924s runs way rich/won't start when warm HELP!

[RR Guitars]

well i'm a newbie to the Porsche world, so forgive me if this is something common. did dist. dist. cap plugs, changed out fuel injectors,replaced all vacum lines i could find,replaced fuel pump, fuel filter,swapped out a used MAF unit i had ( in desperation ) the car is a '87 924s with 19,500 miles on, it it has suffered many Arizona summers so much interior damage, and i believe to have replaced all hoses, belts, anything rubber or plastic has been examined carefully, anyway the car starts fine cold and runs great, idles rough, but won't start after warmed up, or if it does start it blows blue smoke uot tail pipe after cranking forever. i'm no pro but it seems like it's flooded. plugs got dark black coating on them. ANY HELP WOULD BE AWESOME

[Techno Duck]

Check your fuel pressure to rule out any issues that could possibly be related to the fuel pump check valve, fuel pressure regulator or fuel system in general. If you are loosing fuel pressure in the rail, the heat from the engine causes whatever fuel is left in the rail to flash into vapor.

Also try swapping out the DME relay. When they start going bad, they will typically cause problems when warm.

Are the injectors you repalced with new or rebuilt? Its possible one or more is leaking causing the engine to flood.

[John_AZ]

Originally Posted by RR Guitars

well i'm a newbie to the Porsche world, so forgive me if this is something common. did dist. dist. cap plugs, changed out fuel injectors,replaced all vacum lines i could find,replaced fuel pump, fuel filter,swapped out a used MAF unit i had ( in desperation ) the car is a '87 924s with 19,500 miles on, it it has suffered many Arizona summers so much interior damage, and i believe to have replaced all hoses, belts, anything rubber or plastic has been examined carefully, anyway the car starts fine cold and runs great, idles rough, but won't start after warmed up, or if it does start it blows blue smoke uot tail pipe after cranking forever. i'm no pro but it seems like it's flooded. plugs got dark black coating on them. ANY HELP WOULD BE AWESOME

Welcome RR Guitars,

I just checked my odometer and it reads 12,822. It's actually 112,822. The early odometers on our cars do not have 6 digits.

The AZ sun has distroyed the interior and has baked most of the rubber under the hood.

Rough idle: Under the intake manifold is the ICV-idle control valve (number 18 in picture)held in place by 2 rubber mounts. The hoses (# 21 & 22) that connect to the ICV have bends and usually are dry rotted and cracked. These should be replaced. Also, underneath the "J" intake air (big rubber thing) boot, the rubber cracks at small vacuume connections. The easiest way to do it all is to remove the intake manifold and do it all at once. While you are at it, replace the seals on the AOS-air oil separator. The ICV hoses are expensive and you may be able to go to NAPA and find a subsitute. The ICV can be DIY cleaned out. Use quality clamps and not typical hose clamps that may loosen.





While all of this may improve the idle, and following the suggestions of Techno Duck, the real issue will be the head gasket. The 1987 924S is well known for decaying head gaskets. You can continue to poke at all of these "small" fixes and you will eventually have to replace the head gasket. White smoke will normally begin to appear and loss of coolant. This is one of the easiest jobs to fix many of your issues and when you have the head and valves polished and new seals and guides installed your engine will be good for another 119,500 miles.

Welcome & GL
John_AZ
1988 924S 59K (really) and 1987 924S 112,822 miles DD
1979 924 + 1977.5 924 + 1970 914 1.7 + MG Midget +++, gone, past tutors

[RR Guitars]

thank you all, for all your input, i guess i wasn't sure there was many out there that cared about these cars . that being said i would like to restate my mileage as 19,500 and here's the story, supposedly the car just sat outside , while the Benz lived in the climate control garage for more than 15years !!!!! a car fax report seems to support this, but you can never be sure. i actually got the car with 15,500 miles and drove the car trouble free for about 3,000 mlles. and as for the injectors i got the whole fuel rail with injectors from a salvage car ,very close to me ( i couldn't even believe it showed up in my little wrecking yard ) . plan to send in old injectors to be cleaned and rebuilt, they were leaking from around the intake manifold on two of the four injectors. while doing this every line or hose that i touched cracked or broke in half. THANKS AGAIN FOR YOUR HELP !!!! RR Guitars