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

Yeah, I seem to get that hesitation a little also. I think the 91 cam kinda took care of mine though, feels better.

UPDATE:

First and foremost, apparently JWT changed their documentation regarding use of the 97 ECU on a 98+ car. The version I grabbed from them a while back says nothing about the EVAP Pressure Sensor on the back of the car, next to the EVAP canister. Now, looking at the diagram today, it clearly states to unplug this sensor. THAT would help alot with my idle, I'm sure.

Secondly:

These are the pins on the ECU that are not used on the 95~97 ECU, that I've found while doing wire tracing of the schematic today:

1998 SE-R wiring harness (SR20DE, non ABS, MT)
PIN 105: EVAP CANISTER PURGE CONTROL SOLENOID VALVE
PIN 108: EVAP CANISTER VENT CONTROL VALVE
PIN 69: MAP/BARO SWITCH SOLENOID VALVE
PIN 117: VACUUM CUT VALVE BYPASS VALVE
PIN 66: ABSOLUTE PRESSURE SENSOR

Now, according to JWT's diagram, the following happens.
PIN 110 which is the rear heated o2 sensor is rerouted to PIN 108. (PIN 110 is not used on the 95~97 ECU)

PIN 112 on the 98 ECU (power transistor) is rerouted to PIN 111 (Still power transistor, but different lead, makes me think that this is the signal wire, and not power or ground. Obviously want signal to signal, and not to ground or power)

So there we have it. The sensors mentioned above in my original post have no bearing on the 95~97 ECU, as the 95~97 ECU doesn't even look for these sensors.

THAT'S GREAT NEWS! This means that most of the emissions crap for those of us with the 95~97 ECU on a 1998 car can do away with it, with no ill effects. One sensor has already been dealt with for us, by JWT (EVAP PRESSURE SENSOR)

More to follow.

The crap removed:

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Sensor unplugged as per JWT instructions:

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This is another sensor located close to the EVAP canister, not sure what it is yet. Need to look at the routing diagram again...

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Putting stuff back together right now. I need to replace the water pump and thermostat as a precaution, but I'll handle that tomorrow. For tonight, I need to see what happens to the car (how much better it runs, if possible), when I start it back up. I'm also running with the 740cc injectors again, so I need to back off the fuel pressure for tonight's test.

Sorry for the crappy quality on the pics, btw. Those were taken with the camera phone, as the cameras are currently charging.

Nice job. How does it run now?

I recall seeing two open holes on the vacuum gallery on mine fwiw. Also good job. Maybe you an get those photos into paint and label them for those of us who want to duplicate your results.

I haven't finished it just yet. I still need a paper gasket for the throttle body. Broke it on removal.

I'm going to label all sensors, where they were located, and put it into a psuedo write up here when done. The only thing I'm not sure on just yet, is pertaining to the evap service port with the vacuum solenoid attached to it. One line runs to the rear for the canister, and the other runs to the top of the intake manifold where the purge solenoid was located. There's that one solenoid that was left plugged in, on the rear of the vehicle. I need to determine what it's used for, and if it's directly related to the evap canister lines that I just mentioned.

More to follow

Good info! Is that first pic all the stuff off the old mani that isn't needed? cuz thats a lot of sh*t haha

Well,

According to the FSM, the 95~97 ECU doesn't see it, so no, it's not needed. I'll post up once I'm done with the water pump and thermostat today, need to install the 2nd slim fan, as well.

I should have something for you all by the end of the night

Sweet! And what about the sensors? Do you need the ones off the 95-97 or can you use the ones off the 98-99?

What sensors are you referring to? IIRC, there's only one or two sensors that are the same between model years, and those still exist on the 98+ model.

The sensors that I'll label and point out will not be required, nor will you need to use the 95~97 sensors (because they don't exist)

So theres only gonna be like 2 sensors on the manifold? I thought that the 95-97 manifold still had some sensors on it. I'll have to see in your write up cuz im confused hahaha