alexWRX

Had A/F power meter fitted recently and thats what i see. under easy loads a/f shows stoich ratio, off throttle it goes to lean - everything seems to be OK. And than i push the throttle hard a/f goes to rich but only than the revs reach 4000-5000 it rapidly drops to lean. What could that be lambda is not reding correct or maf makes it lean? How to check?

In what concerned maf i had ecu reseted several times and maf didnt show any signs of being broken - i mean revs were stable.

Please give advise as now i have to ride my car like 1.5 diesel.

Jolly Green Monster

iTrader: (4)

Believe it cannot be Lambda as it is not used by the ECU on Wide Open Throttle.

JGM

greasemonkey

I think you've missed the point a bit JGM.

Presumably the power meter takes its AFR readings off the stock narrowband lambda sensor, so Alex is asking whether it's really reading a lean AFR, or whether the lambda sensor is shot, giving the impression that it's a lean AFR. Correct Alex?

If so, balance of probability lies with the MAF sensor, if you're certain the AFR readings look correct during part-throttle driving, but the only way to be sure is to replace it and see if the readings change.

alexWRX

Thats what i mean GM - on part throttle AFR readings are consequent which gives me idea that readings are correct.

What worries me is that on full throttle readings are lean.
What i understand from you replies is that on full throttle you cannot rely on lambda readings cause its shot and is not used by ECU as you say. Does it mean that lambda is not giving signal and it is readed as lean by AFR that way while mixture could be rich actually (i hope)?

I saw some threads on the forum there people were talking about full throttle readings on AFR meters. Is there need for wide band lambda or how can full throttle readings be achived?


[Edited by alexWRX - 9/17/2003 5:42:49 AM]

Jolly Green Monster

iTrader: (4)

Good point Grease monkey.. you are correct, I am sorry.

Alex,

No you should still get rich through to red line from the standard lambda.. but as GreaseMonkey points out is the Lambda under reading at high rpm or is the MAF or something else making the car actually run lean..

Do you have a knocklink.. guess not.. so cannot tell if it is knocking.. after buying both I'd say the knocklink is much more neccassary than the afr.

I'd go to Halfords and buy a new lambda sensor.. around £25

Here is how to fit it http://www.scoobynet.co.uk/bbs/threa...hreadid=228321

Believe it is part number L300 air sensor.

See what happens then..

The lambda under reads once hot but you should get a couple or more high rpm runs in before that happens.. one the engine is warm and the lambda warm enough to read in range.

JGM

greasemonkey

They have Halfords in Russia?

Jolly Green Monster

iTrader: (4)

Oops....

I'll get me car keys....

JGM

greasemonkey

Bollokcs so busy laughing JGM I missed Alex's post...! Doh!

Yes. If you are pretty certain that the lambda sensor is reading correctly under closed loop conditions, the balance of probability is that you really are running lean in open loop mode.

That's not quite what I meant.

Yeah, that's possible, but...

If the lambda is reading correctly, your engine really is too lean at high speeds. You need to find out which is which - and quickly.

All you need is a decent AFR meter with good resolution in the 0.8-1v range. A wideband sensor is nice, but not essential, unless you are into remapping ECU's.

...which gets me thinking. What are you currently using to read the sensor. You say it's a combined power/AFR meter, which one? TBH the best meters are probably units like the Dawes, which has four LED's in pretty much the correct range.

Is your meter actually giving you a voltage read off the sensor, or does it simply say "Rich", "Good" or "Lean"? If so, you really need to find out what voltage values the sensor is using to derive this display, as its idea of what is lean may not tie in with ours, if you see what I mean!


[Edited by greasemonkey - 9/17/2003 10:35:10 PM]

alexWRX

Damn we really aint got Halfords in Russia. New OEM lambda costs in area of 250-300 usd which is extremely f*king expencive to my opinion. You can get used one for reasonable 30 usd but never sure if its sound or not (or is there actually a way to check it while its off the car?)

GM i got Power Meter USA AFR meter - this thing looks quality stuff and i saw good comments on it in some threads. It has lean - stoich - rich areas and many many graduations.

So now im making way of the sorting the things out:
1. Get the new lambda
2. If readings are unchanged and car really runs lean try to check MAF
3. If MAF is OK check the fuel system - Fuel Pump, Injectors .... what else?

Guess the list of possible problems is closed?

JGM - really thinking of getting a knocklink. Not so easy to get in Russia as well.



[Edited by alexWRX - 9/17/2003 10:55:44 PM]

Jolly Green Monster

iTrader: (4)

Can you not try a lambda from a mates car??

Wonder how much it would cost to ship you one..........

JGM

alexWRX

JGM how can you be sure that its sound. If its not?
I think i know there i can get Second Hand lambda. Its from MY 02-03 subaru which more or less makes it likely to be in good condition. Is it ok to fit em on MY 95 wrx?

Jolly Green Monster

iTrader: (4)

I think they are different but not sure..

93 and 94 cars have it in headers but this it is in the downpipe on 95 car.. but you'd have to check.

JGM

alexWRX

I got my lambda in headers but as far as i know fittings are the same. Maybe there are some difference in voltage and is my 02-03 wide band or the same narrow band?

alexWRX

Hey Subaru gurus!
Can you confirm my action list or advise smthng else.