D-jet ecu bad?

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Finallymy73

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e9ers-

Per some of your suggestions, I have done all trouble shooting component testing I can think of from several trouble shooting manuals in regards to my 1972 CSi's no start issue.

Main issue is no activity from the injectors when the throttle is actuated. This leads me to believe the ECU is failing? The fuel pump runs when we turn ignition on and also during cranking. However, the injectors are not pulsing. When injectors are individually energized, they click, but do not when connected to the wiring harness. Could the lack of pulsing be due to something other than ECU failure? Does anything come to mind? Please send any suggestions that might help me avoid buying a new ECU! Appreciate it!

Thanks,
Bob
 
1. check the FI relevant grounds
2. check the harness for broken wires and bad connectors
3. check the TPS with a multimeter
4. check the trigger points in the lower part of the distributor
.... and check the grounds once again

Good luck!
 
Power at pins 16 and 24 from pin 87 of main relay?

Continuity at pins 12 and 21 and also 12 and 22 on your
trigger points when rotating dizzy by hand?

Good ground signal at pin 11?
 
I haven't read much of you thread, but I'm sure you have already replaced the trigger contacts? This is worth doing in any case to increase reliability....

Tom
 
After bad grounds and air leaks, worn trigger contacts are probably responsible for the most bad manners among D-jet M30 engines. They should be replaced every 60.000 km or 40.000 mls. Don't forget to use the correct thick grease and check them every second oil change.
 
As a correction to a previous post by me- djet is hardwired injectors to ground
And triggered by baattery positive. 4 separate circuits and pins-
1+2. 3+4. 5. 6.
 
Finallymy73 said:
e9ers-

Per some of your suggestions, I have done all trouble shooting component testing I can think of from several trouble shooting manuals in regards to my 1972 CSi's no start issue.

Main issue is no activity from the injectors when the throttle is actuated. This leads me to believe the ECU is failing? The fuel pump runs when we turn ignition on and also during cranking. However, the injectors are not pulsing. When injectors are individually energized, they click, but do not when connected to the wiring harness. Could the lack of pulsing be due to something other than ECU failure? Does anything come to mind? Please send any suggestions that might help me avoid buying a new ECU! Appreciate it!

Thanks,
Bob
Click to expand...



Your post regarding the throttle is confusing. You may have meant "starter" - or, are you saying that the injectors fire except when you poke/crack the throttle? (I am guessing the former)


As others have probably advised, the ECU is low on the list of suspects. It is not impervious to failure, yet the wiring (including the relays and grounds) connected to the ECU is the more likely problem. You have not described the overall condition of the wiring, including whether it is original or a quilt with many patches. If the wiring is still bundled, a break could occur virtually anywhere. This includes any area exposed to ozone and heat, e.g., where the FI wiring enters the frame rail (exhaust manifold side) toward the ECU. That does not mean anything is wrong with the wiring, but it is another place to snoop. Although doubtful, the junction between the wiring and the ECU can look like it fits, but the connection may be faulty due to corrosion or to a hastily made fit. If you haven't already done so, carefully examine the wiring connection at the ECU. Another consideration might be the pressure sending unit, usually found on/near the brake booster. The PSU controls the injectors' pulse duration. The Djet wont run without the PSU's signal, but at the moment, I can't recall if the PSU provides integral system continuity for pulsing of any duration. In any event, if the PSU is defective or unplugged, a replacement ECU is no answer.

I'm sure it's been said before, but the easiest means of testing the ECU is by swapping it with another one or allowing someone else to test your unit in their vehicle. Parenthetically, I have heard of a similar Djet situation involving a different make vehicle where the ECU was condemned due to supposed water exposure. The replacement ECU made no difference and the owner converted to carburetors. The discarded parts worked fine when tried by another Mercedes owner.

Check for PM.

http://www.e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/13600100.html


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