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Old 01-10-2018, 02:43 PM   #1
1ofakind03
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Default Ej20g, Only 6psi and bog..

Hey guys hope I posted in the right place, car is a 93 jdm gc8 I'm really wondering what's going on with it. I put a boost gauge in yesterday and was only hitting 6psi.. vacuum is around 15 at idle. it never builds boost in lower Rpms, I can step on it and will only get 1-2psi till I'm up higher in rpm. I re did all my vacuum lines, I do have a crappy stock bpv that the nipple broke off of so I epoxied the hose to it to run to the intake manifold... could that be my issue?

I have two codes. Code 24 and 44.

I made sure my waste gate was opening and closing but maybe its opening to soon? I don't know a lot about these cars yet but I did install the motor my self.

I also tried bypassing my bcs, I just tied them all together and that got my boost up to 7psi or so. But then I'd get a fuel cut or something right at 5000rpm WOT. So I Put my bcs back on and that fuel cut went away.

What's going on here, I don't have any leaks as far as I can tell, but maybe my bpv is garbage? Is there anything else I can check or some ways to diagnose? I've been reading for hours trying to figure it out. Could I zip tie my waste gate shut to confirm it's not opening early?
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Old 01-10-2018, 10:52 PM   #2
monkeyposeur
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44 is the duty solenoid valve inoperative code. So that would make sense that you only get 7 psi when you bypassed the bcs. Maybe you want to go to a mbc and control the boost that way.

24 is the idle air control valve code, so that might be throwing you into some kind of limp mode if I had to guess. The turbo IACVs have a special 90* bend on them so you can't replace it with an NA one, but you can replace the top electronic portion of it with an NA one, these can be found fairly easily and are pretty cheap. It's just a couple of screws holding it on. You can also pop that off yours and see if the valve opens and closes freely. They can get stuck with gunk. You can shoot some carb cleaner in there and free it up after removing the large vacuum hose.

I would also replace your MAF with a new one. I have had so many issues because of bad MAFs with this gen of vehicle. The JDM MAF is the green JECs one and is the same as a lot of first gen NA legacies so you should be able to find a used one although I don't recommend used MAFS since they usually crap out in my opinion.

Get on bbslegacycentral.org and post up your issues over there as well. There are quite a few people familiar with the EJ20Gs over there and might be able to provide more help than I can.

Maybe you clogged that nipple on the BPV with epoxy. You can rig up a WRX BPV to work although it's kinda tricky to do so with the JDM 20g tmic.

Doesn't seem like you have a vacuum leak but you could always build a boost leak tester and pressurize the system to look for leaks.

What rpms are you talking about specifically when you say you don't build boost at low rpms? You aren't gonna build much boost at 1000 rpms obviously.
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Old 01-11-2018, 04:31 AM   #3
1ofakind03
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Quote:
Originally Posted by monkeyposeur View Post
44 is the duty solenoid valve inoperative code. So that would make sense that you only get 7 psi when you bypassed the bcs. Maybe you want to go to a mbc and control the boost that way.

24 is the idle air control valve code, so that might be throwing you into some kind of limp mode if I had to guess. The turbo IACVs have a special 90* bend on them so you can't replace it with an NA one, but you can replace the top electronic portion of it with an NA one, these can be found fairly easily and are pretty cheap. It's just a couple of screws holding it on. You can also pop that off yours and see if the valve opens and closes freely. They can get stuck with gunk. You can shoot some carb cleaner in there and free it up after removing the large vacuum hose.

I would also replace your MAF with a new one. I have had so many issues because of bad MAFs with this gen of vehicle. The JDM MAF is the green JECs one and is the same as a lot of first gen NA legacies so you should be able to find a used one although I don't recommend used MAFS since they usually crap out in my opinion.

Get on bbslegacycentral.org and post up your issues over there as well. There are quite a few people familiar with the EJ20Gs over there and might be able to provide more help than I can.

