I actually spend some time last night with the OEM SVC manual and did some reading about the MDP. The ECU does evaluate it's signal for higher pressure use (16-17 psi is mentioned in the manual), but how accurate it is at that level is beyond me. This is why I thought you may be able to log it or at least find a relationship between it's output and boost levels.

Anyway, so from what I see (and being an LC-1 owner) the cheapest way for me to log boost is with an SSI-4 ($129) and a GM 3-bar MAP sensor ($100?).

Or I could try and evaluate LOAD vs rpm to determine which part is helping me or hindering me? My goal with purchasing some of this DL stuff (tactrix cable and LC-1) was not so much for tuning on my own, but to evaluate different parts to see their effects on low end turbo performance (rpm when spooling, how does pressure build, etc). Is there another way to evaluate this with the current parameters I can log from Logworks/Mitsulogger/Evoscan using the Tactrix cable?

Any input is appreciated.

John

 

I stand corrected, thanks MJ. after all what good is the psi x rpm if it does not correlate to a map on the ecu.

its early on the west coast.

 

Remember, the pressure from the MDP sensor is PSIa (or 1 Bar) its about 16psi absolute, 14.7psi absolute is sea level.. IN other words, it only reads from a vacuum (-30 in/hg or so) to about 4-5psi over sea level.. In reality this would cover anywhere the car would operate..

The Zeitronix (and its boost sensor), or LC-1 (with SSI-4 and 3 bar sensor) are probably the two best ways to log the data inexpensively. You could use an ECU+ with a GM sensor, or a UTEC or Tuner Pro also, but their more expensive options.

Load is a good way to determine how well the car is running as you will see the affect of additional boost on the car's Volumetric efficiency, MAF Frequency is another way you can see how well the turbo spools (although this is affected by changes in intake tract that can affect the sensor)

I understand your point, and if your trying to determine the efficiency of your setup and how it affects boost levels and the spool of the turbo, then you end up needing a bit of additional instrumentation. But its not required for tuning as tuning is really about making adjustments to create the best (reasonable) power for what is already there, and not delta comparisons. Although Load should give you most of what you need.

 

FWIW our calculated load is really only a guestimate, and its only as accurate as the data its given.. The closer to stock the values are, the less of an issue this is, I know on my setup my load is thrown off about 20% because of the Injector scale and latency values I had to use in my calculations, if I interpolated the voltage latency a little, they would be a bit closer.

 

It might be a bit cheaper to get our LMA-3, which includes a MAP sensor and accel, side force, etc., than to get an SSI-4 and an external sensor.

-jjf

 

I have the SSi4 and GM 3.3 bar map sensor. This little sensor is about the size of a quarter, so you can hide it just about anywhere.

I bought my SSi-4 from a vendor on her (primo8998). If I recall the SSi4 was 119 shipped.

For the 3.3 bar, go to gmpartsdirect dot com:

GM 3.3-bar map sensor
9373269

wiring harness
88987997

The sensor is about $50 and the wiring harness is about $20.



Eric

 

I have the pdf for the sensor, but too big to upload here. Here are the two pages saved as a .jpg.

Eric

 

Eric,

How did you calibrate the GM bar Sensor. I followed the info in the link in my signature, but I do not know if the sources (WBC and PLX) are accurate or not.

PLX
http://www.plxdevices.com/AppNotes/PLXApp013.pdf

WBC
http://www.widebandcommander.com/downloads.htm
http://www.widebandcommander.com/techtips.htm

 

To my knowledge, there is no sensor calibration needed. The important thing when using a map sensor is to make sure where your connection for 5V and ground is taken, so that your readings are accurate for reference to the sensor.

I'm going off of memory here, but I believe the SSi-4 takes into account any changes in grounding if the external sensor is hooked up properly.


Eric

 

Yes, the SSI-4 has true differential inputs. You should not have to worry about ground offsets. For calibration, you would normally set the SSI-4 to external 0-5 Input, then set the units, min, and max in LogWorks ('Configure Channel'). If the input is linear, min/max values/voltages are all you need to specify. If the sensor is non linearly, you can enter a table of voltages and values by pressing "Custom Lookup" on the Configure Channel Dialog.

-jjf

 

I log everything And sort it with Excel.

Probably a dumb question, but in regards to the topic subject..

Would selecting fewer parameters to log, cause my logger get more samples/second??

 

My experience is it didn't really make much of a difference in speed.. On slower laptops, or if your really trying to get every little bit of data then remove the items you really just don't need.

 

I have no idea.

 

personally i log everything from evoscan. when i bought my laptop i knew that i will be using it for such things so i got it with 2GB memory...

who is kind enough to explain how we should "translate" load values?

 

From what I've seen, a tad. MUT messages are very short and the baud rate is relatively high (as far as OBD type stuff), so the limiting factor seems to be the ECU's response time.

-jjf