Alfa Pages

Guest

Hi

my freinds car(alfa 33) originaly with 1500 engine now fitted with 1700 EFI 8 valves engine with the 1500 gearbox(the car is 1994 model)
he's saying the car is "eatting" lots of fuel,a specialy at traffic!
here are the diagnose computer results of his car:
CO2.8
CO2 12.6
O2 1.2%
HC 70 PPM

is there some problem acording to this figures?? if so then what should he do for fixing it??
Thank you
Tomer.

Chris Notsis · Posted: Mon Jun 23, 2003 2:46 am Post subject: Emissions

These levels suggest a number of causes: failed oxygen sensor; faulty coolant temperature sensor; inefficient injectors, balancing of throttle bodies. It is possible the coolant temp sensor continues to send a high ohms signal to the ECU making it think the engine is still cold, thus sending a signal to run the injectors in cold-start mode. Check this sensor first. (cold = high resitance between the 2 terminals; as engine warms, the reisitance should drop). Have you had the injectors ultrasonically and chemically cleaned? My approach has always been to replace oxygen sensors when doing the cam belt(s) and including an injector service. O2 sensors degrade with time.
_________________
Chris Notsis

Admin · Posted: Mon Jun 23, 2003 1:08 pm Post subject:

Hi

For a late cat car those figures are very high. UK MOT limit is 0.5% CO and 50ppm HC.

There is a jumper on the ECU for the late motronic 8V engines to select the 1.5 or 1.7 engines (but it wouldn't surprise me if this just changes the rev limiter).

With these late cars the ECU learns the amount of fuel to use by feedback from the lambda probe. When you disconnect the battery it will run badly for a while until it relearns. If the lambda probe is shot then it will not relearn at all (and will drink petrol).

I had this happen once. Car ran fine until I did the cam belts and disconnected the battery while doing it for safety (didn't fancy having a blonde moment and cranking the engine over with the belts off), after which the car ran like a dog.

All the best

Keith

Guest · Posted: Mon Jun 23, 2003 5:50 pm Post subject:

Thank you Both!

so if the lambada prob isnt working properly or at all what should i do now for making it work again as it should?

Chris Notsis · Posted: Tue Jun 24, 2003 4:28 am Post subject: O2 sensor

You could stuff around testing the thing, but if the 33 has done over 100,000 kms and the sensor is original, then it would be more cost effective to replace it. Once done, then you know one variable has been removed. 02 sensors are fairly reliable, often being let down by faulty wiring or a lot of corrosion on the threads where the sensor is inserted. Their accuracy drops with age. In some cases, they can pass all the static tests and so seem ok, but in reality, when under load can fail.

If you want to test the sensor, there are numerous on-line sources that give you directions. Or you could go to my site: < http://members.tripod.com/kcan3106 > under 'Information & Advice'.
_________________
Chris Notsis

Guest · Posted: Tue Jun 24, 2003 5:06 am Post subject:

Thank you very mouch for the information Chris!
you'v been very helpfull Wink