Hi all,

New to the forum and also to Scooby ownership but I'm already having trouble!

Recently bought a 1998MY classic 2.0 turbo, UK version a few weeks ago.

The car accelerates as hard as you like through first, second and third, but if you use more than half throttle in 4th and 5th it hits what feels like a fuel cut and the car lurches back under hard engine braking for a moment, then resumes normal running. If you keep your foot down it does this repeatedly and consistently every second or so. Keep it under half throttle and it runs fine. Annoying as hell when you try to overtake anyone, or join the motorway from a slip road.

I thought it might be the MAF but I cleaned that and the problem didn't go, so I got a replacement pattern MAF and that didn't cure it either. I have been quoted £420 from Subaru for a genuine replacement but don't want to buy that on the offchance it will sort the problem. Any ideas what might cause this? Fuel pump? Boost solenoid?

Other things that concern me - on occasion the car is slow to start, requiring up to 10 seconds of turning over before the car will start. This is only maybe 1 in 20 occasions, but it still worries me a bit.

The two problems above suggest to me there is something electronic wrong which is affecting the fuelling. I have no experience with the car so don't know of any common faults.

Also the car seems to rock a lot at idle. I thought it might be the engine mounts but the car has just had a major service which cost over a grand with the fitting of a Scorpion exhaust and Bailey DV and they reckoned there was nothing wrong with the mounts. Is it usual for the car to shake like an old american V8 muscle car at idle?

 

make sure the dump valve is fitted properly and check pipework for splits.could be drawing in too much air through a split pipe or a fualty dump valve

 

firstly, you could try removing the baily valve and fitting the standard one back on, some cars have issues when aftermarket dv's are fitted, if that doesnt work then check all 4 coil packs to see if they are cracked. i had a few problems with my old classic.. flat spots, hesitation on acceleration ect, i checked my coils and 2 were cracked and falling apart. i replaced all 4 and the car was spot on. i also had the starting problem too but that went after replacing the coils

 

I`m no expert on scoobies but it sounds like a fuel starvation fault,i`d check the fuel pump & filter.Make sure the filter is clean & the pump is working under load.I thought i heard somewhere that scoobies may have a common fault with a weak fuel pump thats why i would also check it.

 

Was doing it before the new DV was fitted. Garage had a look at the pipework at the time and couldn't see anything wrong with it.

 

Fuel filter was changed at service but not sure about the pump. Seems like this and the coil packs are next on the list to check...


Cheers for the help guys

 

try a standard DV, or check the coil packs

 

The car had a standard DV when I bought it, and already had this problem. The new DV was fitted later.

 

The car accelerates as hard as you like through first, second and third, but if you use more than half throttle in 4th and 5th it hits what feels like a fuel cut and the car lurches back under hard engine braking for a moment, then resumes normal running. If you keep your foot down it does this repeatedly and consistently every second or so. Keep it under half throttle and it runs fine. Annoying as hell when you try to overtake anyone, or join the motorway from a slip road. [quote Lummox]

I had a similar problem with my Impreza once. The cause of mine was "overboosting" and the "fuel cut defender" activating causing the car to feel like it's hitting a brick wall.
Mine had a nasty brass adjustable bleed type valve (boost adjuster) on it and once I binned that the problem was sorted. Not as aggresive but runs without problems now. I'd check to see if anyones put one of those on and just bin it if the car isn't re-mapped for it. Sounds like your definately hitting a fuel cut of some sort (engine trying to save it's self from destruction because it knows something is wrong).
Hope that helps but if your still struggling I'd give David at API Impreza a ring (topman) and he might be able to help you. Enjoy your Scoob, Gareth

 

No. Some slight movement is expected.

Definately sounds like fuel cut due to over boosting.

You don't have separate coil packs on your model so discount them you have a single one on the top of the manifold, check your plug leads and plugs.

 

hello mate
the std in tank fuel pump on scoobys will over heat and fail if you run the fuel to low,ie less than half a thank.uprate it to a 255lph and it should be fine

 

I agree with the fuel cut due to over boosting as I've been playing with the manual boost control on mine and when I cranked the boost to high I started to get the fuel cut. The reason yours is doing it in 3rd 4th is that your building up the boost for longer and therefor hitting the fuel cut!!

 

Lummox, did you ever have a Punto GT?

 

sounds like an over boost problem to me,as you have more load on the engine in 4th,5th.a reputable subaru specialist should be able to sort it out for you.

