SR20DET S14 Boost sensor usage?

[Terminar]

Hi,

this is not a general nistune question, but i don't know who i can ask for that technical question, because it happens in the ecu....
Currently, we are trying to investigate where the values from the boost sensor assembled in the S14 are used in the ecu. We are using nistune, too.

A friend doesn't use the stock boost solenoid anymore, a boost controller is working instead there. But - if the stock boost sensor (still assembled) reports an error to the ecu/nistune (error 26), it seems that the performance of the car goes down.

I read several things in the repair manual, but i haven't found any other usage for the boost sensor values. Only the boost solenoid is mentioned. Do i miss something? My car is AT, it seems that the AT is also using the values from the boost sensor?

Does the ecu turn on some limp mode if the error 26 is reported?

I measured 5.11V at the VCC pin to the boost sensor. I found an information that when the car is idle, the sensor should have 2V output to the ecu. I measured 8mA going from the sensor to the ecu...
Can I put a 390R resistor between the VCC and the sensor line? That makes nearly 2V... Is this enough to trick the ecu that a boost sensor is attached and not to produce error 26? Or is there another safer easier way?

Bye
Terminar

[Matt]

in short you could try the resistor and see if that clears the DTC

On the R34 once you get the DTC there is a load cut introduced. The boost sensor needs to be plugged in and also reading boost on that vehicle to avoid the cut, but S14 might be slightly different

There are boost maps etc to control the solenoid on later model SR20s, with earlier ones just having an emergency overboost solenoid

[Terminar]

There are boost maps etc to control the solenoid on later model SR20s, with earlier ones just having an emergency overboost solenoid

I know the difference to the S14A here in germany, we tried to compare it here with different cars. As you said, the S14a model doesn't have the boost sensor anymore, that's why i am trying to find if we can throw away the boost sensor on the S14. My friend broke 3 sensors in the last year and it's annoying to just change the sensor every time.

I still need the sensor because i still use the stock boost solenoid (and the boost tables within nistune), but i think it's useless for my friend using the boost controller (i think apexi avcr)....

Is there a way to deassemble the ecu binaries to "nearly readable" assembler code? I'll try to read my ecu image myself..

If i can find the code where the boost sensor value is accessed and where it is used then my question is answered...

Bye
Terminar

[Matt]

email me and i can give you a disassembled version with some symbols in it. the M7790 processor is tricky because it switches between 8/16 bit instructions using a flag. I had to write a disassembler to parse the code from vector tables to get something that was accurate

[skylinegtrhr]

I did get this error while on dyno but didn't had any impact on performance but I heard from some people that they had so will that resistor be best solution to not have any worries ?

[Terminar]

I'm just doing my homework at the moment, if i have new information i'll update this thread.

Bye
Terminar

[PL]

Interesting.

All the S14 engine conversions I've seen do not run the boost sensor at all - seemingly with no ill affects.

But I've recently done the wiring for an S14 engine conversion on a friend's car. We didn't wire the sensor in, but he's also running a Race Technology Dash2 and DL1 logger - I was gonna wire the boost sensor to this so that we could display/log boost.

I've gotta test the sensor and see what its output is across different boost levels, so I'll let you know the figures.

I'd suggest that adding 2 resistors across 5V and GND would be best. Then just tap off the voltage from the junction of the resistors. If they were both 10K resistors then you'd get 2.5V. I suspect this would remove the DTC.

It wouldn't surprise me if the boost control solenoid was based on airflow rather than boost...

PL

[skylinegtrhr]

Is there any news about this problem?
Maybe problem is only with EDM ECU's?
Would installing JDM ECU image solve the problem?

[PL]

The JDM ECU's don't seem to care. I tuned a 74F00 ECU just this week and it had no boost sensor attached. Seemingly no ill affects.

PL

[Zuikkis]

Is there any news about this problem?
Maybe problem is only with EDM ECU's?
Would installing JDM ECU image solve the problem?

Many (most?) Finnish S14's are running without the boost sensor with no problems, except for the DTC.. I'm pretty sure it doesn't affect anything.

[PL]

I actually had 3 of my S14 tunes at the track on the weekend and all performed perfectly all day with no boost sensor. All were showing Boost Sensor DTC's.

I don't normally like to do any tuning when DTC's are present but this one really doesn't seem to matter. I wire up a lot of SR's for engine conversions and most of the "engine packages" don't come with boost sensors.

PL