very weak mixture

[Cypher007]

ive only recently bought this car and have had the odd problem, but one problem just wont go away, rough idle and progression. so i used a gas analyser to check it out, this is the result:

@idle

RPM = 770-830 variable
HC = 12-28 var
CO2 = 8.40
CO = 0.00
O2 = 9.7
Air/Fuel Ratio = 25.9
Ambient Temp = 17C
High Idle (2400-2600) CO = 0.00

acording to the data on the computer in our motor vehicle section of the college where i work these are the correct readings:

@idle

RPM = 800
CO2 = 14.5-16
CO = 0.5
O2 = 0.1-0.5
A/F = not sure i think it should be about 15
High Idle (2400-2600) CO = 0.3

is this a air leak or lambda (ecu, injectors, temp sensor, air flow meter, etc etc) problem(s). any feedback would be useful.

p.s. Alex (V70 T5, 240 GL) whats your job, cause you look far to young to own a T5;).

Adam (santa pod meet, if anyone remebers me)

dude!

My t5 has had an intermittent weak mixture reading on the check light. 2-3-2 is the code. found that beggering about with the fuel can get the light out but the car runs like a gooden and roling from 85mph today (on a closed road with permission) I was leaving a 328CI bmw in the distance before lifting off at around 135mph. Bruntingthorpe proving ground is a great place to play drag stip games!

Loz

not sure how I'm gonna get through the MOT with it yet though. might try a flush of some kind...

850 T5 CD Auto - The Devil's Playgound }>

I think Alex earns his living by standing around Leicter square at night waiting for MP's to buy his time :)


Sorry mate... :)

G

GARETH!! That was a secret!! ;)

Adam I do remember you, if you were the one without, er, driving documents :)

And no the T5 isn't mine outright, I share it with my dad - in the sense that I put a few k's towards the purchase and I pay for insurance/servicing (do it myself so save some there!) etc. - it works out well between us.

Although he takes the 240 to work so the T5 doesn't get scratched (bloody mercs!) which leaves me with the V70 full time :) Although the bike is more fun! no petrol needed!

[pettaw]

Not an 850 expert, but it sounds to me as though you have an air leak from somewhere, my bet would be the inlet manifold gasket, or a split PCV hose somewhere, what you need to do is hold an unlit blowlamp near where you think it may be leaking in from and the revs will suddenly recover. Be very careful as butane is inflammable (surprisingly). Also, I'm not sure whether it'll spoil the catalyser. Hopefully someone else will be able to give a definite answer

Andy

[Chris_Rogers]

Agree, you have an air leak, IMHO I think WD 40/Damp start is a safer method than butane.

However I would be surprised if the mixture is that far out without the lambda light being on, and fault codes being logged.
Does the Lambda light work (it should be on when the ign is first switched on but before the engine is started) or has the lamp been removed to sell the car?

Suggest you look for fault codes anyway. A 850 Haynes manual will tell you how.

[Cypher007]

thanks all for the info, will try the blowtorch approach. i have since discovered some of the false readings are due to a small gap on the tail pipe chrome extension, letting air into the exhaust gas mixture. yes the lambda light comes on and goes out, no fault codes logged in any of the OBD points.

[Cypher007]

couldnt find any noticeble diffrence when waving the blow tourch around. so ive put a gauge on the inlet manifold and get about 19.5-20.5 hg, with a slow back and forth motion of the needle as the rpm goes up and down between 750-830.