940 LPT cutting out and RPM tac bouncing.

[volvo always]

I have a 1996 940 LPT automatic with the B230FK low pressure turbo. 2.3 TI covered 209,000 miles.

Yesterday I was at work around 7 miles away and all was fine, that evening back at home I swapped some tools around and the car would not start. Tried again and it popped into life and run rough for a bit then moved him into a level parking place as thought fuel related as only a 1/4 of a tank at most.

This morning had another job to do and would not start at all. Tried 3 times and nothing. Cranking and not trying to start. No rpm tac bouncing.

Used my Toyota for work. This afternoon re- fitted the old crank sensor and fired right up. Had replaced, crank sensor, ignition module and fuel relay as preventative maintenance around 7 months to a year ago, only generic parts though.

Thought great, all fixed and stopped at various places, got my post, shopping and £40 of fuel and all was well until on my way back to my Grandparents around 5 miles away.
The car started to splutter with the RPM taco rising and lowering between 500 and around 2,000rpm. losing speed/power and juddering. Backed off and managed to get to my Grandparents house.

Just got back from Grandparents a half mile drive and on turning right same symptoms but this time cut out. managed to roll to a halt with hazards on out of the way of the car behind.

Re started straight away but rpm up and down and limped home down the Marina Drive. Only splutters under load! Parked, ticks over fine, revs fine and smooth.

Any ideas, seems electrical? Have the Forum bought code reader but lost the instructions. How do I use it?

Many thanks. James.

[Suterman]

Probably the crank position sensor.

[loki_the_glt]

PM sent with imstructions for OBD1.5 reader.

[RollingThunder]

If the tacho isn't moving when you crank it, then the crank position sensor isn't sending a signal to the ECU. Either a bad connection or the sensor has failed.

I had to replace mine a few months ago. Easy enough to get to, although you won't be able to actually see it Its at the back of the engine near the bulkhead, near where the gearbox joins the engine. Its held on by a single 10mm (?) bolt. You have to follow the cable down and feel your way to find it. Make sure you seat the replacement correctly.

The sensor itself was cheap enough IIRC, and the car has been perfectly behaved since. The sensor looked perfect btw, but had failed internally.

[volvo always]

Thanks for the suggestions.

Around 7-12 months ago I replaced the crank sensor with a new budget brand Intermotor, I think off ebay and yesterday it wouldn't start so fitted the old one and it fired right up but rpm issues and spluttering after so many miles.

When I start it fires right up but the rpm needle doesn't seem to move until the engine fires.

From what you are saying the rpm needle should move slightly prior to the engine firing?

What is a good brand to replace the crank sensor with? Yep, a 10mm bolt, not a bad job took me 20 minutes yesterday to put the old one back in. Only changed it as preventative maintenance. Sat in the glovebox since, so could of gone faulty.

Many thanks. James.

[classicswede]

Bosch for the crank sensor

Also check inside the dizzy cap for oil

[volvo always]

Today I used the code reader and only got no faults 1 1 1. on ignition and fuel.

Started it up and it started. Then after 10-15 minutes it just cut out and wouldn't start. No rpm counter movement. Tried again with code reader and same 1 1 1.

Where can you buy a genuine Bosch crank sensor?

I will have a look to see if oil inside dizzy cap for oil as not been off or replaced in 5 years. Genuine Volvo Bosch one and Boughicord leads. Car only does 1500 miles a year.

Many thanks. James

[RollingThunder]

I've got a pair of genuine distributor oil seals if you need them. Bought from FRF

[griston64]

Originally Posted by volvo always

Today I used the code reader and only got no faults 1 1 1. on ignition and fuel.

Started it up and it started. Then after 10-15 minutes it just cut out and wouldn't start. No rpm counter movement. Tried again with code reader and same 1 1 1.

Where can you buy a genuine Bosch crank sensor?

I will have a look to see if oil inside dizzy cap for oil as not been off or replaced in 5 years. Genuine Volvo Bosch one and Boughicord leads. Car only does 1500 miles a year.

Many thanks. James

You can buy Volvo ones from FRF

[classicswede]

Originally Posted by RollingThunder

I've got a pair of genuine distributor oil seals if you need them. Bought from FRF

The Green O rings do not let oil into the dizzy cap. It comes through teh bush and washer in teh centre of teh dizzy