Maybe you clogged that nipple on the BPV with epoxy. You can rig up a WRX BPV to work although it's kinda tricky to do so with the JDM 20g tmic.

Doesn't seem like you have a vacuum leak but you could always build a boost leak tester and pressurize the system to look for leaks.

What rpms are you talking about specifically when you say you don't build boost at low rpms? You aren't gonna build much boost at 1000 rpms obviously.
Thank you form the reply, I guess that makes sense being in limp mode? But I removed the line off the actuator and still
Only 7-8psi? It was boggy and cut power hard under acceleration in higher 4000-5000 rpm though, Shouldn't I be running full boost?

I'm going to get a manual boost controller on Friday from a friend and put that's in but I'm almost thinking that won't work now because I bypassed the solenoid.

I'm comparing the driving characteristics to my other ej20k gc8. The 20g is very sluggish and barely makes boost around 3000rpm. 3000rpm in my 20k and I'm making lots of boost..
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Old 01-12-2018, 12:14 AM   #4
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JUST an update. I took my intercooler off to find two potential leaks. I fixed them and will try tomorrow. Also one crack in my turbo inlet pipe I electrically taped since I can't find any new ones (discontinued). Also going to install a mbc tomorrow to see if it helps. If not then I don't know where to start again lol
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Old 01-12-2018, 11:47 AM   #5
monkeyposeur
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03 WRB GD 205/22T 20G-XT

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Quote:
Originally Posted by 1ofakind03 View Post
Only 7-8psi? It was boggy and cut power hard under acceleration in higher 4000-5000 rpm though, Shouldn't I be running full boost?

I'm going to get a manual boost controller on Friday from a friend and put that's in but I'm almost thinking that won't work now because I bypassed the solenoid.

I'm comparing the driving characteristics to my other ej20k gc8. The 20g is very sluggish and barely makes boost around 3000rpm. 3000rpm in my 20k and I'm making lots of boost..
7-8 psi sounds about right if you are just running wastegate pressure which is what happens if you aren't running any form of boost control when you disconnected the bcs.

You will bypass the bcs when you install an mbc so in theory you should be able to run more boost. Some have reported that they still needed to run a vacuum source to the bcs to avoid having the cel come on.

If you are unsure of how to connect the mbc here is a good write up: https://user.xmission.com/~dac/library/hbc.htm

The link is for a first gen turbo legacy but the EJ20g and EJ22T setups share a lot of the same characteristics despite the USDM 22T being sohc.

Quote:
Originally Posted by 1ofakind03 View Post
JUST an update. I took my intercooler off to find two potential leaks. I fixed them and will try tomorrow. Also one crack in my turbo inlet pipe I electrically taped since I can't find any new ones (discontinued). Also going to install a mbc tomorrow to see if it helps. If not then I don't know where to start again lol
The infamous turbo inlet. They crack if you just look at them. When I was fixing up my turbo legacy I had that same problem. I taped it up as a temporary fix but of course it didn't work very well. I was able to find one of the last new inlets in the world in Canada though. The USDM and JDM inlets are very similar but some of the vacuum port locations are in different locations.

Fortunately for you Samco makes an inlet for the JDM GC8. Here is an example of one on ebay: https://www.ebay.com/itm/Samco-Silic...AOMWU7iA_SVpRw

However, it's pretty expensive but it is pretty much your only alternative to making your own. If you want to make your own you can find everything you need on siliconeintakes.com http://www.siliconeintakes.com/

There you can find the proper 90* elbow, reducers, and ports. The ports can be installed in the 90* and line up with the stock locations of your PCV and vacuum lines. But if you reroute some of the lines you could come up with something else that would work that wasn't the exact same as the stock setup. I priced out the parts to make an intake and it was getting close to $80 but that was a few years ago.

