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Discussion Starter #1
Here’s the event... highway driving and all is well. About 20 minutes in suddenly the car goes to limp mode. Posts an CEL and a message mentioning to service engine now. I pull over, car stays idle. i notice that boost is pegged at 23psi. however i cant hear the turbo whining. I power off, restart and I’m on my way. i also noticed looking at logging is map, boost, are both pegged. Anyone experience this? i get 2 cels.1 is p0106 map absolute pressure (map/baro)sensor range and the other is p0236 turbocharger/ supercharger boost sensor A circuit range/ performance.
i replaced both map sensors at intake and intercooler, but issue still remains. my current workaround is to set my guardian angel to 10psi. i guess it catches the increase in boost and keeps the car from limp mode and i can get to work in the morning haha. my commute is about 25 miles to work. the car dies every trip (before my GA trick). heres an image of the logging. anyways thanks in advance!
fullsizeoutput_a553.jpeg
 

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2017 Kona Blue ST1
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So let s look at the map in the diagram (attached 24-4). The MAP (mounted on manifold) sensor is a 3 wire potentiometer. Pin 3 provides the 5 volt VREF (voltage reference), Pin 2 provides the SIGRTN (ground) and Pin 1 is the signal back to the PCM Pin 33 (C1381E) labeled MAP.

The MAP shares the VREF with the both Cam sensors. The SIGRTN with Fuel rail pressure, ECT & CHT sensors.

If you measure across 3 (+) and 2 (-) you should see 5 vdc (or some very close to that effect 4.8x) The real thing to determine is the voltage leaving the sensor. If the wire BU (Blue) wire is damaged or picked up voltage from another source. Crossed with another wire (copper on copper) it could give an artificial reading.

The TCBP/CACT (Turbocharger Boost Pressure / Charge Air Cooler Temperature) sensor (mounted on or near intercooler) is a little more complex. Diagram (24-5) shows that this sensor body houses two separate potentiometers for a total of 4 wires.

Pin 1 is the SIGRTN (ground) and shares this with the A/C Pressure Transducer and Ambient Air Temperature sensor. Pin 3 is the VREF and also shares this with the A/C Pressure Transducer. Pin 4 is the return to PCM Pin 74 (Gray w/Orange stripe) and Pin 2 is the return to PCM Pin 32 (CACT).

Measurement across Pin 3 (+) and Pin 1 (-) should show the same 5 vdc signal. The outputs from Pin 4 & 2 will show the voltages being returned to the PMC.

NEVER CHECK VOLTAGE USING TO SENSOR OR MODULE USING CHASSIS GROUND OR BATTERY VOLTAGE AS YOU MAY PERMANENTLY DAMAGED COMPONENTS.

I will also attach pin outs for each sensor and the PCM. Perform a continuity test between the sensor connector and the PCM to make sure that it isn't damaged.

If it were me I would start on the TCBP/CACT sensor as it is responsible for positive boost signals. The MAP measures both boost and vacuum.

Regardless of where you start unplug the one of the sensors and see if the issue remains. If both are unplugged and the wiring checks out the unfortunately you may have a faulty PCM.

Hope this helps and didn't put you to sleep.

Stay Safe!

J
 

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Discussion Starter #3
this is the best technical explanation i have ever had. i have spent thousands of dollars at big name shops for their motors just for them to give me a 1 liner response. you are awesome! thank you kindly sir! i'll report back my findings.
 

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this is the best technical explanation i have ever had. i have spent thousands of dollars at big name shops for their motors just for them to give me a 1 liner response. you are awesome! thank you kindly sir! i'll report back my findings.
He accepts bourbon and or ammo as payment. No steel case, he's classy.
 

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2017 Kona Blue ST1
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379635


Let me know if I can help.

J
 
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Discussion Starter #6
ok, so this is very interesting. i had to drive to dallas this morning (from austinTX). car died twice on me for the same issue within 20 minutes. frustrated, i switched tunes from another tuner i use. guess what? no cel's no car dying. to and from dallas. i dont understand. the tune?
 

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How long have you been using that particular tune before the issue began? Did you change anything before the issue occurred?
 

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Discussion Starter #8
How long have you been using that particular tune before the issue began? Did you change anything before the issue occurred?
its been a couple of weeks. but yes, i removed the guardian angels 4bar map sensor and a 3.5bar bosch tip sensor. Then returned to stock oem map&tip sensors. the tune adapted well without any adjustments. then this started happening. mentioned it to the tuner but he was certain it wasnt the tune. but i guess it was, ugh. i'll give it the week and see how it goes.
 

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No that would explain everything. There's different feedback from them than from the factory sensors.

This is an oversimplification but here's the way a sensor like that works. 3 wires, a power (VREF), a ground (SIGRTN) & the sensor output (what is returned to the PCM)

For our applications the power wire gets a 5 volt signal from the PCM.

The ground is also supplied by that PCM.

This makes up your electrical circuit for that sensor. Other sensor may share these outputs but almost always will do so in parallel to help prevent voltage drop. If they were tied into each other in series then that 5 volt reference signal would lower after each subsequent sensor until that would become unusable.

But back to the example.

3 wires, check. We know what each one does. The PCM really isn't all that smart. It can only do the tasks it has been instructed to do. There's some self learning but even that is limited to its defined programming.

