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MAP limit problem


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Hi, I’m having problems with my L67 supercharged Buick/Holden commodore. While trying to sort the over fuelling/hot starting problems I have developed an error code for ‘MAP limit reached’ which cuts in at 3000rpm, the MAP sensor is showing 190 kpa, map limit is 200 and cut is 10 before so not surprising but the supercharger pulley is only good for 10psi so I’m fairly confident that (unless u have my kpa/boost psi conversion wrong) some thing is a miss with the map sensor reading

I have tried switching from my Link 3 bar to a GM 3 bar sensor and carrying out all the necessary calibrations but the same pressure shows, So fairly sure it’s not the sensor itself.

Once warm, restarting the engine is nearly impossible as it floods itself, I’m guessing due too the high/inaccurate Map reading?

any ideas? Is this a possible Ecu setting issue that I may have inadvertently changed since it ran correctly or more likely a wiring issue?

I shall upload a log shortly, if anyone has a L67 base map I could compare also that would be great!


Cheers, Jim

Log 2019-02-10 8;32;24 pm.llg

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as you say, the ECU reporting 190kpa and the limit cutting in is all by design. You either have a calibration problem or a spec sheet problem with that pulley/supercharger. 10psi boost should be about 170kpa MAP so you are only 20kpa different - if the crank pulley is larger than their reference or you have some restriction in the intake manifold you might be getting 20kpa more than spec. Remember your supercharger actually pushes volume, not pressure. Volume -> pressure is just a measure of how much the air pushes back. Smaller valves, cams, intake runners, more rpm, or quite a few other things can change "14 litres per RPM" or whatever the supercharger spec is into a different boost psi on different engines.

once its been running for a bit, if you kill the engine does the MAP reading match the BAP reading?

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