1994 940 B230FB misfires like morse code

[Laney760]

Meths, yes alcoholic meths, in fact any alcohol! Alcohol is hygroscopic, it binds with the water and then the water gets burned off with the meths when it combusts

[Laird Scooby]

Hi Bas - sorry, i forgot you're from the Netherlands and may not have heard the word "meths". To try and avoid any further confusion, here's a link to Wikipedia which actually calls it "denatured alcohol" but also gives other names for it and the general composition :

https://en.wikipedia.org/wiki/Denatured_alcohol

Up to about half a tank of petrol i would add about a litre for "serious cleaning" which is probably what you'll need if this is the problem. If your tank is full then add about 2L. If it's quite a way below half a tank, add a litre just before you add a few litres (5~10) of fresh petrol to help it mix in.

For a "routine clean", i add about 500ml to the tank immediately before adding 15~20L of petrol which i do once or twice a year, usually in autumn but sometimes in spring as well.

Usually i add a bit of fuel after adding the meths to help it mix in and make sure it's all in the tank then the fuel system does the rest. If this is your problem you should notice results fairly quickly.
The way it works is the meths forms an emulsion with the water and as the meths part will burn, it takes the water through with it. Don't ask me the chemistry, i scraped a pass in "O" level Chemistry too long ago to even try to remember, i just know it works!

[mocambique-amazone]

Hello Speedmonkey.
Where did you measure the CO?
At the exhaust tail pipe or in front of the catalyst?
At the end it should be nearby zero CO or the cat is gone.

My opinion?
The timing of your engine is out of.
Check the vibration damper in front of the crankshaft. Mark it all over with a pen, paint or whatever. Run the engine and check again, it will move.
Find TDC by lurking trough the spark hole of cyl 1
Check the mark on the damper and the camshaft and voila:
not 100% shure, because I don't have the car in front of me and can't listen, but:
The timing is out!
Good luck, regards, Kay

[Clan]

Originally Posted by Speedmonkey

Hello Wise men from the Volvo world

My name is Bas and I'm from the Netherlands. And I have a small problem with my white Swiss import 940 Polar B230FB: It misfires like it's sending out morse code. Any time, every time. At idle, half trottle, full trottle, warm engine, cold engine...

I'm chasing this inconveniece for 6 months now and I'm getting desperate. I tried every trik of the book, the book that I know, and still cannot find it. No error codes, no CEL nothing

What I did:

Checked every relay
Cleaned every connector
New Knock sensor
New AMM
New TDC sensor
Measured ECT sensor
Measured Lamdba sensor
Tested all the wiring
Rebuilt distribution, twice
New distributer, wires, plug, rotor
Checkes valve clearance
Checked fuel pressure
Replaced fuel pressure regulator
Extended vacuum tests
Tested every resitance en control voltage for the LH computer
Exchanged LH and EZK
Exchanded the spark amplifier thingie
New intake gasket
Checked all grounds, made new one from head to chassis
Checked play on distributer axle
Short wired Radio relay
Exchanged injectors nozzles
Cleaned and exchanged Throttle body
Cleaned and exchanged CIS

So....is there someone who could't point me in the right direction.THE PERSON WITH THE GOLDEN TIP WINS ETERNAL FAME!!!

Thanks guys!

Broken valve spring ! I have come across 2 or 3 of these on that engine in the last 20 years ....

[Laird Scooby]

Originally Posted by mocambique-amazone

Hello Speedmonkey.
Where did you measure the CO?
At the exhaust tail pipe or in front of the catalyst?
At the end it should be nearby zero CO or the cat is gone.

My opinion?
The timing of your engine is out of.
Check the vibration damper in front of the crankshaft. Mark it all over with a pen, paint or whatever. Run the engine and check again, it will move.
Find TDC by lurking trough the spark hole of cyl 1
Check the mark on the damper and the camshaft and voila:
not 100% shure, because I don't have the car in front of me and can't listen, but:
The timing is out!
Good luck, regards, Kay

Unless the timing (cam) belt has jumped, then there's no possibility of the timing being out unless his engine management ECU is dead.
Also his description of the fault (misfires like morse code) implies a random misfire, not a rhythmic one as would be the case with a timing or other ignition (or even an injector) fault.

I did once have a random misfire on one of my 740s, turned out to be a leak from the water pump - it was spraying towards the (engine driven) cooling fan which was then throwing it all round the engine bay and randomly getting the plugs, distributor and even the coil wet at times.

This could be a possibility but more likely to be condensation in the fuel or possibly a faulty/misbehaving fuel pressure regulator - easily checked by running the engine and disconnecting the vacuum pipe from it. Cover the end of the vacuum pipe to avoid introducing a vacuum leak and wait a while (about 30 seconds is the usual) to see if any petrol trickles or even squirts out of the fuel pressure regulator.
However, the fact the CO is low suggests this isn't the case.

[Laney760]

Speedmonkey, do you know about the excellent Volvo Club FAQ pages?:


https://www.volvoclub.org.uk/faq/Eng...injection.html

[Speedmonkey]

Hi guys,

I'll get my hands on some methyl alcohol, can do no harm to try it.

I checked the ignition several times, the stream of pulses is ok. The timing is ok, the belt didn't skip...that's not it...even got everything from the coil to the head new...

Broken valve spring is an option, still have to check for that one...

I have tried several fuel pressure regulators...that is also not the case

About the LH2.4 injector. I can alomst dream the manuels right now, checked every sensor every control voltage, replaced the computer...cannot detect enything weird...

Lets do some valve spring checking!

Keep you informed!

[Laney760]

I am no mechanic, but I have read on a few forums (one ref Volvo Penta engines) that water in the fuel system causes steel to rust and some types of injectors have little steel balls inside them and if they rust the injector will be permanately damaged and a misfire will occcur so water must be burnt off asap, I used the meths within a week of so of realising I had water in my fuel tank, I have no idea if I am sitting on a time bomb of rusting engine parts

Really interesting blog here ref said (not very impressed with his storing fuel under his desk though!):

http://www.tmproductions.com/repairs...er-in-the-fuel

[Speedmonkey]

I'm chasing this misfire for over 6 months now, it's not becoming worse or any better for over 5000km. Can it still be moist in the fuel then? I almost empty the tank completely before putting in new fuel. But with new fuel or almost an emtpy tank, there is absolutely now difference in the malfunction

[Laney760]

It eventually sinks to the bottom of the tank, being denser than petrol, it separates from the petrol so never gets burned off but it will attach itself to the hygroscopic meths and burn itself off


Thats if you have any, just thought it might be something else you can eliminate