680cc injectors on stock ECU... thoughts?

Crashsector · Post by **Crashsector** » Wed Feb 13, 2008 4:19 pm

The EJ22T that I bought has 680cc injectors on it. The original DTEC was destroyed so I have no record of the map or anything. What are the chances of being able to run the car on the stock ECU with these injectors, just to get it up to TurboXS to have the DTEC installed and tuned? I was planning on starting it and watching the fuel trim. If it pegs out on idle I'll just have it towed. But should I even try starting it?

I also have a JECS MAF... would it be best to use this or use the stock MAF?

Any thoughts appreciated...

--Andy

Post by **Legacy777** » Wed Feb 13, 2008 4:55 pm

I'd say you have a slim chance to get it to run well enough to drive it for any distance.

dscoobydoo · Post by **dscoobydoo** » Wed Feb 13, 2008 5:10 pm

If the 440's run with the stock ECU with a bit of a learn curve, and you are running 50% more, I am betting it will start and idle, but that will be about it.

555BCTurbo · Post by **555BCTurbo** » Wed Feb 13, 2008 7:21 pm

It will run like ass...

vrg3 · Post by **vrg3** » Wed Feb 13, 2008 7:38 pm

Annapolis to Gaithersburg is, what, 60 miles? I know I'm in the minority, but I think you might make it.

The fuel trim will hit the rail. At that point you're looking at something like a 10:1 air/fuel ratio. That's really rich, but the car still ought to be able to limp with that AFR.

It might do better with the JECS MAF sensor; it'll throw a trouble code 49 but it might run better overall.

I'd stay off of boost (maybe even wire the wastegate open just in case), but I think you could get the car to TurboXS. Maybe go at night when you can more safely go slow on the beltway and 270.

Crashsector · Post by **Crashsector** » Wed Feb 13, 2008 11:54 pm

Thanks V. I'm probably just going to pay $40 and get a 4-wheel trailer from U-Haul and tow it up. I was just worried that with injectors that big it wouldn't even start. But if you guys think it will that makes me a lot happier.

Pushing/pulling a car, wrecked or not, onto one of those things is NO fun at all.

--Andy

555BCTurbo · Post by **555BCTurbo** » Thu Feb 14, 2008 2:47 am

Crashsector wrote: Pushing/pulling a car, wrecked or not, onto one of those things is NO fun at all.

--Andy

If you have a Harbor Freight there locally...they usually have comealongs for like $10

douglas vincent · Post by **douglas vincent** » Thu Feb 14, 2008 3:11 am

You are going to want to use the JECS MAF if you are using those 680cc injectors. The stock metal MAF maxes out FAST. You need to ground the blue wire (I think and I will check my setup) and then the JECS will work without throwing a code.

The Jecs flow more air before maxing out.

vrg3 · Post by **vrg3** » Thu Feb 14, 2008 3:24 am

Yes, you ground the blue wire if you want to prevent it from throwing the trouble code.

Arctic Assassian · Post by **Arctic Assassian** » Thu Feb 14, 2008 11:02 pm

where do you get this jecs maf from?

vrg3 · Post by **vrg3** » Thu Feb 14, 2008 11:11 pm

Almost any North American Impreza or Legacy from 91 through 98ish, except for turbos and 90-91 manuals.

douglas vincent · Post by **douglas vincent** » Thu Feb 14, 2008 11:42 pm

You can also modify the JECS by filling the exterior with epoxy, the milling out the interior. Then it will flow up to 30 psi out of a GT30 and then it will max out.

When you get the MAF, you will understand what I am saying.

Crashsector · Post by **Crashsector** » Mon Feb 25, 2008 2:22 am

Well it started today, finally. After realizing I had the fuel supply/return lines mixed up, doh. Got a CEL though, and it could be any number of things especially with the DTEC install, but it may very well be the "blue wire" mod. Didn't have time to check the trouble code.

VIDEO: http://www.youtube.com/watch?v=0RHuhE9oeNY

It started to run out of gas towards the end. Have to connect my laptop up and check the fuel trims tomorrow. Needless to say I'm pretty excited at this point.

--Andy

vrg3 · Post by **vrg3** » Mon Feb 25, 2008 3:51 am

It's definitely the "blue wire" thing. Code 49.

At least.

If it runs enough to limp to Gaithersburg, though, who cares?

Boostedballs · Post by **Boostedballs** » Sat Mar 01, 2008 4:23 am

vrg3 wrote:Almost any North American Impreza or Legacy from 91 through 98ish, except for turbos and 90-91 manuals.

are you saying that the n/a MAF flows more air than the turbo unit?

douglas vincent · Post by **douglas vincent** » Sat Mar 01, 2008 8:40 am

We are not saying the JECS "flows" more air. We are saying the JECS allows more flow before the MAF hits 5 volts. And if you modify it like I did, you need to flow about 30psi out of a BAT (big ass turbo) to hit 5 volts.

douglas vincent · Post by **douglas vincent** » Sat Mar 01, 2008 8:42 am

And actually, the Metal maf allows more actual flow (uninterrupted) than the plastic JECS. Its just that the sensor itself on the metal MAF sucks.

douglas vincent · Post by **douglas vincent** » Sat Mar 01, 2008 8:42 am

And actually, the Metal maf allows more actual flow (uninterrupted) than the plastic JECS. Its just that the sensor itself on the metal MAF sucks.

douglas vincent · Post by **douglas vincent** » Sat Mar 01, 2008 8:45 am

Before

After

milling out

After filling in with goo

Adam West · Post by **Adam West** » Sat Mar 01, 2008 8:55 am

Thanks Doug, I understand the milling but not the goo. Didn't you have another thread on this mod? Can you post the link?

Adam West · Post by **Adam West** » Sat Mar 01, 2008 8:57 am

And I suppose greater minds than me have thought about swapping JEC sensor into the Metal one??

douglas vincent · Post by **douglas vincent** » Sat Mar 01, 2008 8:42 pm

The red goo is to prevent the pressure from blowing the lid off the MAF sensor. The "lid" being the protective cover on the outside. I blew mine off on the first one I used.

Adam West · Post by **Adam West** » Sat Mar 01, 2008 8:50 pm

Ah, I see, stick the sensor down since you've undercut it's base. Make sense now.

You've got a pm.

93forestpearl · Post by **93forestpearl** » Sun Mar 02, 2008 8:42 am

Just remember, if you misfire from being over-rich, you will cause damage to the coilpack in short order. If its $40 for a trailer to haul it, go that route.

dzx · Post by **dzx** » Wed Mar 05, 2008 2:49 am

Do you know how much it leans out compared to the stock hitachi maf Doug?

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

680cc injectors on stock ECU... thoughts?

680cc injectors on stock ECU... thoughts?