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Discussion Starter #1
Hey guys! I need your help!
So, I swapped the heads on my buddy's 2000 2.5 rs due to a spark plug hole being stripped. The heads he gave me were decked and OEM headgaskets were used. I set valve lash and torqued everything down properly.
I start it up and its idling good, go to rev it up and it kinda hesitates then smoothens out. I hold it at 3k RPM and its smooth for 5 seconds then starts chugging like its gasping for air. Problem gets worse the warmer it gets. It is pulling up 2 codes but no misfire codes, 1 is an evap and the other is an idle control code.
85225

I naturally checked the timing belt and redid it 8 times. The last 4 I made sure I counted the teeth between the crank and each cams. Got about 47 on passenger and 43.5 on driver.
85221
85222
85223

I checked both main grounds, i checked wiring harness for bent pins or broken wires, i cleaned cam sensor surface and connectors for cam and crank sensors. I made sure fuel injectors connectors were nice and tight. I replaced the wires and regapped the NGK spark plugs( to .040). I even replaced the Neutral Switch with one from the junkyard because I read that it could cause misfires and hesitation. I sprayed brake cleaner around manifold gasket and vacuum hoses for leaks and had no change in idle. I compression tested and got about 150-155 all around.
I am stumped. :mad: Could it be a fuel pump giving out, slightly bent valves or coil pack? Any help would be appreciated!!!
 

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www.jackstalk.com
‘98 RS, 911 Cab, CT6 TT, Escalade ESV
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5,625 Posts
Also, in the future, you can sleeve a spark plug hole with minimal tools and insert a new threaded piece. It's a ton easier than I thought and only took an hour or two to be back up and running.
 

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Discussion Starter #4
Thanks for the replies. I gave my buddy the option to do that but he did not want to go through with it.
I have not replaced the idle control valve yet, as I didn't think that it would mess with the car under load/cruising engine speeds. Ill do that next
 

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01 Impreza 2.5RS, 95 Civic VX
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You plug wires may got damage during removal. Check it with multi meter
 

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Discussion Starter #6
Alright so I fixed it. It ended up being the Throttle position Sensor. It was not calibrated correctly and giving me that misfire under load/acceleration. I stuck a probe into the white wire on the TPS with the engine on and moved the TPS until I got .500 volts. I did however clean the MAP, IACV, change wires, re-gap spark plugs to .040, check timing marks, swapped coil. These misfires are horrible to figure out because tons of components can cause the same issues but hopefully someone can read this and fix their problem. Thanks for everyone that commented! Got another RS back on the road!
 
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