MY99-5DR

Hi folks,

Having exhausted my technical knowledge of Scoobs, I am looking for some serious help...!

About a month ago, I bought a std, unmodified UK '99 car with 41k miles, FSSH and, according to Subaru UK, a clean history with no warranty claims, etc.

The problem(s):
The car suffers from the 2000 - 3000rpm lumpiness common to many '99/'00MY cars, BUT, under certain conditions it becomes utterly intolerable. For example, when driving at a sustained 70-80mph, the car feels as if it's misfiring quite badly - so much so that it is all but impossible to drive in that speed range. The intensity of the lumpiness is 10 times worse on this type of journey, compared to say driving at light load at varying speeds on the average A road where the more common lack of smoothness is evident, but manageable.

The second problem is that the car is grossly underpowered. I would guesstimate that it is only producing about 170bhp, i.e. about 50 short of the mark. It lacks any mid-range punch and generally feels thin and weedy.

So far, I have:
Checked the ECU for error codes - none found
Reset the ECU - no running problems introduced
Checked the MAF - by unplugging it at idle when warm (car died instantly), plus the idle is as sweet as you like
Changed HT leads for new Scooby items
Fitted new PFR6B's gapped to 0.75mm
Flushed through all small bore vacuum piping around the wastegate, etc (all clean anyway)
Used only 97 SUL or Optimax

I don't think the lambda sensor is at fault because most people on Scoobynet who have had a problem with them describe the symptoms as severe hesitation (through the windscreen stuff), or dire fuel consumption - neither of which apply here.

The only other things I have noticed which may/may not be common are that there always seems to be a slight to moderate vacuum in the fuel tank whenever I come to fill it up - whether it's just a £15 top-up, or a full wallet drainer, and the turbo seems quite quiet and subdued. As I don't have a boost gauge (first mistake :-), I can't tell if it's just a smooth & quiet unit, or if it isn't producing full boost?

Basically, I'm at a loss. There are no odd noises, vibrations or smoke that might otherwise provide a clue.

Please HELP - it's driving me nuts!!!!!

Peanuts

iTrader: (15)

buy my boost gauge

I have seen another 99/00 that only ran 0.5bar boost as standard.
I dont know why that is, neither did the owner.

a good way to check is to get a boost gauge as you say,
then a manual boost controller will allow you to play with the boost level.
be aware though that you will need a knock sensor and afr meter.

Dark Blue Mark

Where are you based? Your best bet is to take it to somewhere like Power Engineering for a rolling road health check. Or BRD are very good - as are TSL for that type of thing. Good to see you've researched it and checked all the obvious. Silly idea, but worth a check, is the intercooler clear of devris, including the scoop? Also worth opening the filter box lid for any foreign objects.

Aside form that, the cars mileage is inot MAF / 02 failure territory if they've not been changed.... An AFR will show if the lambda is dead, but I like to change it as part of the service schedule (wne I owned a scoob )

If it boosting low, you need to find out why. I wouldnt suggest fooling it by adding a controller is the way forward...

MB

MY99-5DR

Thanks for the offer

I'm contemplating fitting the ECUTEK Data Monitor, but I'm not too keen to shell out that kind of cash until I know the extent of the work required to sort the car out (and hence the size of the repair bill)!!

I believe standard boost pressure for a 99 spec car is around 0.9bar, so it sounds as if the car running at 0.5bar was stuck in limp mode. As I'm not getting any error codes, I don't see any reason why the car should be in limp mode, although that's what it feels like!

MY99-5DR

Cheers Mark. I'm based in Pembrokeshire, South West Wales, but I'm hoping to meet up with TSL in the not too distant future.

Valid point on the intercooler - when I bought the car it had evidently been used as a tool tray, so I painstakingly straightened all the bent fins with a compass point. I actually wondered if I might have accidentally holed one of the passages, but as there is no additional whistling/whooshing noise, I'm guessing not?

I don't think the MAF has ever been changed, but it doesn't seem to be displaying any obvious signs of failure - hunting idle, etc.

I should have mentioned that I checked the airbox too. The filter was a tad grubby directly in line with the air intake duct. I turned it round 180° so that the incoming air flow is now aligned to a spotlessly clean area of the element.

Dark Blue Mark

I like it when someone does some thinking first Most dot check any of the stuff you have.

Re the pressure in the tank, all 4 of my scoobs did that and I think its quite normal.

Mine (MY99) behaved exactly as you describe until I decatted it and changed the 02 sensor at the same time. The o2 controls fuelling off boost (or below 0.5 from memory) so if its low RPm it would point towards that from a fuelling point of view. Failed MAF's generaly run leaner so the car feels quicker than normal. This doesn't appear to be the case with yours.

As said, a good RR operator with delta dash will spot the problem very quickly. Bob of BRD deas travel and the cest man for the job....

MB

Dark Blue Mark

PS - how many miles do you get from a tank and how balck it the tailpipe?

MB

MY99-5DR

I generally tend to drive the car lightly with the occasional squirt to overtake and put a grin on my face - this type of driving results in 23mpg on local "A" roads and 27 on a long journey - about what I expected from the car really.

The tail pipes are fairly sooty. If it was my old MKII Golf GTi, I'd be leaning the mixture and changing the air filter, but I understand Scoobs use over-fueling to cool the charge under boost(??), so I thought it might be a result of that?!

Dark Blue Mark

Yep, it should be a bit sooty as the are mapped to run on the safe / rich side... And your MPG figures look right.

Best route is to get it looked at, boost gauge and knock link is a must anyway in my book, but it will take an expert to diagnose any probs you find after fitting the bits of kit...

last try,but check the boost solenoid isn't gummed up. if you do a search, you'll find out how to do it. It lives just above the airbox, and can be a cause of low boost.