 

Seems to do it regardless of the level in the tank. Feels very much like the fuel cut that used to happen on my modified 200SX S14A due to overboosting. But I haven't yet seen a bleed valve anywhere, will need to keep hunting. Plugs were changed at the last service a couple of weeks ago, along with all fluids, filters, cam belt and tensioner, rocker gaskets (due to leaking), exhaust and DV.

I doubt it has had the boost upped, as the car was shown a clean pair of heels by my mate's Focus RS through 1st, 2nd and 3rd on the way back from Le Mans... I'd have thought if the boost was increased it should be a match for a Focus! If the car is overboosting and doesn't have a bleed valve or boost valve fitted, might it have had an adjustable actuator fitted that has been set too high? And if none of these things, what would be the likely cause of a fuel cut and how would I remedy it? Apexi FCD?

 

Nope. I've had a Nova SR, 309GTI, 200SX, XJR, TVR Chimaera, 2 Scimitar GTEs, an S4, and a raft of others too boring to mention, but never a Punto!

 

Whaaaat ?? Where did that come from?

 

Full decat by per chance?
If so then go with what the others are saying, your car is overboosting and hitting the fuel cut, you need a boost controller or a mappable ecu to control it.
If not then try cleaning the boost solenoid

Tony

 

Ah OK. There was a user a few years back on a Punto forum with same name.

 

It still has the downpipe cat but the main cat is gone. The original exhaust appeared to have been modified to remove the cat also. Guess this could be the issue maybe.

Where do I find the boost solenoid in order to clean it? Thinking I should probably take off the pipes connected to it and give them a good blast with carb cleaner too.

 

Cat in the downpipe is your only cat IIRC.

Boost control solenoid is usually found on the drivers strut.

 

Will go mad with the carb cleaner tonight and see what happens...

 

Well, cleaned the solenoid, seemed to make a little difference, but problem is clearly still there. HT leads appear intact but are also looking like the original ones, which at 100k miles are probably well overdue for replacement. Coil pack appears intact.

Can a new solenoid be bought for reasonable money anywhere?

 

Do a compression test. Subaru engines don't rock about on idle they are steady. rocking can often mean one cylinder low on comps.

Otherwise it sounds like a fuel cut due to boost overshoot, fit a bleed valve, manually set it to 1 bar [ish ] and see what happens.

If you can get to us at APi easily, we'll take a look for you, no obligation to buy anything. Probably just an hours labour cost.

Have you done an on board diagnostic by plugging the wires together under the dash ? l cannot remember if it is mentioned and can't look back without losing this text.

David APi

01926 614333

 

as dave has said it could be overboosting do you have a boost gauge if so what does it boost at.

dave its a 98 so wont have the connectors under the dash i dont think iit should be obd socket ??????

 

Oddly my car has both? It was actually registered 04/01/09 so it has the connectors and an OBD port.

Just gave it a crack and it's clearly showing fault code 23 - MAF, right? I didn't do an ECU reset after fitting the replacement, could this be the problem?

Will disconnecting the battery for an hour reset the ECU?

ETA: I have a gauge sitting in a box waiting to go on the car. Need to have a look on here for pointers on how to fit it

 

yes it should do if not there is a procedure you can follow but with mine i just dis coned the battery as you have said.

did you fit a brand new maf ??????

 

A new one, but it was a pattern part. Didn't fancy paying Subaru 420 quid for a genuine one!

 

As everyone else has said - sounds just like overboosting. If its a new car to you check the original boost control pipes are all connected correctly E.g. reducer pill is on the turbo outlet not the actuator side of the T connector. (Cleaning out the valve won't work if they are connected up wrong - and it does happen)

As for the not starting for ages once in a blue moon mine does exactly the same. I assumed its fuel draining back to the tank and needing to be pumped back up. I also heard you shouldn't ever touch the accelerator pedal when cranking.

 

I haven't checked the reducer but everything seemed to be hooked up right.

I've found a breaker that will sort me out with a replacement solenoid and coilpack if the ECU reset doesn't work, plus a few other trim pieces I need, for £60 delivered so it might not cost a bomb to sort out. Am also going to change the HT leads as they weren't done at service and look to be the original set which at 100k miles is probably due (or overdue) for replacement anyway. Battery too for that matter appears to be original.

Is it really any surprise I've spent more on servicing/repairing/upgrading the car than I did buying it, in the last 4 weeks?