I've just bought an 2002 156 twin spark manual.
And it has the dreaded warm start problem with the common recipe to fix being to change a crank angle sensor. However, the sensor was replaced less than a year ago (roughly 10 000 km). Should I still try to replace it first? Or could there be any other things behaving the same way?
The car starts perfectly when cold, ok when hot, and terrible when warm. It also idles at 1100 rpm. Is that normal?
The second question is, where do I get the crank sensor (or other minor stuff) locally? In case I don't want to wait for delivery from UK. Or is it worth the wait? What kind of markup I would be looking at if buying locally?
Thanks.
If you're in Sydney or Melbourne there is EAI who carry a modest range of Alfa bits.
For the issue you describe I would be first checking the stored error codes in the engine ECU and also you could do an empirical check for continuity on the ECU connector pins that correspond to the CAS.
How is the thermostat?
Thermostat seems ok to me. As in it lets the engine to warm up quickly and then the temp seat at 90 give or take 5 degrees.
The problem id NOT the Crank Sensor. I sent you a PM. Give me a call and I may be of help.
Barry
Ok, so I've connected via AlfaOBD and it seems like the coolant temperature sensor is way off.
It shows 24 C when warm and 38 C when hot. The gauge seems to show as it should be, i.e. goes from nil to 90 while warming up. Also, target idle speed is 1060 when hot which seems a bit high.
I guess that could be the reason for high idle. But can that cause warm start issues as well?
Also, how to I determine a faulty crank sensor with AlfaOBD?
I would be taking another look at the thermostat. A well known weak point on the 156.
Hi
A simple method on checking thermostat is included on the following post which links you to Youtube link (No need to remove thermostat to check, uses squeeze method)
http://www.alfaclubvic.org.au/forum/index.php?topic=16784.msg96500#msg96500
Cheers
bonno
Bazz was right - that was not the crank sensor. I was also right that it was the coolant temp sensor. I fiddled with the sensor wire and the sensor itself, unplugged and plugged it back a couple of time and voila - idle is now at 800 rpm & warm start is just as good as cold.
And it started to show realistic temperature in AlfaOBD as well.
Likely that it was trying to hot start with an overly rich AFR (and a high idle) because it was still in cold 'closed loop' mode (and unable to get into 'open loop' because the ECU 'thought' that the engine was still too cold, even when it wasn't). It would be like trying to start a warmed up carburettored engine with the choke on, i.e. flooding it.
Regards,
John.