1986 BMW 525 - E28 Will not start in Cold Weather - Bimmerfest - BMW Forums

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E28 (1982 - 1988)

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Old 09-27-2013, 01:54 PM
karenfraser karenfraser is offline
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Location: Halifax
Join Date: Sep 2013
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Mein Auto: 1986 BMW 525
1986 BMW 525 - E28 Will not start in Cold Weather


I am new to this site and have a 1986 bmw 525. A year ago it started having problems starting in very cold weather (0-5 degree C. Now it is having these same problems in weather that is only 12-15 degrees C. Once it starts it runs fine.

Any ideas?

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Old 09-27-2013, 04:56 PM
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catso catso is offline
Location: Chicago
Join Date: Dec 2009
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Mein Auto: 2000 323i, 1988 528e
Cold start valve, idle air control, plugs, wires, coil, fuel delivery system; lots of possibilities.
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Old 09-28-2013, 12:46 PM
cjmertz cjmertz is offline
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Mein Auto: 325i
A quick check would be to remove the cold start valve..2bolts...set it aside, point it by twisting/spinning at the hose clamp in a safe direction, like straight up

when it's cold enough, climb inside and turn the ignition on to START,.. be quick to turn it right back off! ....you should observe a large fuel mist spray coming from the nozzle end..., if not you may have other issues, could be a bad valve itself...easy enough to replace, but I'd go one more step...

disconnect the electrical connector from the valve, and connect a voltmeter or 12v test lamp between the two connectors and do the same cold day test as above...

you should get 8+ volts there or your test lamp should lite if not...suspect the thermo-time switch.

it's been a long time since I've seen these, I thought 1982=84 were the last of the cold start valves...either or both of the above checks were pretty standard with this complaint.

Your engine is a 6 cylinder, with one fuel injector for each cylinder... the cold start valve is essentially a seventh injector , spraying a little extra fuel on cold mornings to enriching the fuel mixture across the plenum just a little more, kind of like a choke, but in reverse ( the choke will allow a little less air) ..
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Old 09-29-2013, 05:14 AM
south26 south26 is offline
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Location: Dayton, OH
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Mein Auto: 535i 1989
They had the cold start valve until 88 with the 528e seta. I am assuming the 525i had the m20 so it would be like the 528e here in the states, so I would also guess the cold start valve.
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Old 10-05-2013, 07:37 AM
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BMWFatherFigure BMWFatherFigure is offline
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Mein Auto: E23;E32;E34;E38;R50;R55
Cold start control switch or (and) temp sensor for the ECM.
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E21 318i; E23 735i; E30 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i
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