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Old 05-10-2008, 02:43 PM   #1
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Question MAP sensor problems

I'll try and explain my situation from where it began. I bought my AEM EMS a while ago from a member and it came with a Honda MAP sensor. After installing it and wiring it up I found the ecu reading a retarded number for the MAP psi, like 23k something so I assumed my sensor was faulty or that I could not wire it correctly since I didn't know what model or year it came from. If you aren't familiar with the AEMPro software is has a MAP sensor wizard, which you just select the sensor manufacturer or part number from and it loads the settings for it.

Well there is only one sensor that Honda uses and with it selected, still no luck, so I decided I'd just buy a GM 3 bar, which I purchased from this link It's part# 12223861. I wired it up using the pinout he sent with it, and wired it to my ECU harness, which requires me to use 2K for my 5v (power), 4F for my MAP input (signal), and I tried using both 2C for a sensor ground and then my own ground to the engine bay. My sensor is reading a much smaller number now, with it selected in the sensor wizard within AEM. I changed my MAP input to MAP Voltage and besides that I left the values as the wizard had set them. It reads -8.5 psi with no vacuum line attached, just the ignition on. I had bryantaylor come by and do what he does best (suck and blow baby ) and it jumped 3 psi so my sensor is definitely getting a reading based off pressure. Jk by the way bryan, hehe. I tried uploading TurboTim's map from EMS and although he uses the same exact sensor I'm still getting the same -8.5 psi. I used a voltmeter and checked the wires at the pigtail and they're reading correctly.

I read something about changing offfset to compensate for altitude and such that could affect the pressure read by the sensor. So I fooled around a bit and got it pretty damn close to 0 psi, but then I couldn't get it to read when I tried sucking on the nipple on the MAP. I duno if it's just my weak lungs or if the sensor is buggy now that I changed both the sensor offset and scalar. The offset is actually maxed out now at 32.77 and the scalar is at 5.5. I'll upload a few pics of what I'm seeing just to help. First is with the default map with just the wizard's settings, second is with the offset and scalar adjusted.

Basically, I wanna know why my sensor is reading like this. Is my sensor not wired correctly? My EMS not working correctly? Thanks a bunch in advance, help me get my car boosted!


PS: wanted to say huge thanks to TurboTim and bryantaylor for all the help they've already given me.
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MAP sensor problems-aem-ss-default.jpg   MAP sensor problems-aem-ss-offset.jpg  

Last edited by rollin904; 05-10-2008 at 08:32 PM.
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Old 05-13-2008, 11:16 AM   #2
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I use the default "wizard" settings for that map sensor; they should be correct. You could send your ecu to me to check it...other than that I don't know, other than your wiring being bad but it's pretty simple to wire 3 wires. Next time I am by my car with my laptop I'll see what my MAP volts are when the engine is off. 0.63V isn't'd think with a 5volt 3 bar MAP sensor it should be around 1.7 volts at 0psi.
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Old 05-13-2008, 04:56 PM   #3
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Yup, default wizard settings and I'm 100% my wiring is correct. If anything I'd be scared I didn't insert the pin correctly but the sensor wouldn't read at all in that situation I'd think. Also, my battery may be a tiny bit low. I checked it the other day, 11.87v. I have a charger, I can see how that impacts it. Let me know if you want me to send it your way Tim. Thanks.
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Old 05-13-2008, 05:29 PM   #4
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needs less AEM and more megasquirt
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