PowerLogger and 3-bar map sensor

G

granatl

TRCM Author
Joined
May 25, 2001
I bought what I think is a 3-bar MAP sensor from GM today, part # 12223861 and matching pigtail 15305891. Even with my discount, they're over $150. These were to replace my "cheap" e-Bay ones.

Both the old and new ones just register completely wrong in PowerLogger, including the 2.0 version. I'm setting the config parameter to "3 Bar Sensor" but the values on the data screen make no sense. (ex. 4 PSI at idle, etc.) When I try to adjust the offset, I can do +/- .4999 (and it's a little tricky to enter values), but it doesn't seem to help.

Ex.
Offset: 0
MAP Sensor Volts: 1.424 (in the config screen)
MAF: 12.0 g/s
Boost: 8.5 PSI
TPS: 0.42

I have the sensor grounded to the body which might be the problem as well.
 
As I have a digital dash, and the e-Bay pigtail doesn't fit the GM sensor, yeah, I did need it.
 
Digital Dash here as well....you dont need the pigtail. The factory harness has the connector right next to the hobbs connector.

Bryan
 
If you used the pigtail, it may have been wired for the TTA, they were backwards. Double check your wiring...

Bryan
 
with the digital dash cars, there is no power or ground wired to that plug.

all of the investigations I have done have led me to the conclusion that the TTA was not wired backwards, and the pigtail is not (ever) required.
(this is based on actual experience, as well as looking at the specs of the sensors, and the car wiring diagrams...)

Razor has a wiring harness that gets power from the TPS wiring, which is an easy fix, or you can feed the sensor from the ECM's TPS feed and ground.

Bob
 
Bob, the original 1989 TTA MAP sensor had the 5v and ground pins reversed. GM sold a harness to switch the pins for about $30.00, I think i still have one here somewhere. The pigtail on the digital dash cars like mine just needed the 5v reference which I got from the TPS and a good ground. Julio made the adapter after mine was done, which makes it easier and cleaner looking.

Bryan
 
And I'll add the power and ground are piggybacked off the TPS. I noticed this lowered my TPS voltage at idle.
 
Got your 5v reference/power signal sent to the PL? Instead of the signal wire.
 
Key on, engine off, the PL distribution block shows 1.49v (with cig lighter as my ground). This is right on target with Vortex Buicks' site, as I'm at roughly 2200 ft. PL Config fluctuates 1.444-1.439 (0 offset). I then go to the data screen and it shows 10.1-10.2 PSI (93.61 kPa).
 
I would not trust the cig lighter as a ground. Move the ground to the lower part of the dash.

Bryan
 
granatl said:
Key on, engine off, the PL distribution block shows 1.49v (with cig lighter as my ground). This is right on target with Vortex Buicks' site, as I'm at roughly 2200 ft. PL Config fluctuates 1.444-1.439 (0 offset). I then go to the data screen and it shows 10.1-10.2 PSI (93.61 kPa).
Click to expand...

Well, 1.4v & 93 kpa isn't bad for your altitude, mine reads about 95 kpa at 1,000 ft. BUT........ Why is it reading 10psi when it should be reading zero??????
 
you need to clear the barometric pressure offset. while PLC is monitoring, hit Ctrl B

Bob
 
Phoneguy said:
Bob, the original 1989 TTA MAP sensor had the 5v and ground pins reversed. GM sold a harness to switch the pins for about $30.00, I think i still have one here somewhere. The pigtail on the digital dash cars like mine just needed the 5v reference which I got from the TPS and a good ground. Julio made the adapter after mine was done, which makes it easier and cleaner looking.

Bryan
Click to expand...

I have heard this before, but only as hearsay. I have also heard that the pigtail was not a wiring correction, but had a resistor in it because the replacement sensors were calibrated slightly differently. That is hearsay also.

I have the original specs for the old and new sensors, and the wiring is the same. I also (many years ago) borrowed a stock TTA sensor from an all original TTA, and plugged it into my GN, it worked fine and the boost gauge did what I expected it to do. I have plugged in the new sensors with the same result.

so, until someone shows me one, I stand by my statements.... :)

Bob
 
TurboBob said:
I have heard this before, but only as hearsay. I have also heard that the pigtail was not a wiring correction, but had a resistor in it because the replacement sensors were calibrated slightly differently. That is hearsay also.

I have the original specs for the old and new sensors, and the wiring is the same. I also (many years ago) borrowed a stock TTA sensor from an all original TTA, and plugged it into my GN, it worked fine and the boost gauge did what I expected it to do. I have plugged in the new sensors with the same result.

so, until someone shows me one, I stand by my statements.... :)

Bob
Click to expand...

I will look for my pigtail adapter...it was sold as a fix for the newer MAP sensors.
Maybe John Spina has an original TTA MAP that he can check as I have never had one in my hands.

Bryan
 
i'd still like to see the adapter harness.... or one of the original TTA sensors....

in any case, all the new 3bar sensors plug right into the GN's, which is what we care about anyway.
 
TurboBob said:
you need to clear the barometric pressure offset. while PLC is monitoring, hit Ctrl B

Bob
Click to expand...

Oh Geeezzzz Bob! I forgot all about the Ctrl B!! Thanks !! See what happens when you get old!!
 
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