hi people i need some expert help.
i have had this little prob for a month now its on my97 uk turbo standard. i will explain it as best i can and i am hopeful that your expertize can help me fix this, right here goes- i have a very faint hesitation problem that only occurs under light throttle between 2-4k rpm. i feel it miss/hesitate slightly but as soon as i put my foot down its fine and this does not happen at all. it seems to happen mostly as i pick up speed steadily. when i put my foot down the car pulls as it should n boosts fine under load but as soon as i drive it steadily the hesitation happens.
to date i have changed the following to try and rule this problem out
new maf, new plugs (spaced correctly),new fuel filter, cleaned boost solenoid, cleaned icv,checked all the necessary pipes for leaks, also looked in header tank no signs of oil, no gunk in my oil ,fuel pump still priming loudly when i turn the key..
i am at my wits end with this 1 ,ive heard of smiler probs of this happening in the rain and mostly under boost, but mines different.
just before the prob started i pulled up 1 day and i could hear the boost solenoid clicking away loudly(as if in ecu reset mode)with the engine still on which never happened before then i shut the engine off and i heard the clicking again, then the revs got a mind of there own for a few days so i changed the maf and still nothing. could i need a new boost solenoid or a knock sensor, i just dont know . please all you knowledge is much needed. thankyou to all who read thisp.s ive tryed ecu test no fault codes

 

what about your lambda sensor mate?

 

ecu reset? try manual boost control see if it does it then

 

this is one thing i have not change as of yet, can it course these symptoms if its on the way out then. and it is located just behind the turbo on the neck of the down pipe? thanks

 

yes i have done an ecu reset mate and still the same. "manual boost control" how do i go about that.? cheers

 

yes it can mate.and yes it is located in the down pipe behind turbo
Are you running a standard airbox or cone filter mate?

 

standard air box with k+n replacement filter.

 

It could also be throttle position switch or coolant sensor,id get a emission read out mate as it could be running rich/lean and that is what is causing the hesitation.

 

also the other day i replaced the pipe that contans the brass pill coming from boost solenoid to turbo an in let manifold as i broke it whilst cleaning n checking. anyway changed it for diffrent pipe put the pill `back in and it now boosts to 20psi instead of the normal 12-15psi . the car has a abc chip wired into the ecu(noticed it last week)and i know this would eliminate fuel cut and give it slightly more boost but why would it jump upto 20psi just from replcin a bit of pipe. the pipe i replaced with is slightly smaller inside but the pill fits snug and aint moved ?????????????

 

how much smaller inner diameter is the new pipe and is the pipe the same length as the old one?

 

i will go see if i the garage will check the emmisons for me tomoz as i think it is running bit rich, and if it is running rich what should my next move be or should i say part cheers again

 

id say if the emissions are out then its possibly the coolant sensor giving wrong readings to the ecu mate

 

Replace the pipe with a proper item from Subaru, they only cost a few quid! With regards to the hesitation problem. No one has yet mentioned leads or the coil pack. That's where i'd start next.

 

only very slightly smaller inside compared to the old 1, and it is abit longer in places as i cut it all to size myself and coz the old one was so brittle it just went into small bits. i have a 2 port and where the pipe comes from the bottom and goes to the T then off to turbo n inlet well the piupe work after the T is what i changed.

 

leads and coil would have a tendency of braking down under load not on light/constant throttle,not always but mostly.

 

i have looked at the leads and they seem ok. how do i know if there dud same with the coil pack ?????

 

thankyou for the advice on this, i will get a emissions test tomorrow and see what it reads if it is out i will try replacing the coolant sensor and see how i get on thanks again

 

no worries let me know how you get on mate

 

These motors are particularly sensitive to the spark and a poor spark could be the cause here. It's worth checking out.

To rectify or eliminate I'd change both items for new.

 

Me to tbho but its the cost for most.

 

could i suggest taking it to a subaru specialist?

 

John mate, are you de-catted? If so emissions will be high whether theres a fault or not.
A good sign of a fluffed lamdba is bad mpg.

 

HI STEVE, no i have not yet got round to fitting my de-cat down pipe or the up-pipe , but its on the to do list. this little issue has to be rectified first before i start anything else. i also have a japspeed second de-cat straight through section on the way.
i have noticed she uses abit more fuel than normal now you mention it, and also i have noticed when i let off the throttle to slow down the engine braking is not as good as it was, so could, or is this down to a faulty lambda sensor ????

 

Easy way to test the lambda John, is to put a multi-meter to the signal wire, either the ecu end (pin-outs alailable on JGM's site) or find the connector in the engine bay, near the air-box and BCS assemby. It should flick continually from 0.1 to0.9 volts, if it just sits around and does not fluctuate wildly then odds on you need a new one. Free and quick

Failing that, get to the MOT station and ask them for a emisson check, if your cats are good and it fails, then lambda it is.

 

[i did drop in the garage but they where flat out today with mots so i am going back tomoz to see if i can get the emmisons checked out. i will have a rumage in the garage as i did have a multi meter but cant say ive seen it for a good few years. cheers again steve[/I]

 

id the same problem. changed plugs, leads, MAF, ECU Reset... still no joy

turned out to be a gummed up boost solenoid. cleaned out with carb cleaner in one end and out other. sorted

there is a guide on here for it also

 

that is a good point as i did hear it clicking away whilst i waS parked up with the engine running and revs went abit mad, and that was just before the problem started really. i did try cleaning it out, and got side tracked half eay into it as i went n broke a few pipes that connet to the b.solenoid as they where really brittle, so replaced them. i will give the boost solenoid a real good clean this time round as it cant hurt. cheers