1997 855 GLT Cranks but won't start

Post by **misha** » 04 Jan 2015, 19:49

If either of those sensors are bad,there would be a code stored.

Crank position sensor would throw a code.

RunningMike · Post by **RunningMike** » 07 Jan 2015, 11:35

I finally got the car firing up. It turned out to be "the lawn mower syndrome". I have come across this before but always got it started again by flatten the pedal to the floor while cranking until it starts. This time I had to fill in a couple of tea spoons of oil in the cylinders to get the compression right. I should have guessed after doing a compression test if I had better understanding of what happens during lawn mowing syndrome.

I´m still confused about the OBD2 tool saying 63,5 degrees and my strobe light showing that value while cranking.

Post by **esl_97_850_T5** » 07 Jan 2015, 13:17

63.5 degrees is what an OBDII tool says when at ignition pos II and the engine is not running.

Then the degrees yield meaningful results to an OBDII tool after the engine is running.

I've never measured it during the actual cranking process, but it would be very plausible to me to see 63.5 degrees from an OBDII tool until shortly after the engine is running.

Someone more knowledgeable than I might explain exactly when the 63.5 degree [?max scale?] reading starts appearing as the normal values we see while the engine is running.

esl_97_850_T5

Post by **abscate** » 08 Jan 2015, 05:07

Probably the default bit set point in software more than a relevant physical angle reference.

Post by **esl_97_850_T5** » 08 Jan 2015, 11:12

The Wikipedia OBD-II_PIDs page states that Mode 01 PID 0E is "Timing advance", involves 1 byte of data, has a min of -64 and a max of +63.5, and has units of "degrees relative to #1 cylinder".

Since we see timing advance as +63.5 degrees when the engine is not running, that simply tells me that the byte is initialized to FF (instead of 00) when the engine is off.

Seeing the 63.5 degrees advance is one way that I determine the engine is (most likely) not running (when I'm looking at someone's OBDII data submitted to kwpd3b0_interpreter). The other obvious way to determine the engine is (most likely) not running is to see the Engine RPM = 0.

esl_97_850_T5