Hello,
My 98 Sonoma (street cruiser) Ln2 motor ecu is not capable of reading positive boost pressure firing my tuner to work from the TPS. Needless this is not ideal. I can considering adding an external 2 bar map sensor and connecting the 3 wires from the TPS to it. They both operate 0-5v only now it will be reading manifold pressure rather that throttle position. My hope is this provides more accurate fueling and a better driving experience. I cant think of any reason the ECU would know the difference. Has anyone toyed with this idea? Any input would be much appreciated.

Thank you

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I'm not familiar with the stock ECU but I don't see how using a MAP in place of the TPS would help. Did the stock setup use a map and/or MAF?
Are there tuning options using what you have? It may be easier to use a standalone.

 

The stock setup has map but the ecu can not read anything over atmospheric pressure. The tuning is done with HP tuners using TPS to control fueling (alpha-n) and this is the only real option. My thought is that by using a second extrenal map and using the TPS circuit I can now read speed density rather than throttle position. Both of these sensors have an operating range of 0-5v. I would basically just be using a different sensor to send the signal to the ecu. This truck is a driver so my goal is to achieve more controled fueling while driving up hill and cruising.

 

Stand alone would obviously be a better option but I am just looking for options to improve on what I have.

 

A TPS and a MAP sensor don't act the same way. They're not providing the same info and I would nearly guarantee that all you'd end up doing is wildly confusing your ECU.

For example a MAP sensor will show more vacuum going down a hill with your foot off the throttle than it will sitting at a stop light with your foot off the throttle because your RPMs are higher coasting than idling. Your vacuum level will go over 'full throttle' as you come into boost even though your pedal itself might not be at 'full throttle'. And you could also peg your throttle and NOT be in boost.

 

Is HP tuners not able to scale for a 2 or 3 bar map? Microsquirt is affordable. RUS EFI probably has an adapter for the ECU pin out that would let you leave the harness in place.
Setup looks good what engine are you using?

 

My guess is you need to do load based tuning rather than trying to incorporate a sensor that the PCM doesn't understand. Can you upload your tune file, or a link to your HPtuners thread?

 

Pretty sure the map in the pcm can be changed. If your guy cant do it , someone can.
You need the tps, map and rpm or things aren't gonna work right.

Not sure why alpha-n is being used to tune this if it has a map sensor. alpha is only rpm and tps based which doesnt account for load.