'96 Impreza Overboost cut

[Guest]

Hi, another overboost question...

My 96 Impreza (Gravel Express) gets an overboost cut (I'm assuming that's what it is) if I go to full throttle at 3k rpm in 5th gear. It will cut once or twice then runs OK above 4k. Above 4k the acceleration is good to begin with but then fades slightly and will come back on then fade repeatedly as the revs increase, nothing dramatic, I can just feel it surging slightly. I think the car has a freeflow exhaust (how do you tell for sure?) and muffler (nice rumble), otherwise standard. I don't have any cel showing up when it cuts.

Any suggestions on things I can check?

Cheers,

[QRAF]

have to taken it to a garage 1st?

but thing i would look at would be your afm also have you checked your computer to see if it's flashing up any fault codes?

any smoke when boosting if so what color?

how many kms has it done too?

[Guest]

Not taken to garage yet, nearest one that does suby's is an hours drive from me.

Not checked codes, would codes be logged if there's no cel? I'll check anyway.

Never had any smoke from the car, if there is it's not been enough to see in the mirror anyway.

It's at 230k's.

[Guest boostin]

Have you actually checked the boost pressure??

[QRAF]

check your sensors mines done 220k and thats what i'm finding is the sensors are going e.g 02 sensor and knock sensor.

do you have a boost gauge? not very expensive from repco and not hard to fit either helpful hints in the DIY section.

my car had a hard out surge from the 02 sensor playing up (well thats what the check engine light said) replaced that and it went slightly away i could still feel it on my bum o'meter(my seat) a surging feeling around 3k just before boost comes on so i changed the spark plugs, leads and fuel filter which made the problem go away for a little while but its back now.

I think its just because i'm the driver i feel it more as i've done the km's i've been told to take it to a auto electrician but i have to find the time, like you say

were are you located?

[Guest]

Thanks for the replies.

No, I don't have a boost guage, I'll have a look see at fitting one. I've had the spark coils checked about a year ago and had one replaced then. At this stage I'm gona see if there are any stored codes and after that disconnect the batt to see if a reset will have any affect.

I'm near 'Kune, so miles from anywhere, haha.

[DRFVDR]

And i am in raetihi

and I have a spare boost guage lying around and of course knowledge (not sure if it any help though)

Oh a gravel express

red

Dave green ????

[QRAF]

 daveymg said:

Thanks for the replies.

No, I don't have a boost guage, I'll have a look see at fitting one. I've had the spark coils checked about a year ago and had one replaced then. At this stage I'm gona see if there are any stored codes and after that disconnect the batt to see if a reset will have any affect.

I'm near 'Kune, so miles from anywhere, haha.

disconnecting the battery won't reset the computer you need to get under your dash you need to follow this post

http://homepages.ihug.co.nz/~ccgrant/celcheck.htm

[Guest keltik]

Sounds like a dodgy wastegate duty solenoid to me. Had the same problem on my mums old volvo, Surging under boost.

[Guest]

 DRFVDR said:

And i am in raetihi

and I have a spare boost guage lying around and of course knowledge (not sure if it any help though)

Oh a gravel express

red

Dave green ????

Cigar 4 Daz!

[Guest]

 QRAF said:

disconnecting the battery won't reset the computer you need to get under your dash you need to follow this post

http://homepages.ihug.co.nz/~ccgrant/celcheck.htm

OK, thanks QRAF, will give that a go.

[DRFVDR]

I can come have a look if u like

[Guest]

 DRFVDR said:

I can come have a look if u like

Yeah, would be good. Is it poss to do a temp install of the boost gauge or does it need hoses to be cut?

[DRFVDR]

yup it easy to do a temp install

I will try and get out over weekend

will pm u my number

[Guest]

I checked for ecu codes and it came up with code 23 which is air flow sensor. I did the ecu reset but still got the engine cut in the same way.

So, is it airflow sensor replacement time or is there any kind of cleaning I can try?

[QRAF]

best to replace

[Guest]

I checked the ecu error codes again this avo as the engine is still cutting but all I got was a steady flashing on the cel which I'm assuming means no error codes stored?

If it does, that means that whatever is causing the cut isn't being treated as an error condition.

Frustrating.

[Guest keltik]

Leaky split wastegate acutator/hose?