Welcome to the North American Subaru Impreza Owners Club Monday August 21, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo)

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Thread Tools Display Modes
Old 02-22-2008, 04:20 PM   #1
Scooby Newbie
Member#: 69959
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Madison, WI
02 WRB Impreza WRX
03 Dodge SRT-4

Default Shuddering on acceleration


I recently put my engine back together after doing a bunch of upgrades. Now, it seems when accelerating past 4k the car will start to shudder and push back. I recently did a bunch of upgrades including the XPT 2.5 map although I donít believe this is a tuning problem since the logs look fine. I think this is something mechanical which is also what XPT told me.

The first time I tried to log the car threw 4 CEL's:
P0102 Mass air flow sensor circuit low
P0328 Knock Sensor 1 circuit Malfunction (high input)
P0303 Cylinder 3 Misfire detected
P0113 Intake Air Temp Sensor Circuit malfunction (high input)

Here is a list of my mods:
3" A'Pexi GT Spec Cat-back
BPM Turbo Inlet Pipe
3" Helix Down Pipe
Ported & Coated Intake/Exhaust Manifolds
STi "pink" Injectors
STi Up pipe
VF39 Turbo
XPT Stage 2.5 Map

Last weekend I visually checked for vac leaks and double checked clamps. I also cleaned my plugs and maf. I noticed that my plugs had a lot of carbon build up on them for only having 200 miles. I then took the car for a test run and it only shuddered once and ran beautifully after that.

Then about 3 days later, the symptoms came back. This time only one code which was detected cyl 4 misfire. I have yet to take the plugs back out, but im sure they are full of carbon again.

Does anyone know what would be causing these symptoms or the plugs to keep getting fouled? The car is running at a conservative mid to low 11's at full throttle. It was also suggested that fuel pump might be a problem. The last log I have does show it being at 100% between 3500 - 5k rpm.

I plan on trying to make a vac tester this weekend, but Iím not so sure the problem is vacuum related. I'll post up my last log tonight.

Thanks for your help,

Here are the links to the logs. In both logs, the shuddering started around 4500rpm on up

* Registered users of the site do not see these ads.

Last edited by kleen; 02-23-2008 at 09:06 PM.
kleen is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 02-23-2008, 03:00 AM   #2
Scooby Specialist
Member#: 82476
Join Date: Mar 2005
Chapter/Region: AKIC
Location: Anchorage, ak


it sounds like your running rich enough to choke it out, whats the afr's looking like, nevermind just saw. well if the plugs are all carboned up and fouling out, this is generally do to running to rich. is that afr from a true wideband or from the ecus front sensor cause thats not a good tuning tool using an access port and reading that.
zachary.berrier is offline   Reply With Quote
Old 02-23-2008, 09:07 PM   #3
Scooby Newbie
Member#: 69959
Join Date: Sep 2004
Chapter/Region: MWSOC
Location: Madison, WI
02 WRB Impreza WRX
03 Dodge SRT-4


I added the logs to the original post.

Yah I am just going by the front sensor unfortunately. Im working on finding a deal or trying to borrow a wideband though.
kleen is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Odd Shudder/ thunk on acceleration from stop dobiewrx Transmission (AT/MT) & Driveline 3 04-15-2009 06:24 PM
White/blue smoke on start - blue smoke on acceleration bcblues Factory 2.5L Turbo Powertrain (EJ Series Factory 2.5L Turbo) 17 11-22-2006 12:33 AM
Clutch shudder while accelerating sphinx Warranty Issues & SOA Problems 5 08-07-2002 04:37 PM
shudder on engaging w/ cold engine Sophocles Transmission (AT/MT) & Driveline 7 09-21-2001 01:07 PM

All times are GMT -4. The time now is 04:24 AM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.