low idle speed and cut out once or twice during mot test

high emissions at fast idle but possible to get them in limits by blipping the throttle by a few hundred revs at fast idle test, however, still fails the idle test with co around 5.4 lambda 0.8 hc around 250,

i have added forte gas treatment to the tank and gave it a good high rev clear out at high temp as this car is owned by a v/ill old man therefore doesn't do much and while the fast idle emissions improved, the idle figures were almost the same

disconnecting the lambda sensor didn't make much difference and i don't have any software to plug into this even though it has a 16 pin plug it won't comm on eobd!

any further info much needed  as i don't want to send them to the dealer as i have hear of several horror stories

alistair

ALL IN A DAYS WORK

The first item to test would be the lambda sensor, but you will need a scope voltmeter to test the performance, because the switching is too fast for a standard voltmeter.

The O2 sensor can be tested as per the instructions in this link: http://forums.delphiforums.com/cartune/messages?msg=38.1

If I understood women as well as I understand cars, I'd be the envy of every man.

Can you clear a  few things up, What is the year?. Does it have Pre and Post cat Lamdda,s ?. And what code reader was you using to pull the EOBD codes.

If it has pre and post cat lambda,s it should be EOBD compliant

KEV.

OOOOP,s see it,s 1999 so it does not have to be EOBD compliant, but would be nice to know what you are trying to pull the codes with?

"If you dont KNOW how it works, don,t try to test or fix it"

cartech; ta for the info, I do however know how to test the lambda sensor mate

tested it tonight with engine warming up, at 2,000 rpm h2os switching 0.8-0.1 volts, not as quickly as it should but that would explain the helping hand needed to pass the fast idle test.

when you then blipp the throttle and then let it settle to idle however, the h20s signal falls to virtually zero signalling the ecu to richen up the mixture, hence the idle test fail, cos the signal stays at 0.021v approx while at idle but gas readings are as above.

looking at a lambda sensor then hopefully!

kev,

tried to "pull the codes" TM using my trusty solus, no joy, although this car has no downstream lambda sensor, so no eobd or obd requirement then?

ALL IN A DAYS WORK

Have you "checked" for the ECU's reaction to the Lambda sensor...ie what are the injector durations ?

Have you got a scope ?

If so,   can you check the lambda and the injector durations at the same time...?

As you raise the revs and release you will see the lambda go "rich" and then stay lean as the injectors are switched off (over run) then see what the injector durations return to at idle. Are they being commanded rich ?

Does it have an air leak before the lambda .

Regards

DaveH

   

Perhaps it will be useful in the search box.

If I understood women as well as I understand cars, I'd be the envy of every man.

Bensar (alistair) does not make things easy by having two TAG names one at work and one at home (very posh)

KEV.

OOPs that should read Car TECH sorry.

"If you dont KNOW how it works, don,t try to test or fix it"

    At risk of stating the obveious, have yo checked the heater circuit of the lambda sensor. I got caught out on a toyota (which I could not plug into), the lambda sesnor appeared to be working but the ECU not responding. I think because the ecu had seen a fault with the heater circuit it was ignoring the signal and using a substitute value.

Aidan

Definition of Experience :- `Something you get, when looking for something else.’  I think I'm getting to much experience nowadays

glad to say ,this car is now fixed

fitted a new mitsy lambda sensor and re-tested to find all gasses and lambda well within limits,....phew!!!

however i had taken on-board the preceding advise and checked for air leaks etc which would knock the lambda sensor to zero at idle, none apparent,

you hear so many horror stories about these gdi's that you automatically fear the worst!

I have learned so much from this website that I could safely say my garage would not have the reputation it has to-day without the help , advise and information available here, soppy I know but we all need to be told now and again, don't we ?

so thanks again all of you for helping me to another successful,.....oot the door as we say up here!

alistair

ALL IN A DAYS WORK