Here's the deal. I want to run a stock map sensor connected to the fpr line as a vacuum source but still be able to use the TMAP sensor's iat part. That way, I can get post supercharger iat's in my tune. I pulled out the three wires from the MAP harness going to the TMAP harness and connected them to a 1 bar map sensor.
I kept the iat wires going to the TMAP sensor and in theory, it would all work.
My MAP reading is 19 kPa, and my iat's are either normal or -40*F. What's going on. I can see the iat's not being right because of a loose connection, which I think is right, but I don't understand why the MAP isn't working. I have a stock tune uploaded with VATS turned off and my injector constant changed. I forgot to save a data log because I'm dumb.
Any ideas what's going on?
Alex Richards wrote:ECT = no
IAT = no
Both variable reluctance sensors, they are both negative coefficient sensors, meaning when temp goes up resistance goes down. PCM measures resistance through them.
MAP and MAF both have a 5v Reference circuit, so yes technically they have "power" and "gnd" wires along with a third signal wire. MAF is a digital square wave frequency variance where as MAP is a piezo-resistive membrane.
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Alex Richards wrote:ECT = no
IAT = no
Both variable reluctance sensors, they are both negative coefficient sensors, meaning when temp goes up resistance goes down. PCM measures resistance through them.
MAP and MAF both have a 5v Reference circuit, so yes technically they have "power" and "gnd" wires along with a third signal wire. MAF is a digital square wave frequency variance where as MAP is a piezo-resistive membrane.
The IAT has a GND and signal, make sure that both the connections are very good and that the wire that you used to make the connections is good.
As far as your MAP sensor goes, there are 3 wires referenced above, +5V, GND, and Signal. Signal is usually the blue wire, ground is black and white is power. Verify that you have 5V between the + and gnd wires. With the ignition on (but the car not running) you should have about 5 volts coming out of the signal wire to ground. With the car running you should get a much lower value, less than or right around a volt.
19kpa is a very low voltage, so that means its getting some signal, but not much. Is 19kpa shown all the time, or just when you are idling?
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To add to Ron's post, If you shut down the scanner(completely), and turn back on and re log, do the readings change at all? I have ran into instances where the scanner wigged out and did something similar, Also, if you have a VAC pump and a meter you can test your MAP sensor and see if its faulty.
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I got my iat working accurately, it was a loose connection. The kPa however still remains at 19. Its the same all the time. When the car is struggling to idle, it's 19 when it's powered,, but not on, its 19.
For wires on the MAP, I have an orange, a bright green and a putrid green. They're matched up. Could it be a faulty sensor? I have it hooked up to my fpr line.
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Update...I just finished re-wiring the TMAP, so it should run and idle fine. It doesn't. With my supercharger reflashed ecm in like before this fiasco started, it's saying I'm idling at 8 psi. My timing is jumping up and down at idle and it's rough. Driving it seems fine. I have a CEL for a Map sensor low voltage. Help?
I'm pretty sure about my wiring. I've checked it a few times. Help?
I've attached a log on the HPT forums.
http://www.hptuners.com/forum/showthread.php?p=152548#post152548
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The shop tuning my car was having the same problems ultimately they said they could do it but it would be garbage unless paired with this mapecu II at www.mapecu.com
-40F on the IAT means High resistance so check your wiring and connections...Youve got an intermittant open somewhere in the circuit.
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