740 GL computer problems

Have you tried unplugging the air mass meter? It's a common problem that causes exactly those symptoms.

Is that the wide flat plug near the air cleaner and do you leave it unplugged temporarily?

Yes, and yeah, it won't run right with it unplugged, but it will start and run in limp mode and be drivable enough to get home or to a service shop. If the behavior improves with it unplugged then you need to replace the part. You could try cleaning the connections, some have reported success with that, but the only time I've had a problem, the AMM was truly dead. It's an expensive part, but you can find used ones on occasion.

Thanks I will try that

Of course, you're assuming he's got the Bosch fuel injection system. My 1990 740GL is Rex/Regina, and doesn't have an air mass meter, just an intake air temp sensor (as he said) "near the air cleaner". I guess it depends on how wide his "wide flat plug" is.

: >>>> I left it for about one hour after use, tried to start it, would not : >>>> go so I disconnected battery for five min, reconnected and it : >>>> started which suggests something tells computer to not allow engine : >>>> to go and after I wipe its memory it goes again : >>>> can faulty temp sensor cause engine to stop and misbehave in such a : >>>> manner or some other sensor? : >>>>

: >>>> Have not had time to install sensor as it is in the most difficult : >>>> position the designer could find : >>>>

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: >>> Have you tried unplugging the air mass meter? It's a common problem : >>> that causes exactly those symptoms. : >> Is that the wide flat plug near the air cleaner and do you leave it : >> unplugged temporarily? : >

: >

: > Yes, and yeah, it won't run right with it unplugged, but it will start : > and run in limp mode and be drivable enough to get home or to a service : > shop. If the behavior improves with it unplugged then you need to : > replace the part. You could try cleaning the connections, some have : > reported success with that, but the only time I've had a problem, the : > AMM was truly dead. It's an expensive part, but you can find used ones : > on occasion. : Thanks I will try that

Hi "F. Murtz",

Regarding the "cleaning the connections" advice, wisely suggested by James, I've enjoyed considerable success using dielectric grease on both the sockets and the pins in that AMM and then plugging it in and out ten times. Don't laugh! That procedure was given to me by our local Volvo dealership technician. It worked........

Good Luck. Andy I.

Continuing saga,(I think it is regina)In the morning it kept conking out over and over again with me disconnecting wait 5 min restart go a bit conk out. not all morning but about 1 1/2 hours then it started and went for the rest of the day no trouble. So I think it is going to be murder to diagnose.

The plug near the air cleaner is wide and flat attached to a square thing in the air intake near the cleaner it does not look like the small temp sensor in a round air intake pipe that is in the picture of regina engine but the rest looks like regina layout PS disconnecting it did not alter its conking out behaviour

An air mass meter looks like this

Is your check engine light on? I believe 1990 is new enough that it should have OBD.

Thats what it looks like And fault code says temp sensor but car has been working since I got it with fault light on

Well if you have a temp sensor fault code, then I would definitely start with the temp sensor, if it has no signal from that it will run very rich. Change that part and go from there.