Porsche 928 The Porsche 928 was made from 1978 to 1995, during which time it was Porsche's most expensive model.

HELP with 928 - heat and idle issues

Old 05-24-2009, 10:56 AM
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Join Date: May 2009
Location: Tampa FL
Posts: 1
Default HELP with 928 - heat and idle issues

Hi folks!

I just found this forum and, having had my baby for ten years now, thought I'd throw this out for discussion.

She's an odd bird: everything onboard is straight 1987 928S4 except the wheels (17" five-spokes v. stock 16") and the block (which is circa 1993 GT product). ORDINARILY, she runs fine, BUT:

- When she's warm (NOT from cold start), she tends to stall out at idle. I can keep her running with a toe on the gas but that gets annoying. Idle + 150 rpms (650-700 range) seems to do the trick.

- In warmer weather she heats up dramatically. It generally takes 80+ F for this, but more than once she's gone from fairly cool to blowing hoses in half an hour. Driving conditions (open fwy or heavy traffic) don't seem to matter much.

I've replaced the entire cooling system (yes, with OEM parts, radiator to water pump), and I've had some stellar mechanics look into what makes her run like this - so far without closure on either item. I'm just about to dust her off again (she's been in storage for a while) and I'm debating whether to take one last shot at solving her quirks or just chuck it in.

Any suggestions?
Old 05-25-2009, 09:56 AM
Super Moderator
Join Date: Apr 2005
Location: Overland Park, KS
Posts: 3,532

Have you done a leakdown test on the motor recently? Might be worth looking in to.

The idle issue sounds like a stabilizer valve, tps issue, etc. My 928 knowledge is limited.
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