Plums!

Bought a AFR gauge of t'ebay fitted it last weekend.....

connected to ecu,

general tick over flickers between first bar of rich and down to lean but mainly in rich....

general driving off boost night rider effect up and down always 1st 2nd bar staying mainly rich.

On boost 0.9 bar no reading at all from AFR!!!!!!

The car is a completely standard MY99 GT 110k kms (65k miles)

Anyone have the same or know what's going?

Cheers,

Plums.

silent running

When you floor it the ECU doesn't use the lambda signal, it uses its own lookup table for fuel and ignition. I'd guess that the disappearance of the signal means you've got the wrong connection somewhere, almost as if you've hacked into a lambda OUTPUT signal from the ECU rather than the lambda input TO the ECU.

Best to tee into the wiring close to the actual lambda sensor to get your signal which should vary between 0 and 1 volt, rather than taking it from the ECU.

I could be wrong here, but by 'no reading' I take it you mean the thing just goes blank, rather than the display heading off the scale one way or the other?

The readings you are getting seem fine btw.

Plums!

Cheers Silent!

I wired it up as directed to the oxygen sensor wire on the ecu block 136 terminal 21 (a black and silver stripped wire).

If i understand rightly this is the wire that comes from the Lambada?


Plums.

scoobyboy

what year is it as later cars have an afr sensor and a lambda sensor

dazzlers82

iTrader: (3)

my afr gauge use to do this as lambda sensor was knackered and mine also was when boosting up and the gauge should go from lean to rich on tickover.

Plums!

Yeah I was starting to think it might be the lambda sensor?

Plums

Plums!

Well tried Silent running's idea and connected it directly to the lambda sensor.....

Unfortunately it hasn't made any differance at all....

Everything seems o.k. until WOT then all blank.....

Guess it's lambda change time!!!!!

Cheers

PLums!

silent running

If it's directly hooked up to the lambda sensor then you've either got a knackered lambda sensor or a knackered gauge. I'm inclined to think lambda sensor rather than gauge, because flooring the throttle doesn't directly affect the gauge but it does affect the gas flow past the lambda. But I could be wrong.

Plums!

Cheers Silent!
Picked up a lambda gauge today, bosch one 0258 003 995,

will plumb it in tomorrow if I get chance!
Also picked up a fuel filter as just to be sure!

Cheers,

Plums!

Plums!

Oh dear......

I have connected the afr sensor wire to ecu.... no response at WOT,
I have grounded the earth directly to chassis.... no change
I then spliced afr sensor wire directly into the lambda sensor.... same old same old
I changed fuel filter £20 and lambda sensor £75 today (How fun )

and you guessed it no signal at WOT.....

This has become a very time consuming and costly exercise.

Why am I not getting a signal at WOT?

Anyone know?

Cheers Plums

Plums!

Nobody got any ideas then?

Would it be possible (safe?) to somehow restrict airflow into the engine?
To possibly richen the mixture and see if it really is too weak at WOT?

Cheers for any ideas,

Plums.

Plums!

Sorted it!

Cost me an arm and a good part of my left leg plus a whole lot of worry and time.....

But all tickerty boo now!

The problem was.........







wait for it.....




















The flippin MAF sensor bought one on the way home from work and low and behold green lights on full boost!

Scary thing is if I didn't have a AFR gauge I would never of known I was running so lean as to not even get a reading and that's on a standard car! The car ran perfectly and boosted lovely, real glad I got a AFR probably saved my engine

Chuffed to mutts nuts I am!

Plums.

P.S. I hope that this thread will be of value to all who suffer the same defect.

highlandwrx

Ive been having the same problem, the gauge would read up into optimal and then as soon as you get to about a tonn the gauge goes totally blank, i thought i had just a bad connection, need to get a air flow meter! is your scoob a import? wot fuel do you use? and how far into the rich does it read now uve changed the MAF? ive already changed the lambda which did help a bit.

cheers
highland wrx

Plums!

Hi Highland, sorry didn't see your post until now.

My car is a standard car it ain't an import, but it is a Swiss car (I live in Switzerland)

I always run with V-power...

