940 running problems.

[Sando]

Help!

I'm getting close to wanting to get shot of my formerly beloved Volvo.

I bought the car nearly a year ago and fell for her quirky charms.

No i'm considering a divorce.

She never wants do the same things as me anymore, and when we do manage to go out together, she kicks up a fuss and we end up having to come home.

To start with I had running problems. Simply caused by the silencer collapsing internally and partially blocking the exhaust off. Easy fix.

Secondly, just a bit off lumpy running and the Lambda light on. A broken wire on the sensor was the fault. Again, easy fix.

Then an intermittend complete cut out of the engine which deteriorated into a full non start. Chased this for ages. I've changed the rotor arm and dizzy cap, coil, plugs, fuel pump relay and the ignition amplifier. Finally I changed the crank position sensor. Great joy, after weeks layed up, problem solved.

Now, after all this and 4 or 5 months easy living, problems have struck again.

On anything more than tiny throttle opening I get a misfire on all cylinders at about 2500 to 3000 rpm. I can still here an explosion, but there's absolutely no power.

So far on this one i've changed the fuel pressure regulator, the MAF sensor and the fuel filter. I've also changed some of the vacum hoses and cleared a partially blocked up crankcase brether pipe.

Applogies for the long post but I wanted to give a comprehensive history to avoid miss-diagnosis.

Please help me re-discover my passion for the old girl.

[OldBlueVolvo]

940s aren't really my area, but have you had the fault codes read?

[globetrotter]

Have you tried a new radio suppression relay?, located on the right hand side in front of the strut, (looking at the engine), this relay supplies power to the fuel injectors and the coil, and if intermittent can cause your symptoms, or not start at all, try getting a 12v led and wire it with 6.3 female spade crimps across the coil, the flashes should be regular,it takes the guesswork out of it, if not the problem lies up stream of the coil

[Sando]

I have had the fault codes read previously, when it wouldn't start at all. And it showed 1-1-1. Which, correct me if I'm wrong, is no faults. This was despite the CPS signal being completely absent.

I have suspected the RSR in the past, but have never got arouund to changing it. Are they hard to come by/expensive?

Annoyingly, I've just taken here for a spin and everything seemed fine. Not faultless, but a good as it's everbeen. Yet two days ago the problem was present. Doh!

[Dr. Rog]

Sounds scarily like the problem I had.

We never got to the bottom of it. So I can only recommend trying the advice above.

[RealEstate]

have you checked the FAQ? It suggests faulty knock sensor?

[Alasdair1]

Had similar problem. Car was ok at low revs but when above 1500 misfired badly and no power. My problem was cylinder head gasket burnt out between cylinders. No compression and no power. Found out by checking compression on all cylinders. two and Three were well down compared to one and four. Worth a compresion check anyway.

[TonyS9]

You seem to be very unlucky, or has this car previously been a donor for faults and ended up with a collection of faulty parts. My 95 car has been impeccable.

What about a weak spark? You've changed most of the HT parts but oil in the disty could cause your problem.

Air leaks?

[Sando]

Originally Posted by RealEstate

have you checked the FAQ? It suggests faulty knock sensor?

I'm not sure what you mean by knock sensor. Is that the same as the crank posistion sensor? If it is, I've already replaced that. If not, what and where is it?

[james 1992 940]

Taken from FAQ http://www.volvoclub.org.uk/faq/Engi...ngaKnockSensor"The knock sensor is located on the cylinder head under the junction between number two and three intake manifold runners. It is next to the two coolant temperature sensors also bolted to the head. "
Gives other details on purpose and fault syptoms.