Cel and overboost

phum · **Posted:** Sat Mar 30, 2019 12:54 am

Hello all,
Very occasionally I am getting a cel code telling me of overboost.
I am thinking of installing a boost gauge to monitor this.
Question is, what is the maximum boost pressure that I shouuld see?
Thanks

iakj11 · **Posted:** Sat Mar 30, 2019 9:08 am

Using OBD2 and the Torrque Pro app as a gauge, mine maxes out between 18 and 19 psi. I'm not sure how high it would need to be to trigger the cel.

WWDiesel · **Posted:** Sat Mar 30, 2019 2:51 pm

The normal range on the OEM (3 Bar) MAP Sensor Air Temperature / Boost Pressure sensor if it is functioning correctly is 20 kPa to 300 kPa.
That equates to: 2.9 psig to 43.51 psig boost gauge pressure
There is some variance due to atmospheric pressure which the ECM is supposed to compensate for.

If you are able to achieve greater than 43 psig boost pressure, which I doubt, you are overspinning the turbo. :shock:

I suspect your MAP sensor could be bad and giving an erroneous reading to the ECM which is causing the overboost DTC?

OEM Bosch PN 0 281 002 437
Mopar PN (old 05140331AA) (new 68031593AA)

It can be replaced with a much less expensive MAP sensor used on GM vehicles:
BOSCH 0 281 002 845
GM PN: 55206797 :google:

https://www.gmpartsdirect.com/oem-parts ... r-55206797

flash7210 · **Posted:** Sat Mar 30, 2019 5:24 pm

Roughly 22.5 psi is where a overboost code will be set.

diesel_guy86 · **Posted:** Sat Mar 30, 2019 5:42 pm

WWDiesel wrote:

The normal range on the OEM (3 Bar) MAP Sensor Air Temperature / Boost Pressure sensor if it is functioning correctly is 20 kPa to 300 kPa.
That equates to: 2.9 psig to 43.51 psig boost gauge pressure
There is some variance due to atmospheric pressure which the ECM is supposed to compensate for.

If you are able to achieve greater than 43 psig boost pressure, which I doubt, you are overspinning the turbo. :shock:

I suspect your MAP sensor could be bad and giving an erroneous reading to the ECM which is causing the overboost DTC?

OEM Bosch PN 0 281 002 437
Mopar PN (old 05140331AA) (new 68031593AA)

It can be replaced with a much less expensive MAP sensor used on GM vehicles:
BOSCH 0 281 002 845
GM PN: 55206797 :google:

https://www.gmpartsdirect.com/oem-parts ... r-55206797

Just wanted to correct here, this is an absolute pressure sensor, not gauge pressure. It reads from absolute 0, or -14.7psi at sea level. So maximum boost it can read is 29.4 gauge pressure. But due to the 255bytes available on obd, i believe only 21/22 psi is all that can be viewed through the obd port.

When i ran my custom turbo setup my mechanical gauge would show 32lbs, but torque would always stop at 21psi.

phum · **Posted:** Sat Mar 30, 2019 7:00 pm

Thanks all

flash7210 · **Posted:** Sat Mar 30, 2019 8:51 pm

This is my mechanical boost gauge
https://youtu.be/TlFmOlS8oHk
I drilled and tapped the intake elbow for the pressure port.

Dzldust · **Posted:** Wed Apr 10, 2019 10:45 pm

Make sure vanes in turbo are not sticking ,that’s what was wrong with mine after replacing all the mentioned parts and it’s free to check

Cel and overboost

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