1800: - Fuel Injection ECU

Trevor Ford · Aug 30th, 2020, 13:35

Fellow members, good afternoon

I am doing some checks on the wiring to the Bosch Control Unit on my 1800E. Can anyone through any light on what the knurled adjuster knob on the Controller does? I can find no information in any manual I have. Might it be a sensitivity setting? I am wondering as it may have moved a ‘click’ or two whilst it has been out of the car.

Photo attached hopefully

Any assistance would be appreciated whilst I continue to look!

dingov70 · Aug 30th, 2020, 15:19

Afternoon ,if my creaking memory serves me rightly , that is the external fuel trim control allowing you too adjust the idle / run mixture . This function has no effect once the throttle pedal is operated . It is very much akin to adjusting a carb & providing a smooth idle and efficient combustion .

If, however , my creaky mind has given up the host , it is the volume control directly linked to the loud pedal in the exhaust . Hope i've helped

c1800 · Aug 30th, 2020, 16:21

Dingov is correct, adjusts mixture at idle only.

For your reading, not sure if this document addresses the adjustment knob, but it provides lots of info on troubleshooting D-Jet. The only way I know of adjusting the idle mixture is with a gas analyzer in the tailpipe.

http://volvo1800pictures.com/documen...lt_tracing.pdf

142 Guy · Aug 30th, 2020, 18:02

Creaking memories agree.

It is the idle speed mixture adjustment. Test is done by measuring tailpipe CO at warm idle speed and adjusting to 1-2% CO. The procedure is the very last two paragraphs in the section of the service manual covering the D jet. If you have a 1970 1800E you may have to find the 1800 provisional service manual for details (or a later service manual). I would not go to the effort of finding details on the test procedure because it is based upon using a CO analyzer which most people do not have access to.

Side note - that is one seriously corroded control unit. Do you have some water leaks into the passenger compartment. I would definitely be looking at the terminals in the connector plug to make sure that they are not similarly corroded.

Trevor Ford · Aug 30th, 2020, 20:21

That’s a great help, thanks everyone and thanks for the link C1800. Thankfully the corrosion, 142 Guy, is only external and the terminals and internal components are clean. I will double check for water ingress again though.

Many thanks again.

Aug 30th, 2020, 15:19	#2
dingov70 Master Member Last Online: Yesterday 06:42 Join Date: Jan 2015 Location: Blackpool	Afternoon ,if my creaking memory serves me rightly , that is the external fuel trim control allowing you too adjust the idle / run mixture . This function has no effect once the throttle pedal is operated . It is very much akin to adjusting a carb & providing a smooth idle and efficient combustion . If, however , my creaky mind has given up the host , it is the volume control directly linked to the loud pedal in the exhaust . Hope i've helped __________________ To stupidity & beyond

Aug 30th, 2020, 16:21	#3
c1800 Master Member Last Online: Yesterday 18:48 Join Date: Oct 2013 Location: Alberta	Dingov is correct, adjusts mixture at idle only. For your reading, not sure if this document addresses the adjustment knob, but it provides lots of info on troubleshooting D-Jet. The only way I know of adjusting the idle mixture is with a gas analyzer in the tailpipe. http://volvo1800pictures.com/documen...lt_tracing.pdf Last edited by c1800; Aug 30th, 2020 at 16:31.

Aug 30th, 2020, 18:02	#4
142 Guy Master Member Last Online: Today 15:48 Join Date: Jul 2020 Location: Saskatchewan, Canada	Creaking memories agree. It is the idle speed mixture adjustment. Test is done by measuring tailpipe CO at warm idle speed and adjusting to 1-2% CO. The procedure is the very last two paragraphs in the section of the service manual covering the D jet. If you have a 1970 1800E you may have to find the 1800 provisional service manual for details (or a later service manual). I would not go to the effort of finding details on the test procedure because it is based upon using a CO analyzer which most people do not have access to. Side note - that is one seriously corroded control unit. Do you have some water leaks into the passenger compartment. I would definitely be looking at the terminals in the connector plug to make sure that they are not similarly corroded. Last edited by 142 Guy; Aug 30th, 2020 at 18:05.

Aug 30th, 2020, 20:21	#5
Trevor Ford New Member Last Online: Feb 1st, 2024 19:19 Join Date: Jun 2015 Location: Stamford	Fuel Injection ECU That’s a great help, thanks everyone and thanks for the link C1800. Thankfully the corrosion, 142 Guy, is only external and the terminals and internal components are clean. I will double check for water ingress again though. Many thanks again.

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