'onest"

The plug electrode shows burning at the base, more interestingly the design

of the NGK BP etc has changed, the top tip used to be removable, now it isn't

and the design changed, unsure how / why this seems to have happened here, but

I "think" it may be the issue ?

Nige

[steve_d]

Heads up

Being a pedantic old bugger, I wnated to be sure I had "Got" the misfire,

so I removed Plug No 1 on the V8 and placed each of the old plugs in turn,

3 plugs later I found the misfiring plug, did the others and they seemed ok

Sat and studied the misfiring plug.

On seriously close examination I think I may have discovered the issue

as the phrase goes "It just came apart in me hands guv - 'onest"

The plug electrode shows burning at the base, more interestingly the design

of the NGK BP etc has changed, the top tip used to be removable, now it isn't

and the design changed, unsure how / why this seems to have happened here, but

I "think" it may be the issue ?

Nige

Not had one apart but logic says the burnt bit is probably where the resister should have been. This ties in nicely with the earlier comment that the resistor won't take the extra voltage produced by EDIS.

Steve

[TSD]

I think you need to break (sorry, subject to the same careful handling) some of the other plugs to get a useful comparison.

With very short reach plugs you sometimes see the effects of spark erosion of the insulator, as very fine slots cut through the ceramic nose. Never seen any oxidation though, but thats always exposed to the combustion cycle.

Since the resistor is typically made of a composite of carbon, ceramic, copper oxide and aluminium oxide, I wonder what it turns into when you burn it?

[Aragorn]

As has been said before though, spark voltage will peak at the point where an arc is struck. If the standard coil only manages 9kv and can strike an arc, then even with a coil capable of 40kv you should still only need <9kv to strike an arc, and therefore the plugs shouldnt be seeing THAT much more voltage than normal?

[TSD]

In the normal case, the plugs don't see a higher voltage, though they do see a higher energy per spark. This is either a higher spark current (with associated higher terminal voltage, but this is still lower than the ignition voltage) or as a longer duration of spark.

I there's not enough energy available to destroy the resistor normally. A quick back of fag packet sum suggests a dissipation of less than 2.5W in the resistor even if it were firing 50% of the time. I doubt that's enough to damage something thats being heated to 1000C at one end, pressure cycled to many atmospheres, stresed to 10kV, and which remains pressure tight the whole time.

On the other hand, once a misfire is prompted, due to poor mixture, poor timing, failing plug or whatever, then the voltage seen at the resistor could be very much higher (easily 30kV or more with EDIS), and then I would think that arcing might occur around the resistor.

I'm purely speculating here, as I've only ever owned one RV8 (and that was carp), but given the combustion chamber design is fairly inefficient (evidenced by high timing advance requirement under acceleration), and the big overlap cam will be throwing lots of unburnt fuel out of the exhaust port at low rpm, is it possible that Nige's tuning is actually too lean and/or over advanced due to lambda being confused. That could give rise to high CHT and pressures, neither of which is nice to spark plugs.

...dunno, just thinking out loud.

[missingsid]

Heads up

Being a pedantic old bugger, I wnated to be sure I had "Got" the misfire,

so I removed Plug No 1 on the V8 and placed each of the old plugs in turn,

3 plugs later I found the misfiring plug, did the others and they seemed ok

Sat and studied the misfiring plug.

On seriously close examination I think I may have discovered the issue

as the phrase goes "It just came apart in me hands guv - 'onest"

The plug electrode shows burning at the base, more interestingly the design

of the NGK BP etc has changed, the top tip used to be removable, now it isn't

and the design changed, unsure how / why this seems to have happened here, but

I "think" it may be the issue ?

Nige

Hi Nige,

I hope that you have found your problem.

For me I hope that they have stopped making plugs with screw on caps. I have lost count of the number of times I have taken plugs out and re-tightened the caps

Marc.

[evo828]

Nige, have you already found some better plugs for MS + EDIS8 combos? I am having BPR6ES for last 6 months (do they look ok ? I think yes - see the picture) - but I seem to get occasional/rare MAP spikes which might be related to misfire - caused by fouled plugs. I ran the car usually short trips; lot of slow driving and lot of starts. So would need some more robust plugs may be.

