Welcome to the North American Subaru Impreza Owners Club Wednesday June 26, 2019
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Pre-2002 Factory Turbo Powertrain

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. 
Reply
 
Thread Tools Display Modes
Old 07-10-2018, 11:50 AM   #1
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default V1 EJ20G High Load/High RPM Cutout

I'm in the process of resurrecting an EJ20G-powered 1987 RX coupe. As I catch up on the two previous owner's deferred maintenance, I've noticed that the car tends to cut out in high load, high(ish) rpm situations. It almost feels like a boost/fuel cut or a rev limiter, but I don't believe it's being caused by those safeguards. This happens after a few WOT pulls through the gears at my low boost setting (10 psi) and pretty quickly at stock boost (14 psi).

I've gone through the fuel system, new 255lph Walbro, new filter & soft lines (original, stock injectors though, waiting for my RobTune to upgrade). I've done the EJ coil-on-plug conversion in preparation for a RobTune, new NGK Iridium plugs (out-of-the box gaps), new green label MAF and I have a new, OEM o2 sensor that I'll be installing shortly.

The problem seemed to improve after the new fuel pump (can make more heat soaked pulls at 10 psi with a couple more pulls at 14 psi before it cuts out).

I spoke with SuberDave, who built the car, and he suggested dropping my plug gap down to .2xx, since he had experienced spark blowout on a similar set up in the past.

What do you folks think? I don't want to install the RobTune ECU and 550 injectors until I've got this sorted out.
* Registered users of the site do not see these ads.
car_freak85 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 07-23-2018, 04:35 PM   #2
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I spoke with SuberDave over the weekend and he suggested keeping the plug gap under 0.030. Any thoughts on that tight of a gap?
car_freak85 is offline   Reply With Quote
Old 07-27-2018, 04:26 PM   #3
contaminatrix
Scooby Newbie
 
Member#: 435611
Join Date: Dec 2015
Chapter/Region: International
Location: Nairobi
Vehicle:
2002 SG5-2.0-XT-JDM
45A, originally 18L

Default

also check your system voltage - ensure it's good
also, one time i had a bad map sensor and it did the same thing - violent cut but car wouldnt go off.
switch map sensor with known working one and revert.
contaminatrix is offline   Reply With Quote
Old 08-02-2018, 11:54 AM   #4
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I installed a brand new OEM MAF only a few hundred miles ago, new OEM o2 sensor is now installed. I'll be re-gapping the plugs this week or next. Also on the hunt for WRX coil packs with the longer boot (I think I have STI packs).

Just take the voltage reading at the end of the coil harness? What should I be looking for, number wise?
car_freak85 is offline   Reply With Quote
Old 08-13-2018, 06:23 PM   #5
wtdash
Scooby Specialist
 
Member#: 59182
Join Date: Apr 2004
Location: N. Idaho
Vehicle:
2002 WRX GG>>
2016 Focus RS

Default

Fixed yet?

The post above is for the MAP not MAF,...if you missed that.

and you've checked for stored codes?

Changing plugs is a PITA on the DOHC so I understand your reluctance. But I don't see why it wouldn't do it all the time if the gap was an issue...I just know if never fixed any of my related issues.

I'd be more suspicious of the coil packs?
wtdash is offline   Reply With Quote
Old 08-15-2018, 11:05 AM   #6
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Pulling plugs on an EJ20G isn't so bad.... if it's installed in a different chassis! (It's in a 1987 Subaru RX: @templeoffuji on IG)

I pulled the plugs on Monday and re-gapped them down to 0.028 in. While I was in there I replaced the plug boots on the coil packs, two of the original boot/spring combos were shorter than the others, despite the all four coil packs having the same part number.

At full, stock boost (14 psi) I was finally able to make multi-gear WOT passes, got the engine good and hot and it still pulled strong, no more power cut!

Where is the MAP sensor located on this engine? Got a part number?

Have not checked for codes yet, but I will do that today.
car_freak85 is offline   Reply With Quote
Old 05-01-2019, 10:14 AM   #7
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

OK, power cut is back...

I parked the car for the most part in the fall (windshield wipers weren't working at the time) and only pulled her out to shake off the dust a few weeks ago.

Nothing has changed with the engine that I'm aware of (Did install the STI high-pressure rad cap), but I'm still getting the same "slam into a brick wall" feeling during WOT pulls. I had a passenger confirm via my ECUDataScan that my "high boost" setting is 13.4 psi (stock is 14), so it's not cutting out due to high boost. When in the "low boost" setting (~ 10 psi) I can do WOT pulls all day long without issue.

