NGK spark plugs
NGK spark plugs
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Discussion

Chim326

Original Poster:

279 posts

242 months

Sunday 25th January 2009
quotequote all
Mk1 Tuscan s 2001
Car has recently had 12000 mile service, I assume the plugs are replaced then. On inspection the plugs are gapped at 0.7mm and are a nice bronze colour at the electrode, the china is uncracked and tight also looks like new. Problem is the engine every 200 miles starts to misfire briefly under load not high revs. check the diag software and there are no faults recorded, HT leads seem to be in good condition (Magnecor). Change the plugs and all is well for another 200 miles approx when misfire reappears, change the plugs again and all is well.
Just wondered if spd 6 engine is renouned for eating plugs NGK DCPR8E or maybe just a dodgy batch.
Does anybody know if there is a more robust plug
Thanks in advance
Steve

Whitey

2,508 posts

313 months

Sunday 25th January 2009
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from the fault you describe I would suggest it is actually the HT leads. The heat kills them, and of course they look fine but are not. Cheap to replace. I replace mine yearly no matter what.

Macey

1,326 posts

222 months

Sunday 25th January 2009
quotequote all
Had the same symptoms after I had mine serviced. I had the HT leads replaced during the service but it started to misfire once warm. Got the dealer to check and it turned out that a couple were faulty, they changed them and it's been great since.

shep1001

4,620 posts

218 months

Monday 26th January 2009
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Same problem on my Tam, it also used to pop & bang as you accelerated as well as on the overun. Castle fixed it with new HT leads £40 plus a whopping £90 to fit which included diagnosing the fault on Friday. I think the theory goes..... Greater load at lower revs which is why you get the misfire/hesitation as the strength of the spark is effected as the lead breaks down?. The std TVR leads fitted from new were a bit bobbins.

There is also a article I read somewhere about HT leads which in a nut shell said price isn't everything; good leads have to strike a balance between heat resistance and durability and the best material for heat resistance is silicone which is not so good when it comes to durability


Edited by shep1001 on Monday 26th January 22:19

Chim326

Original Poster:

279 posts

242 months

Tuesday 27th January 2009
quotequote all
Just waiting for a set of 8.5mm magnecors to be delivered
will let you know the outcome
Thanks for your help
Regards
Steve

Chim326

Original Poster:

279 posts

242 months

Thursday 29th January 2009
quotequote all
Engine now runs as god intended it too!!!

Macey

1,326 posts

222 months

Thursday 29th January 2009
quotequote all
That should save you fortune on spark plugs.......laugh

Glad you got it sorted

yzf1070

814 posts

260 months

Friday 30th January 2009
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An interesting read this topic.
After I had fitted an Emerald ECU to my Tuscan and got it started it was running rough (new NGK plugs fitted). I eventually got things running better whilst messing with fuel settings etc... shut the engine off to allow things to cool. Went to restart and it was a bh to get it to catch and keep running. Stopped the engine and selected the previous map that I had managed to get the car started with. Turned the engine and heard a loud back fire. Then the car would not start at all, no matter what not even a cough. I checked for a spark on number one.... nothing, number 2 nothing. After ruling out the coil and leads (resistance check), I was scared I had done something with the triggers in the ECU. Eventually put the old plugs in.... started fine. 3 of the 6 new plugs were goosed.... never come across this before. Now having read the posts above I am guessing NGK's are somewhat intolerable to out of time cylinder explosions....?!?

Can anyone elaborate?

Chim326

Original Poster:

279 posts

242 months

Friday 30th January 2009
quotequote all
yzf1070 said:
An interesting read this topic.
After I had fitted an Emerald ECU to my Tuscan and got it started it was running rough (new NGK plugs fitted). I eventually got things running better whilst messing with fuel settings etc... shut the engine off to allow things to cool. Went to restart and it was a bh to get it to catch and keep running. Stopped the engine and selected the previous map that I had managed to get the car started with. Turned the engine and heard a loud back fire. Then the car would not start at all, no matter what not even a cough. I checked for a spark on number one.... nothing, number 2 nothing. After ruling out the coil and leads (resistance check), I was scared I had done something with the triggers in the ECU. Eventually put the old plugs in.... started fine. 3 of the 6 new plugs were goosed.... never come across this before. Now having read the posts above I am guessing NGK's are somewhat intolerable to out of time cylinder explosions....?!?

Can anyone elaborate?
I went for 8.5mm leads, thing is I don't like the way the leads are squashed under the spark plug cover. So when fitting new leads last night I fitted some spacer washers between the plug cover and the rocker/cam cover so that the leads are free to move around and less chance of 2/3 of the leasds being pressed down on each other, finally because the plug cover is now raised slightly due to the spacers I sealed it from water ingress using Hylomar silicon sealer. Don't look to pretty but hey the bonnets bolted down and no ones gonna see it anyway. Drove the car hot and cold and there is a major improvement obviously because of the new for old leads. I just want to prevent the leads/plugs from breaking down when it does get hot.

Steve

BGB autosport

1,044 posts

216 months

Friday 30th January 2009
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Im after some new leads, where did you get the mags from and how much£

Cheers

Chim326

Original Poster:

279 posts

242 months

Friday 30th January 2009
quotequote all
BGB autosport said:
Im after some new leads, where did you get the mags from and how much£

Cheers
Tvr car parts 01884266755
Think they were £130 odd delivered
ACT performance also has them on the shelf about £2.00 more

BGB autosport

1,044 posts

216 months

Friday 30th January 2009
quotequote all
Than, will have a look. Mine has got a high rev miss and a sooty exhaust on one side. Going to give it a good service inc leads and hopefully it will sort it.

Chim326

Original Poster:

279 posts

242 months

Friday 30th January 2009
quotequote all
BGB autosport said:
Than, will have a look. Mine has got a high rev miss and a sooty exhaust on one side. Going to give it a good service inc leads and hopefully it will sort it.
Trouble is you tend to think the worst "Disaster spd6 misfire engine gonna blow up" as i did. But at the end of the day there's only a coil pack, leads and plugs.

nelly1

5,665 posts

260 months

Friday 30th January 2009
quotequote all
Chim326 said:
Trouble is you tend to think the worst "Disaster spd6 misfire engine gonna blow up" as i did. But at the end of the day there's only a coil pack, leads and plugs.
Ha! We'll have none of your wretched optimism on here!

Away with you...

wink

Chim326

Original Poster:

279 posts

242 months

Friday 30th January 2009
quotequote all
nelly1 said:
Chim326 said:
Trouble is you tend to think the worst "Disaster spd6 misfire engine gonna blow up" as i did. But at the end of the day there's only a coil pack, leads and plugs.
Ha! We'll have none of your wretched optimism on here!

Away with you...

wink
Many a true word said in jest
You coming for a drive next Sunday Niell
Did you get your car fixed?