I have been using the internal map sensor which lags a lot inbetween shifts. so I bought a 3 bar map and wiried it in and put in the vacuum line.

A- ground
B- map signal
C- 5v

I tested out a, b and c with a volt meter and they all check out ok with B @ 1.6v with the ignition on engine off.

In the Haltech I change the main setup to external MAP and downloaded the config file for gm 3 bar map.

I turn on the car and drive for a little bit and it's running terrible. The A/f ratio is completely different in between banks. When i'm crusing bank 1 is 12 a/f (normally 14.7) and bank 2 is 17-18 a/f. They used to be pretty much even give or take .5 points in vacuum with the internal map sensor.

What is going on here? Faulty 3 bar map sensor?

thanks

 

now that is a good question

 

From memory you can set it back the internal map sensor and also leave the external plumbed in and conneted. (ie both connected and plumbed)

Monitor the following and see how they compare

MAP
C - Ext Map

I'm not sure why you are seeing different AF per bank. Even if the MAP sensor is faulty the AF should be the same'ish for each bank

Did you buy the haltech 3 Bar Map Sensor? If so are you using the 3 Bar GM CAL?

 

What vacuum reading is it giving with the key on and engine off? Does everything run fine if you switch back to internal and hook the vacuum line back there?

Faulty map sensor or improperly wired map sensor should not give bank to bank differences.

 

Switch back to the internal map sensor and then LOG both sensors and compare the two. You can adjust the calibration of the external sensor until the graphs overlay each other (assuming a proper functioning sensor). Mine was pretty much spot on and required no fine adjustment. Sounds like you have some other issue with the AFR being off bank to bank...

 

Hal I only plan on running about 8lbs of boost, do you recommend I use the internal MAP sensor in the haltech or go with a 2bar map external?

 

You will be just fine on the internal map. It is a 2.5bar, so it will read to roughly 21psi.

 

I remember my internal MAP sensor having issue and only reading down to -10hg. Switched it over to external GM and it has been working fine ever since. The wiring was rather simple, but I know that Hal had to do something with my map (not MAP sensor related). This was 2.5 years ago, and I don't remember the details.

The switch over was smooth.

 

The most important thing is what Hal said: map sensor changes shouldn't cause a bank to bank difference.

 

it's so weird. i got the bank to bank difference when i installed the map sensor. i'll datalog tonight and recheck the wiring again.

 

For what it's worth, I also switched from internal to external and the difference was huge. The throttle response is so much better than before!! I even datalogged both sensors during a transient throttle event and the difference in response time was obvious. I kept the vacuum line to the external map as short as physically possible - about 3 inches. It's also on it's own vacuum fitting so there aren't any other hoses teed into the same line.

Back on topic...I agree with everyone else- a faulty sensor or incorrect calibration would affect both banks. Did you accidentally change the calibration on one of your o2 sensors? Are you running dual o2 sensors with individual bank o2 correction?

 

ok here we go.. I have pictures and videos

FYI: I had an extra GM 2 bar map sensor to test. same thing. testing below is with the gm 2 bar map sensor.

1) shows i tested out the plug A) ground B) 1.6v engine off ignition on C) 5V





2) Manifold pressure with the engine off:
internal haltech map sensor: 0.2
2 bar map sensor: -0.5

3) 1st video (with gm 2 bar map sensor)
<iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/5qWsVUP-esc" frameborder="0" allowfullscreen></iframe>

2nd video switched to haltech internal map sensor with stock calibration file

<iframe title="YouTube video player" width="640" height="390" src="http://www.youtube.com/embed/mnI8q_IpPTc" frameborder="0" allowfullscreen></iframe>

5) data logging the 2 bar gm map sensor and internal map sensor




am i doing something wrong?

thanks for the help.

 

if your first vid for the GM 2 bar is supposed to be in PSI then maybe the values are wrong. See image below. Seems like one cell is in PSI and the other in inhg. Also u mentioned you were seeing 1.6v at 0 vac this should be 2.45v according to the calc and the chart in the ECU

 

The Haltech supplies 5V to the sensor and the sensor lead must be hooked up before you apply voltage or you can apparently damage the sensor (there was a warning with my GM-type sensor to this effect). Are you measuring voltage at the Haltech plug or on the sensor side? Connect up the plug and then tap the sensor line and read the voltage. You should get around 2.5 volts at 0 psi.

Instructions for my sensor in case you didn't get instructions with yours: http://www.aeroforcetech.com/files/2...structions.pdf

 

thanks. when I get home tonight i'll test out the voltage with the sensor connected.

I wanted to verify my wiring was correct so the voltage test was with the sensor not connected.

 

Actually 1.6 volts is exactly what you should get for 0 psi with a 3 bar sensor. Hmmm... how did you get a sensor reading with the sensor not connected? Not sure what that testing represents

 

hmm i was under the impression the wires comming out of the haltech (4 pin connector) is supposed to give that reading? or do you only get that reading when the sensor is connected?

 

ok so i connected the 3 bar map sensor and tested out the voltage: 1.6v on "B" wire . I hooked up an air compressor and set it to around 29psi and "B" wire read reads out around 4.5 ish volts

I then took off the 3 bar map and hooked up the 2 bar map and i am getting a 2.4 v readout at zero which mr rizk shows in his calculations. I set my air compressor to around 14 lbs and I am getting a 4.5-4.9 ish read out which is correct.

What is going on? all the connections read OK. and my afr is extremely different between banks with the map sensor. As you can see in the video, the internal map is working ok.

 

map sensor sounds like it is working perfectly fine. Something else is going on because the map sensor should have no effect on bank to bank differences.

 

So, this GM 3 bar MAP sensor is something I can get from the GM dealer?