Disassembly: Manifold Pressure Differential Sensor

[Jesters Deadd]

Stock MAF (evo MAF ready to install but limiting variables). Yes I've constantly had CELs since testing included keeping all peripheries as stock - and stock '99 code is also the same. I can double-check what is stored after dinner and should be able to run test you requested tonight. Unfortunately that will be the last input from me on this for 10 days. Anything else you want me to squeeze in tonight?

OK.
Start car turn off all electric load. Ie lights, defrost, brake light, moving mirrors, etc.
Once the solenoid starts clicking test pin 52 and see if it has 12v going to it.
Remove the wire and see if the solenoid still clicks when the car is running at idle.
The thought is you have something tripping your electric load switch, pin 52 with 12v power.
When your elec load switch is tripped the solenoid will activate.

[awdonly]

BINGO! 150 points to Adam.

Turned on my headlights, fog lights, AC, rear defrost, stereo and 4 ways. Engine warmed up, purge solenoid started clicking! Now to figure out which address is the load switch and I'll have something for you to test again awdonly! Thank you Adam!

Few other notes:

*The purge solenoid on my car shows a resistance of 38.9ohms. Lower than what awdonly is showing HOWEVER the manual shows a spec standard value of 36-44ohms for ALL year cars (91-99). So even though they may be different part numbers, they have the same specs.

*On the 98/99 cars the purge is mounted onto the intake plenum instead of on the firewall. So when it's active on my car, I can't hear it. Had to touch it with my hand in order to notice it was active.

*The EGR solenoid on the 98/99s was moved down into the position of the purge solenoid on the 91-97 cars. That tricked me earlier....

*The vent system even though it functions with the purge system, it's a completely and totally separate system. The purge does NOT use the fuel tank sensor for operation. Only a few condition bits activate the purge which I'm currently testing. The only thing the two systems share is periphery 2 bit 13 and NONE of the peripheries disable the system. Only the OBD checks for them. The purpose of the vent solenoid is just to check the operation of the fuel tank sensor. Since this isn't present on the 91-97 cars, periphery 2 bit 13 needs to be switched off to keep the CE light off. This will NOT effect the purge system in anyway.

Going back into my little hole for a bit but I hope to have something for you to try later awdonly. BTW, what's your real name? I appreciate your help with this too!

No problem - I'm having fun. I wonder why I'm getting clicking with 0 accessories on.... My name is Marc.

[99 vr4]

I just checked the list of empty pins, and they match to what I have as empty pin also. The very early conversion harnesses did have pin 75 (Muffler mode changeover) connected, but I have left that out, as I'm sure it's useless for a 99 ECU.

One thing I want to point out is that signal ground on the ECU is not the same signal ground used on the LCD BC. How much of an impact this has, I don't know. Sharing the sensor could potentially cause a problem. Does Evoscan show correct readings for the MAP sensor?

Mitsubishi threshold engineered this car. With that in mind, yes there is a potential of a different voltage potential between the grounds. For instance, if you measured voltage between sensor ground and your LDBC ground, you could have +/- 0.2 volts . . . . that means that all of the inputs would be offset +/- 0.2 volts. For the MAP, that might mean several pounds . . .

[awdonly]

I just checked the list of empty pins, and they match to what I have as empty pin also. The very early conversion harnesses did have pin 75 (Muffler mode changeover) connected, but I have left that out, as I'm sure it's useless for a 99 ECU.

One thing I want to point out is that signal ground on the ECU is not the same signal ground used on the LCD BC. How much of an impact this has, I don't know. Sharing the sensor could potentially cause a problem. Does Evoscan show correct readings for the MAP sensor?

Thanks. Haven't datalogged MAP output yet - Is it possible to datalog MAP data from ECU and MAP data from LCDBC separately?

[99 vr4]

OK.
Start car turn off all electric load. Ie lights, defrost, brake light, moving mirrors, etc.
Once the solenoid starts clicking test pin 52 and see if it has 12v going to it.
Remove the wire and see if the solenoid still clicks when the car is running at idle.
The thought is you have something tripping your electric load switch, pin 52 with 12v power.
When your elec load switch is tripped the solenoid will activate.

Hmmmmm . . . Adam, why does THAT solenoid activate with the electric load switch connected. Should it? I thought the purpose of the electric load switch was so that the ECU knew when their was a large draw on the system and then it could compensate accordingly . . .

[Greg E]

I just checked the list of empty pins, and they match to what I have as empty pin also. The very early conversion harnesses did have pin 75 (Muffler mode changeover) connected, but I have left that out, as I'm sure it's useless for a 99 ECU.

Actually it's not useless.

That's another disassembly discussion for another time though.

One thing I want to point out is that signal ground on the ECU is not the same signal ground used on the LCD BC. How much of an impact this has, I don't know. Sharing the sensor could potentially cause a problem. Does Evoscan show correct readings for the MAP sensor?

EVOScan does show the correct readings for the EVOX MAP sensor if you're using my data.xml definition file! Marc noted something about coolant temp scaled which I know is not in my file but it is in the data.xml file that came with EVOScan. I don't think Marc has EVOScan setup right.

[99 vr4]

Actually it's not useless.

That's another disassembly discussion for another time though.



EVOScan does show the correct readings for the EVOX MAP sensor if you're using my data.xml definition file! Marc noted something about coolant temp scaled which I know is not in my file but it is in the data.xml file that came with EVOScan. I don't think Marc has EVOScan setup right.

Marc is using EvoScan 2.9 . . . he would be a GREAT beta tester for my new 2.9 file . . .

[Greg E]

Marc is using EvoScan 2.9 . . . he would be a GREAT beta tester for my new 2.9 file . . .

I have much to go thru and correct in that file though. That's still #3 on the list.

*fix purge issue
*configure ROM to work with only 2 O2 sensors
*test/configure new 2.9 data file
*write up 3/S specific ECUFlash manual
*release V2 to the public

[awdonly]

I'm using 2.9 with the stock rom tests (that we just did) and 2.6 with Chrome. In 2.9 there are scaled temperature values that the evoscan notes indicate should be used for '98+ cars. I've found some of the evoscan notes to be a bit misleading at times though.

[Greg E]

I'm using 2.9 with the stock rom tests (that we just did) and 2.6 with Chrome. In 2.9 there are scaled temperature values that the evoscan notes indicate should be used for '98+ cars. I've found some of the evoscan notes to be a bit misleading at times though.

It's been assumed for years the 3/S was like the EVO/DSM. It's really not.......

Best to use my 2.6 with the stock ROM too.

I will be releasing a 2.9 data file in the very near future (thanks to Brett)!