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Car question - MAP sensor

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Car question - MAP sensor

Old 03-14-06, 08:23 PM
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Car question - MAP sensor

I have an aftermarket supercharged car. It will throw a P0108 - MAP sensor voltage too high code under medium throttle.

The vendor says my MAP sensor is bad. I think their box (piggy back system to control aux. injectors) is probably what is bad.

Their box modifies the MAP sensor voltage and the crackshaft position signal.

So what are the chances it really is the MAP sensor? Their exact response to my question was "your map sensor is gone".
Old 03-14-06, 08:38 PM
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I don't know, my car doesn't have a navigation system, but a bad MAP sensor really can't affect too much...

Is the swap difficult? Maybe go to Murray's and buy one, try it and return it if the problem is not fixed.
Old 03-14-06, 08:45 PM
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It's the manifold air pressure sensor. It's supposed to measure the vacuum going into the engine (which is a measure of engine load). The piggy back system has to trick the engine computer because the supercharger puts in more pressure than the car's computer is expecting.

I'm not eactly sure where the sensor is. A quick search online looks like they run about $50 but I'm not sure if they'll have one for my car at Autozone.
Old 03-14-06, 10:16 PM
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so, your car is NA stock, but has a MAP sensor? usually, only FI cars have a MAP sensor. anyhoo, on my car, the MAP sensor is on the pipe leading to the throttle body/intake mani. you might wanna check with some forums specific to your car. what does your boost gauge read at that time?

btw: why didn't you get someone to modify the ECU? they could set the pressure to the correct setting, so you don't need this box.
Old 03-14-06, 11:02 PM
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It's a Chrysler 300c and they make it a PITA to get into the ECU (it's all encrypted apparently). Superchips only recently released a tuner for it (last month I think) and lots of people are having problems. So for now, you can't modify the ECU significantly. They say the flashes for a supercharged car are a year out, which means at least two years out.

I don't think the sensor is on the input to the intake manifold. I'll have to check again, but I think I just have the throttle plate then the manifold. Maybe it's hiding on the back somewhere.

I don't have a boost gauge, I have to have a laptop hooked up to the piggy back box to get a reading. I haven't done that, but I'm guessing a pound or two of boost, maybe even 0psi is triggering the CEL. I only get around 4-5psi boost at redline.

Last edited by asabase; 03-14-06 at 11:25 PM.
Old 03-15-06, 01:52 AM
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well, the MAP sensor should be somewhere along the intake piping. follow it from the intake box to the intake manifold and you should find it.

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