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Cold Start Valve
#1

Where is the cold start valve? What are the symptoms if it's faulty? How hard is it to replace? What's the cost?



Anyone know the answers?
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Michael Sorbera

aka San Antonio Silver Bullet

2002 VW Beetle TDI

2004 Nissan Titan Crew Cab

2004 Cherokee 33ft Travel Trailer

1990 Mercury Grand Marquis

1993 Amazon Green 968 Coupe (sold)

2002 Speed-Yellow Boxster (sold)

1987 Slate Grey 944 Turbo (sold)

1987 Guards Red 944 (first Porsche - sold)
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#2

I don't believe the 968 has a cold start valve. Cold starts are accounted for by the DME and the idle stabilizer valve. Older, less sophisticated, fuel injections had them. I know my '79 Datusn 280ZX had one.
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#3

Okay, then how about the idle stabilizer valve?



Where is that? Symptoms? Cost?
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Michael Sorbera

aka San Antonio Silver Bullet

2002 VW Beetle TDI

2004 Nissan Titan Crew Cab

2004 Cherokee 33ft Travel Trailer

1990 Mercury Grand Marquis

1993 Amazon Green 968 Coupe (sold)

2002 Speed-Yellow Boxster (sold)

1987 Slate Grey 944 Turbo (sold)

1987 Guards Red 944 (first Porsche - sold)
Reply
#4

The ISV's function is a computer controlled air valve that opens and closes to keep the idle at the 840 rpm regardless of engine load or temperature. It is a cylindrical device on the bottom of the intake manifold, just behind the throttle body. Symptoms of a bad one would be erratic / poor idle.



It also apparently has the function of making people ask circuitous questions! <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



How about describing the symptoms?
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#5

[quote name='Greimann' date='Sep 11 2005, 06:13 PM']...circuitous.. 

[right][post="9756"]<{POST_SNAPBACK}>[/post][/right][/quote]



Hey! That's a BIG word. I always think " why bother using a big word when a diminutive one will do just fine ?! " <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />
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#6

Well, after a check of the dictionary to find out the meaning of cicuitous... <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



When the car is cold it doesn't want to idle and dies sometimes. Gets worse the colder the engine is.



Any clues?
Partial Post: Please Login or Register to read the full post.

Michael Sorbera

aka San Antonio Silver Bullet

2002 VW Beetle TDI

2004 Nissan Titan Crew Cab

2004 Cherokee 33ft Travel Trailer

1990 Mercury Grand Marquis

1993 Amazon Green 968 Coupe (sold)

2002 Speed-Yellow Boxster (sold)

1987 Slate Grey 944 Turbo (sold)

1987 Guards Red 944 (first Porsche - sold)
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#7

There is a temperature sender for the fuel injection and the MAF has temperature sensing capabilities too. Do you have any warning lights? Any blink codes? If the car idles OK after warming up, it is probably not the ISV.
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#8

Perhaps you need to tap into THE MATRIX.

.pdf 968_troubleshooting_table.pdf Size: 29.84 KB  Downloads: 40
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#9

Hey, is that whole table posted somewhere? This is the first I've seen of it. Thanks!



-Jon
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#10

That is the whole table, but it is part of DME diagnosis section of the manual that also contans the blink codes and test parameters.



.pdf 968_DME_Diagnosis_tables.pdf Size: 312.45 KB  Downloads: 18
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#11

I just replaced the temp sender at the front of the engine - (blue one)



I'll let you all know if that fixes the cold starting problem.
Partial Post: Please Login or Register to read the full post.

Michael Sorbera

aka San Antonio Silver Bullet

2002 VW Beetle TDI

2004 Nissan Titan Crew Cab

2004 Cherokee 33ft Travel Trailer

1990 Mercury Grand Marquis

1993 Amazon Green 968 Coupe (sold)

2002 Speed-Yellow Boxster (sold)

1987 Slate Grey 944 Turbo (sold)

1987 Guards Red 944 (first Porsche - sold)
Reply


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