MAP interchangeability question for MB 280sel 3.5 d-jectronic

Thanks for your help! I thought this would be a separate problem, but it turns out it is highly related to my previous problem that I asked in this forum ( jetronic.org/en/forum/jetronic/1980-d-jetronic-problem?start=0 ). All I did was renewing the D-Jet system's 23 wires and changing back to MAP 0 280 100 012, but it goes back to the same previous symptoms.

I disconnected all 8 electric plugs of injectors, and install 8 LED lights for examination. When ignition on (not cranking), only no.4 & 8 cylinder lights are on. When cranking, only no.4 & 8 and no.7 & 2 cylinder lights are on, but not no.1 & 5 and no. 3 & 6 cylinder lights.

After that, I disconnected the trigger wire connector and ignition on again (not cranking), only no.7 & 2 cylinder lights are on. When cranking, only no.4 & 8 and no.7 & 2 cylinder lights are on., but not no.1 & 5 and no. 3 & 6 cylinder lights.

To my understanding (not sure if it is correct), when ignition on (not cranking), all 8 cylinder LED lights should not be on. While cranking, all 8 cylinder LED lights should be on.

My problem now is, except ECU problem, what would cause only no.4 & 8 and no.7 & 2 cylinder lights are on when ignition on? As I said in my previous topic, I have recently sent ECU and MAP to BOSCH Classic for repairment, therefore, I cant and wouldn't suspect it is caused by the ECU malfunction. Appreciate your support and input as always!

Hi Unknown,

either it is still ECU - I have one on my desk that shows a fault every other day- or it is your wiring or trigger contacts if not all injectors are pulsed during cranking.

Thanks for the new information! May i understand more about what fault in the trigger contacts will make injectors pulsed when ignition on (not cranking)? I have checked 4 trigger contacts and they are all of 157~160 dwell.

 

Pulses from throttle switch.

Thanks for your prompt reply!

When I disconnected throttle switch wire and ignition on, i can observe pulses in cylinder 4 and 8. Can we conclude that it is faulty ecu?

If i want to fix the ecu and map, should i contact bosch-classic koller & schwemmer or bosch-repair-service.com? are they the same company? Thanks again for your help!

Best regards,
Danny

Hi Danny,

if you just turn on ignition, throttle siwtch is dicsonnected and injector 4 and 8 create pulses without cranking engine: Yes then there is a fault.