OBD-II Question For Aftermarket Turbo Users On NA Platform

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 3:50 pm

I am working on putting together a turbo system for my 99 Leg GT but am wondering how to run boost without receiving CELs as well as be able to pass OBD-II scans when emmissions testing.

Anyone out there been able to accomplish this?

Brad

vrg3 · Post by **vrg3** » Tue Oct 25, 2005 4:14 pm

Yes.

When NASIOC comes back up you should read through the stickies in the aftermarket forced induction forum.

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 4:25 pm

Glad I'm not the only one that can't get to NASIOC. Was surfing there all day yesterday on thought maybe our firewall admin caught on a blocked the forums section of the site.

Will search.

In all actuality what I want to do is swap in a 2.2 turbo legacy shortblock I have sitting around into my 2.5 DOHC 99 Legacy GT. I'm having headgasket trouble again, 2nd time, in 90k miles. The only obstacle I haven't been able to figure out off the top of my head is fooling the ECU and still making it OBD-II compatible.

Brad

vrg3 · Post by **vrg3** » Tue Oct 25, 2005 4:42 pm

Wilma's left millions without power. Many web servers in Florida are inaccessible.

Depending on how you deal with engine management, you may have little to no problem with the ECU.

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 5:03 pm

Didn't realize NASIOC was down in that region. For some reason I was thinking New York area.

I'm not planning anything extreme with this swap it just happens to be the cheapest way to getting a running and hopefully reliable car for the time being.

Off the top if your head do you remember some options or management scenarios that may suite the needs I explained above?

Brad

vrg3 · Post by **vrg3** » Tue Oct 25, 2005 6:26 pm

If you're just going to run light boost, you might get away with slapping on a rising rate fuel pressure regulator and doing almost nothing else. If you get a trouble code for the pressure sensor, use a restrictor, tee, and check valve to vent pressure away from the sensor. Put a check valve in the charcoal canister's vent line.

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 7:42 pm

Is a voltage clamp necessary?

I was planning 14-16 psi with a VF30 or 34. Seemed like a good mach for the low compression 2.2 and the higher flow 2.5 heads.

I was planning Apexi AVCR for boost control, I have an SAFC, I guess I could go with an ITC or MSD. All of this with fuel pump and uprated injectors of course.

So you think there wouldn't be any problem as long as I ran piggy back engine management rather then full programable. I wouldn't mind using a WRX computer but that seems to be an impossible task for research and determining sensor compatability.

Brad

vrg3 · Post by **vrg3** » Tue Oct 25, 2005 8:28 pm

MY99 2.5GT wrote:Is a voltage clamp necessary?

The restrictor/tee/check-valve arrangement should do more or less the same thing as an appropriate voltage clamp.

I was planning 14-16 psi with a VF30 or 34. Seemed like a good mach for the low compression 2.2 and the higher flow 2.5 heads.

Oh. An RRFPR won't do.

I was planning Apexi AVCR for boost control, I have an SAFC, I guess I could go with an ITC or MSD. All of this with fuel pump and uprated injectors of course.

Isn't that gonna add up to about as much as an actual engine management system?

So you think there wouldn't be any problem as long as I ran piggy back engine management rather then full programable.

Not that I'm an authority on it or anything, but I didn't say that.

Don't ITCs and BTMs cause misfire DTCs on early OBD-II Subarus?

You may end up having to use your stock ECU for emissions testing and using an aftermarket ECU the rest of the time.

I wouldn't mind using a WRX computer but that seems to be an impossible task for research and determining sensor compatability.

Why would that research be impossible?

The WRX uses different cam and crank position sensors than the EJ22T and the Phase I EJ25. But maybe you could swap WRX sprockets over.

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 8:47 pm

"You may end up having to use your stock ECU for emissions testing and using an aftermarket ECU the rest of the time."

I wouldn't mind that as long as the swap out is fairly easy. I guess all I would have to do is find a way to keep the wastegate fully open for a while previous to and during the port scan.

"Isn't that gonna add up to about as much as an actual engine management system?"

I haven't had a chance to research newer EMS. The last time I took a look at standalones the TEC 2 and earlier Link was about all that was available. Ive heard buzz about the Greddy Emanage system working well without effecting OBD-II. Honestly i'd rather spend more for a complete solution rather then fill up my console with blingy controller boxes for individual aspects.

"Not that I'm an authority on it or anything, but I didn't say that."

"Don't ITCs and BTMs cause misfire DTCs on early OBD-II Subarus?"

Sorry I meant to put a ? at the end of that sentence.

I wasn't aware of the codes tripped by the ITCs and BTMs. Its been so long since I have done research along these lines.

vrg3 · Post by **vrg3** » Tue Oct 25, 2005 8:55 pm

You can easily wire a wastegate open if that's really necessary. It may not be, though.

Like I said, I'm no authority, but my understanding was that OBD-II EJ-series engines that use the earlier cam and crank angle sensors often falsely detect misfire when you start messing with the angle inputs or spark outputs. The problem is apparently less prominent with the new sensor designs, which provide much higher resolution.

Makes sense to me... frankly, I'm amazed that FHI was able to make ECUs detect misfire with the early type of sensors.

MY99 2.5GT · Post by **MY99 2.5GT** » Tue Oct 25, 2005 9:49 pm

"Like I said, I'm no authority, but my understanding was that OBD-II EJ-series engines that use the earlier cam and crank angle sensors often falsely detect misfire when you start messing with the angle inputs or spark outputs. The problem is apparently less prominent with the new sensor designs, which provide much higher resolution."

I have a 95 Impreza L 2.2 that happens to be OBD-II. I have received everthing from knock sensor failure codes to missfire on cylinder 3 to front 02 heater malfunctions. Ive replaced the 02 and knock sensor and still getting missfire codes.

555BCTurbo · Post by **555BCTurbo** » Wed Oct 26, 2005 3:25 am

I would say that a Perfect Power would take care of your issues, but the OBDII tends to learn around the PP...

Your next option could be to change things around to run a BC Legacy turbo ECU, or maybe an OBD I JDM ECU...

MY99 2.5GT · Post by **MY99 2.5GT** » Wed Oct 26, 2005 4:13 pm

I looked up information on the Perfect Power and find both their stand alone and piggy back to be promising. More research ahead.

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OBD-II Question For Aftermarket Turbo Users On NA Platform

OBD-II Question For Aftermarket Turbo Users On NA Platform