wanted

I bought the car running rough and have replaced what i can think of within reason. Car now ticks over nice, engine sounds good (no knocking) but has bad stutter/hesitation at 4k-4.5k revs.
I have changed/replaced

Plugs
maf
fuel pump
belt/tensioner (timing was out)
downpipe (was leaking)
Dump valve
Most pipes changed/uprated

It's got a cheap looking front mount intercooler on it and i'm thinking that it may be leaking?
If it is would it cause the stuttering.

Any suggestions would be a big help

Splitpin

The cheap looking front mount is probably doing more harm than good but may not directly be causing your problem (although it won't be helping). Do you know whether the car was mapped properly after it was fitted?

If the standard airbox and induction tract has been removed and replaced by a cone to facilitate the fitting of the FMIC, and the car hasn't been mapped, then this may well have a direct role in the misfire, although there are plenty of other potential causes so you have to decide whether you're going to continue to chuck money into a process of elimination, or get the car looked at by someone who'll be able to pinpoint the problem immediately.

If you can get hold of standard induction parts and intercooler and can swap them in yourself it might be worth trying. However, probably the most constructive suggestion at the moment is to take to a specialist. It'll be easy for them to identify the cause of the problem. Driving round with it in the meantime isn't a particularly good idea. If the "stutter" is caused by airflow sensor misread, the consequences won't be good for the long-term health of the engine.

Devious

iTrader: (4)

knock sensor?

wanted

Hmmm yes it has aftermarket induction and i have no idea if it's mapped. I was kind of thinking the same about taking it somewhere, I was just wondering if i had missed something obvious. It's not being driven it's in bits, only been test diven with no bumper, lights etc.

Hadn't thought of knock sensor, i'll swap it tommorrow.

Turbotits

iTrader: (2)

Trouble is you could just keep changing things and it may be the mapping and all sensors are ok.

Lambda's another posibility

how much money do you want to throw at it? and then may still need a map> mind you everything will be new lol

sy.

iTrader: (8)

scrap that lambda has no effect once car is on boost!!

Turbotits

iTrader: (2)

i agree but he doesnt say on boost he just says 4 to 4.5k. but its the point thats important you could go on for ever coil packs,leads dependand on year of car etc. etc.

wanted

It is on boost when he problem starts.You guys are echoing my thoughts about going on forever, had a chat with a well known scooby specialist that i have known for a number of years and they have said i can take it up there and find a corner to work in so i can swap parts without it costing me anything, and when i find the one that works i'll pay for only that. I think i'll try a top mount inercooler first and failing that stick it on the rollers.
The only reason I haven't gone to them first is cost of labour and time waiting to get booked in, I may aswell try the obvious possibilitys on mine and my mechanics time before handing it over to the rolling road. most of the parts i have swapped up to now, i would have changed at some stage anyway but now it's come to intrcoolers and/or mapping it may be more cost effective to let them at it

Splitpin

No.

It may be that you have missed something obvious. As we're not exactly in a position to stare over your shoulder, or look at your car ourselves, we can't exactly tell you!

Not really worth it. A failing/failed one won't cause the car to miss or stutter in the way you've described. Take the sensor off and check the resistance if you want - should be around 555K, no lower than 530K, no more than 590K - and obviously not open circuit, but this is just for academic purposes to assure yourself it's functional.

Why is a Subaru specialist suggesting you carry on a "blind" process of elimination? If they're set up to work on these cars they'll have a Select Monitor or an emulator like DeltaDash, if not You'll be able to see very clearly what's going on by logging the car on the road. Pretty much all the common causal issues will rule themselves in or out within seconds.

If they've got diagnostic kit, ask if they can use it.

Incidentally, can you describe this "stutter" in a bit more detail? Does it happen in all gears, for example, or just 5th/4th (or is it worse in the higher gears)?

wanted

My mechanic can use Delta Dash so I was going to borrow theirs and take it out. They didn't suggest i carry on "blind" I just haven't picked their brains properly yet ......but i will.

It's in all gears at same revs on boost. Drives fine off boost although i haven't tried going that high in the revs off boost yet. Ticks over fine (afer the timing was corrected) Doesn't drive through it easily but will. It could be described as a massive flat spot but stutters whilst in it.

wanted

Ok, drained the oil last night and put pro s in it today. Took it out and problem gone?, now i've got a new problem.

After hard acceleration, change gear and i've got a big flat spot for a second then it's fine. It does this after every gear change if i've accelerated hard. doesn't do it with normal driving.