Problomatic 97 945

[LowRezz]

Howdy.

I have a manual '97 940 estate B230FK that i've been tinkering with for years now. Made a big push this summer to try and sort out the issues. Car is difficult to start. I have cleaned the PCV, the throttle body, idle air control valve. I have fitted a new cap and rotor, air intake, fuel pressure regulator, fuel filter and run some meth spirits through the tank. None of this has made any difference to the starting issue. I have pulled the fuse so the ECU "relearns" the mixture. The car runs smoothly once started but can take 10+ attempts to start.

I read a passing comment on the forum the other day. Am i right in saying that when priming the ignition the fuel pump turns on (mine does this. i can hear it) and then it should stop once enough fuel pressure is in the rail (i dont think mine ever turns off it just constantly runs). Eventually the volvo gods will bless the car and it will start and it is (mostly) fine.

The car is hesitant from 750 rpm > 1500(ish). I have to very gently rev it up to this and then it will rev freely. To me this sounds like a fueling issue but i have been wrong up until this point.

A new problem that I had just this past bank holiday; I had the car idling on the driveway for 5 or so minutes. The car would refuse to rev past 4k and all of a sudden the taco just stopped reading the RPM and the car slowly died. I had to jump start the car and after that i was able to reverse it the 10 meters i had to move it. In the years I've owned the car I havent driven it more than 400 meters only been starting it on the driveway trying to solve issues.

I have bought a new intank fuel pump can someone point me to an AM secondary fuel pump that has worked well for them?

Looking forward to your assistance with this fussy car.

-Rezz

[griston64]

I'm a little confused when you say AM secondary fuel pump ? Are you planning on fitting an extra pump somewhere ?

[TonyS9]

There is only 1 fuel pump on this car, in the tank.

Priming should go for about 1s then stop, if its continuing there could be a problem with the fuel pump relay, but its normally "not going" that is the problem. It does not measure pressure, it is merely timed.
If you try to prime again (ignition off-on) it won't prime unless you wait about 10s.

The pump going continuously should not be a problem with running, it is a safety problem if you crash. Someone could have bypassed the safety relay, which is known to fail.

Heasitant is normally weak spark related from oil in the distributor cap, or perhaps old leads. The richer mixture from opening the throttle can drown it.

What component is 'air intake'?

Generally you need to stop replacing parts and start diagosing.

When the car isn't starting are you seeing the rpm needle flickering (after about 1s of cranking)? No fuel will be (normally) be injected unless you are getting crank turning signals from the crank sensor. This signal goes to the ignition computer which (after TDC) starts sending fire pulses to the coil, the back emf from the coil drives the tacho. The ignition computer then sends 5v pulses to the fuel computer and it then engages the relay and fires the injectors. I'm not 100% sure if the injectors don't fire if there is no crank signal, but it seem pretty logical and likely to me.

No tacho signal means no spark. This could be related to a failing ignition amplifier or crank sensor, although they both can be heat related.

When you turn the ignition on is there a click shortly after from behind the headlight switch? This is a relay in the key reader immobiliser module (fuel authorisation module). Although it seems unlikely to be an immobilise issue. Normally a failed read results in engine starting for 1s then immediately stopping.

Have you read the codes?

Have you checked for air leaks?

Do you have spark checkers?

Can you measure the fuel pressure?

[Laird Scooby]

What Tony said ^^^^^

Given the symptoms of when it failed, the first two things i would check are the Crank Position Sensor on top of the bellhousing and the ignition amplifier module (sometimes referred to as the "power stage") located on the inner wing behind the headlamp.

You might find removing it and cleaning the back of it and the mating face on the heatsink with a non-abrasive cleaner to a bright shine then adding some heatsink compound will get the car running again, manufacturers are known for being tight with heatsink compound!
Also check the earth for it, if you follow the loom back you should find a wire coming out with a ring terminal on the end bolted to the body. Remove the bolt and clean the terminal and body where it bolts on with a wire brush, emery cloth or similar and once refitted, smear some silicone grease over it to prevent corrosion.

Also what plug gap are you running? Should be 0.65mm - no more! A thumbnail is usually a good alternative if you can't find your feeler gauges. Don't assume that new plugs come set correctly, they usually don't!

[360beast]

0.7mm Dave

[aardvarkash10]

Originally Posted by LowRezz

Howdy.

In the years I've owned the car I havent driven it more than 400 meters only been starting it on the driveway trying to solve issues.

-Rezz

Once you have sorted the latest issue (probably CPS or amp as Dave suggested) take the car for a thoroughly obnoxious thrashing for 15 or 20km. Beat it like a horse running close fourth in the Melbourne Cup.

A car that intermittently is driven 400m is like a person who occasionally moves from the couch to the refrigerator. It's arteries clog and it forgets how to run.

[loki_the_glt]

Originally Posted by aardvarkash10

Once you have sorted the latest issue (probably CPS or amp as Dave suggested) take the car for a thoroughly obnoxious thrashing for 15 or 20km. Beat it like a horse running close fourth in the Melbourne Cup.

A car that intermittently is driven 400m is like a person who occasionally moves from the couch to the refrigerator. It's arteries clog and it forgets how to run.

AKA an Italian tune-up. Once the engine's hot run it hard through every gear all the way to the redline and hold it there for a goodly distance. Initial fuel consumption will suffer, but the engine will be a lot happier afterwards.

Thereafter, take it for a decent (3-5 mile) run at least once a fortnight to keep its "memory" of what it's supposed to do alive. This will also help drive off impurities from the lubricant. And make you feel like a hooligan

[Laird Scooby]

Originally Posted by loki_the_glt

Thereafter, take it for a decent (3-5 mile) run at least once a fortnight to keep its "memory" of what it's supposed to do alive. This will also help drive off impurities from the lubricant. And make you feel like a hooligan

It also helps keep the injectors clear and clean so they don't clog up with the natural gum that occurs in petrol. That means better idling and better low end torque in between Italian tune-ups.

[Rversteeg]

Did you check the engine temperature sensor? If this is not working properly, the ECM might get an "it is very cold" signal, resulting in injecting too much fuel when starting. If the engine does pick up, it takes a few moments to clear the fuel before it will idle smoothly. Note there are two sensors, one for the ECM and one for the temperature indicator.
By the way, you are not touching the throttle pedal when starting, do you?
Rob

[john.wigley]

Why do we refer to it as an 'Italian tune-up'? Our Swedish friends looked at me blankly when I once used the term in respect of their 144. When I explained, realisation dawned and they said "Ah, you mean drive it like a Norwegian!"!!

Regards, John.