Tonight on my way home from work my Cosworth developed a misfire over 1.2 bar in 5th gear Boosts up to 1.2 bar perfectly but once it gets there is starts to misfire and hold back so I backed off

When I got home I took the plugs out and they look good but the gaps are slightly all over the place & I don't know what they should be gapped at and can't get hold of anyone at MSD at the moment. The gaps are currently between .60 and .75mm and the car is a stage 3 on one of Stu's chips.

Anyone know roughly what the gaps could be or what else might be causing it?

Thanks

 

.6mm i used to gap mine at...if this dont cure it..new plugs time.

 

Thanks Phil I thought .75 was a bit wide, if that doesn't fix it I'll get some new plugs, it hasn't done hardly any miles but the plugs have been in there 3 years That's about 2,500 miles use at a guess What plugs do you recommend?

 

Motorcraft 071's mate avalible thru rainbird

 

Do I get a discount if I say you sent me?

 

Phil, speaks wise words

 

I just took the plugs down to mate who is a mapper and he agrees that the engine is (was ) running well and it's just a little bit rich. The plugs in there were NGK 9's but they are worn out and he's advised me to get new plugs so I'll get some off Mike and gap them to .6mm and try that

Thanks for your help

 

Don't forget you have to gap them at a 45 degree angle

 

Sorry what is that? You lost me there

 

+1

 

the tip doesnt go straight over the middle bit like a normal plug hence the angle setting, you will see when you get the 071's

 

Thanks for explaining I'm just trying to see where I can get some the quickest at the moment, I want the car back on the road by the weekend.

 

your local ford dealer should have the plugs in stock FINIS 1120834 plug AGPS 071C.


You can see the reason behind the 45 degree gapping!

 

...warren i beleive they are obsolete from ford...only source i know was rainbird!

 

I have about 600 in stock and you should gap them to 0.65mm
However, you would do far better with a set of denso iridium IK27's.

With regards your friend reading the plug colour and advising engine mixture conditions, did he ask you for a detailed explanation of engine run time and load and then ensure that you cut the engine dead under load and coasted to a halt before removing them from teh engine? If not, with all due respect, ignore any mixture advice he gave you.

 

...stu didnt know that i thought mike bought out the entire stock!!!

 

Sold them for many years mate. Ł8.50 a set.

 

Agreed with stu on the plug colour readings, you HAVE to dip the clutch and kill the engine when under max load for it to mean anything, which people generally avoid doing on a turbo car obviously!

 

Is that recently then??? I bought several sets from my local dealer just before xmas 2009.

 

I bought 071s from my local ford main dealer recently too.

 

Bought some last week from Ford. Readily available

 

Well fuck me.

 

Thanks for the kind offer, but I fear that if I do, Mike Rainbird will get very jealous.

 

I wish I'd known you stocked them Stu because I know how quickly you ship things I checked your shop on ebay last night and it only had the denso ones.

My friend did advise me that was the only real way of diagnosing plugs, he said that's how they used to do it tuning bikes. It was just an indication I was after

New plugs ordered today from Matt Lewis after a quick call to see when he could deliver them.

 

Things you shouldnt say which can be completely taken out of context

I suspect mike has plenty of "fresh meat" to break in

 

What should IK27s be gapped at?

 

Now i am going to be honest here, the denso plugs are NOT meant to be regapped from out of the box, you do sometimes hear of these tips dropping off and destroying engines, maybe you can get away with it once???...they are very weak in tip terms.

Not trying to annoy anyone its just what i have been told and shown when a tip falls off!

 

iirc NO need just FIT and PLAY