aem 35-8460 boost guage questions | AEM
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boostede30
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Joined: 07/31/2017 - 21:36
aem 35-8460 boost guage questions

i have an aem 35-8460 digital boost guage, and am running a vipec v88 ems system, ive looked at the pinouts for the boost guage and cant seem to find a description for what the other blue and white wires are for, the reason why i am wondering is because looking over my engine(bmw m52b28 turbo) i see that i have the aem 5 bar brass fitting fitted into my intake, and the plug with the 3 wires going to my boost guage inside the car, and i know i have a map sensor and in the vipec program i can see it says that it is hooked up and working, but i dont have a map sensor anywhere else in the engine bay, so my question is are the blue and/or white wires go to the ems and also provide a map signal? the previous owner had a shop do the wiring and id just like to have a full understanding of how things are wired/work and this is pretty much the only thing im confused about

AEM_PT
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Joined: 05/22/2014 - 08:13
It sounds like you have one

It sounds like you have one of our classic boost gauges that has a range od -30 to 50psi. The blue and white wires are optional. White is the 0-5V analog output while the blue wire is the RS232 datastream wire. Are you attempting to hook up the gauge to your vipec?

boostede30
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Last seen: 2 years 10 months ago
Joined: 07/31/2017 - 21:36
sorry for the late response

sorry for the late response been getting side tracked with some other things, thank you for the help so far though, the reason i am asking is because my vipec ecu is saying its not getting a map signal, and i only have one aem pressure sensor on the car, so when i traced the 3 wire harness it leads to my boost guage inside the car with no splices in between, and then there is the other white a blue wires going to my ems, so im trying to figure out how the ecu originally got a map sensor signal and boost signal from the same sensor, the car ran before i pulled the motor to build it so something must have got jostled around and now the ecu is getting a map limit and 100% fuel cut and not getting a map signal, my guess is that from the boost guage one of the blue or white wires provides an analog input for boost pressure and the other provides an analog input for manifold pressure, id like to know if this is possible so i can start tracing the wires and look for breaks, personally i woukd have just had a seperare sensor for both but i wasnt the one who did the wiring so im just trying to figure it out

AEM_PT
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Last seen: 2 months 2 days ago
Joined: 05/22/2014 - 08:13
What you have to verify is

What you have to verify is the source of the MAP signal that your Vipec unit is referencing. Your gauge aside, it might be sharing the signal with your Vipec unit. This is ok but definitely not recommended. A seperate sensor as you mentioned is ideal and should be a Stainless unit. As for the analog output (white wire) on the boost gauge. Although the signal can be used as a MAP reference, it is highly not recommended. The Blue wire (RS232) is a datastream wire that is not generally used when there is an analog available.

FYI Manifold and Boost pressure is kind of the same thing in this case. Your boost gauge reads and displays vacuum as well as manifiold+ pressure (boost).