Your problem seems to be something more physical like a bad sensor than the ECU program. Do you get any DTCs?

 

I've been thinking about this again recently and I think I have a pretty good idea as to why this ASC light thing happens now...just a theory...

The Evo X comes with a 3 BAR (44.1psi) MAP sensor. Now, this doesn't mean it can read 44.1psi of boost, it means 3 BAR/44.1psi total...1 BAR (14.7psi) for atmospheric pressure, or 0psi of boost. Below 0psi, or less than atmospheric pressure, is the vacuum created by a running engine with a closed or partially closed throttle. The remaining 2 BAR (29.4psi) is what it can read in positive boost pressure. Myself and a few others, through datalogging on the Cobb AP, have noticed that the actual logged boost pressure will max out 28.XXpsi. On my car, I can boost over 30psi and watch it on my boost gauge, but the datalog shows nothing more than 28.52psi at it's highest point, where I know it hit more than that. We know that the boost information on the datalog comes from the engine's MAP sensor, and technically it should read up to 29.4psi of positive boost pressure, but the actual maximum reading (depending on atmospheric conditions) is probably somewhere in the 28psi range like some of us have seen.

As Tephra has stated before, the MAP sensor sends information to the combo meter ↓↓↓ (between the Tach and Speedometer), which displays the "Service Required" message...



With previous posts from several people (like those seen below ↓↓↓↓)and my own personal experience, it seems as though the car pops the light and disables the ASC when boost peaks above 28psi. What I think is going on here is the combo meter is seeing the MAP sensor being maxed out. When the MAP shows it's highest possible value of 28.whatever psi, the ASC sees this and decides that it no longer knows how much boost is being made and therefore disables itself to prevent any kind of damage that may come from so much boost/torque. Also at this time, the "Service Required" light comes on, and if we could read whatever kind of code it throws, maybe it's showing something about manifold pressure exceeding the MAP sensor's range...

Thoughts?

 

according to my tests its exactly 30psi when the ASC will disable..

thats using the onboard manifold pressure sensor...

gauges are most likely 1psi off (out of calibration) or just slow to react (long hose)

 

But your if you log with evoscan you can see 31.9 -32 PSI through the map sensor.

 

oh yeah... I can see upto 32-33... it might not be 100% accurate at that level, but 30psi definitely isn't the limit of the sensor...

 

hey ScottSpeed21, what kind of "Service Required" light? is this the "4wd System Service Required"?

 

Teohra and Rogue,

If you are higher than sea level, your atmospheric pressure will be less than 1 bar. (14.7 psi) So your 3 bar map sensor will be at a lower absolute pressure then those of us at sea level. Therefore you will see higher Relative pressures than the rest of us. Mine maxes at 28.8 psi.

What ScottSpeed is saying is that the ASC shuts off when the MAP pressure reads higher than 3 bar (44 psi). This is irrelevant to atmospheric pressure, so the boost level it happens at will vary with atmospheric pressure.

 

i'm at sealevel...

 

It doesn't say anything besides "Service Required" with the little car and squiggly lines. It doesn't tell you why it's there or "what kind" of light it is. This is what happens to most people when they approach 30psi of boost...the ASC light turns on, the dash 'Pings' at you and it says "Service Required". You can turn off the car, turn it back on and everything is back to normal.

That's kind of what this whole thread is about...
You're right it might not be accurate...there's no way it could be accurate that high because it shouldn't be able to read that high if the atmospheric pressure in your reigon is somewhat normal (14.7psi, 29.92inHg on the barometer). We know for sure it's a 3 BAR MAP sensor, how would it be able to read more than 3 BAR?
Yes, exactly...that's what it seams like, to me at least. When the MAP sensor gets maxed out right to the limit of 3 BAR, it looks like that's when the car pops the ASC light.

 

Whether they should be able to or not, they have been tested to 33 psi (or more in some cases)

 

Thats not my experience..

Like I said, mine will ALWAYS pop service screen at 30psi.

And I can get mine to read even higher than 30... ie I can get the MAP sensor to log upto 32/33 psi..

So it's not poping the service screen because the sensor is maxed out...

 

I was running 33ish psi before and I did get a MAP sensor over current code once after I got off the dyno...weird thing was it happened at idle when it popped, it never happened on the dyno.

 

I must be missing something here.

The MAP sensor is a 3 bar sensor, right? If Tephra is at sea level, his atmospheric pressure should be 1 bar. Therefore if he is maxing his 3 bar sensor out, it should read 3 bar. Atmospheric sensor is reading 1 bar. So his boost would be right at 2 bar. Correct? 2 bar is 29.4 psi. How is he seeing 32/33 psi?

To read 33 psi, you would need atmospheric pressure to read ~11 psi. Thats around 8000 feet above sea level.

So, am I missing something?

 

The sensor is good for more than 3bar. It looses accuracy over 3 bar but can read slightly higher...GST has shown the sensor to flatline just above 33psi.

 

Again, are we assuming that atmospheric pressure is at 14.7?

Maybe the issue is the "Map Max Reported Value" (Cobb's definition). Stock it looks like it's set to 36.98. Is this value available in ECUFlash to modify? I don't have the definition for my rom (55570005).

Cobb sets the value to 42.93 in their stage 2 maps. I'm guessing we could set it higher than 44 psi? (aka 3 bar)