I recently was able to hook up my mechanical boost gauge. It reads 50% higher boost than what my cts3 gauge reads thru the whole range. Cts3 gauge reads what the tune is commanding. Mechanical gauge was checked for accuracy. I’m at a loss of what could be wrong. MAP sensor? Seems it would follow the tune if it was bad.
Logged boost vs mechanical boost.
- Thread starter darkness
- Start date
Stock MAP.
I don’t have an obd2 splitter to do that, but could check certain areas I know what the cts3 reads. I know for a fact at max boost, the cts3 was reading what the tune was calling for. I was operating on boost map b and my max boost is 37psi. Boost was 24 on the cts3 and baro was at 13. And the mechanical gauge was 35psi.
37 - 24 = 13
Baro reads 13
Looks good
37 will be psig
24 is psia
13 is psia
34 looks like psig which is only 3 psi off the 37 psig. Might be a small error in either or both gauges/sensors. Nothing to worry about
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Ok, I have a log. My computer is a pain in the ass so I have some pics instead of zip files. The boost numbers on the cts3 which read in psig, are the same as what my efilive log reads after the math (psia). All these numbers all point to everything works correctly…cts3 and MAP sensor. I verified the mechanical gauge also works in 5 psi increments on the regulator on my compressor. For reference, the original cts on my ‘02 and the mechanical gauge follow each other. I just don’t understand why the mechanical gauge reads 50% higher across the whole table than both the cts3 and efilive log.
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Your mechanical gauge reads absolute pressure?
No, it doesn’t.
It’s an auto meter mechanical gauge. It does not read absolute, obviously. What it does read is 50% higher than what the cts3 boost number shows across the board. I’m trying to figure out why.
Did you check to see if the hose was pinched? Good wiring? etc?The hose is good. I actually verified the gauge was good thru the hose as it was easier to get to than tearing the dash apart. As far as wiring, not yet. Not gonna lie, I’ll replace the map sensor and short jumper harness before I trace the wire out. This is on my Kodiak and the wire harnesses runs across the motor to the ecm on the pass side firewall in a heat shielded cover. Perhaps my lack of due diligence is going to get the better of me.
Why is MAP and BOOST the same in your log? MAP should be absolute (PSIA), but it is tracking with your BOOST. According to your BARO, MAP should be reading 13.5 points higher. Calling for 38.7psia in the tune, and reading 33.6 on the MAP... boost should be reading more like 20psig. Something is looking fishy. If your MAP is right, then it's agreeing with your mechanical gauge. But I don't understand why the MAP isn't showing PSIA. No chance that someone changed the sensor and/or recalibrated the MAP at some point or something else fishy?