When I was building my turbo leggy I had similar issues to what you are dealing with. Every line was cracked and brittle so I had to replace everything. I also had stumbling, fuel cuts, etc. After fixing all the boost leaks I was still getting the bogging and stumbling. I replaced my fuel injectors, my coil pack. Kinda helped. I then realized my fuel pump was on it's way out. Replaced that with a Walbro 255lph. That helped, still had stumbling.

Eventually I replaced the MAF like I mentioned in an earlier post and that fixed the stumbling and the car finally ran like it should. Sometime later the stumbling came back and I checked the plugs and one of the plugs was a bit loose. Tightened that up and everything returned to normal.

I love these old turbo subarus but they are a lot of work to get back to good running condition, and keep them going.

edit: You don't need to spend a lot on an mbc. The simple brass ball and spring NXS controllers work just as well as any Hallman or GS. They are just not quite simple to adjust: https://www.ebay.com/itm/NXS-MANUAL-...RZReOU&vxp=mtr

Try cleaning your MAF in the meantime with a can of MAF cleaner. Even if your MAF isn't complete toast a new one will work much, much better than your old worn out one.
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Old 01-12-2018, 02:37 PM   #6
1ofakind03
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Quote:
Originally Posted by monkeyposeur View Post
7-8 psi sounds about right if you are just running wastegate pressure which is what happens if you aren't running any form of boost control when you disconnected the bcs.

You will bypass the bcs when you install an mbc so in theory you should be able to run more boost. Some have reported that they still needed to run a vacuum source to the bcs to avoid having the cel come on.

If you are unsure of how to connect the mbc here is a good write up: https://user.xmission.com/~dac/library/hbc.htm

The link is for a first gen turbo legacy but the EJ20g and EJ22T setups share a lot of the same characteristics despite the USDM 22T being sohc.



The infamous turbo inlet. They crack if you just look at them. When I was fixing up my turbo legacy I had that same problem. I taped it up as a temporary fix but of course it didn't work very well. I was able to find one of the last new inlets in the world in Canada though. The USDM and JDM inlets are very similar but some of the vacuum port locations are in different locations.

Fortunately for you Samco makes an inlet for the JDM GC8. Here is an example of one on ebay: https://www.ebay.com/itm/Samco-Silic...AOMWU7iA_SVpRw

However, it's pretty expensive but it is pretty much your only alternative to making your own. If you want to make your own you can find everything you need on siliconeintakes.com http://www.siliconeintakes.com/

There you can find the proper 90* elbow, reducers, and ports. The ports can be installed in the 90* and line up with the stock locations of your PCV and vacuum lines. But if you reroute some of the lines you could come up with something else that would work that wasn't the exact same as the stock setup. I priced out the parts to make an intake and it was getting close to $80 but that was a few years ago.

When I was building my turbo leggy I had similar issues to what you are dealing with. Every line was cracked and brittle so I had to replace everything. I also had stumbling, fuel cuts, etc. After fixing all the boost leaks I was still getting the bogging and stumbling. I replaced my fuel injectors, my coil pack. Kinda helped. I then realized my fuel pump was on it's way out. Replaced that with a Walbro 255lph. That helped, still had stumbling.

Eventually I replaced the MAF like I mentioned in an earlier post and that fixed the stumbling and the car finally ran like it should. Sometime later the stumbling came back and I checked the plugs and one of the plugs was a bit loose. Tightened that up and everything returned to normal.

I love these old turbo subarus but they are a lot of work to get back to good running condition, and keep them going.

edit: You don't need to spend a lot on an mbc. The simple brass ball and spring NXS controllers work just as well as any Hallman or GS. They are just not quite simple to adjust: https://www.ebay.com/itm/NXS-MANUAL-...RZReOU&vxp=mtr

Try cleaning your MAF in the meantime with a can of MAF cleaner. Even if your MAF isn't complete toast a new one will work much, much better than your old worn out one.
Thank you so much for all that's info! It's to cold out today to take apart some of my car (don't want to risk breaking anything plastic) I am going to change my coolant temp sensors (my temp gauge is spiked out) while i have my intercooler off. So tomorrow morning I'll install the mbc, got a grimmspeed for $60. Then hopefully my car will run full boost. Cause wow what a difference the other gc8 is compared to mine right now.

