Engine: 2.0 Carb B200K/B200F: Lambda sensor

[Volvodrivingbiker]

Ok me again Wooble thank you for pionting out the diognostic thread
I have now managed to reset the fault codes

( press button five seconds then let go light comes on press again while lit five seconds let go code cleared )

the warning light has now gone off now and after quick quizzing of previouse owner who only lives two doors up from me it turns out that at its last MOT the guy asked garage to fit new air filter this looks like it leaded to a loose conection on the maf sensor ( fingers crossed ) wich sits just after it and has to be removed to fit filter , it wouldnt suprise me as :
they over filled auto box caused a leak / flushed the petrol tank and cloged up the fuel filter and then charged £1500 for rear breaks service and MOT

hence my distrust in garages

[Volvodrivingbiker]

Originally Posted by tannachyallen

I read this a couple of years ago. It put me off changing to a cone filter for a long while. However it contains quite a lot of bollocks. Hot wire MAFs are called so because they heat up on startup/shutdown to burn any crap off the wire and not because they like supercharged hot air which is what you will get if your old style filter box get stuck in the open position. This will quite simply fry your MAF. Hot wire MAFs are giving signals as to the air temperature=density so that the management can throw the right amount of fuel at the mix.

If you position your cone filter so that it gets warm ambient air in the engine bay you will find that all will work well. Sounds like the writer of the article had his where water could get on it while driving......well what does he expect to happen if he lets water get into an air intake?

I took the plunge after reading what Wooble and some others had done to their air filters. I am more than happy with the performance and simplicity of maintenence of my setup.

Dave A.

must admit you got to read between the lines i just found interesting as it high lighted the importance of the MAF sensor would you like me to edit out the crap bits

[tannachyallen]

Originally Posted by Volvodrivingbiker

........they over filled auto box caused a leak / flushed the petrol tank and cloged up the fuel filter and then charged £1500 for rear breaks service and MOT......

As Wooble said 'find a new mechanic/garage.'

Dave A.

[Volvodrivingbiker]

this was before i bought the car , i dont use mechanics if possible having been in the trade breifly as a YTS ( remember them lol ) ive allways done my own stuff

[tannachyallen]

Originally Posted by Volvodrivingbiker

must admit you got to read between the lines i just found interesting as it high lighted the importance of the MAF sensor would you like me to edit out the crap bits

Well of course it's important. Without the MAF the system has no way of knowing how to mix the injected fuel. There isn't any manual adjustment on most of these injection systems, so if the MAF is dud it'll run like crap and the only thing to do is to get a new MAF (or used one from Braydons). I know, because I've I've had to do it, and since putting on a cone filter and performance exhaust it hasn't missed a beat and gets around 29-35 on a 600 mile run.

Dave A.

[Fancourt]

I inherited my 240 with an intermittent Lambda light problem - meaning I would disconnect the battery to reset it and it would come on again in due course.

For some years now I've routinely used BG additive products to clean everything up, which have long since been licensed by some major manufacturers for their major service intervals. BG109 oil system flush will flush out masses more gum, tar, varnish and sludge than your average high street product and restore compression - but you do have to remember if you're freeing up a lot of crud that a single new filter and normal interval afterwards is virtually criminal....use a couple of filters at 500 and 1500 miles after the flush to ensure you mop up all the crud and don't cause a filter to have reduced oil flow, and if you know there's lots of sludge, be very careful and consider secondary filtration. BG44 fuel system cleaner also works massively better than high street stuff, and again for an old car I would tend to change the filter after the first couple of tanks. This routine has transformed many of my cars, especially the older ones, but of course caveat emptor applies.

I've had no issues with the Lambda light since I followed the routine and I suspect fouled injectors were causing poor burn. i expect my emissions will be a whole lot better, too - will find out at the MOT next week!!

For the record, I'm not affiliated in any way with BG Products or their UK distributors.

[rippedoffagain]

Originally Posted by Volvodrivingbiker

Ok ive followed the code sequence as discribed , I printed out the list and wrote down on it what was signaled it went like this

ECU ....... 1 - 2 - 1 ......... mass air flow meter signle faulty or missing
......... 2 - 1 - 2 ......... 02 Lambda sensorsignalmissing or faulty

EZK ........ 1 - 4 - 4 ............ Load signal from ECU missing

I then tried to clear the codes so i can see if it happens again but even after 10 seconds the led didnt come on to clear , could this be because the fault is still evident

im asuming the lambda fault came on now because i did unplug the sensor and run the engine not sure what to do next any ideas ?

I remember now, those first two codes are exactly the ones I used to get on my previous 940, until I replaced all the ignition bits. You should have seen the inside of my dizzy cap when I took it off. It was a miracle the car even started at all.

Its worth having a check of your air box too. If its the same as on my old 940 (which is different to my current one), they have a recurring problem in that the little thermostat that operates a little flappy valve thing fails. The consequence is that it is stuck permanently on the 'hot air' channel, instead of switching to cool air once it warms up. It means the car runs a bit poor when its hot, and when it gets very hot, your ECU starts throwing warnings at you. The MAF sensor works by maintaining a wire or film at a set temperature, which it does by varying the amount of electrical current needed to keep it there. Air flowing through will cool that wire, the electronics will pass more current through to compensate, and then that variation in electrical current gives you an accurate reading of the cooling effect of passing air, and therefore the volume of air. When the air coming through is already as hot as the wire/film in the sensor, there will be no fluctuation in current, so the ECU has no idea how much air is going through. It reports that your MAF sensor signal is missing or invalid. It will result in poor combustion, which I expect would be enough to throw the lambda signal outside of normal range too, hence the other code.