Chip

iTrader: (3)

Ive changed to coilpack now, as part of which:

out: leads, plugs, dizzy cap, rotor arm, coil

in: additonal amp, new leads, set of 071 gapped to .65, new coilpack


Without a doubt the spark is better now (visibly so), but im still getting a problem under load that feels like spark being overcome to me, although its doing it less than it did before the coilpack conversion (which further renforces my belief its a spark issue).


Im going to put additional earths onto the engine/battery today to make sure im not suffering a voltage drop, anyting else anyone has done to fix this though?

AFR is fine (high 11s till the misfire) and nothing else seems untoward, compression tests ok etc.

Feeling a bit stumped here so could do with people pointing out anything I might be missing out on even if its obvious!

Going to order a set of iridiums again just to rule the plugs out from my enquiries, but 071's have worked fine before on this setup without the coilpack so I fail to see why they shouldnt do so even better now im on the coilpack.


Ideas?????

Chip

iTrader: (3)

Note for Doug Stirling.

Do you think it could be the absense of the word "cosworth" on the logbook causing the problem?

Jay,

iTrader: (4)

intake manifold gasket mabey ?

Si B

iTrader: (59)

Change the plugs... my 071s fouled up a LOT due to running ever so slightly rich... I literally changed mine every track day to make sure they were clean as whistle before getting used hard.

Denso Iridium IK31 (IIRC) cured my problem - thanks to Karl Norris who suggested them. Have never had a spark problem since.

071s are only Ł12 ish at local Ford dealer - I've probably got a spare set kicking round here too if you need them.

Si

Alg1k

iTrader: (2)

Check the new harness out
You may find as i did that one of the leads to one of the amps is a tad loose and just making contact
IT WILL eventually burn one of your amps out
Hope this helps.

bud-weis

phase sensor?

zippyobrien

iTrader: (2)

not a valve issue, valve springs?

JjCoDeX75

Might be worth checking the phase sensor gap and the crank sensor gap again - though cant imagine why it would have changed.

Otherwise, I have a set of plugs that I know dont cause a misfire in my engine (which is running more boost on otherwise a very similar setup), which you can borrow if you like?

JJ

cossiemanden

Have u tried to ajust the tps?

Is it at a cirten rpm or different?
Is it only at full load?

Chip

iTrader: (3)

Si B have tried 2 different sets of 071s and its not running mega rich anyway, mid-high 11s is as rich as it gets.

I will order some IK31's though to try them




cossiemanden
Tps hasnt been touched since it was running perfectly before.


Alg1k
Will have a look at the plugs on the new subloom, cheers for the tip


bud-weis / JJ
Phase sensor gap is fine and its only a coupe of K miles old and again it hasnt been touched since it was working fine.


zippyobrien
Seems unlikely the valves would suddenly have an issue, but I have compression tested it and its all fine, annoyingly had the wrong adaptor for the airline to go onto my new leakdown tester as it has arrived with a different fitting to the ones I use and thats the first time I tried to use it.

Chip

iTrader: (3)

I dont think so mate as ive never seen a car manage to hold over 20psi on a leaky inlet manifold gasket, but will spray some WD40 around it tomorrow perhaps just in case

Karl

Chip,

Trying closing your plug gaps down to 0.5mm. Remember to gap them diagonally due to the short reach ground electrode. If the misfire improves, then there is a high chance it is spark plug related.

JjCoDeX75

Glad Karl said this, as I didnt feel qualified to suggest this, but as per my previous post - I have a set of plugs in the box that I KNOW will not cause the problem on my engine...

James

Deleted by Request

Take it to a pro,instead of fucking it up more

..DIY is not for idiots.

Si B

iTrader: (59)

How constructive...

Chip

iTrader: (3)

I tried this yesterday and TBH it didnt seem to make much difference, Ive ordered a set of those IK31's Si says you recomend though mate, so fingers crossed that will help.