I found a used turbo inlet and bpv for 60$ in good shape I'll get shipped to me today. Probably won't be here for a while but either way it will be much better than my epoxied crap... I was looking at the samco ones, I'll try that next if i end up breaking mine lol

Thanks again! Very helpful! Do you happen to know which maf I need to have? When I got my car it came with two... I might have the wrong one insalled
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Old 01-12-2018, 02:44 PM   #7
monkeyposeur
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You need the Green Jecs MAF with the plastic housing.

I just got one out:
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Old 01-12-2018, 03:59 PM   #8
1ofakind03
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Quote:
Originally Posted by monkeyposeur View Post
You need the Green Jecs MAF with the plastic housing.

I just got one out:
Ok that is the one i have in right now. Aqeaome! Thanks!
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Old 01-13-2018, 05:30 PM   #9
1ofakind03
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OK bad news. Getting frustrated now. Put in the mbc fixed what I thought were all my leaks and now I still get the hard cut right at 7-8psi. IT is a little better but still Boggs if you WOT at any rpm under 3000. I swapped my iacv and my coolant temp sensors and did not help still get the codes.. I wonder if I have s bad ground.. shouldn't I be able to boost much higher now though regardless?

What now?
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Old 01-15-2018, 01:03 AM   #10
1ofakind03
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I think after my research the last day or two here I will start by

- Pulling my already new plugs and checking gap.
- Boost leak test.
- Clean the pressure exchange solenoid.
- Clean maf
- Check my tps is within spec
- clean and reapply all engine grounds
- Change pcv valve

I have a couple more things on my list to do but I think I want to start with that stuff. Then tomorrow I'm taking my car to a repitibale guy in my area who is willing to have a look at it, seeing as I've neve Owned a gc8 before I'm not really sure what to look for exactly but I'm pretty knowledgeable and mechanically inclined.

If anyone has anything to add I'm open to options here. I think I may pull the fuel pump and check it's not plugged with crap (car sat for 2 years prior) but I pumped the fuel dry though the fuel pump before I put my motor in. Fuel filter is probably due too so I'll get a new one just for the fun of it. I always run 94 octane and nothing less.
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Old 01-15-2018, 01:35 AM   #11
1ofakind03
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Also can someone maybe post a pic of their 20g vacuum lines routing? I almost think mine are routed wrong.. like I said before I never had a gc8 before so just tried to piece it together as I could via the internet and forums.
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Old 01-15-2018, 10:02 PM   #12
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Well problem solved. I went to a reputable Subaru mechanic and we had it running in an hour. Turns out I had two dead coil packs causing me to run on two cylinders. DId a compression test and was at 120. Cleaned out the fuel injectors and also had no power to my boost solenoid so it went in limp mode causing the violent cut. All added up to be just a bad wire to the solenoid and two bad coil packs. Now I just need to turn down the boost since I get fuel cut around 16psi lol!! What a relief, so much better to have it back to normal ! Thanks all for the help hopefully this helps you guys as well. Funny thing is, I replaced all my coil packs with 02wrx ones and never would have thought to recheck them.

Code are now clear and runs flawless!
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Old 01-16-2018, 04:01 PM   #13
monkeyposeur
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That's great news!
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Old 01-16-2018, 09:08 PM   #14
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That's great news!
I get an intermittent engine light that comes and goes, thinking it is my iacv but havent been able to catch it. my idle hangs sometimes, ill drive at say 50km an hour and instead of down shift ill go into neutral and the rpm sticks at 2000rpm till im slowed down around 15km/hr. maybe my tps too but either way it runs great regardless.
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