In Reply to: Warm start problems posted by Rick Robinson on March 28, 1999 at 02:59:54:
: Here is the symptom. When the car ('89 535i auto) is cold (and I mean COLD, -20C or so), the car starts like a dream. Under warmer conditions, the car cranks for upto five full seconds or more before slowly catching. It then stumbles along for a few more seconds and then evens out and runs normally. Performance when driving seems to be quite normal.
: To date, here are the things that have been done or tried:
: - Injectors have been pulled out and tested - ok
: - Fuel system pressure tested - ok (but with some inconsistancies
: - Cracked boot between throttle body and intake replaced
: - O2 sensor replaced (it was pretty bad when removed)
: - Double dose of injector/fuel system cleaner used
: I am losing my patience with this, the only angle I haven't tried yet is the thermo-time switch and related cold start injector. Any other ideas? Any help is appreciated.
: (take out the "REMOVE" in email address)
My '89 E34 5spd does something similar. If it is cold it starts fine, but warm it requires 10-15 seconds of cranking all at once or two attempt to start (I don't want to overheat the starter) where it always starts on the second attempt. There is no separate cold start injector on the e34 motronic and it can't be the check valve in the fuel pump or a leaking injector as others have suggested because then it would be hard to start cold as well not having any line pressure.You should check the thermo switch in the thermostat housing as this is the temp input to the DME. Mine checked out Ok . Any insight to this problem by anyone would be appreciated. I also have the off idle stumble that others have reported and have tried all the recommended fixes to no avail .I don't know if the two are related or not.