Mot emissions failure

[carsy]

Just drop some water onto the manifolds where they bolt to the heads. You will soon see if one cylinder is not firing.

[Chimp871]

Picking up a IR heat gun today to point at manifold. Thanks for the idea. I've also ordered some new leads and an air filter as I don't know how old they are.

Car goes like it should and last weeks RR confirmed this, 280 bhp/310 lb, so wasn't thinking of a misfire.

Wouldn't a misfire cause the HC to shoot up, way over the max numbers I was given e.g. 500 plus.

[QBee]

Dunno, but it only takes 5 minutes to check for a misfire. Remember not to stand admiring your beautiful engine bay - you need to test temperatures while it's warming up, before heat transmits through the manifold to the dead one and makes them all the same temp. Aim the gun at the manifold, one inch from the block.

[Paulprior]

Just beware that the IR guns are not always that easy to use, depending on surface finish they can be very inaccurate, but assuming that your exhaust has a dull matt finish its not so bad, chrome pipes like on a motorbike render the IR gun virtually useless, also just experiment a little with the angle you are using, try to keep position you are monitoring straight in front so you are measuring the center of the curve rather than half way around it, usually there is a little red dot showing where you are actually measuring.

[Chimp871]

IR temp gun (£7) gave some interesting results.

It seems that temp readings on exhaust outlet cylinders: 1, 7 & 2, 8 (the corners) are always hot especially 1 and 2 and consistent.

As for the others well the temperature was lower by 100oC on one random cylinder. It kept moving between 3, 5, 4 and 6 and usually just one. Wierd!

I had a new ignition coil and put it on and perhaps it was better but there was still a random low temp cylinder.

FWIW - the old coil, if you shook it, you could hear oil sloshing about whereas the new one (Bosch) you couldn't.

Possible the injectors are playing up. I bought some wynn's injector gold stuff as a cheapo fix to see if there's any st to shift.... Time will tell.

Running out of ideas..... so:

Would worn extenders/leads be a cause of the woes?
Normal for a coil pack oil to slosh about?
Anyone know of temp drop on after the Cat's?

going in for a quick emissions test tomorrow.....

[QBee]

Remind me if you have inspected inside the distributor? Is it tight in its location?

[Chimp871]

Qbee - it's clipped in properly, it'll swivel a little in it's position but its minimal. I did undo it to clean the top of the rotor arm.

Curious to know would knacked HT cables and shrouds cause cut outs - I should add they are magnecor?

Edited by Chimp871 on Thursday 4th August 22:49

[QBee]

Leads earthing on the engine will.

I see you are in Herefordshire. Anywhere near the M50/A40?
I have a complete spare set of leads and am passing through on the way to Newport this weekend.
Happy to have a look see if it would help.

[Paulprior]

I measured the temp after the precats before I removed them, I think it was about 250C, I will find the data tomorrow and let you know if it's any different.
Last time I tried looking for a problem on manifold temps I ended up touching them very quickly and lightly during warm up, mine showed very clearly 2 cold cylinders which were corrected with new plugs, obviously I can't really recomend this method, but I found the IR gun inconsistent

[Chimp871]

Yes, as M50 ends near Ross-on-Wye, about 20 mins from there. I'd be great to meet to get your thoughts/analysis but I'm off camping Saturday for a couple of weeks wasted chance.

You got me thinking about 'leads earthing to engine' - boot on #5 is charred and somewhat cracked after touching hot manifold perhaps it's arcing there? Got a couple of old leads to test it.

Would it affect the performance of the other cylinders?

[QBee]

I'm down to Newport every 3 or 4 weeks. Let's meet up when you're back.

[blitzracing]

Paulprior said:

I measured the temp after the precats before I removed them, I think it was about 250C, I will find the data tomorrow and let you know if it's any different.
Last time I tried looking for a problem on manifold temps I ended up touching them very quickly and lightly during warm up, mine showed very clearly 2 cold cylinders which were corrected with new plugs, obviously I can't really recomend this method, but I found the IR gun inconsistent

You can use a cable tie, and see when it melts or not as a crude test.

[QBee]

blitzracing said:

Paulprior said:

I measured the temp after the precats before I removed them, I think it was about 250C, I will find the data tomorrow and let you know if it's any different.
Last time I tried looking for a problem on manifold temps I ended up touching them very quickly and lightly during warm up, mine showed very clearly 2 cold cylinders which were corrected with new plugs, obviously I can't really recomend this method, but I found the IR gun inconsistent

You can use a cable tie, and see when it melts or not as a crude test.

Which is exactly what Rob (V8 Developments) did when he helped me find the first of my many misfires.....

[EGB]

blitzracing said:

"or certain contaminates can foul them like zinc from engine oil (if you use a high zinc oil) that wont burn off, but Ive yet to see a genuine failure".

Surprised at this Mark.
Please can you give us if possible, a published research reference where it has been proved that Zinc can make a catalyst disfunctional and cause a MOT failure? If so,can a catalyst cleaner help to clean off the Zinc. Thanks.

[N7GTX]

http://www.motorweek.org/features/goss_garage/too_...

http://www.drivenracingoil.com/news/dro/training-c...

https://www.catalyticconverters.com/damage/

Some bedtime reading for those concerned about zinc and catalysts. From 2006 it seems the zinc content was reduced in mainstream oils as it contaminates the cat. That appears to be agreed in the 3 articles above.

To remove this type of contaminant, raising the cat temp significantly will remove it by burning it off. So a prolonged thrash will be sufficient.

[Chimp871]

I like to close the loop, to help others.....

So went away camping with family and happily forgot about the issues. Got back and changed the dizzy cap and arm. There's still a little/random subtle quick dip in the engine at idle and revving.

Spoke to a recommended local garage (another one) who knew a fair bit about v8's after building several himself for racing. first he gave me some trade only injector cleaner (forte?) the day before the test.

He said my timing of 28 degrees on my cam should be changed to 34 degrees (I've a V8D stealth cam), which I did and well, there's a bit more torque.

He did the mot test and it's now passed , CO is right on the limit at 0.30%. What I did notice is he didn't trust the rev counter and tweaked revs himself. I'll post the results later.

There's still that engine dip but it's almost impossible to spot unless you've been made paranoid by the other 2 garages . Fella didn't think it was misfiring but the result of the cam, curious to know if any stealth cam have a perfect smooth engine it there's a still a dip.

So end of saga for now, thanks for help. Can't wait for next year's test

Edited by Chimp871 on Sunday 4th September 19:53

[Paulprior]

Just out of curiosity did the IR gun prove useful?, if so what did you get?
Paul

[Chimp871]

Paulprior said:

Just out of curiosity did the IR gun prove useful?, if so what did you get?
Paul

I don't think its perfect it it just gives you an idea. I found if the laser hit wg a piece of enamel paint it would vary a lot and so you have to take several readings.

Mine showed random temp variance on cylinders 3,5,4 and 6 and would move about all the time. Not all 4 at once just one.

I think there must be better solutions and i read on here v8d using zip ties on exh. Manifold. If misfiring the tie wouldn't melt (as fast, as temp reached 400oC+)

[QBee]

Cannot help feeling that the misfire moving around those four cylinders is distributor related - something wobbling around?
I found the IR gun invaluable for tracing misfires when they were extender-related, as the misfire(s) weren't playing hide and seek with me.

[Chimp871]

Qbee - when you're passing to S.Wales let me know. I'd like to meet up to get another opinion.....