MY99-5DR

Hi folks,

A few of us MY99-00 owners seem to be experiencing an irritating misfire at light load. Is there any way to check the integrity of the coil pack without "trial by substitution"??!

I took the coil pack off last night and checked the resistances between the four connectors (low tension/signal side), but they were all over the place. No two were the same.

I have attached my original post on the sidc forum below, but in retrospect I'm intrigued by the fact that the two cylinders that showed the arcing damage were powered by the same coil - the HT path to cylinders 1 & 4 showed no damage at all.

I would like to be 100% certain that the coil pack is ok before experimenting with a new maf sensor, lambda sensor, etc as the car doesn't exhibit any other signs of rough running - Ideas???!

As a newcomer to Scooby ownership and the forum, I wonder if you can help shed some light on a gremlin afflicting the running of my new pride and (cautious) joy?!

The car in question is a completely standard UK MY99 wagon with 41k miles and FSSH from new. It is running on SUL - usually Optimax, although that may not always have been the case.

The problem is a hestitation/misfire at around 2500rpm +/-200rpm. This is most obvious when maintaining a steady speed or under very gentle acceleration; i.e. sticking reasonably close to the national limit in 5th: 70-80mph. Increasing speed (& revs & load) to 80-85mph all but wipes out the problem. Although, it must be said that it is sometimes more generally obvious than others.

Idle is smooth as silk and once through the period of lumpiness, the car pulls willingly - if not quite as urgently as it perhaps could? I say this because I briefly owned a Boxster S and, if my memory serves me correctly, it would give the Scooby a good shoeing in most circumstances.... Having driven half a dozen or more Scoobies of different vintages over the past few years, I expected a little more, even from the standard car.

So far, I have changed plugs and leads, reset the ECU (no faults in the memory), checked the intake system for dirt/leaks, cleaned the wastegate solenoid & piping (all spotless) and the car has just had a routine 54 month service. After a 15 minute unsupervised test drive round Cardiff the technician was unable to find a fault, describing it as "perfect, nothing wrong with it mate". Again, their diagnostic system revealed no faults past or present.

I'm not convinced!!! I thought I had found the source when I removed No.3 HT lead and found the plug cap loose and badly burnt. The No.2 terminal on the coil pack was also badly burned, but unfortunately a clean up, change of leads (new OEM Scooby leads) & plugs (NGK PFR6B gapped to 0.75mm) has achieved bugger all. It's as bad, if not worse than ever :-( !!! If it's relevant, I previously took out the original plugs (also PFR6B's & in v.good cond) and gapped them to 0.7mm and the car seemed to be slightly better - can't believe 0.05mm would make such a difference though, esp when Subaru fit them gapped at 0.8mm...

If anyone has any ideas, I would be mighty grateful to hear them!!!

jjones

hi,

i have a my99 PPP with h&s downpipe. it also does this. more noticeable when cold. when hot it is there but barely noticeable.

i have just changed the maf sensor as these were a weak point and considered a service item on this vintage - it has made no difference to this problem. i also did an ecu reset after the change of maf.

i should be able to get hold of a coil pack and will let you know whether it makes any difference or not. i have not checked the plugs or leads as yet as the problem although irratating when cold doesn't really cause any problems. it will probably be a week or two before i get the chance to try it tho.

i also suspect the lambda sensor may be a problem but i will eliminate the coil pack first.

dwk*

I had an MY99 over 3 years ago that done this, there were lots of threads about it at the time. A lot of people suffered from this, I think from new. With their cars still under warrenty at the time, quite a few went back to the dealers about it to be told "it's a feature of the car sir".

I have just bought an MY00, this does it as well.

jjones

my dads my00 "V" plate (completely standard) does not do it at all. from cold or hot.