Things I've replaced:

New Samco inlet hoses
New OEM MAF
New OEM o2 sensor
New spark plugs gapped to 0.028
Used USDM STI coil packs
New Walbro fuel pump
New OEM fuel filter

Any ideas on what I should tackle next? I found the part number for the barometric pressure sensor, it is still available, but is pretty damned expensive. Not that I have much choice right now

Last edited by car_freak85; 05-10-2019 at 01:28 PM.
car_freak85 is offline   Reply With Quote
Old 05-01-2019, 12:15 PM   #8
wtdash
Scooby Specialist
 
Member#: 59182
Join Date: Apr 2004
Location: N. Idaho
Vehicle:
2002 WRX GG>>
2016 Focus RS

Default

So..did you check for codes? :-)

Also, i had a similar issue (10 years ago...just found the post - in this same forum!): Turned out to be the hose connection from my intake to the TD04's inlet. It was approx. 10" and was too soft to hold up. It was collapsing >@ higher boost<, esp. once the temps and engine warmed up. Replaced it with a shorter 90 and metal pipe and been good to go.

Last edited by wtdash; 05-01-2019 at 12:31 PM.
wtdash is offline   Reply With Quote
Old 05-10-2019, 01:27 PM   #9
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I have NOT checked the codes yet, but as I recall, the EJ ECU is wired up to the CEL in the chassis, so it should light if there is a fault (lamp test works), however I have never pinged the ECU for any codes to date.

Any idea how to do that on an EJ20G?
car_freak85 is offline   Reply With Quote
Old 05-10-2019, 01:42 PM   #10
wtdash
Scooby Specialist
 
Member#: 59182
Join Date: Apr 2004
Location: N. Idaho
Vehicle:
2002 WRX GG>>
2016 Focus RS

Default

Quote:
Originally Posted by car_freak85 View Post
I have NOT checked the codes yet, but as I recall, the EJ ECU is wired up to the CEL in the chassis, so it should light if there is a fault (lamp test works), however I have never pinged the ECU for any codes to date.

Any idea how to do that on an EJ20G?
Hmm. since you're not in the original chassis, are the (single-wire) black and/or green connectors still in the harness you installed?
Like this:
wtdash is offline   Reply With Quote
Old 05-10-2019, 03:18 PM   #11
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I expect SuberDave kept those diagnostic connectors. I'll pull off the trim panel and have a look when I get home.
car_freak85 is offline   Reply With Quote
Old 05-15-2019, 04:56 PM   #12
vica153
Scooby Specialist
 
Member#: 76586
Join Date: Dec 2004
Chapter/Region: RMIC
Location: Denver, CO
Vehicle:
2006 9-2x Aero

Default

Fuel pressure regulator? Partly because its the only fuel system part you haven't replaced yet lol. Not enough fuel pressure at high boost. I would expect that to cause you to run lean and misfire,but not necessarily a sudden harsh cut. Maybe the ECU notices it somehow and cuts ignition.
vica153 is offline   Reply With Quote
Old 05-15-2019, 09:26 PM   #13
binny
Scooby Newbie
 
Member#: 198108
Join Date: Dec 2008
Location: Australia
Vehicle:
MY98 WRX
Blue

Default

Did you check the idle voltage yet? 14v when running and 13.2 off the battery with the ignition on
binny is offline   Reply With Quote
Old 05-16-2019, 03:13 PM   #14
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I'll have to see if I have a fuel pressure gauge handy to check that, I'm sure I can borrow one.

Have not checked voltage yet, but I'm driving the car today, so should be a quick check when I get home.

I have noticed the car occasionally backfires. If revved to redline twice in a row, I can sometimes get the car to backfire. I also noticed it happens occasionally at cruise when I back out of the throttle then it backfires just as I start to roll back into it. I wouldn't be surprised if this is related, so I'll be checking the inlet hose clamps today as well.
car_freak85 is offline   Reply With Quote
Old 05-17-2019, 03:25 PM   #15
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

I'll have to borrow a fuel pressure gauge from a coworker.

But I do have the battery data:
  • Pulled into the driveway yesterday and shut the car off, went inside to let the dog out.
  • 10 minutes later walk outside, pop the hood, key-ON - 12.2V
  • Engine at hot idle - 13.2V climbing to 14.1V while running
  • Engine shut off, still key-ON - 12.9V

Will pull codes this afternoon.
car_freak85 is offline   Reply With Quote
Old 05-17-2019, 03:55 PM   #16
vica153
Scooby Specialist
 
Member#: 76586
Join Date: Dec 2004
Chapter/Region: RMIC
Location: Denver, CO
Vehicle:
2006 9-2x Aero

Default

Running voltages look pretty normal. 12.2 is a bit low, but as long as it doesn't drop below 12.2 after a few days.
vica153 is offline   Reply With Quote
Old 05-20-2019, 03:14 PM   #17
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Quote:
Originally Posted by vica153 View Post
Running voltages look pretty normal. 12.2 is a bit low, but as long as it doesn't drop below 12.2 after a few days.
Are you suggesting the battery needs to be replaced? The car sat for four months outdoors this winter and started in the spring without a jump.

I poked around under the dash over the weekend and only found a single green test connector. I'll have to see if the other one is tucked away out of sight.
car_freak85 is offline   Reply With Quote
Old 05-20-2019, 06:46 PM   #18
vica153
Scooby Specialist
 
Member#: 76586
Join Date: Dec 2004
Chapter/Region: RMIC
Location: Denver, CO
Vehicle:
2006 9-2x Aero

Default

If it starts after sitting for months and running voltages are fine, then I think the battery is fine for now. 12.2 is technically just a bit lower than the 12.4 that you would like to see.
vica153 is offline   Reply With Quote
Old 05-21-2019, 04:03 PM   #19
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Thanks for the explanation.