What ever this sensor returns is a numerical representation of that 5 volts. Again oversimplification, let's say the no boost is 0 (zero) VDC and full boost is 5 (five) VDC. That sensor applies that volts across that 3.5 bar (1 bar = 14.504 psi) so your sensor has a working range of 50.764 psi.

Divide that 5 volt across 50.764 psi and you can see just how fine of an adjustment it can return. Now take that learned volt reference table and replace that sensor with another one that has a working range of 2.5 bar (36.26 psi) you can see how this would effect what the PCM is trying to translate.

Even switching from 3.5 bar to 3 bar will effect the outcome. I have personally witnessed a 10% variation between two separate identical sensors.

Give it some time and and try reflashing the tune you were experiencing the issues with while the factory sensors are in place. As long as that tune wasn't built around those specific sensor parameters it should be OK.

Please remember that the above example isn't representative of your sensors output but a description of how a potentiometer works.

Glad you're on the right path.

Please let me know if I can help you out or if you have specific questions about some of these functions. If I don't know I'll be the first to say so, but we can figure it out together so we will both know.

Stay safe!

J
 

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Discussion Starter #10
No that would explain everything. There's different feedback from them than from the factory sensors.

This is an oversimplification but here's the way a sensor like that works. 3 wires, a power (VREF), a ground (SIGRTN) & the sensor output (what is returned to the PCM)

For our applications the power wire gets a 5 volt signal from the PCM.

The ground is also supplied by that PCM.

This makes up your electrical circuit for that sensor. Other sensor may share these outputs but almost always will do so in parallel to help prevent voltage drop. If they were tied into each other in series then that 5 volt reference signal would lower after each subsequent sensor until that would become unusable.

But back to the example.

3 wires, check. We know what each one does. The PCM really isn't all that smart. It can only do the tasks it has been instructed to do. There's some self learning but even that is limited to its defined programming.

What ever this sensor returns is a numerical representation of that 5 volts. Again oversimplification, let's say the no boost is 0 (zero) VDC and full boost is 5 (five) VDC. That sensor applies that volts across that 3.5 bar (1 bar = 14.504 psi) so your sensor has a working range of 50.764 psi.

Divide that 5 volt across 50.764 psi and you can see just how fine of an adjustment it can return. Now take that learned volt reference table and replace that sensor with another one that has a working range of 2.5 bar (36.26 psi) you can see how this would effect what the PCM is trying to translate.

Even switching from 3.5 bar to 3 bar will effect the outcome. I have personally witnessed a 10% variation between two separate identical sensors.

Give it some time and and try reflashing the tune you were experiencing the issues with while the factory sensors are in place. As long as that tune wasn't built around those specific sensor parameters it should be OK.

Please remember that the above example isn't representative of your sensors output but a description of how a potentiometer works.

Glad you're on the right path.

Please let me know if I can help you out or if you have specific questions about some of these functions. If I don't know I'll be the first to say so, but we can figure it out together so we will both know.

Stay safe!

J
thank you again for the detailed explanation. i'll keep everyone updated if this can help anyone in the future. thanks again!
 

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So let s look at the map in the diagram (attached 24-4). The MAP (mounted on manifold) sensor is a 3 wire potentiometer. Pin 3 provides the 5 volt VREF (voltage reference), Pin 2 provides the SIGRTN (ground) and Pin 1 is the signal back to the PCM Pin 33 (C1381E) labeled MAP.

The MAP shares the VREF with the both Cam sensors. The SIGRTN with Fuel rail pressure, ECT & CHT sensors.

If you measure across 3 (+) and 2 (-) you should see 5 vdc (or some very close to that effect 4.8x) The real thing to determine is the voltage leaving the sensor. If the wire BU (Blue) wire is damaged or picked up voltage from another source. Crossed with another wire (copper on copper) it could give an artificial reading.

The TCBP/CACT (Turbocharger Boost Pressure / Charge Air Cooler Temperature) sensor (mounted on or near intercooler) is a little more complex. Diagram (24-5) shows that this sensor body houses two separate potentiometers for a total of 4 wires.

Pin 1 is the SIGRTN (ground) and shares this with the A/C Pressure Transducer and Ambient Air Temperature sensor. Pin 3 is the VREF and also shares this with the A/C Pressure Transducer. Pin 4 is the return to PCM Pin 74 (Gray w/Orange stripe) and Pin 2 is the return to PCM Pin 32 (CACT).

Measurement across Pin 3 (+) and Pin 1 (-) should show the same 5 vdc signal. The outputs from Pin 4 & 2 will show the voltages being returned to the PMC.

NEVER CHECK VOLTAGE USING TO SENSOR OR MODULE USING CHASSIS GROUND OR BATTERY VOLTAGE AS YOU MAY PERMANENTLY DAMAGED COMPONENTS.

I will also attach pin outs for each sensor and the PCM. Perform a continuity test between the sensor connector and the PCM to make sure that it isn't damaged.

If it were me I would start on the TCBP/CACT sensor as it is responsible for positive boost signals. The MAP measures both boost and vacuum.

Regardless of where you start unplug the one of the sensors and see if the issue remains. If both are unplugged and the wiring checks out the unfortunately you may have a faulty PCM.

Hope this helps and didn't put you to sleep.

Stay Safe!

J
Dude awesome explanation! I love seeing some real diagnostic skills!


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