Thread: 98+ SR20DE vacuum removal (to 95~97 standards)

Okay guys, I'm starting the undertaking, to convert the 98+ SE-R crap I have, back to 95~97 standards. This will likely end up confusing me, so I'm using this thread to post my findings, in order to keep myself sane.

So far, this is what I have that is different on the 98+ vs. the 95~97. This definitely matters, because if you are running a 95~97 ECU, the ECU shouldn't even SEE these sensors. (I hope!)

1998+ SR20DE: (What it has, and what the 95~97 DOESN'T have)
1. The Vacuum cut valve bypass valve
2. The Vacuum cut valve
3. The EVAP canister purge volume control valve
4. The EVAP control system pressure sensor
5. The EVAP canister vent control valve (cannot verify, this could be what sits on the charcoal canister on the 95~97 SR20DE?
6. The Absolute Pressure Sensor (JWT tells you to remove this for 95~97 ECU operation, as well as re-route vacuum lines in order to have the EGR system function properly. What I didn't check, is whether or not leaving the lines stock caused any ill effects)
8. MAP/BARO switch solenoid valve
9. EVAP service port (tied into the EVAP canister purge control valve)

ALL of the above crap, isn't shown on the diagram for the 97 SE-R SR20DE I have in my hands.

The only thing shown on the 97 SE-R SR20DE is:
1. EGR valve and EVAP canister purge control solenoid valve
2. Main purge orifice (on the carbon canister according to the FSM?)
3. Purge Control Valve (on the carbon canister according to the FSM?)

Now, assuming that the 95~97 ECU doesn't even LOOK for every single sensor/solenoid/junction as listed on the 98+ diagram, this would mean that the ECU will NOT throw a CEL, as it doesn't recognize the sensor/solenoid to begin with.

Calum/ECU guys, can you confirm this to be true?

Now, as far as the LARGE vacuum nipple on the rear of the 95~97 intake manifold... This runs to the booster, I assume? Reason I ask, is because on the 98, there's a huge vacuum line that runs from the purge control valve, to the purge volume control valve on top of the intake manifold.

So far, that's NINE ADDITIONAL SENSORS THAT DIDN'T EXIST, on the 95~97 SE-R SR20DE.

Once verified that the 95~97 ECU doesn't see these sensors, they will ALL be ripped out, and vacuum lines routed accordingly. I'm now off to search, to find out what you all do when you remove the charcoal canister all together. (Where does the fuel vapor in the tank vent to? What are the effects of not venting the tank? Etc.)

Once this is all finished, I'll do a nice write up with colored diagrams, etc.

Send TOKES a PM Tek..........He was all over this stuff on the old forum when he did his swap.

I'll shoot him a PM. I had asked about this on the other site and didn't really get a concrete answer.

Tekster... I'm pretty sure you are far ahead of the game as far as what I know... I apologize - I never jumped ship and swapped back to the 97 ecu since I chose not to turbo the b14. In fact, I still have the damn thing sitting on my shelf somewhere.

I'm only limited to which pinouts you are supposed to change and where the vacuum hoses are supposed to be switched (via jwt) when switching to a pre 98 ecu; which you have probably done already.

I can honestly say that I am pretty worthless and have a lot to learn when messing with the 98/99 bull **** - I swapped my 98 manifold back on during my swap and since then have aquired two 95-97 manifolds and an ecu with intention to do exactly what you are talking about, I even had a couple emails I found back and forth with calum from 2 years ago... At one point I was waiting for him to get map tracing done... and I was going to wait until after the holiday to send him the ecu... I went b13 crazy and totally forgot all about this, and take a guess where those manifolds are sitting. ::shakes head:: I dissapoint myself.

I am a worthless bum. But I will do what I can to help.

It's okay. I figured you decided not to go thru with it, because last time I searched I didn't find a how-to thread from you. I know you tend to do VERY detailed how-to's.

Anyhow, I'm going to maul it over for a day or two, and will more than likely end up pulling the 98+ upper manifold and slapping the 95~97 on it, along with removing all of the sensors mentioned above. Just doesn't seem like those sensors are worth a damn to me with a 97 ECU, if the 97 ECU can't see them.

Tek, this is what I was trying to IM you about, I had thought you already did it lol. But I would like to do this also, so a write up would be awesome!

I don't think all that crap does anything.

Minor thread jack question; Do any of you guys with 98/99 get a part throttle hesitation that ordinary tune-up items can't seem to cure? mine has this a bit but was worse with the HS wai.

It's in the works bro If I don't get CEL, I'm happy. I only have the scan test here. I'll post it for the world to see once it's done. I brought the paperwork home with me to do the research.



Not really, no. I have heard from some people getting it, but it doesn't seem to be something that's consistent across the board.

Thanks man, and thanks for sessing this out.

Anyone else?

My **** bucks like a freshly woken bull that got shot in the ass. Yes, this is mostly recent. If I leave it in first gear and low/no throttle I bite the steering wheel. The only thing that has fixed it for me was raising the idle.