my00 stuttering under load
 

parents bog standard FSSH my00, 43,000 miles, driven "carefully".

the car is "mis-firing" under load. if you accelerate moderately without booting it, it will pull cleanly to the red line. if you put your foot down slightly more vigourously then it develops a stutter. not a head through the windscreen boost cut but a definate stutter. i am guessing this is a mis-fire.

the stutter occurs as soon as the boost comes in and as i say you can drive through it with a little caution on the throttle. if you pin the throttle it seems to stutter more and build revs much more slowly than if you took it more easily. it is more apparent in higher gears.

i have changed the MAF to a known good one and reset the ecu.

i have also cleaned the boost solenoid out using the 2 green plugs and carb cleaner (no brake cleaner available). it clicks freely and i also sucked/blowed though the pipes that connect to it and they seemed fine. the car hasn't been serviced for a couple of months and the oil level was mid-way between holes (same as when i checked it 6 weeks ago).

it is a "bit better" (i did not drive the car pre changes so this is my dads guestimate) than before but still not right - very noticeable at 3k when you have load on the engine.

the plugs in the car were changed at a main delaer service (according to the receipt - 16,000 miles ago).

what would be the next avenue?..

so my next thinking is ignition. i have a set of plugs to try (ngk 6s) and also a spare coil pack. i have checked all the leads are on the coil and firmly on the plugs.

any other ideas?

thanks

and i was going to tell you to loose some weight.


edited to say sorry for not being helpful

i had a problem the same, subaru replaced my coil packs which solved the problem
(went at about 50k) sometimes you can take the coils out and pull the rubber off the end of them and u can see wer they have cracked which causes them to short to earth other times they breakdown internally which you cant c,

it will cost you about £60 per coil pack

i have a spare coil (the my00 has a single coil on top of the engine). so i can try this easily - i ran out of time last night. i think this single coil pack is pretty reliable tho.

Are you sure it's getting fuel in properly (dodgy fuel pump / blocked filter)?

Check the oil level. Must be between the marks even when hot. :)

I think you'll find it's got too much oil in...

checked the oil - it is spot on. the boost solenoid clicked freely even before applying the carb cleaner and very little "oily residue" came out of it. the car hasn't been serviced for 3 months and this problem has obly just started. the car hasn't had any oil top ups either.

the fuel filter is a possibility, but it is more of a misfire than a general fuel starvation.

keeping the boost at low levels (no gauge) down the car drivers perfectly. accelerate a bit harder and it starts to miss at about 3000rpm. i accelerated up to 80 (km/h ;) ) using reasonably throttle and it pulled cleanly to the red line but give it a little bit more throttle and the miss starts up. it isn't boost cut - it is no where near that violent.

will try the leads off my my99 and the spare coilpack before i attack the plugs.

I got something with similar symptoms which is related to damp - it only occurs when the car is cold and is fine when warmed up. Giving the leads a good coating in damp start or WD40 (and the distributor cap) usually sorts it.

got around to changing the plugs today and that solved the problem.

:)

Bringing up an old thread :norty:

How does overfilling with oil affect this problem?

Too much oil in the sump results in large amounts of it being ejected out of the crankcase and head breather system, through the turbo and up the boost control pipework, from where it can interfere with control of the wastegate and lead to overboost - and, if you overshoot the boost target by a sufficient margin, fuel cut.