It goes completely round to the C (in RICH) at WOT now

Mine always went blank at WOT no signal at all!

I didn't need to be going fast to test this, I could test it by simply selecting 3rd a little too early and pressing the accelarator all the way down.
As soon as the pedal was fully pressed down the lights went off lift a little and it came back on, it was almost like a switch if you see what I'm getting at?

Hope this helps?

Plums.

highlandwrx

thats the exact same as what mine is doing aswell, need to get a new maf quick. hope i havent done any damage

thanks plums

Plums!

Don't think you'll of done any damage..... fingers crossed!

Just stay off the boost until it's been changed.

You'll need a special T20 torx screwdriver or if your lucky you can get the screws off with a pair of pliers, or if your even luckier ask your friendly scooby mechanic to replace it for you.... literally 30 seconds of a job!

You'll feel the differance on boost.........


Plums.

Plums!

Highland WRX did the new MAF resolve your problem?

Plums.

highlandwrx

getting one tommorow to try, ill let you know the outcome

cheers plums

lightwave693

BTTT

did the new maf solve your problem? i have wired in an afr to my 98 turbo and its reading very very lean on WOT and still in the lean on light throttle just on boost, and rich when slowing down from speed with no throttle. thinking Mr Maf might be on its way..

Rich

highlandwrx

hi there mate, i tried another maf and it didnt make any difference, the car seems to be running ok but i think my coil packs are on the way out wich is causing the holding back.

as for the gauge ive spoken to a few people and they think either the gauge could be faulty or its just the way its wired up, ie: bad connection, ive got mine wired to the plug side of the sensor, im going to change it to the output at the ecu.

wot kind of gauge do you have and where is the feed taken from?

P.S sory plums i meant to get back to you bout this!

rasheedn

the car's stock sensor wont read anything in open mood (under WOT conditions)

i wouldnt trust the stock o2 at all, get a wideband if u want 2 get the correct AFRs

Plums!

No problem Highland!

Sorry to hear that it didn't resolve your problem

They're a pain in the **** problems like this and a real bugger to sort out!

It took me a lot of time and coin to get to the bottom of mine!

Unfortunately we don't have any real good scooby specialists over here and Subaru garages are a bit sh**e to be honest..... So I just do my own work and get tips from here and other sites....

Lightwave it could be normal (but not good) that your AFR is reading lean on light and full boost, it all depends on what mods you have, increasing boost and/or having a direct air intake without a remap can prove costly and will weaken the mixture also the quality of the fuel you use can make a difference..... You'd be surprised how many people are running unwittingly lean by simply moding their motors without monitoring Air fuel ratio or Knock! Then again if your car is standard then it could be the MAF or lambda are mullered, the only other hint I had that something was wrong was that on full boost it was very off and on (read lumpy or felt like it was slightly miss firing) and very occasionaly some difficultly starting when the engine was already warm.... plus of course no signal at all at WOT on the AFR.

Again sorry Highland ..... just an idea but you could try borrowing the coil packs from someone to see if that makes any change?

Cheers,

Plums...

Plums!

Lightwave I just read your post again, and you say that your getting green light when slowing down with no throttle?

That's just wrong! You should have no signal at all when slowing down in gear (clutch depressed) with no throttle.

Maybe you plumbed your sensor wire to the wrong wire?

Plums.

P.S. Rasheedn the Lambda will still send a signal in open or closed circuit the chemical reaction created with the zicornia will constantly send a voltage, just the ECU doesn't read from Lambda at WOT, but your AFR can!

rasheedn

it can read but its not good enough to get accurate reading

thats y we use wideband and thats why tuners use their own wideband and not just use the car's

The stock O2 is not accurate under 12.5-13:1 or so in practice

rasheedn

this thread is worth checking also
Finally, LC-1 ready to be integrated!

Rasheed

Plums!

Your right Rash....
'The stock O2 is not accurate under 12.5-13:1 or so in practice'

It's true it isn't as accurate as a wideband, but it will let you know if your running too lean or too rich..... and for me that's exactly what I need to see when on full boost, solid greens on full.

Cheers

Plums.