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Check the Crank Angle Position Sensor (archive)

[ Follow Ups ] [ 5-series (E34) Message Board ] [ Msg. Board FAQ ]

Posted by keith on March 30, 1999 at 14:56:42:

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.

: Rick
: (take out the "REMOVE" in email address)

I had a very similar problem with my 1991 Volvo 240. When it was cold, it started fine. However, when the motor was hot, it was hard to start - this problem started getting worse as time wore on. However, even after finally starting when hot, the car seemed to run fine. It turned out to be the crank angle position sensor. It, like most other eletrical sensors, tends to have more problems when hot than when cold. I diagnosed this problem myself first, but took it to the dealer, who confirmed my diagnosis. Apparently, the sensor was not totally dead - when cold, it worked fine. However, when hot, it only gave out a signal intermittently, but not often enough for the computer to determine where it should be in its startup program. However, once started, it did apparently update the computer enough to keep the car running. Hope this helps.

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