MAF setting Questions

Amonra · Post by **Amonra** » Thu May 31, 2007 12:59 pm

thanks for the photo and sorry about the wet part.
ok i think i got but in mine it is just blue ( red arrow ) and there seems to be another wire which clips into it which is brown ( blue arrow )
look at the photo:

is it still the same one or is mine different ?
what would happen if i clipped them together ?

Thanks

crispy-d · Post by **crispy-d** » Thu May 31, 2007 1:54 pm

Hmm...well I'm afraid I don't know, and don't like to guess either. But I can only imagine the blue wire is the MAF test point. It is possible that the brown wire is an earth for the test point? I don't know. I wouldn't like to join them before you know exactly what they are, through fear of frazzling something!

The blue wire looks like the one to use though.

Amonra · Post by **Amonra** » Thu May 31, 2007 1:58 pm

ok so i connected the blue wire ( assuming it's the right one ) to an LED and an appropriate resistor ( around 500 ohms ) as 12V would fry the LED ( an led's max voltage is around 4V ) and to the battery positive. i started turning the maf pot anti-clockwise ( starting from 400 ohms ) and went all the way down to 200 ohms at which the engine almost stalled and had no blinking of the led. i then turned the maf pot clockwise slowly and went all the way up to 740 ohms at which point idle revs were up to 1300 and still had no blinking of the led.
i then stopped as 1300 revs seemed a bit much to me and turned the pot back to 438 ohms which seems to be a popular figure.

did i do something wrong ?
i used a white 5mm led which normally consumes 20mA @ 3.6V is that too much ?

Amonra · Post by **Amonra** » Thu May 31, 2007 2:38 pm

could it be that i have a faulty lambda sensor ? i recently removed the catalytic converter and replaced it with a straight pipe to which i had a nut attached for the lambda sensor and she is wasting more fuel since then so maybe the sensor was damaged.
the problem is that i cannot trace the connector for the sensor to test it. the wire seems to go under the engine and disappears from there. i am assuming that it is connected to the maf somewhere but i just cant find the connection. can anyone please point out the location. a picture would be helpful as i am a total idiot and a newbie.

Thanks

JohnTurbo · Post by **JohnTurbo** » Thu May 31, 2007 2:44 pm

The wire in question should be attched to the grey loom. The other wire, if from a different loom, is, i think, the wire to turn tracs on and off in a post 93 turbo.

Amonra · Post by **Amonra** » Thu May 31, 2007 2:54 pm

what do you mean by it should be connected to the grey loom ? mine is an early 1992 turbo

crispy-d · Post by **crispy-d** » Thu May 31, 2007 3:24 pm

Well, unless I'm being a prat here, I've always attached the test points to earth...The wire coming from the loom with grey tape wrapped round it gives a signal, so you should connect it to earth with the LED & resistor in between (the right way round of course

)
The wire in your picture with the red arrow should be the right one.

*Oh, and if you had the MAF set at 600ohms or higher then you would be using more fuel anyway.

JohnTurbo · Post by **JohnTurbo** » Thu May 31, 2007 5:11 pm

by attached to, i mean 'PART OF'.

If you trace it back it should got to the loom with the grey tape.

Amonra · Post by **Amonra** » Thu May 31, 2007 5:39 pm

ok got it. well then i guess i was connecting the right one. i also made sure the led was connected the right way round, but still no blinking.
dunno

Oese480T · Post by **Oese480T** » Thu May 31, 2007 6:13 pm

The red(plus) of the battery is the minus for the led. If you connect a meter, red pole to the red of the battery and black to the connector we're speaking about, it shows -13.8V and -900mV as on/off... the connector is of positive potential relative to the plus of the battery...

So the plus of the battery is actually the minus for the testing LED

@ amonra: Perhaps it works like this on your car as well??

Didn't try with a LED until now... It would be fine if we would find out how this is to be used because it would then be a very easy way to control and set up the correct CO...

Amonra · Post by **Amonra** » Fri Jun 01, 2007 7:23 am

ok i get it so i think i connected the LED the wrong way round as i connected the +ve of the led to the batt +ve when it should have been the -ve of the led to the +ve of the batt as Oese480T says. this could mean that the led is being connected in series to something.

Oese480T · Post by **Oese480T** » Fri Jun 01, 2007 8:09 am

I'll try adjusting with a LED instead of a meter tomorrow, will fit the original Volvo Sparkplugs before... I'll post my results here...

Amonra, did you already try again??

Yours,

Oese..

Amonra · Post by **Amonra** » Fri Jun 01, 2007 9:42 am

Ok just tried it again with the LED -ve connected to the battery +ve and LED +ve connected to the blue wire.
started the engine and let it warm up to 75 deg Celcius on idle.
with the enging still on idle and warmed up starting from 438 ohm setting on the MAF i went slowly up to 990ohms - no blinking.
Went back to 438 ohms and went slowly down to 190 ohms - no blinking.
put it back to 438 ohms shut the bonnet and gave up.

still looking to find the lambda sensor connection

Oese480T · Post by **Oese480T** » Fri Jun 01, 2007 1:14 pm

mmh weird...

I did check with a LED a few minutes ago, same behavior as with the meter, need 585 Ohms to get the right mixture. LED was definitely blinking

Perhaps you use a resistor with a resistance somewhat too high? I use a 560 Ohms resistor for a normal LED. Does your LED light up if connected directly to the battery? One or the other way round?