Thanks for the input

Chip

iTrader: (3)

Good suggestion, im sure Stu or Karl would have it running perfectly in no time at all, however its my hobby and I enjoy doing it myself, just like I enjoy fucking birds myself even though I could get Ron Jeremy to come round and do the job far better, I just find it more satisfying making say 400bhp for the car and 4 orgasms for the bird but doing all the work, then I would with 450bhp and 7 orgasms with Ron and Karl on the case (or should that be the other way around, lol)

True, but educated and experienced individuals like myself manage to do a pretty reasonable job of it

Minor issue that I will sort is not the same as a fuckup

Dave McB

i had a similar issue. spent hundered at a tuners, replaced everything from leads to coil then by chance discovered one night that 2 leads were too close together and arc'd when under load.

try spacing out ur leads a it and c if it works

JjCoDeX75

Glad you have twice now simply ignored my generous offer of plugs (you cunt )

JJ

Chip

iTrader: (3)

I can't be arsed to come and get them jj. lol

besides if its 071s I've still got more new sets in stock anyway.

thanks for the offer though.

JjCoDeX75

Looked like you couldnt even be arsed to respond until prompted ROFL.

The sparks in question by coincidence are not 071s. As previously stated though - they do not give a misfire in my engine, which with the exception of the fact that I run more boost than you is pretty much the same (notwithstanding the NOS which presumably you are not currently using).

JJ

Deleted by Request

..for a self confessed guru...this is pretty damaging to your reputation..a bit like the NOS incident aswell.

..atleast i admit i am an idiot!

Karl

Chip, also worth checking ecu power supply voltage when the misfire occurs. I've had ECU's dropping to 9v under load and causing misfires. Simply remove loom plug cover, and bridge volt meter between pin 20 and earth.

Dannn

Perhaps you just need a stronger spark...

I used to run something like this on my Escort:

http://www.jacobselectronics.com/Pro...&minselection=

Can't see the exact model I had - it was called "import blah blah".

Thing was amazing IMO - could run 40 thou plug gaps at 34psi from a T4 without any misfire.

Not just a coil btw - come with a controller. Had some HT leads from them as well which seem pretty good.

I still have it here somewhere - your probably not interested but I may be up for lending it out...

edit - this looks like a cool product as well:

http://www.jacobselectronics.com/Pro...minselection=1

polly_x

iTrader: (2)

Chip, I had the exact same problem on mine.

I was getting a bit of arcing down the side of the plug. You could see a tiny brown burn down the side of the plugs on the ceramic.

Squeeze some silicon grease down the leads before pushing them onto the plugs and see if that helps.

Cured mine.

Bobby Singh

Sorry havent read the post in detail - but might be worth running a earth from the battery to the ign amp

Chip

iTrader: (3)

Will check that out, certainly sounds like a good possibility on an old loom like I have!


Bobby ive got a new subloom going to the two ignition amps that all seems to be in good order.


Polly, plugs dont appear to be arcing out at all, have looked carefully at them.


Dann, im on wasted spark mate.


JJ, thanks for the offer, have ordered some anyway now and wouldnt want to borrow plugs off someone to put in a misfiring engine as odds are they could easily get coked up or similar.

foreigneRS

it may be related to how your leads are all running next to each other and cable tied together - have you tried spacing them out?

Chip

iTrader: (3)

I havent yet, will perhaps give that a go next time im down near the car.

Chip

iTrader: (3)

Karl
Thanks for the tip on the ECU, there was indeed a voltage drop that I traced back to a corroded end of the live for the ecu in the engine bay.
Ive sorted that now, and now my misfire has moved from:

Bad misfire at 24psi held (strangely the peak was still ok though)

to:

Slight intermittant misfire at 27psi held


So thats definately made a huge improvement, thats without swapping the plugs out yet too and im sure they are a bit the worse for wear from being in it while it was misfiring.



Shows how important it is not to take these snotty old looms for granted now they are 20 years old!

Fiecos Dan

Wasted spark conversion didn't help my cossie much, was running 0.45 gap on gpA coil, and .5mm on coil pack. both via my p8.


but also found different plugs can run larger gaps

ECU Monitor Enthusiast

iTrader: (1)

PMSL at the quote of the year


Chip,

Try earthing both the ignition amp heatsinks to the battery negative.

Try a temporary link first to see it that improves things