[Hybrid_From_Hell]

I have done much research on this and spoken to helpfull tech guys at NGK

The bottom line was that the platinum plugs werer basically made for long service

intervals etc, and its a side effect that they produce a (slighly) improved spark, but, and

its a key one, wet plugs / richness / fouling / misfires any or all of these

individually or quicker if more than 1 KILL ANY plugs

On that basis

Spend a great deal of time on the

Ceranking / More cranking

ASE (after start enrichment)

and esp the warm up table - as it spennds quite some time here

and this I belive casued much of my oplug probs, run WUE as LEAN as you can without it

affecting the warming up smoothness, too lean will fel and behave as too rich, get the PWM up

to say 1600 RPM and set the linear degredation from say 68-73 so it keeps it up and huigh till warm

this helps plugs

Gap to 0.6mm

Carry spares, the ford coils do shove out a big spark, and the plugs can die soon or last ages,

Also go for BP not BC its regarded that the C's can be fussier / more problamatic than the chunkier P

odd, and its just advice I took from a Tech NGK expert. You could feurk about with plug temps, but that will onl;y

mask a WUE ASE issue, get in there and lean right off and tweak dialy, took me around 35x tweaks to get it

sorted, I did then stop mid warm up and remove plugs and they were good, prior they were not !

This / plugs / ruichness etc may be your spikes chnage the plugs fior new ones forget their age,

I killed some in less than 2 weeks when I riched it to see what the affects would be age of plugs means little.

HTH

Nige

[evo828]

Thanks Nige - so will get another set of BPR6ES from Santa

I was also looking at the WUE and just had it decreased yesterday - will see what is brings.

[Diff]

Nige, it has been mentioned before, but why don't you try the BP6ES. These do not have the resistors in them.

I know that you are 'supposed' to use resistor plugs if you have an ECU, but you have decent modern leads which will be suppressed, and the megasquirt is robust, so I would be suprised if there would be any electromagnetic interference from the plugs. Without the resistors, they will not fail.

I use these plugs and although I don't have an ECU, there is no radio interference, they are very robust, and without the resistor, require less voltage than resistor types.

Regards,

Diff

[SteveRK]

Good suggestion Diff as I have pondered this - most modern leads are 'suppressed' so resistive plugs should be redundant?

Begs the question as to Mega squirt being better than a stock RR ECU in terms of engine management??

(runs for cover)

[Aragorn]

I doubt megasquirt is as robust as an OE ECU when it comes to things like interference from the spark system.

[Hybrid_From_Hell]

Nige, it has been mentioned before, but why don't you try the BP6ES. These do not have the resistors in them.

I know that you are 'supposed' to use resistor plugs if you have an ECU, but you have decent modern leads which will be suppressed, and the megasquirt is robust, so I would be suprised if there would be any electromagnetic interference from the plugs. Without the resistors, they will not fail.

I use these plugs and although I don't have an ECU, there is no radio interference, they are very robust, and without the resistor, require less voltage than resistor types.

Regards,

Diff

This was one of many subjects raised with the plugguru at NGK. His view was that this is more in the depths of the past, and have little efect

on modern systems, although he pointed outthat some people would argue the sky isn't always blue and has shades, but in reality the sky is the sky

and minor ifferences don't fundementally change that, his view was it would make either no difference or only a technical difference, which is a

duifference that can't be felt / seen / etc

His view was if the engine runs OK with BPRs then thats not the issue, more flooding / richness / misfires killing plugs, and BP Non Rs would make F all

difference, the think I liked about the 2 guys I dealt with was other than knowing their stuff, and also chatting to me with enthuiasm, they neither recomended

anything whizzy or expensive, destroyed much "Plug Fables" I had in my mind, and I belive proved there advice as spot on

Nige

[Bull Bar Cowboy]

I doubt megasquirt is as robust as an OE ECU when it comes to things like interference from the spark system.

The sparks are derived from EDIS8 ........ so very robust indeed ......... but Ford do recommend resistive plugs.......

MS seems to suffer from earth loop interfenece above all else, but that is due mainly to bad installation practise.

MS in its own right is quite robust (you might destroy the coil driver, but that is a simple replacement) …………also I have known many an ECU that has been taken out by minor coil failure ……….. most Fiats, late Ford Ka, Vauxhall, etc …….. but no Jap stuff in the list………………….

[Aragorn]

Yer a mate of mine killed a coil driver in a MBE967E by connecting it up with the wiring screwed up.

I just would have expected a Bosch Motronic or similar to have a lot more in the way of signal filtering and suchlike, although i guess the fact they're built by machine and hooked up with carefully assembled wiring looms which lots of quality control etc will make the biggest difference.

I've never heard of an OE ECU being killed by coil failure, but i'm only really familiar with VAG and early 90's vauxhall management systems.

[nicks90]

I've never heard of an OE ECU being killed by coil failure, but i'm only really familiar with VAG and early 90's vauxhall management systems.

our Fiat Marea ECU died in that way. By the time i had factored in a new (used) ecu, master key reprogrammed and a second key - it made the vehicle uneconomic to repair and i scrapped it. Flipping shame cos it was a good old bus.