If this is a repost, my apologies. The only other places I saw this topic were on the 3SI and GVR4 forums.
While checking the GVR4 forums, I came across this thread:
http://www.galantvr4.org/ubb/ultimat...c;f=4;t=000536
This thread linked to the 3si boards which had the link to
mmcd ver 1.6n,
http://www.3si.org/forum/showthread....6&page=1&pp=10
which then lead me to this thread where the discussion about being able to log your
boost through the use of a MAP sensor
http://www.3si.org/forum/showthread....highlight=mmcd
What it boils down to is that for DSM's with Federal emissions, you can tap into the unused egrt connection with the MAP sensor. With the updated
MMCD program, it will convert the voltage that the egrt sees into your
boost pressure.
The previous thread gives instructions on using both a 3-bar GM sensor, and a 2-bar sensor chip developed by Motorola (they have the part number and link to who sells the Motorola chips in that thread as well)
So seeing that it worked well for 3si cars, I figured why not give it a shot on the ol' 1G? I cracked open my Chilton's manual, and checked the ecu diagrams and this is what I came up with:
The egrt connector for 1g's is located behind the intake manifold, It should not be connected to anything, so it's probably still taped to the engine wiring harness.
The signal side of the connector is blue with a yellow stripe.
The signal ground is green with a black stripe.
They also indicate that a 5v source can be tapped from the TPS, on the green/white stripe wire.
After that, use a t-fitting to hook up the sensor the same way you would install your
boost gauge.
So how did it go?
With fingers crossed, I checked my connections and started up the ol' bird. She came to life, settled down to a nice idle of 750 rpm, and no CEL. So far, so good.
Next came a few highway runs. With one eye on the speedo, one on the road, another on the
boost gauge, and my last eye on the logger, I did a couple of 3rd, 4th, and 5th gear pulls. My
boost gauge read 16 psi, my logger read 15.9. I tried a few more 5th gear pulls to see if the logger would match the movement of my
boost gauge needle. The logger matched it at 5 psi, 10 psi, and 15 psi.
The only thing that bothered me about the run was that the whole time while driving, I encounted random misfires. Some happened at cruising speeds, and I had a few at my full throttle runs. Thinking it was a loose spark plug, I checked and found nothing wrong. I then double checked my connections to make sure none of them were shorting to ground, and did two more runs. The misfire was still there. I finally decided to pull the 5v wire that I had tapped into my TPS. Obviously, the TPS is not going to be a good place to get my 5 volts. Suprisingly enough, the map sensor worked just fine without it. I even went back on the highway to record a few more runs to see if it would work any differently. It ran great all the way up to max spool.
So, is this modification worth it? You bet your bottom dollar! This can only help to make tuning on your car that much easier. The beauty of this modification is that with
MMCD, they can use this egrt connection not only to monitor
boost, but you can connect your wide-band o2 sensor, EGT, oil pres, oil temp, and fuel pressure sensors to this connection (keep in mind, you can only hook up one item at a time
)
So if you have
MMCD, this just makes it 10X more beautiful. If you use the TMO software, they have an input for the egrt, but I'm not sure if they upgraded their software to allow you to read it a map sensor reading. If you use pocketlogger, you'll have to create some sort of table to read the raw egrt data which will come out as a value from 0-255 and convert it that way.
I've checked the ecu diagrams for 2G's but I don't see where the egrt connectors are for those cars, if you're willing to give it a try for your 2G, let me know if it works.
Many thanks to Clint Batters from the 3si forum who helped with the software upgrades, Shaun Polson for developing this kick ass program, and all the other contributors to this program for giving us DSM'ers another wonderful tool to use to help with our tuning!
Linear Mode
