ej25 & ej22 ecu, would it work?

[greg donovan]

will a ej22 ecu in a 90 run a phase II ej25 or is this just crazy talk and i would need to get the whole ej25 shebang?

just engaging in a little armchair engine building!
greg

[LegacyPGT]

Hey Greg im going to try this swap within the next month or so. I have a 2003 ej25 on my shop floor and i'll be puting in my wagon. I'll keep you posted on how this works out.
Mike

[vrg3]

Does the Phase II EJ25 have the new type of crank and cam sensors? If it does, then you'll need to somehow switch back to the old style.

Also, if the MAF sensors are different, you may need to use your 1990 MAF sensor.

Some other sensors may need to be taken from a 1990 if they've also changed, and you'll probably have to do some signal conditioning for at least the TPS, since I believe the EJ25's TPS will be reversed as compared to the EJ22 and also lack an idle switch.

But you ought to be able to make it mostly work... It won't be quite right since the engine is different and the injectors are different. How do you plan to account for that?

[boostjunkie]

Yes, the cam/crank angle sensors are different if I remember correctly from when I did the SOHC engine swap into my 97GT a couple years ago.

I remedied this by using a crank sensor from a 1.8L impreza. I'm not sure about the compatability of the sensors on the 2.2L engines compared to the phase 2 2.5L.

Also, do the 2.2's have egr valves, because the phase 2's don't. If your stock engine does, then you're screwed for emissions unless you can figure out a way to incorporate your egr assembly into the new engine (or vrg3, or someone else electronically inclined can fabricate you a egr simulator). I've tried every sort of mechanical fix there is, but the ecu keeps constant tabs on egr function.

I'm pretty sure that within the first 10 minutes of operation, the ecu sends a signal to the egr to open and measures the o2 sensor output of a closed valve vs. an open one. Unless you're going to be driving WOT all the time (preventing the ecu from opening the valve), you will throw an egr code.

Which reminds me . . . vrg3, is there a way to bypass the egr monitoring of the ecu? I figure it would involve a switch that activates via the signal from the ecu that triggers a change in the o2 sensor values to the ecu.

A couple friends with turboed vws are wondering this. And I KNOW you'll hacve quite a money-maker if you can figure out a circuit that can circumvent the egr system.

[greg donovan]

mike, maybe you should try the ej25 block w/the ej22 heads first? that could be fun. and it wouldn't require so many sensor swaps. my friend here is trying it soon. if not now. we are guessing power would be right between the 25 and the 22 if not better. the big variable is how much detonation might occur and how the flow of the heads will limit things since the 22 valves are so much smaller than the 25 valves. it is essentially the same thing the g2 vw guys have been doing for years.

greg

[vrg3]

BC/BFs don't have EGR.

I don't know too much about EGR or EGR monitoring... If all you need to do is make the oxygen sensor read slightly rich when the ECU tries to open the EGR valve, that'd be no big deal, but I'm not sure that would do it, since I wouldn't expect a reliable change from the oxygen sensor when the valve is opened and closed.

Don't some cars have EGR valve position sensors?

From what I know, EGR is operative only while cruising, and is disabled at WOT by lack of manifold vacuum and at idle by an ECU-controlled solenoid. Someone please correct me if I'm mistaken about this.

Why do turbocharged VWs need to bypass EGR?