MB

Turbo_Steve

Sounds like a faulty coil-pack to me?

MY99-5DR

Thanks Steve.

I certainly haven't ruled that out on my list of checks. Before changing the plugs, I checked the originals (all were in excellent condition) and I gapped them to 0.7mm. After doing so, I thought the car felt a little better, but unfortunately I didn't fully test it as I had no long journeys to make at the time. When I then changed the HT leads and plugs (gapping the new ones to 0.75mm), the car seemed to be as bad as ever. I thought it was probably just my perception though, I couldn't believe that a difference of 0.05mm would make any difference.

This car has single coil pack on top of the inlet manifold, but I don't know if it can be tested, or if it's a matter of trial by substitution.

Also, could the coil pack cause the loss of power, or is that likely to be something else?

MY99-5DR

Just been talking to Subaru Tech Department about this and one of the things they suggested was the front cat being choked up. Has anyone experienced this and might it give rise to the above symptoms?

Dark Blue Mark

Wouldn't like to think it could get choked, its quite restrictive, but there shouldn't be anything other than a bit of soot to block it with.

Best to decat it to free up 20 bhp though

MB

edmy716

mine is doing the same but not as bad, it still feels good and did a quarter mile in 13.8, but it is so annoying, does ur car go back and forth through early revs? apparently the cause is the ecu mine is being remapped by tsl end of aug so i will let u know how i go on.

MikeWood

A failing AFM can cause the symptoms you are experiencing. The engine runs lean and dets enough for the boost to be resticted to actuator pressure. The lean mixture also can make the midrange lumpy as well.

Mike

ScoobyDoo555

Another vote for the AFM...... mine had the same symptoms, got my local dealer to change it under warrantee. Prior to this, just before I picked the car up, the salesman was saying that my new car was one of the fastest he'd been in!!!

Right before it destroyed half the engine!!! Still, all done under the warrantee

Dan

MY99-5DR

The only reason I doubt that it could be the MAF sensor are that it is so breathless it would hardly pull the skin off a rice pudding - ok, I'm exaggerating a bit, but it's definitely not lean & super fast with added det :-) !! It also idles just fine, no hunting or spluttering - thoughts??!

Dark Blue Mark

Rolling road diagnostic job. Its one of those thats very hard to diagnose over the net...

MB

Jim_B

iTrader: (1)

my MY00 had a hesitation - most noticeable when accelerating from about 2500RPM, seemed like a misfire / stutter and was more noticeable if I had been keeping a constant speed for a while and then accelerated. Ended up being the Lambda sensor. You could feel it sometimes higher up the rev range but as you were pulling more revs it didnt have such a noticeable sudden lack of acceleration.

Bob Rawle

Try this check, unplug the lambda sensor, just leave it like that, then drive it around and see how it feels, you may get a CEL, just ignore that as the ecu is warning that the lambda sensor is not there and doesn't actually do anything about it. If this improves the lumpy feel then you will have a bad sensor probably but they can feel like that as std.

You ought to get the boost level its running checked out, its possible that a previous owner messed around with the restrictor or even removed it, that would severely limit boost.

bob

MY99-5DR

Many thanks Bob, I will try that as soon as a new MAF sensor arrives...

Last night, I considered all the things that could be wrong, based on the advice from these posts etc., and to my knowledge, the only one that could actually destroy the engine is the MAF. Given that they are known to be an achilles heel anyway, I thought it would be prudent to change it regardless. I don't live near a dealer, but I've ordered one and it should be here on Thursday. As soon as I've fitted it, I will go for a drive to see if it has helped, and if not, I'll disconnect the O2 sensor.

Cheers,

Andrew

Dark Blue Mark

Just to check, you should have paid around £90 for the MAF element?

MB

MY99-5DR

Thanks Mark, I have ordered one from the ever obliging A F Noble outside Edinburgh for £77.27 inc VAT.

They said they have sold 4 in the last 2 days, so I'm guessing they're familiar with the part number... !!

Dark Blue Mark

Just checking as Subaru used to fip people off and chage them for the whole thing, rather than just the element.

MB

grahamfrary

Just a long shot but I had similar symptoms on a MY98. Turned out to be a poor ecu earth. Again there were no fault codes showing.

Graham

MY99-5DR

Thanks Graham - something else I should have mentioned: I have fitted extra earths to the ECU bracket, both front suspension turrets, both sides of the inlet manifold and the alternator. It made a big difference to starting performance (as if I had fitted a new battery), but alas, it did bugger-all for the running problems...

MY99-5DR

Right - the latest on the car's running problems:-

1. Fitting a new MAF has made no difference to the running, but I am now sleeping more comfortably !!

2. I recently visited TSL on an unrelated issue and Richard Bulwer (technical guru) kindly hooked up his laptop and we went for a spin. This revealed hyperactive fuelling correction which we thought could be early signs of a lambda failure. A new sensor was fitted, but to no avail. For some reason, it is running a tad lean off-boost, with sporadic correction and corresponding lumpiness felt within the car. Unfortunately, we ran out of time so couldn't delve any deeper. The only other observations were that the new MAF is working 100% and the car isn't making quite as much boost as it should be - only 0.8bar instead of the more usual 0.9. Fuel was Optimax...

Are these conditions purely down to a gash factory ECU map, or are there other potential explanations???!

One befuddled Scoob driver...

micared

If you can borrow another ecu to try, I think that's your next move. If it turns out to be that, it's a relatively cheap fix....2nd hand ecus run at about £100-£150, and shouldn't be too difficult to come by.

MY99-5DR

Thanks mate.

Does anyone have an unmodified AE801 going for sensible money???????????!!

edmy716

if i remap my ecu is this going to solve it? or do i need a new one, cos do want to go to tsl spend my savings and it still b the same???