Hi My "86" 928 auto Idles way to low.Around 500-RPMs, it seems to miss? or Skip? like a wire is bad ? as far as I know from 1st owner the wires are new. I really do not what to replace them just to test it. is there a test method that I can do some how on wires or plugs. The car runs Great once moving. Thanks Bob

 

I think if you watched the engine at night time.see if you see any sparks around the wires and conection end by plug, that may be grounding out and causing the stumble. You can run you hand and fingers around them to and you'll get shocked if it's bad. I think a tool is made to run over the wires to look for a short? You can check the resitance of each wire. some one else may know the spec. for that. and you can pullout each plug and ground it out and see the spark, one may be weak. hopes this helps some I'm sure SOMEONE here can advise you better than I canbut I've owned 4 Porsche's and 30 other Volkswagens and Audis. So I have some time under the engine bonnet. Toby

 

It's still a vacuum leak Bob.

 

Still ?? Randy I'm sorry I couldn't Logon for a week or so I lost track of any earlyer post. How do I find this Vacume Leak???? hanks I'm desperate Thanks Randy!! Bob

 

Robert,
You checked the O2 sensor? Is the O2/hand brake warning light coming on? Are the rubber intake tube clamps snug? Tubes aren't cracked/mounted correctly? Done the Quick fix on the 'flapper valve'? Tightened anything with a vac.line and a clamp? Don't forget that one behind that panel to the rear of the right front tire-there is a plastic 'Y' connecter there that the hoses can fall off or the plastic connecter could break-. Then there are possible leak zones under the air intake/MAF the intake manifold itself...? My 82 idles around 500rpm smoothly
, for awhile she would develope a wild fluctuation/drop in rpm and sometimes stall after sudden stops or even idling at a stop light. Did all of the above suggestions with the O2 sensor change supplying best results.I, finally, tried some high end injector cleaners -two tanks- which helped.
Then tried 104 Octane Booster, problem resolved. Still idling low ... but smooth.
Hey! How big is Travlers rest? I had an old Army buddy named Clements from TR, SC. Curious...
John S. 82'Weissach, Auto., 'Pattycakes'

 

Idle stabalizer - prime suspect (search the archives here for previous discussions).

Check all vacuum lines for integrity/tightness - especially the large hoses from the brake booster to the warmup regulator.

 

Randy,
From the brake booster to warm up regulator?
Christ! Something else to check.
Thanks! I Think...
John S & Pattycakes

 

Wow!! Guys This is what I call good help Thanks I talk this place up to all my friend Non-porsche owners they all are amazed we have such a support group. It's Wonderful!
John thanks for the info.as for Travelers Rest, It's a small place I'm the only person up here that doesn't own a Pick'em up Truck! we moved in with the Passat Wagen and a Euro Van and then the Porsche They know we are not from around here. Tr is a very Peaceful small town. we are 9 miles from Greenville which is a big city.

 

Hi Robert,

Here is the most relevant vacuum link on Greg Nichol's page. http://ourworld.compuserve.com/homep...ols/tip367.htm

See here how you use an old intertube piece to pressure test the system. The whole upper part of the engine is sealed to form the vacuum. This includes tiny elbows, rubber hoses, rubber sleaves, oil filler o-rings, a 7 point female connector, valve cover gaskets, etc.

Also see other posts under engine, vacuum...

I would scotch brite all engine sensor connectors too.

 

Thanks Thom, I'll do that!