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Old 11-26-2012, 10:45 AM   #1
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Default MAP input sensor question

I do appologize, i'm on hotel wifi thats realatively spotty, so seach hasn't been my best option, but - here goes.

I've been using a different tuner for a while, and was using an AEM -30 >35 PSI boost/vacuum gauge with a 0-5v anaolg ouptut to provide MAP data for the ecm.

With the MSPNP, is it better to run the MAP tube all the way back behind the passenger seat (95 miata) or, is there an acceptable way to use the analog output from the AEM digital gauge?

Pro's I'd think, the AEM gauge sensor is wired right into the manifold, so zero lag, and zero chance for a blocked, pinched, cripmed or cut pressure tube, negative being I'm not 100% sure what the senor resolution is.

Any thoughts?
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Old 11-26-2012, 11:15 AM   #2
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run the vacuum line all the way from a tee off the FPR to the ECU behind the passenger seat.

If you had a MSPNP2, then you could input the signal from the AEM, but still more trouble that it's worth.
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Old 11-26-2012, 11:52 AM   #3
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Quote:
Originally Posted by Braineack View Post
run the vacuum line all the way from a tee off the FPR to the ECU behind the passenger seat.

If you had a MSPNP2, then you could input the signal from the AEM, but still more trouble that it's worth.
I'm building a DIYPNP2, i guess i should have qualified that in the OP. The reason that I ask, is because the AEM signal line is already spliced into what would be the ECU MAF signal line. Unfortunately, I don't have access to a scope or anythnig to check the resolution of the AEM signal, I think that it's not terribly fast (2hz?) I'd assume that it would also require manal Baro correction tables as the gage has no atmosphereic input?

I'll prob. just go with the on board i guess.

Thanks for the quick answer!
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Old 11-26-2012, 12:02 PM   #4
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the DIYPNP doesn't have baro unless you DO add the second sensor. Your either dont use baro corrections, or you have it take the reading on bootup.

if the sensor is already spliced in, it would easy to wire in the 0-5v output to the MAP sensor inout on the board and simply not populate the onboard. then calibrate the sensor in the software once up and running.

it's up to you.
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Old 11-26-2012, 06:08 PM   #5
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Quote:
Originally Posted by Braineack View Post
if the sensor is already spliced in, it would easy to wire in the 0-5v output to the MAP sensor inout on the board and simply not populate the onboard. then calibrate the sensor in the software once up and running.

it's up to you.
I'm expecting the answer to be yes, but, if I configure it that way, do you think noise will be an issue if they don't share a common ground? Right now I've got oil( press/temp), boost and water on a bus installed behind the dash. The mtx-l already shares the engine ground with the ecu, and analog output from that is feeding the OEM narrow band o2 wire?

It's a bit of a pain taking somebody's half done project and trying to clean it up.

Doing this twofold, the current piggyback is horrid, afr at idle swings from 13-16.5, steady state cruise on the highway seems to hold 13.8-15.7 which is fine, I expect some swing, but WOT to a shift followed by WOT it seems like the ECM gets behind and holds 15-17. I'm adding FI as time permits, and have a secure feeling that the current set up would grenade the motor in short manner.

I also add, as time permits because we just had twins, so I get about 30 minutes a day to work on this. I'll apologize now if I ask redundant stuff, I'll try not to... But I just don't have the time to sift through the tons of posts on here
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