One for the FOAT

Hi All,

Got a 1994 Volvo (sorry) 940 Turbo Estate. More and more regularly now
it's cutting out. Tacho drops to zero (even if the wheels are still
turning the engine) and Lambda light comes on. Leave it a minute or so
and it will restart and drive normally - until it happens again.

Seems mostly to happen after a hot restart - not so often when cold.

Now the fault code that is set (although it doesn't set a code every
time) is 1-4-4 - no fuel load signal.

My first thought was the ever troublesome fuel pump relay - but with
the tacho dropping too it could be the ignition amplifier on the front
inner wing... Or am I wrong?

Checked all the connections to the AMM and to the ignition module on
the wing and to the sensor just downstream of the AMM - all look good -
clean and tidy with a smear of grease on them.

Any thoughts would be jolly helpful!

 

Blimey, haven't seen you around here for a while. How's life?

 

uk,rec,cars.maintenence? Slow group, but knowlegable.

 

Really? Rumour has it, there may be people there who fill their bikes with
diesel.

 

Timo said:

Life's pretty good at the moment young Timo. You?

 

I'd say it must be electrical/electronic for the tacho to drop.

I'll be seeing my mate the ex-AA roadside blerk over the weekend and
I'll ask him. He'll know.

 

Pip said:

I think so too - so far it seems to be either the Crank Angle Sensor or
the ignition power stage... One is 20 quid the other is 50...

Cheers Pip.

 

<Innocence mode>

Oh?

 

Has its ups and downs but not too bad at the moment, thanks.

 

Simes scribbled:

If its a manual ignore everything from here on.

My auto volvo developed a habit of stalling occasionally when I took my
foot off the throttle completely coming to a halt, or sometimes when
going slow and turning steering (i.e. sharp roundabouts), basically
when the engine returns to tickover but there was a high load still on
it via power steering, air con, alternator, whatever.

The rev counter dropped to zero when ever it did this.

Turns out the Mass Air Flow sensor is fecked.

I've removed it, cleaned it up, blew the crud out of it, and its a lot
better now, but not completely cured. When I've got a spare £100 I'll
see if I can pick one up to cure the fault completely.

Check it itself, they do go titsup.com shortly after a Volvos run in,
like 150k milesish

 

frag wrote:
on.

Had something very similar on a Vectra. Ye Gods. I actually paid money
for a Mk I.
That was the MAF sensor.

 

The ex-AA man he say it will be the ignition module overheating. If
it isn't too far gone then a simple unscrewing from the base and a
reapplication of heat transfer grease betwixt base of ignition module
and heatsink will sort it - if not, it is a DAB410, as fitted to all
Vectras and will be available in any decent factors for 20 quid.

 

Pip said:

 

frag said:

I /think/ the MAF is OK - as it runs perfectly smoothly and ticks over
fine. This one will cut out dead at (say) 3000 rpm just as easily as
at tickover.

After a minute or two it will usually restart. And yes - it's an auto.

It's possible...