88 760 crazy idle and stall Topic is solved

dmf volvo freak · Post by **dmf volvo freak** » 07 Feb 2005, 19:47

Hi - My 760T occasionally stalls while driving. Will start OK but runs rough - most curious part is tachometer needle that dances like mad - but doesn't appear to correspond to actual engine RPM. After a bit - car runs as if nothing happened - days on end. I am thinking fluky Hall sensor or Power Boost module - but I would like confirmation before proceeding on diagnostic. I cleaned up coil connections - no improvement.

Thanks!

dmf volvo freak · Post by **dmf volvo freak** » 11 Apr 2005, 09:40

Well - changed out power stage to no avail. In course of fishing around busted off brittle hall sensor connector and noticed large amount of oil back there. Long story short - replaced internal distributor seals and cap and rotor and connector - all good running then a week later - total dead - no spark - tried one hall sensor test from pin 5 of power stage - not seeing much action, but doing hall test from ignition control unit is hard given the way the connector is built.

I tested the coil and that may be it - going to replace today and see. Yipes./

dmf volvo freak · Post by **dmf volvo freak** » 12 Apr 2005, 14:42

OK - not the coil - thinking hall sensor again - someone posted insight about signs of it working or not.

I did the test on pin 5 of the power stage - no jump or flutter above 2v as suggested would result if working. I get a flat .04v when the engine is turning over.

Other test mentioned in cyber space is pin 24 on ignition control unit. I have a hard time seeing how to tap that lead with the connector on.

Somebody else said that the tach jumps slightly when you turn the engine over if the hall is working. I get one barely perceptable twitch then flat while cranking. Is that a sign?

Anyone? anyone?

knut nygaard · Post by **knut nygaard** » 02 May 2005, 15:15

http://www.altech.com.pl/wbt/_inne/ccvv.htm

This helped me with diagnoses
Knut, Narvik Norway

dmf volvo freak · Post by **dmf volvo freak** » 02 May 2005, 23:07

Thank you for the response. Unfortunately I am one year shy of diagnistic circutry. My poor wagon sits idol for time and money.

I found used CPU's locally for $50, but I think I have to yank the recently rebuilt distributor and replace hall senor (and plate) $100 first. No time with 5 mo old and job. I wish it would just run on desire.

dmf volvo freak · Post by **dmf volvo freak** » 07 Jul 2005, 04:32

spent all neede on ignitoion to no avail. towed to shop - dahhh - timing belt gonzo. needed to replace tensioner too and covers - 3 hrs labor and 200 bucks in parts later - works fine - moral: think before you replace!