MAFFA

Okay here's the exact symptoms of my MY95:

*Start the car - fine
*Run off boost - fine
*Nudge it anywhere over 10psi - Car exhaust note changes from a roaring flat 4 grumble to a loud rasping noise & really doesn't feel like accelerating much. It accelerates a lot more on <10psi.
*On tickover the revs fluctuate between 1100RPM (normal for my car with the Walbro fuel fump) and about 500RPM, but with no distinct pattern. It does it erratically. At 500RPM it is acting weird in the engine bay. When the revs drop to this the engine shakes and my mate says that it's like it is running on 3 cilinders!! It's kinda like it's running on 4, drops to 3, then back up to 4 etc...

Now i've gapped the spark plugs (NGK6's) to 0.65, checked the MAF, solenoid etc... but there is only one weird thing I can find. One the set of plugs I took out (didn't check to see if the ones in there are the same) one of them looks a bit buggered. The top where the plug meets the HT lead has changed colour from the gold colour to a kind of copper colour. Also the very top of it is black when the rest are clean.

Could I be consistently be blowing a plug & if so why does it not constantly run on 3? It has been suggested that I get NGK7's as they run cooler but any other suggestions would be greatly appreciated.

Thanks

MAFFA

sammyh

iTrader: (1)

Have you checked for loose / split boost hoses?

dnb

Have you done a compression test? (Just to be on the safe side!!)

Agree with the split hose examination. They can be difficult to spot.

Also get Steve to look at it with "The Brick", He should have some new software to look at the car with.

ScoobyDuck

iTrader: (1)

I thought this had stopped?

the plug bit - this sounds like it is sparking between the lead and the plug top. which would account for a miss-fire underload.

u dont have coil packs anymore, so it's not them.

u've tested MAF ? by unplugging it ?

we can try logging again - but last time we did that it didnt help much , as everything goes potty when it miss fires - but we might be able to see something with the a later version of code (the one we used was really early! - no graphing etc)
but we can only do this if Dave takes pitty on my for my stupidity & licenses the right laptop!

Steve

MAD-MATT

Dont know mate but how are your side repeaters?

MAFFA

Steve,

I haven't actually checked the MAF. I've cleaned it . We could plug your PC into my car when you're off next week See if anything crops up. It could be a hose I suppose but that's gonna be a bugger to find . If it's sparking between the lead & the plug then that can't be good.

I also took a look at the NGK website & it says they should be gapped to 0.8mm?? So how come everyone on here says between 0.6 & 0.7 Oh well it's always been okay between those gaps

Mat - I ain't going out in that cold & dark to fit them

MAFFA

dnb

Steve - YHM.

mart360

maffa,

run the car at night and lift the bonnet...

if it looks like the auora borealis on your leads,,, that may be the fault...

had a similar prob on the wifes fiesta,, could not spot any obvious faults until i checked at night...

just a thought

mart

MAFFA

Might give it a go but at what is effectively 2am (not taking ito account the clocks going back) my neighbours might not be impressed LOL Tomorrow maybe

MAFFA

MAFFA

Okay here's an update. This morning I put an old set of HT leads on the car, cleaned the plugs and re-gapped them to 0.7mm. Now this cured the tickover problem that I was getting but once again it was doing the same thing over 10psi.

I drove to Steves & plugged it into the laptop & we checked pretty much everything, revs v airflow, revs v injectors. God knows what all the stuff was (I'm sure Steve will fill you in) but the basic result was that the fueling, airflow etc were fine. What did occur was that the problem got worse & my car now has a major misfire at anything over 5psi. Steve thinks that it's not actually related to boost & that it is actually related to the load. More load on the engine = more problem.

We decided that it was now one of four things:

1) The HT Leads
2) The Bosch MEC723 Coils
3) The Denso PK22PR8 plugs (PFR7B equivalent)

The next thing we did was check the HT leads with a multimeter for resistance. 2 of them showed nothing & 2 showed something. We didn't 100% know what we were testing but if they did nothing when the other 2 & my 3 spares did something that this was not a good sign. I changed those 2 & hoped it would help. It seemed slighly better but the misfire was still there in a big way.

The plugs look fine but you never can tell really. The next point of call is the coils which aren't that old. I'm going to take a coil pack & rotate it in place of each Bosch Coil & HT Lead to see if one of them has gone. If they are fine then our thoughts are that the Bosch coils are just to strong for standard leads & keeps cooking them. Replace with Magnecor 8.5 or 10's would be an option.

If the coils are to strong then this could have created a break in the leads & therefore wouldn't read on the multimeter but would create a small spark for lower revs due to the current jumping the gap. This spark would not be strong enough for heavy load though...hence misfire. Why this was not fixed with the leads changed I don't know?

One other thought we did have was the ignition controller thingy being up the spout or maybe something to do with the ECU? Worst case scinario would be to do a compression test & hope

I'll keep you posted

MAFFA

MAFFA

Bet you can't guess i'm happy Went and picked up a set of NKG PFR7B's for £24.00 from the gaff down the road & fitted them at work. Runs like a wild banshee now

So there you have it. After all that it wasn't the leads, coils etc... but those blasted Denso plugs!!! Won't be getting them again, even if they are the equivalent of PFR7B's LOL

MAFFA

ScoobyDuck

iTrader: (1)

Women mate cant trust'em, cant kill'em !

glad all the hyperthetical babble was just that !
knew it was something boring, mechanical and simple!

lets hope they last & this problem dont re-appear!

Steve

[Edited by ScoobyDuck - 10/29/2003 2:15:13 AM]

MAFFA

Problems with women mate?

Yeah let's keep our fingers crossed. I know now that it's not the coils & I have some Magnecor leads on route to my gaff as wee speak so if the symptoms arise again then i've buggered some more plugs LOL Well at £24 for 4 I aint gonna moan. At least it's not serious

MAFFA