1985 745t

Brickers:

There have been some posts on this problem over the past few months (by myself and others), but as yet no resolution. Hoping someone has an idea what it might be.

The problem occurs when the car is started from a cold start and you engage first to begin moving. As you let the clutch out and apply gas the tach begins to drop a bit and the car starts to stumble. Applying more gas corrects the problem, but it seems like I am definitely having to rev more than I should to keep the car from dying.

The car doesn't usually stall (as long as I counter it), it's just weak and feels like it's not getting enough gas. However, I'm fairly sure it isn't a gas supply issue since my fuel system has been almost completely replaced (the only parts in the past 8 montsh are most of the tubing and the main pump).

This problem also only surfaces when the car is cold. If I engage first from a start while teh engine is warm I don't experience the symptoms.

After a a bunch of analysis I'm leaning towards the Hall sensor. Is this a possible culprit? What other sources might I look at? I should also mention that I think the knock sensor might be going and am planning on replacing it. is it possible teh knock sensor is reporting false knock when the engine is cold and triggering a retardation of the time, thus indirectly causing my stumbling?

Any help is greatly appreciated.

Thanks,
rt

p.s. I also considered the IAC as a possible culprit and should clean it to make sure it isn't involved. However, I don't think it is responsible since the tach is fairly stable at idle (maybe a cyclical variance of 50 rpms or so while it idles).

Hall effect sensors generally fail with heat, not cold, in my limited experience. Poor running when cold tells me to check the resistance values of the Coolant Temperature Sensor from the connection point at the ECU.

Hall effect sensors generally fail with heat, not cold, in my limited experience. Poor running when cold tells me to check the resistance values of the Coolant Temperature Sensor from the connection point at the ECU.
Could u put that in plain english for the 760 V6 non turbo 1986
mine feels a bit guttless when it's cold in the mornings, and she'd got No get up and go, seems to hesatate a bit. and it feels like it's gonna die.
Also i was goin down the freeway today and my tach started twitching, any ideas i need some help befour what ever is wrong goes out

I have never worked on a V6 760, but the North American market 760s have LH 2.2 Jetronic fuel injection which is almost identical to the LH 2.2 used on the B230F and B230FT engines which I am quite familiar with.

What my statement means is this: There is a Coolant Temperature Sensor in the engine. This Coolant Temperature Sensor has a specific range of resistance for any particular temperature. There are figures in the 700/900 FAQ, and they are the same for the B280 as the B230F and B230FT. If you want to check the resistance of the Coolant Temperature Sensor, you remove the ECU and remove the cover of the electrical connector for the ECU so you can see the terminal numbers. Then you check the resistance to ground and note the temperature of the engine. The figures should check with the information in the 700/900 FAQ. Use terminal 2 of the ECU connector for this check for resistance to ground.

i got that bart, but it's the stupid stuff like what does the ECU look like? location?, where is the sensor? plerase forgive my ignorance this is the first import i have ever had to work on, not to mention it's a volvo and it's my first Real car

The ECU is located just to the right of the right front passnger's right front foot, behind the plastic trim with the lump in it.

I don't know where the sensor is on your engine, but I would recognize it. You need to check it's resistance from the ECU, just like I stated. That way you verify the wiring connections.