E9 D-Jetronic Injectors not Triggering

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DrivenE9

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First post. This forum has been a valuable resource over past months. Much appreciation and many thanks in advance for the following questions.

Background:
Putting back together an E9 CSL that was completely gutted for a bare shell respray. Disassembly was 3 years ago, and not carried out by myself. Last time the engine/drivetrain ran was 3 years ago.

Am not sure whether the problem is the Distributor Contact Trigger, ECU, MAP, or something else?
- Really hope it's not the ECU.

Diagnosis so far, what have I missed? o_O

:)Thank you!

Engine turns over.
Verified spark and fuel pressure (set at 28lbs).

Fuel injectors are not receiving voltage, verified by NOID test light. The NOID lights up for a single temporary flash on Inj 2 & 4 when providing switched power (is that normal?).
- Test light triggered for duration of 1-2 seconds, once during cranking, but was unable to repeat this result at any other time during testing.

MAP (This unit has been modified by the engine rebuilder to be adjustable)
Resistance on Pin# 8 to 10 & 7 to15, verified.
Continuity to ECU pins, verified.
Voltage test to be conducted...

- Tried searching, is there a good link with MAP voltage testing instructions?

Distributor Trigger Contact
- Distributor Trigger wires output to the ECU pins # 21, 12,. 22 continuity verified. Is this the correct sequence, facing the connector on the housing, from left to right, #12 in the middle?
- Distributor trigger: Is there anyway to test the signal?

ECU
Pin #
11 - ECU ground verified
16 - Power to ECU verified
24 - Power for injectors 12V verified

Inj. harness
Injector grounds and connector continuity to Pin# 3, 4, 5, 6 verified
Injector Grouping verified

TPS
Pin # 17, 20, 9 continuity & ground on 45 verified


Injection System Wiring Diagram
Source: https://e9coupe.com/forum/threads/d-jetronic-rebuild.18687/page-4
1757324535992.png


D-Jet ECU Pinout
Source: https://jetronic.org/en/d-jetronic/pinout#bmw
1757325733391.png
 
You can contact me for a loan of parts from the Forums lending library.
Do it quickly- I leave for Europe tomorrow morning until October 7th.
 
Comments…

note that the black wire coming from the ignition switch goes into connector 168 and 2 white wires and a red wire come out of the connector.
1 white wire goes to the computer and one to cold start relay. The red wire goes directly to the starter and cranks the engine. Be advised there are no colors noted on the schematic..

You should know that if the wires are not correct to the manifold pressure sensor or the manifold pressure sensor is not operational the car will not start because injectors will not fire.

Ljet computers are widely available.

I have remanufactured trigger points and throttle position sensors available.

“- Distributor trigger: Is there anyway to test the signal?”
Continuity between pin 12 and 21 and also 12 and 22 will show health of points when engine is cranked.


You are aware there are 3 different d-jet engine harnesses?

Which year car?

Look carefully at bottom of schematic- that green (gr) MUST get connected either by the coil or by the brake booster depending on harness version for the injectors and computer to work.

Are you in Hong Kong? I have a coupe guy on Lantau island I think leaving for Osaka tomorrow. He might be able to drop by.
 
Last edited:
TomHom said:
....is the ground cable from engine to fire wall installed? Ground terminal at firewall not coated, metal contact ok?
Click to expand...
Thank you for the suggestion.Yes:
1) Batt ground post, direct to to unpainted grounding tab in engine bay.
2) Ground strap from valve cover to firewall.
3) Engine Block to post under bonnet hinges of radiator frame.

All locations about 5 ohms resistance.
sfdon said:
You can contact me for a loan of parts from the Forums lending library.
Do it quickly- I leave for Europe tomorrow morning until October 7th.
Click to expand...
PM sent thank you
 
sfdon said:
Comments…

note that the black wire coming from the ignition switch goes into connector 168 and 2 white wires and a red wire come out of the connector.
1 white wire goes to the computer and one to cold start relay. The red wire goes directly to the starter and cranks the engine. Be advised there are no colors noted on the schematic..

You should know that if the wires are not correct to the manifold pressure sensor or the manifold pressure sensor is not operational the car will not start because injectors will not fire.

