A/C Idle Surge & Stalling at Idle

wagenwerkstatt

Two issues I have been trying to diagnose and not finding a solution for before performing the calibration steps.

Vehicle: 1992 MB 300TE 4matic - M103
Firmware: 4.1.7
Boot Vers:2.4
PCB Vers:2.4
Prod Date: 24.09.2024

Air Conditioning Idle Surge
When the EXT input is turned on the idle jumps to 2000-2500 RPM then drops over and over in quick order - have checked the On and Off Voltage settings, made adjustments, no change.

Engine Stall at Idle
If engine temp reaches approximately 100c, engine stumbles, idles poor then stalls. Can be restarted normally, sometimes has extended crank before restarting.

Fuel pumps are two brand new oem Bosch units, new MB fuel filter, O2 sensor is brand new MB OEM Bosch, ignition system recently serviced before converting to the Invent ECU which included oem bosch coil, cap, rotor, spark plugs and NGK wires.

I've reviewed logs and cannot find anything unusual, it just starts behaving as described above.

Any help/insight would be appreciated!
Thank You!

JHM

Air Conditioning Idle Surge - it seems like too much correction is set. Show your Idle tab.

Engine stall - I need logs

wagenwerkstatt

JHM

Thanks for the reply, I will follow up with logs and screenshots in the next few days.

wagenwerkstatt

JHM
4-Pin Coolant Temp Sensor as the values via Commander and via multi meter are not within specification, it was previously stable but now it gives a value of -20C when it is actually 24-28c .

I reverted the firmware back to 4.1.6 with no change, the CTS value is way too low based on actual temperature.

It's the original sensor from 1992, I ordered a new OEM 4 Pin sensor, will replace and advise.

VladimirYesin

where did you connect your EXT for AC?

wagenwerkstatt

VladimirYesin

Its all working now after replacing the 4 pin CTS with a new facet one

VladimirYesin

wagenwerkstatt
Great that you figured it out. But I just wanted to know what is the connection of the EXT wire from Invent ECU - where did you connect it to?