Volvo 1800ES D-Jetronic MY73

Hi Jean-Pierre,

at least prositive prgress !

You can also remove pin 19 from ECU connector. Then fuel pump relais should be inactive and be activated when you put that line on ground. If FPR is still active, you know that is does not come form ECU. If it is only active when you apply ground, then you know that it is ECU. See Download section for a wiring diagram for Mercedes-Benz.

Yes, I understand, great test to do ! Thank you.
I'll do it after Christmas

Although I did not do the test described above by Dr-Djet, I progressed on other items :
- injector #4 seal (the small one) was leaking, so I replaced all
- hose between intake manifold and auxiliary air valve was cut just after hose clamp ; this was the reason of variating idle speed... this is solved now
- ignition distributor was in bad condition and was not the one for B20E engine ; I found the right one and overhauled it so that now dwell is ok, ignition advance is very stable and the engine runs smoother
- fuel pressure regulator was slightly leaking under the lock nut, so I found another one (unfortunately not a new one, which is very rare as you might know) 
- fuel pressure is set to 2.1 bar again
- valve clearance is set properly (0,40 to 0,45 mm at intake and exhaust) and checked in hot engine condition
- spark plugs were not the right ones (too hot index) ; so replaced with Bosch WR5BC
- rubber boots of all connectors are new now ; this is a piece of patience to replace...
- idle speed is set at 900 rpm
 
Now, the car is quite smooth, engine is responsive, a much more pleasant car to drive than one month ago !

Aux air valve seems not to close at 100%, so I plan to change the plunger that I suspect to be a bit lazy with age.

 I keep in mind to check pin 19 test !

 

I just realised that on the starter solenoid there is no white wire. There should be one white wire to thermal time switch and wire 18 from solenoid to ECU.

I'm quite sure wire 18 has been plugged to a permanent + source, which would greatly explain that fuel pump run permanently before cranking..

Another check to do !

Hi Pierre,

if that turns out to be true, you might also have starting enrichment ON all the time.

What a crazy mistake.

Bingo !
Double white wires connector was plugged on +12V on coil... The distance is quite the same to coil and to solenoid, so someone has been confused... since when is it like this ?

Now that this connector is plugged on starter solenoid, fuel pump activates 1 second when key is at position II !
I'm happy with this, as it is a simple resolution. Hopefully, ECU is not faulty. I always incriminate ECU in very last hypothesis. I have taught from my previous job that 98% of ECU coming from warranty exchange are 100% perfect condition. They are very rarely faulty, but often changed because it is so easy for the garage.

Then I measured exhaust gases and the result is : 4.05% CO ; 11.3%  CO2 ; 227 ppm HC ; lambda 0.91
It may be better but it's quite correct for a 1973 car. What's your opinion ?

Driving test show some hesitation just above idle, TPS should have some maintenance...
 

Hi Pierre,

congrats for having found the fault !

4.05% CO seems too high. I would drive a bit and then adjust to workshop manual values. At a quick glance I saw 1-2% as normal value.

I received all the parts to build a fuel pressure manometer, as Dr-Djet suggested.
I just have chosen the "cheap" version of reader, without glycerin inside.

So I tested it on the 1800ES. It works fine and is very accurate, either because of construction and thanks to the big diameter of the reader. A great tool, which can be used for any other injection system with small adaptation.

One point on the 1800ES : the fuel pressure is not constant as the engine temperature rises. If I adjust the fuel pressure to 2.1 bar when engine is hot, I am not far from 2.5 bar at engine start around 0°C. What can be the cause of this ?

Hi Pierre,

normaly that means an issue with pressure regulator. In rare cases it could be too little fuel volume from pump or blockage on return line to tank.

I will measure with another fuel pressure regulator.
If the problem remains, it will be an interesting point.

Some information about work done on this car :
- engine oil drain revealed dark oil, sign of excessive enrichment, probably linked with bad electrical connections... 
- fuel pressure is well stabilised when engine is hot, but remains higher when engine is cold (2.3 bar). As a consequence, warm-up phase is a bit erratic. Unfortunately, as fuel pressure regulator is not available in new condition, it is a bit tricky to find a reliable one.
- throttle sensor has been carefully opened :





PCB was dusty (means some risks of erosion), so I carefully cleaned it with a small and soft pencil, some brake cleaner fluid, dried it with low pressure compressed air, then cleaned it again with a electrical contact cleaner and a thin piece of soft paper inside the contacts.
Then I adjusted and checked the right positioning of the sensor to obtain the resistance change when leaving idle position and the 10 resistance changes when accelerating and nothing at decelerating. Everything is ok.

Finally, I replaced the thin foam barrier around the sensor, hoping to improve the sealing of the housing.

This throttle sensor is the first version, right ? Is it the right one for '73 Volvo 1800ES ? Not sure...

...

Hi Pierre,

yes Throttle switch is an early version with scres and soldered wires inside.

Hi Pierre,
you could use an alternative pressure regulator like this one: www.ebay.de/itm/233599329216 or this one: www.ebay.de/itm/272270476505
This cheap item could work, too: www.ebay.de/itm/373722429530?hash=item57...tkp%3ABk9SR_yr-KGtYw

Regards
Norbert

Vielen dank Norbert !

the first one seems perfect !

Today I took some time to have a 30 km ride with the ES.
The car is now fine to drive, fuel consumption seems reasonable. Thank you to you all for help and assistance !

One point is still not perfect : when the car quits its place, during clutch coupling and just after, the car hesitates, just one second. It was worse before cleaning and adjusting throttle sensor, but it still hesitates. I can't say if mixture is too lean or too rich just at this moment. I know that ECU enriches mixture at this specific moment, and the engien runs smooth. So I would say that it's a bit too rich...

I will test again tomorrow with the ECU enrichment knob fully turned anti-clockwise to lean the mixture. Unfortunately I can't measure any more CO level so I'm blind about that for the moment.

Any advices ?

Hi Pierre,

rheostat is only active when throttle switch idle contact closes. Is that properly adjusted? And of course you should measure exhaust gas.

yes it is properly adjusted. Idle contact closes immediately when throttle opens.

Hi Pierre,
I think you mean it closes when the throttle closes?

Regards
Norbert

Yes Norbert, but now I have a doubt... I'll check again