Ljet computers are widely available.

I have remanufactured trigger points and throttle position sensors available.

“- Distributor trigger: Is there anyway to test the signal?”
Continuity between pin 12 and 21 and also 12 and 22 will show health of points when engine is cranked.


You are aware there are 3 different d-jet engine harnesses?

Which year car?

Look carefully at bottom of schematic- that green (gr) MUST get connected either by the coil or by the brake booster depending on harness version for the injectors to and computer to work.

Are you in Hong Kong? I have a coupe guy on Lantau island I think leaving for Osaka tomorrow. He might be able to drop by.
Click to expand...

I am in Hong Kong.

1973 Manufacture Year, RHD

Have the black wire from ign switch going to 168 to 50 of starter motor. The white wire #44 is connected to the cold start relay.

The wiring for the Fuel Pump Relay has been modified and there is currently no FP relay. The FP is powered by switched 12V.

Cold Start Relay isn't being powered. Judging by the wiring modifications I did not think the CS Relay/Valve was working when the car ran 3 years ago. Did not pursue this further, because the way I read the diagrams, the 6 fuel injectors are independent of the cold start system?

Think you are referring to the green wire that runs through fuse 7, device #15 on the diagram. This car is missing this green wire. From the diagram, on the other side of fuse 7, is wire #3 which feeds power to term 30 of the fuel pump relay. When the car came to me, it did not have a Fuel Pump Relay and the Harness near the ECU had been modified so that only 3 wires remain:
#63 - power from main relay,
#19 power to Cold Start Relay, and
#62 From Fuel Pump Relay to Connector to #19
#14 to Pin 19 Output to FP relay was missing. Ignored this as the FP has been wired to switched 12V.
#3 fused power to FP relay term 30 - missing. Ignored this as the FP has been wired to switched 12V.

The Main Relay has power at #16 & #24, 42 is ground, and 41 is attached pre-resistor to switched 12V.

Are L-Jet and D-Jet interchangeable?

Was not aware there are 3 different D-Jet harnesses but the diagrams you posted helped a lot. Re-Posting these diagrams here again, as they might help others coming across this info. Thanks SFON, I had no idea where (X) (W) (T) where supposed to connect, last week.

Injector Wire Harness
Source: https://e9coupe.com/forum/threads/how-to-verify-injector-wires-attached-to-correct-injector.41918/
1757343671013.png

1757343708777.png
 
I’m off to work- last day in town. You can call me or - I will be in Hong Kong in 2 months and can drop by. Staying on Lantau Island by airport.
 
DrivenE9 said:
Thank you for the suggestion.Yes:
1) Batt ground post, direct to to unpainted grounding tab in engine bay.
2) Ground strap from valve cover to firewall.
3) Engine Block to post under bonnet hinges of radiator frame.

All locations about 5 ohms resistance.

PM sent thank you
Click to expand...
5 ohms resistance is not correct!
From the engine at the connection to the fire wall towards the battery ground connection you should measure no resistance at all! Engine ground should be at the connection shown here.
20250908_182404.jpg20250908_182433.jpg20250908_182536.jpg

The value of 0.4Ohm shown on the instrument is the resistance of the measuring cords.
 
TomHom said:
5 ohms resistance is not correct!
From the engine at the connection to the fire wall towards the battery ground connection you should measure no resistance at all! Engine ground should be at the connection shown here.
View attachment 208026View attachment 208027View attachment 208028

The value of 0.4Ohm shown on the instrument is the resistance of the measuring cords.
Click to expand...
Yes agree its too high if a reading and that under 1.0 is ideal. The batt cut switch, itself is the weak link.

To be rectified. But can this be the source of the injector issue? The starter motor cranks strong. Will re-test whilst bypassing the batt switch.

Thank you
 
....verify the connection from the engine block (not valve cover) to the fire wall as shown in my first pic!
 
DrivenE9 said:
Yes agree its too high if a reading and that under 1.0 is ideal. The batt cut switch, itself is the weak link.

To be rectified. But can this be the source of the injector issue? The starter motor cranks strong. Will re-test whilst bypassing the batt switch.

