Timing belt Volvo 740 200k miles.

[Retired MVS Contributor]

1: Make sure that the distributor comes from the correct year. A distributor for a car with LH 2.2 will not be the same as for LH 2.4. The same distributor is used on these cars:
89-92 740 B230F
90-92 740 B230FT
90 760 B230FT
91-95 940 B230F & B230FT

2: Sounds like someone doesn't know what they're talking about, if I'm not mistaken.

+1 on all...There is no "programming" on these control units...However, you cannot just "hang" it from the cable to test it out, it has to be grounded to the car's frame, so you will need to screw it into place...

You did not clarify whether you have the Bendix or the Bosch system...If you have the Bendix, LH-2.2 or LH-2.4 does not apply, LH designates Bosch Jetronic...The vehicle should have either REX 1, which is the Bendix-Regina system, or EZ116K, which is the Bosch LH system...I could be wrong, but I don't think your car has the Bosch system...I have not seen a 740 in the US with Bosch...240, yes, 740, no...

It all points back to the speed sensor, the system relay, or the radio suppression relay in my mind...

Jerry

[dunamis]

thanks lummert,

I am not sure how to tell whether my vehicle has a hall or impulse sensor on the distributer. If you want to tell me how to check I would appreciate it.

I am assuming I have the bosch system, it has a cylindrical coil, the main computer reads "Bosch Jetronic" and engine type is B230F. But, I could be wrong. Where on the engine can I find/tell if it is Bendix or Bosch?

Thanks jerrymcc,

thanks for clarifying the the computer unit issue and programming assumption. i find it interesting that the computer unit needs to be grounded. the vehicle would work OK with the old unit just hanging from the cable. maybe when testing a different unit it would be best ground it.

I tried switching the sensors as you suggested and it ran the same. I also tried a different 'power stage (ignition module)'' and it made no difference. The crankshaft speed sensor seems to be working OK at this time since it stars and runs. It is the intermittent lose of power between 1500-2000 rpms and at 3000 rpms that continues. And, the fact that it will at times shut down at hight speeds. I connected a timing light to the cables and cable #1 is the only one where the timing light stops flashing between the above mentioned rpms.

[Retired MVS Contributor]

Got some info from Vadis...You have Bosch 2.4, Bendix started in 1991...Regardless of year, Bendix, or Bosch, they all have a Hall speed sensor at the flywheel...It is the same sensor, PN 271949...Hall sensors are widely used as counters in distributors, RPM counters, speedometer sensors, ABS wheel sensors, automatic transmission shift controls, etc...

Grounding the control module is important...Some connections inside the control module are grounded to it's case, and several of the wires entering it are shielded cables...Those shields need to be grounded...The shields keep the enclosed cable from acting like an antenna and picking up stray RF energy...They are connected to the heat sink/sole plate/case of the control module...If it is not grounded, those points are not connected to the car's electrical system...

Jerry

[dunamis]

thanks jerrymcc,

very detailed explanation on grounding issue for main computer and makes sense.