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Boost problems at motorway speeds?
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Old 24 Apr 2005, 04:46 PM   #1 (permalink)
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Boost problems at motorway speeds?

Has anyone got any ideas on what would cause boost problems at 70mph+??

I've been driving it this weekend and after an hour or two I put my foot down, the boost pressure goes upto 1bar, then drops to 0.5 bar, does this a few times and then seems to settle into just under 1bar :?

Its a 99my uk turbo
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Old 24 Apr 2005, 09:18 PM   #2 (permalink)
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Could be a few things mate.

However my first port of call would be the boost control solenoid. These can become contaminated causing fluctuations in boost / low boost over boost etc. Has the car been recently serviced ?
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Old 25 Apr 2005, 06:37 PM   #3 (permalink)
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Cheers for the advice nelson!

I've cleaned out the boost solenoid valve and vac pipes on turbo and all seems to be well at the mo. I'll find out for sure next time i go on a long drive
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Old 25 Apr 2005, 10:20 PM   #4 (permalink)
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If the solenoid keeps playing up mate then do what I did and buy a new one - honeslty its not worth messing about with it too much.

I cleaned it countless times and it would just get worse - so I bit the bullet and got a new one from the dealers

I hope you have sorted yours though 8)
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Old 27 Apr 2005, 07:04 PM   #5 (permalink)
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It played up again a bit tonight, was fine for a while blatting around the country side, then after a roundabout it wouldn't let me go above 0.5 bar boost. Think the full decat might be causing problems ?? Re-map needed i think but havent got 800 lying around after just buying the car

I'll try the boost solenoid once more and if that cures it i might get a manual boost controller to replace the solenoid, i've heard a few good reports about them
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Old 28 Apr 2005, 02:03 PM   #6 (permalink)
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i had this the other week it would only give me 7 psi and it turned out to be the maf :roll:
cheers kirky
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Old 28 Apr 2005, 10:55 PM   #7 (permalink)
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Yes it could be the MAF - have you checked the ECU for fault codes ?
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Old 29 Apr 2005, 04:04 PM   #8 (permalink)
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No not yet.

Has anyone got a link to the instructions on how to read codes.

I remember seeing it somewhere before i bought it but cant find it now. Is it something like connect the green wires together, ign on, foot on accelerator for 2 secs bla bla??
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Old 29 Apr 2005, 07:25 PM   #9 (permalink)
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Heres the thread:
http://www.subaru-impreza.org/subaru...ight=ecu+reset

Here your fault code list:

http://www.saxonfields.freeserve.co....iag%20Page.htm
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Old 29 Apr 2005, 08:08 PM   #10 (permalink)
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Cheers dude!

I'll check it tomorrow and post my results up. Think i'm going to for a new maf anyway just to be safe... and maybe a bltiz stainless induction kit
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Old 30 Apr 2005, 02:42 PM   #11 (permalink)
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All sorted, i think!

Went for drive this morning to the nearest scoob dealer, most of the way there it didnt go above .5 bar, it had got worse! Picked up a new maf and fitted that, then took it for a drive, but it was still the same. Then i decided to check codes, and i think there was none set, the engine lamp just flashed on and off regularly. After checking for codes i've done an ecu reset and its been ok since. Seems to drive better 2 now, before it was a litlle lumpy on acceleration when not on boost, now that appears to have gone

Cheers again for all the advice guys :jump
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Old 30 Apr 2005, 03:36 PM   #12 (permalink)
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Nice one, Well done Hope your probs are sorted and that car is running as it should
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Old 30 Apr 2005, 10:44 PM   #13 (permalink)
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HA HA!

Guess what. Been out for a spin again tonight and it would not boost above .5 bar again for a while! Is it that i'm not giving t enough time to warm up?? I normallly wait until the temp gauge is nearly half way up.... Is boost even governed by the ecu until a certain temp is reached??

Starting to really bug me now as to what it causing this
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Old 01 May 2005, 07:49 PM   #14 (permalink)
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Anyone got any more ideas??

Gonna take it for a remap soon if no-one has got any more ideas of what it could be. Sent andy forester a pm and he's given me a good quote for a remap!
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Old 02 May 2005, 06:27 PM   #15 (permalink)
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Quote:
Originally Posted by Mr_Wid
HA HA!

Guess what. Been out for a spin again tonight and it would not boost above .5 bar again for a while! Is it that i'm not giving t enough time to warm up?? I normallly wait until the temp gauge is nearly half way up.... Is boost even governed by the ecu until a certain temp is reached??

Starting to really bug me now as to what it causing this
I am not sure on your problems mate to be honest - boost solenoid / MAF / Plugs and O2 Sensor are the ones to watch for You have followed all the correct procedures and as you are not getting any fault codes then I am not sure what to suggest However one word of advice - Don't go on the temp gauge before you use boost.....the water temp gauge goes up pretty quickly but this is not Engine Oil temp. This can take considerably longer I'm afraid. I tend to drive the car off boost for about 15 minutes and or 5-10 miles (this allows the oil to come up to normal opertating temp before I am bit heavier with the throttle)
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