Alfa Romeo Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
Hello.

My fuel consumption has increased to 15l/100km (about 20mpg). Got 400 km with full tank mostly motorway driving. A lot of white smoke on cold weather(cat produces a lot of h2o) and grey smoke when revving.

Air and lambda maf connected:



Maf disconnected:


I tried to change maf output voltage, but that did not help. When i dimmed the output to 10-12 kg/h, idling went rough.
A Simple MAP/MAF Enhancer
Also tried different oxygen sensor.

Had a cambelt change at summer, after that original bosch maf showed signal low error and engine did not start(car was not started 2 months, i think original maf went bad). Tried another maf which resulted a 10-20% higher fuel consumption, also replaced my lambda and consumption went back to normal. After few weeks lambda graph was bad again, but i don´t think it's lambda because when I disconnect the maf, after some time lambda graph goes normal, as shown at third pic.
Is this possible that if timing is slightly off, the engine would only run rich mixture.
I doubt if its maf because lowering its output made no change either, until engine stalled.

Can someone provide me engine parameters(air quantity, lambda, timing...) of 2.0 ts engine, so i can compare them with mine.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #3
When driving steady on motorway it's fine but jerks at low speeds when pedal slightly pressed or under load.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #5
I think the lambda is giving bad or low output and ecu thinks it's lean. MAF may be faulty too, it's not original Bosch.

I got some fault codes when started engine after battery disconnected for some hours.
Lambda was not connected.

Maf signal low
Engine rpm sensor
Phase sensor

Maf error was present untill restarting ecu(disconnecting and shorting battery leads).
Other errors were stored.
Its interesting that if i disconnect lambda I don't get error relating missing o2 sensor signal, there's only lambda heater circuit fault.
 

·
Registered
Joined
·
450 Posts
The lambda and maf works closely together. If you manipulate the signal from the maf, the ecu might get confused and you might as well disconnect the lambda sensor if that's your plan. Be aware that running the engine too lean is not good (too much heat), it should actually run slightly rich for optimal performance.

Any faults with the lambda signal will not throw any fault codes on these. The lambda switches just fine once you disconnect the the MAF. Change the MAF for a Bosch and leave the fuel trims up to the ECU would be my best advice.
 

·
Registered
Joined
·
1,271 Posts
As above but is the thermostat failing.This results in the car never reaching optimum running temperature and poor economy.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #8
Thermostat is fine, i think both lambdas i tried are faulty. It's very rich, i think lambda is about 0,8, there is a lot of gasoline smell and grey smoke. Lambda output is 0-60 mv, flat line with some errors, what is sign of a lean mixture. ECU gets lean signal from lambda and increases fueling time. The injection time is 6-7 ms lambda connected and 4-5 disconnected. Wonder if anyone knows correct injection time when idlin at 90deg.
 

·
Registered
Joined
·
1 Posts
I have similar problem with AR 156 2.O TS 1999r.
The 15l/100km, white smoke and RPM fluctuation when engine is cold. And Additional P0170 error sometimes.
I already change Water Temperature Sensor, MAF. The lambda seems ok.
I Already check the Air inlet but not yet the exhaus Outlet.

I have not idea what it is.

I'm going to check the cylinder pressure to examine the Head gaskit. And replace the Collector gaskit.

I have question, do the dead Cam variator can give this kind of symptoms?
And what it mean the white smoke from exhaust,
I know it can indicate dead Head gaskit but i read somewhere that it can indicate when the mixture is lean. But if this is lean mixture why the high gasoline consumption and P0170 error?
 
1 - 11 of 11 Posts
Top