Wasn't able to dig around for test connectors yet, but I did poke around the induction system and I miiight have a leak in the intake silencer box. The thing has the part number molded into it, but sadly, after looking up the P/N is appears to be a JDM-only part...
car_freak85 is offline   Reply With Quote
Old 05-22-2019, 10:49 PM   #20
binny
Scooby Newbie
 
Member#: 198108
Join Date: Dec 2008
Location: Australia
Vehicle:
MY98 WRX
Blue

Default

That won't affect anything
binny is offline   Reply With Quote
Old 05-23-2019, 02:49 PM   #21
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

A post-MAF/pre-turbo intake leak won't affect anything? Surely you jest, sir...

Or were you talking about battery voltage?

Last edited by car_freak85; 05-23-2019 at 02:57 PM.
car_freak85 is offline   Reply With Quote
Old 05-23-2019, 03:02 PM   #22
wtdash
Scooby Specialist
 
Member#: 59182
Join Date: Apr 2004
Location: N. Idaho
Vehicle:
2002 WRX GG>>
2016 Focus RS

Default

Quote:
Originally Posted by car_freak85 View Post
A post-MAF/pre-turbo intake leak won't affect anything? Surely you jest, sir...

Or were you talking about battery voltage?
ha...you edited your response after I got the email from NASIOC.

I'd bet that it WAS the voltage.

....But No leaks allowed. :-)
wtdash is offline   Reply With Quote
Old 05-28-2019, 03:40 PM   #23
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Found the green and black connectors tucked away and hidden over the holiday weekend, connected them up and the CEL flashed at 1 Hz, which would indicate no stored codes.

Next steps for me are to inspect the intake silencer to address the possible leak, as well as install a new throttle cable. Current cable is too long, leaving lots of dead play. Pretty sure I'm not able to get true WOT, and the aftermarket boost controller may be overboosting (boost set extra high b/c of the long cable) with temperature change.
car_freak85 is offline   Reply With Quote
Old 05-28-2019, 05:06 PM   #24
vica153
Scooby Specialist
 
Member#: 76586
Join Date: Dec 2004
Chapter/Region: RMIC
Location: Denver, CO
Vehicle:
2006 9-2x Aero

Default

Too long of throttle cable? As in the length of cable after the adjustment nuts is somehow too long? So you have the cable adjustment maxed out and its still too loose?

Its pretty easy to test if you're getting to WOT. Have someone hold the pedal down and then see if the throttle is up against the stop or you can still rotate it further. If you're not reaching WOT, then you need to adjust the cable or the RX pedal travel isn't long enough for the EJ throttle.

.....Might have an intake leak.......may be overboosting....

It seems you have been guessing at the cause and replacing parts without any sort of real information. Boost, fuel pressure, AFR, or anything really. Based on your previous comments about boost levels and running a modified/swapped vehicle I had assumed you had some sort of boost gauge.

A real hard cut makes me lean towards overboosting. If you have no clue what boost you're hitting, then I'd suggest investing $40 in a boost gauge.
vica153 is offline   Reply With Quote
Old 05-29-2019, 04:22 PM   #25
car_freak85
Scooby Specialist
 
Member#: 13530
Join Date: Dec 2001
Chapter/Region: NWIC
Location: Cascadia
Vehicle:
EA63 , EA81T, EJ20G,
EJ205

Default

Quote:
Originally Posted by vica153 View Post
So you have the cable adjustment maxed out and its still too loose?
Yes, exactly. This vehicle represents maybe the second or third time this swap was ever done in the US some 10+ years ago. I didn't do the conversion, so every time I tear into this car to fix something, I learn more about how it was built in the first place by Suberdave.

Quote:
Its pretty easy to test if you're getting to WOT. If you're not reaching WOT, then you need to adjust the cable or the RX pedal travel isn't long enough for the EJ throttle.
I haven't done exactly what you described, but I can hook the exposed cable between the sheath and the throttle bellcrank and pull roughly 3/4 -in. of slack in the cable without the throttle plate moving at all.


Quote:
.....Might have an intake leak.......may be overboosting....

It seems you have been guessing at the cause and replacing parts without any sort of real information. Boost, fuel pressure, AFR, or anything really. Based on your previous comments about boost levels and running a modified/swapped vehicle I had assumed you had some sort of boost gauge.

A real hard cut makes me lean towards overboosting. If you have no clue what boost you're hitting, then I'd suggest investing $40 in a boost gauge.
I have an Omori gauge on the steering column and an ECU scanner on the dash, so not driving blind.

To an extent, yes, I am throwing parts at it. At the same time, these are parts that need to be replaced anyway due to the age of the powertrain and that I plan on turning up the wick once this cutting out issue is in the bag. This isn't my first rodeo, I'm just not familiar at all with the early JDM stuff.
car_freak85 is offline   Reply With Quote
Reply

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

All times are GMT -4. The time now is 10:10 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2019 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.