edmy716

my99 is slightly missing under low load not wen booting it, its like its going backwards and fowards ever so slightly any ideas??

JOHNSTI

mine was very lumpy at low rev's it was a cracked coil pack. if you take them out pull off the rubber like end cap that goes over the spark plug and check for crack's around the pot even very fine crack's i replaced three then it ran fine

RB5_245

MAF sensor is a good place to start looking on an my99 for everything from 'windscreen wipers not working' to 'wheel has fallen off'

Get it checked out.

Dave

dij

Heard that it could also be lambda sensor related
btw ,my99 has one coil pack not 4 seperate

Gidney&Knowlesy

more likely to be maf, spark plugs, lamda.........diagnostic will show most of the symptoms.

jjones

Is this only when cold - or when the car is warm also?

edmy716

wen warm aswell. its goin in on wed just trying to eliminate a few things cos if it goes in it will be there all week and its not quite close to me were i got it from, so id rather fix it if it is only a minor thing

MY99-5DR

I have exactly the same problem and have just put the msg below on the SIDC forum pages:

Hi folks!

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

Best of luck with your car - please let me know what you find!

edmy716

no joy either mate it so annoying!!! my other scoob didnt do it so why should these? a guy came out and said it he was 99% certain it was the lambda sensor changed that **** all.

MY99-5DR

Having just had a lengthy chat with the super helpful Colin Noble at A F Noble in Penicuik (nr Edinburgh), I think I now have a better understanding of the problem...

There is a Subaru service bulletin (1-1B-017 issued 28/02/2001) that explains this characteristic.

"At engine speeds of 2500-3000rpm, exhaust gas velocity can be relatively low, and turbo boost pressures correspondingly lower. This caused by the turbine wheel and the impeller wheel in the turbo-charger unit not having attained sufficient rotational speed to create a smooth flow of turbo-charged air pressure into the engine. This causes the airflow to pulsate, and to produce a sensation of unsmooth combustion."

Unfortunately, this is a function of the MY99-00 ECU, turbo charger and inlet/exhaust pipework and there is no simple cure. It is not detrimental to the car, but as I - and clearly others know, it is bl**dy annoying !!!

Colin advised that the only real solution is a Prodrive Perfomance pack which will completely eliminate the problem, as well as making the car much more responsive and potentially more fuel-efficient.

It's worth saying that there may well be other problems giving rise to these symptoms which when rectified may make the car tolerable, but it's kind of reassuring to hear that there is a known issue - rather than to spend the equivalent of a PPP on futile repairs and sensor replacements...

jjones

mine is a rb5 (my99) wr sport. so it has the PPP ecu already. it aslo has a decat downpipe. still doe it tho. going to try lambda sensor replacement and also try coil pach exchange.

MY99-5DR

Will be very interested to hear the outcome of your coil experiments...!

edmy716

they dont have coil packs!?

MY99-5DR

Aye, just a single "coil pack" with two physical coils in it located on top of the inlet manifold......

edmy716

im having a remap by ecu tek at tsl in aug will this cure it same as the ppp?? cos it driving me crackers!!!

MY99-5DR

Please let me know how you get on - I am thinking of following in your footsteps! I haven't spoken to TSL yet, but I did speak to Power Engineering and they were confident that they could iron out the problem.