Thank you
Click to expand...
Is the battery cutoff switch on the ground side? I thought it is best on the 12V.
Adding resistance on the 12V side is not the same as on the ground path, especially for digital circuits that have a voltage reduction and regulation on their VDD.
 
Last edited:
DrivenE9 said:
I am in Hong Kong.

1973 Manufacture Year, RHD

Have the black wire from ign switch going to 168 to 50 of starter motor. The white wire #44 is connected to the cold start relay.

The wiring for the Fuel Pump Relay has been modified and there is currently no FP relay. The FP is powered by switched 12V.

Cold Start Relay isn't being powered. Judging by the wiring modifications I did not think the CS Relay/Valve was working when the car ran 3 years ago. Did not pursue this further, because the way I read the diagrams, the 6 fuel injectors are independent of the cold start system?

Think you are referring to the green wire that runs through fuse 7, device #15 on the diagram. This car is missing this green wire. From the diagram, on the other side of fuse 7, is wire #3 which feeds power to term 30 of the fuel pump relay. When the car came to me, it did not have a Fuel Pump Relay and the Harness near the ECU had been modified so that only 3 wires remain:
#63 - power from main relay,
#19 power to Cold Start Relay, and
#62 From Fuel Pump Relay to Connector to #19
#14 to Pin 19 Output to FP relay was missing. Ignored this as the FP has been wired to switched 12V.
#3 fused power to FP relay term 30 - missing. Ignored this as the FP has been wired to switched 12V.

The Main Relay has power at #16 & #24, 42 is ground, and 41 is attached pre-resistor to switched 12V.

Are L-Jet and D-Jet interchangeable?

Was not aware there are 3 different D-Jet harnesses but the diagrams you posted helped a lot. Re-Posting these diagrams here again, as they might help others coming across this info. Thanks SFON, I had no idea where (X) (W) (T) where supposed to connect, last week.

Injector Wire Harness
Source: https://e9coupe.com/forum/threads/how-to-verify-injector-wires-attached-to-correct-injector.41918/
View attachment 208022
View attachment 208023
Click to expand...
@DrivenE9 - are we an architect? writing + organization looks very architectural
 
rsporsche said:
@DrivenE9 - are we an architect? writing + organization looks very architectural
Click to expand...
I didn't draw the injector harness drawings, it's a Re-post from SFDON.
Arde said:
Is the battery cutoff switch on the ground side? I thought it is best on the 12V.
Adding resistance on the 12V side is not the same as on the ground path, especially for digital circuits that have a voltage reduction and regulation on their VDD.
Click to expand...
Yes, have always matched cut off switch to car's ground polarity, but now that you mention it, it makes sense to use positive side. Just spent the morning re-wiring, thanks for the tip!

TomHom said:
....verify the connection from the engine block (not valve cover) to the fire wall as shown in my first pic!
Click to expand...

After removing the cut switch from ground side, happy to report meter readings with in spec!

Unfortunately, no change on the injectors.

SFDON kindly expedited parts from the Lending Library that should arrive soon. Thank you for the community's help!

1757499271656.png
 
What I see here is not correct! You connected a thin wire to an intake manifold, guess the other end is connected to the firewall. The manifold is isolated on both sides by it's sealings, so there is no proper connection to the system ground, common ground terminal of the injectors.
My first pic above shows the location where to connect the ground strap.
There's another ground terminal in the fuse compartment. Make sure there's s proper ground connection, with the coating removed
 
Last edited:
TomHom said:
What I see here is not correct! You connected a thin wire to an intake manifold, guess the other end is connected to the firewall. The manifold is isolated on both sides by it's sealings, so there is no proper connection to the system ground, common ground terminal of the injectors.
My first pic above shows the location where to connect the ground strap.
There's another ground terminal in the fuse compartment. Make sure there's s proper ground connection, with the coating removed
Click to expand...
The image is unclear. There's no ground wire connected at this nut, the "line" is the seam for heat insulation wrap. Multi-meter testing ground from the nut, to the neg batt post. The engine ground strap is bolted into the block using an unused thread, and grounded to a chassis post behind the radiator.
 
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