background information:
2002 wrx 2.0litre (stock except for fuel pump, grimmspeed ebcs and k&n short ram filter kit)

Since changing my inlet pipe (from maf to turbo) i have been having an idling issue. i have cleaned the iacv and replaced the gasket and still no luck.
what it does is run smoothly, hits full boost (tuned for 19.4psi) and idles ok. however especially when its cold (more noticable) if i drop the clutch to change gears or to come to stops etc. the rpm's sometimes drop to 200/300rpm and then back up to 750 odd rpm. when the car is warm its much less noticeable and the car runs perfectly fine.

what i want to know is if my maf is ok (included a video) and a video of the rpm dropping.

does anyone have an ideas? i am an "ok" mechanic and can do most things in terms of what you can suggest

should i look at adjusting the tps (when i changed the turbo inlet, the problem started). i didnt fully remove the manifold, i just unbolted it a bit to lift it up to remove the stock one. however i could have accidentally adjusted/bumped the tps. i know i shouldnt have changed the inlet pipe but the stock one had a split in it.

is there anything else i could try? i have checked all my hoses and they seem to be ok and when idling normally the vacuum sits at 18hg which to me seems ok. i never got the inlet pipe retuned and perhaps that could be the problem too, but i dont want to fork out $350+ to redo a tune.

other than that, i cant think of any other problems it could be, i did get a well known ebay inlet pipe (payed about $180) for it. could that be the problem too?

I thank you all for any advice, ive been dealing with this now for nearly 4 months :'( as a final note, the car does hesitate to pull away too and sometimes when hitting boost it feels "bumpy" and a bit hesitant too. seems to have come on since doing the inlet, so could be the tps if i moved it, etc.

cheers guys, have a good easter

Josh

Attached Files

	maf testing.zip (3.41 MB, 4 views)
	rpm dropping.zip (1.58 MB, 5 views)

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2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

K and n filter the oil on them kills afms

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363hp and 499.5nm
gtps03 turbo on 98ron BP
2012 Wrc Blue Wrx Sti R spec (ARGH SPEC)

You have an air leak between the MAF and the turbo - it won't show up on your boost gauge.

The hesitation you are feeling is the motor running lean (sucking unmetered air) - DO NOT boost it until you find the air leak!

Double & triple check the bov recirc hose, crank breather returns etc.

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[CENTER][SIGPIC][/SIGPIC][/CENTER]
[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]

i ran it with stock filter and still issues are there

@rossco sorry to sound dumb what is the best way to find the leak? do i need to run the "bubble test" with a squirt bottle that has some dishwasher liquid in it and spray and look for bubbles? or do a pressure test for a vacuum leak/smoke test etc?

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2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

As Rossco said check all hoses my oil breather hose had a split a few months ago on the underside couldn't see it and had simalar problem .They perish go hard and split.

Sent from my GT-I9505 using Tapatalk

could it be that after installing inlet pipe and reinstalling the maf that its now not in the same position it expects it to be, i know they are quite sensitive in terms of where they are located on the pipe?

So basically you all think its somewhere from the maf to the turbo and check all the pipes running off the main inlet pipe? hope its not the oil breather pipe as only had it replaced a couple of months back.

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2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

And if any of you watched the clip, the maf is ok right? Sorry to ask so many questions

using the Perth-WRX mobile app

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

Josh, as your on the suction side, you wont see bubbles from the leak.

using the Perth-WRX mobile app

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Race Torque Dyno 399 NM, 248Kw @ 20PSI

Straight roads are for fast cars, twisty roads are for fast drivers. I have or am neither.

http://tttmsp.smugmug.com/

Best way to test as its vacuum side? Do the leak test with a compressor and see if air leaks?

using the Perth-WRX mobile app

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

Buy a can of carby/throttle body cleaner.

Clean the MAF sensor with it.

Start car - win?

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[CENTER][SIGPIC][/SIGPIC][/CENTER]
[CENTER][COLOR=#ff0000]Built Ej207: Semi-closed RA Cases - Wiseco Forgies - Manley rods - BC 272 cams - GDA Heads - billet f/whl - Vi-pec - WbO2 - 800cc Yellow tops - TD05-20G - 409Hp ath @ 1.75bar on E85[/COLOR][/CENTER]