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Old 09-04-2007, 09:21 AM   #1
Patman015
Scooby Newbie
 
Member#: 106542
Join Date: Feb 2006
Default MY02 built Hybrid: Please help!!!

Hey all,

I recently spent about a year building my 2.5L shortblock with 2.0L heads. Once I got her up and running, the engine seems to stumble at idle and has a dead misfire. I have driven the car about 1200 miles to see if the misfire would disappear and have taken the car to Agile Auto in Fallston, MD to have it tuned to see if that would take care of the misfire as well. Hill would not tune the car because it is not firing right and has low compression of 80psi on cyl #1 and #4. I have done almost everything I can think of to fix this misfire and to no avail. I need help on this one as I don't want to scrap the engine and start over. I have spent alot of money on this thing and just want it to run right. Here is my current setup:

World One Stage 2 2.5L Shortblock with forged pistons (stock compression)
2.0L heads with PNP and o-ringed compression chamber
1mm oversized valves
GT30R .63AR Turbo Rotated with the Perrin Kit
Gruppe-S spec header
Perrin FMIC
LINK Standalone EMS (not sure which generation LINK)

Any ideas? Do cams with bigger valves have to be timed differently than stock?

cyl #1 has 80psi, #2 has 150psi, cyl #3 has 150psi, and cyl #4 has 120psi.
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Last edited by Patman015; 09-04-2007 at 09:30 AM.
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Old 09-04-2007, 11:10 AM   #2
Precision Tuning
Former Vendor
 
Member#: 38696
Join Date: Jun 2003
Chapter/Region: Tri-State
Location: Lakewood, NJ
Vehicle:
2002 WRX
White

Default

Quote:
Originally Posted by Patman015 View Post
Hey all,

I recently spent about a year building my 2.5L shortblock with 2.0L heads. Once I got her up and running, the engine seems to stumble at idle and has a dead misfire. I have driven the car about 1200 miles to see if the misfire would disappear and have taken the car to Agile Auto in Fallston, MD to have it tuned to see if that would take care of the misfire as well. Hill would not tune the car because it is not firing right and has low compression of 80psi on cyl #1 and #4. I have done almost everything I can think of to fix this misfire and to no avail. I need help on this one as I don't want to scrap the engine and start over. I have spent alot of money on this thing and just want it to run right. Here is my current setup:

World One Stage 2 2.5L Shortblock with forged pistons (stock compression)
2.0L heads with PNP and o-ringed compression chamber
1mm oversized valves
GT30R .63AR Turbo Rotated with the Perrin Kit
Gruppe-S spec header
Perrin FMIC
LINK Standalone EMS (not sure which generation LINK)

Any ideas? Do cams with bigger valves have to be timed differently than stock?

cyl #1 has 80psi, #2 has 150psi, cyl #3 has 150psi, and cyl #4 has 120psi.
You need to do a leak down test to see where you are loosing compression. Do a leak down and figure out where the air is escaping from. It could be a piston issue, a valve issue or a head sealing issue. A leak down should give you the answer.

Rich
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Old 09-04-2007, 02:24 PM   #3
Patman015
Scooby Newbie
 
Member#: 106542
Join Date: Feb 2006
Default

I don't have a leakdown tester and none of the techs I work with at my dealership have ever had a reason to own one (it's just R&R here). I performed a wet compression test on cyl #1 and the compression raised to 110-115psi. The questions are:

-The raise in the compression during the wet compression test-is that enough to worry about rings? Did they not seat right during break in?

-Is there a spec for compression on high performance hybrid 2.5L engines like this?

-Since the compression raised during a wet compression test, is it 100% sure that it's just the rings that are making the cylinder lose compression?
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Old 09-04-2007, 09:18 PM   #4
Precision Tuning
Former Vendor
 
Member#: 38696
Join Date: Jun 2003
Chapter/Region: Tri-State
Location: Lakewood, NJ
Vehicle:
2002 WRX
White

Default

Quote:
Originally Posted by Patman015 View Post
I don't have a leakdown tester and none of the techs I work with at my dealership have ever had a reason to own one (it's just R&R here). I performed a wet compression test on cyl #1 and the compression raised to 110-115psi. The questions are:

-The raise in the compression during the wet compression test-is that enough to worry about rings? Did they not seat right during break in?

-Is there a spec for compression on high performance hybrid 2.5L engines like this?

-Since the compression raised during a wet compression test, is it 100% sure that it's just the rings that are making the cylinder lose compression?
More than likely it is a ring issue. You should really get a leak down test though. The tool isnt all that expensive, and even in an R&R shop it helps to know what went wrong so you can properly make the repair. If you have the ability to use it, the tool costs about what having someone else to the test would charge.


Rich
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