I'm kind of disappointed, used original Volvo plugs and it makes a difference... With around 440Ohms I get a really hot engine (90Ã‚Â°C rapidly when driving in town), but very good response. Really speedy...

but..

with my weird 585 Ohms I get a blinking LED, very low fuel consumption, but kinda slow response and relatively low power subjectively...

Looking further to find a solution.. What is really correct here??

Oese...

Amonra · Post by **Amonra** » Fri Jun 01, 2007 1:30 pm

well i am using a 510 ohm resistor and a white led. the led works just fine when connected directly to the battery only the right way round though as an led is a diode.

The wierd thing that youre getting low consumption and power with a richer mix rather than vice versa.

Oese480T · Post by **Oese480T** » Fri Jun 01, 2007 1:42 pm

Yes, I don't understand either...

Perhaps it's because if the lambda-sensor detects a mixture too lean it triggers the injection ports to richen the mixture??

But, on the other hand, a hot engine seems to indicate a lean mixture??

crazy...

98kellrs · Post by **98kellrs** » Fri Jun 01, 2007 1:54 pm

If you're looking for the lambda sensor connection it's located underneath the battery tray. It's easiest to disconnect the battery, undo the bolts on the tray, and lift it off, it should be under there

Oese480T · Post by **Oese480T** » Fri Jun 01, 2007 2:15 pm

OK, we don't mean the wire to the lambda-sensor itself...

We mean a connector for a LED-Diode with which you can adjust/check the CO...

@ amonra: a simple check if it's the right cable (or at least the one I think it's the right one, blacvk-blue and with response to mixture settings and the "female" connector..) is to disconnect the maf-cable. The engine then runs in a emergency-program which is rich. then the LED should light up...

If all this doesn't happen, you could check directly at the lambda-wire, it should be idling between ~80 and 900 mV relative to the battery-minus...

Edit 1: OK, I drove home just a few minutes ago and must say, the car is not slow and accelerating better and smoother with volvo plugs than with my old ngk-plugs... So I will drive it some time this way round... 585 Ohms still seem a bit too high, but unless this question is solved... 100 Ohms is the difference only between 74Ã‚Â°C and 90Ã‚Â°C, and I picked the higher setting now

Any suggestions on this? I could try the other way round, but I want ONE setting and not many many different...

What makes me think also is the colour of the old plugs... It was a little bit too dark I think, greyish-dark, so not covered in soot but not brown as they should be... Could this be because of driving with many different mixtures in the last weeks? One time lean, one time rich, and many test drives accelerating fast and such...

Edit 2: Now it's at 500 Ohms... Blinks in most conditions there

... Will try further...

Oese480T · Post by **Oese480T** » Sat Jun 02, 2007 4:42 pm

Okay,

for everyone who want's to try this way of CO-setting, I must say it's only suitable to do a coarse tune, unless you (or someone who tells you) know(s) what you do...

For me, my LED blinks all the way from about 440 Ohms to 585 Ohms, so that's really a wide range. This is dependent on engine temperature, so it's quite tricky to adjust in idle without constant cooling...

I found best performance and good economy manually now at 495 Ohms, so quite in the lower middle range between the two "extreme" settings.

I think a good way to set the CO by using the LED is to drive the car until engine is warm (at least 74Ã‚Â°C), then adjust CO by using the LED until it flashes (at my car, you can only achieve more or less equal on and off times, as the whole thing is quite a bit irregular). One must take into account that there's some time needed (a few seconds) to get an effect after the MAF-potentiometer has been turned, so use steps not that wide...

Then let the engine heat up till the ventilator sets in, then, after it is off again, wait about a minute. At my car, directly after the ventilator was cooling, the engine runs a bit lean, although it is at middle temperature... Don't know why. Then the LED should flash again, if not, adjust. Do not adjust directly after the ventilator is benn switched off! Then the mixture will be too rich as you need a few Ohms more...

After all this is done, do a test drive. If everything is to your pleasure, fine, if not, try to find out if you need a bit more or less fuel to get it running as you wish it... At least, one knows a margin of the resistance after doing the LED-CO-thing, and this lets me feel better when, after that, doin a manual fine tune.

I hope, I will rest on this opinion still in a few weeks... At the Moment I'm fine, although one of my new Volvo-Plugs broke and i had to put an old ngk in until my volvo dealer opens again on monday

Good luck,
Oese..

madtuning · Post by **madtuning** » Tue Jun 12, 2007 12:15 pm

crispy-d wrote:Ummm, not sure what you mean by lambda-proof-lamp-connector, but the voltage read at the lambda should be between 0-1V, and when mine's idling it's 0.56V
0V is rich and 1V is lean.
The MAF is said to be set to 382ohms, but mine was at 446ohms when I tested it, and most others seem to report their's being higher than 382ohms too. I had mine set to 650ohms for a bit, but it's drinking too much fuel at the moment for some unkown reason, so I've put it back down to 446ohms. I'm pretty sure it's not supposed to be up at 800ohms tho.

Crispin

How you exactly tested the MAF??
I canÃ‚Â´t get it right!
It shows me one time 900ohms and then 1200ohms

How correctly put the voltmeter into the MAF cable?

Sorry for little OT