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1990 740 gl continuing saga

latest symptoms, car is hard to start but after starting goes for 1/4 hour or so then conks out it sometimes starts and idles but conks out when accelerated if I manage to start at high revs the engine runs till I move accelerator or put in gear then it stops.I have tried an other second hand computer , same symptoms.

I am having trouble identifying system (to check codes) The engine is a B230F, It has a bosch comp.with these numbers 3547777 0 280 000 935,it has an air mass meter, it has standard looking round can coil and the distributor is on back of cam shaft.

Fault codes on socket 2 are 1:2:3 and 1:3:1 (131 does not seem to mean anything) Fault codes on socket 6 are 2:2:4 and 2:1:4

If it is rex regina this would mean temp sensor and rpm sensor but I am told rex regina does not have air mass meter ???

I have changed temp sensor but old one had the same resistances aprox 4k ohms near freezing and 210 ohms near boiling. If it is the impulse sensor (rpm sensor) Where is it and can it be got at.I have changed fuel filter and can hear pump and if I break fuel line it pumps fuel but I have not measured pressure.

The temp guage reads half way after warm up and stays there. these engines seems to run very cool and do not seem to have much pressure even when warm you can take cap off oval tank

Reply to
F Murtz
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You have a Bosch LH Jettronic fuel system and Bosch ignition. The Regina system has a square coil and no air mass meter.

Are you sure you changed the correct temperature sensor? One is for the gauge on the dash, the other is for the ECU.

Reply to
James Sweet

Yes because I disconnected the other one and the gauge did not register that proved which is which. My problem is which fault code chart do I use do the "Table 1: Bosch LH2.4 and Motronic 1.8 Fuel Injection Fault Codes"? If so the 131 seems to mean rpm sensor.

Reply to
F Murtz

A bad RPM sensor would certainly lead to poor running as well. My cars are too old to have one of those so I can't offer specific advice on it, but usually those are variable reluctance sensors, about the only thing that can go wrong with them is a physically broken connection, so if you check it out with an ohm meter and it is not open, then it is probably ok. I would guess a good one to be a few tens of ohms.

Reply to
James Sweet

A2 is Fuel Side

123= ECT Sensor Signal Missing or Faulty 131= RPM Signal from Ignition Control Module (ICM) Missing @ Start A6 is Ignition Side 224= ECT Sensor Signal Missing or Faulty 214= Engine Speed (RPM) Sensor Signal Missing Sporadically The ECT sensor you changed where was it ? Check the engine speed sensor there should be a color band near the connector if yellow change It sounds like you have a faulty engine speed sensor (Common problem)the sensor is held in a bracket which bolts to the rear of the engine be careful the speed sensor has been known to get stuck inside the housing DO NOT attempt to try to use something long to loosen it up you will end up breaking the housing & the only way to replace is to remove the transmission Glenn K Volvo Certified Technician 2008 ASE Certified Technician 2008
Reply to
Glenn K

In the most awkward spot the designers could think of under no.3 injector. I have changed the rpm sensor and so far the car is going. I will go for a run tomorrow. Engine light still lit on dash, code on socket 2 is 123 code on socket 6 is 224 .The only thing I can see is that I probably have open circuit or short in temp sensor wiring which is going to be difficult as I have not got wiring diag with colour codes and following wires in looms is difficult but at least car goes with this fault

Reply to
F Murtz

There is another sensor close to the front of the engine this is what most likely is giving you the 123 code very rarely have i changed the sensor in the rear of the engine Glenn K

Reply to
Glenn K

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