Fortius

For some time now my car give me trouble with warmstarts. Even on bitter cold morning it starts fine but once driven, I can only awake the engine by steping on the gas. To keep it running, I have to remain on the accelerator pedal for a few seconds. Once idle has stabilized the engine runs nice and smooth. The statement of the garage is starter!

As you may be aware, German cars have to undergo emission tests regualarly. My car is due this month. During the test we found out that the CO values are to high (TL Lambda Wert). The range is supposed to be between 0.970 and 1.030, it is 1.037. Not much but to much for the ASU test.

I have read in one of Adrians technical postings that the Lambda sensor could be a cause for warmstart problems. If the sensor is in the process of vanishing (after 152K km) it would explain the warmstart problem and the emission issue.

The garage said that a thorough search is necessary (DME, sensor, air by-pass, chip, starter, injection, etc.)

I would like to gather some intelligence before surrendering my check book.

PS: I had some injection cleaner in my gas during the test. Could that change the emissions as above?

Adrian

Dear Fortius,
There are normally only two major causes for failing the CO2 test. The most common being the O2 sensor. If the O2 sensor has failed you have no emissions control you are in what is known as emergency mode. This will cause your 964 engine to run rich and you will fail the emissions test every time.
After 152,000km I am not surprised that the O2 sensor has had enough.
The CO2 levels can be adjusted but you have running problems so you have to fix the failure first.
I think you have to replace this sensor before you can move forward,
Ciao,
Adrian
911C4

PS: How can the starter affect the engine after it is running. All the starter does is turn the engine over. As long as it reaches 30rpm and you have fuel and spark you start and the starter is disconnected. I feel you need anthother mechanic.

Fortius

Dear Adrian,

maybe I was not clear in explaining the problem. Of course the mechanic treated the starter and the sensor a two issues. After reading your article, I thought that the issues could be related.

I n my opinion the starter is fine, because cold start is perfect (or am I wrong?).

Adrian

Starter is fine,
Ciao,
Adrian
911C4

PS: Put the Bosch hammer on and confirm fault for O2 sensor failure. Do not forget you have to start the car and let it run until the O2 sensor has heated up. Takes 90 seconds or longer to achieve operational conditions.