EJ20G swapped but having starting/misfiring problems

Heads, valves, pistons, rods, crankshaft, etc...

Moderators: Helpinators, Moderators

Post Reply
fatgc8
First Gear
Posts: 214
Joined: Fri Dec 19, 2008 5:48 pm
Location: Phoenix

EJ20G swapped but having starting/misfiring problems

Post by fatgc8 »

Alright guys so some of you already know i went ahead and swaped a 97 ej20g motor in my 91 legacy ss. I went ahead and used the full harness of out of the ss and merged it in the ej20g motor. This was fairly simple since most of everything clipped right in without changing pigtails. It runs really great and im very happy with the swap. However, on start up the car takes forever to start usually about 8 seconds and when its really cold its about 15 seconds of holding the key on the start position (yeah i know its bad for the starter). Anyways so once it starts its usually fine but when it warms up to full operating temperature it misfires on idle? I will be stopped at a red light and it will misfire consistently. I usually hold my foot down on the brake and hold it to 1k and it stops misfiring.I am now wondering if this could be a ecu problem? My question for everyone is how would i fix the long start up and idle misfires? Here is what i already have done to try to solve the problem..

Leakdown was 0% on 1,2,4 cyl and %1 on the 3rd cyl
Compression test was 140,140,138,140

-Cleaned IAC
-New coolant temperature sensor
-New plugs (ngk)
-New coilpack
-New cam angle sensor
-Injectors are in the process of being professionally cleaned and balanced (stock ss injectors)
-New fp
-Used but in good condition tb with tps sensor from a 92 na legacy
2005 STi (500WHP with "SlowSTi" as the license plate lol (Weekend Warrior)
1991 Legacy ss JDM EJ20G swap with STi goodies (DD)
Legacy777
Site Admin
Site Admin
Posts: 27932
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: EJ20G swapped but having starting/misfiring problems

Post by Legacy777 »

You mentioned most stuf "clipped" right in. Are you sure all the pins in the wiring were the same?
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
fatgc8
First Gear
Posts: 214
Joined: Fri Dec 19, 2008 5:48 pm
Location: Phoenix

Re: EJ20G swapped but having starting/misfiring problems

Post by fatgc8 »

Legacy777 wrote:You mentioned most stuf "clipped" right in. Are you sure all the pins in the wiring were the same?

Well the only thing that didnt clip in was the cam angle sensor so i ended up getting a pigtail and soldered it in.
2005 STi (500WHP with "SlowSTi" as the license plate lol (Weekend Warrior)
1991 Legacy ss JDM EJ20G swap with STi goodies (DD)
SLODRIVE
Third Gear
Posts: 662
Joined: Fri Nov 21, 2008 1:27 am
Location: Colorado, north of Highway 52
Contact:

Re: EJ20G swapped but having starting/misfiring problems

Post by SLODRIVE »

A couple of things that won't hurt to check out:

-Make sure there's no vacuum leaks. Triple-check all hose connections and check the intake manifold/TB gasket areas while idling.

-Clean your MAF with the proper stuff.
http://www.slodriveracing.com
-92 SS 5MT- EJ20H swap, Haltech standalone ECU, TD04, FXT TMIC, 3" exhaust, STi/AGX struts, JDM 5-speed, 4.111 LSD rear, Blitz EBC, etc.
-'93 L Wagon - Pink Roll Cage - "Dirty Leg"
-And more!
fatgc8
First Gear
Posts: 214
Joined: Fri Dec 19, 2008 5:48 pm
Location: Phoenix

Re: EJ20G swapped but having starting/misfiring problems

Post by fatgc8 »

SLODRIVE wrote:A couple of things that won't hurt to check out:

-Make sure there's no vacuum leaks. Triple-check all hose connections and check the intake manifold/TB gasket areas while idling.

-Clean your MAF with the proper stuff.

Cleaning my maf wouldnt be such a bad idea.. Ill go ahead and try it and let you guys know how it worked out..
2005 STi (500WHP with "SlowSTi" as the license plate lol (Weekend Warrior)
1991 Legacy ss JDM EJ20G swap with STi goodies (DD)
Post Reply