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-   -   Carrera Barely Runs (http://forums.pelicanparts.com/porsche-911-technical-forum/552943-carrera-barely-runs.html)

SVKarl 07-13-2010 07:22 AM

Carrera Barely Runs
 
Friday night I got stuck in an hour long traffic jam. Lots of idling and creeping along but the oil temp, while pretty hot, did not get into the red or really very far above the higher white bar.

After the traffic cleared, probably ran about five minutes at 60 or so then through town for another ten minutes and it ran normally.

Sunday, started it up and really ran bad, missing smelling of unburned gas, grey/black smoke, etc. Pulled the plugs yesterday and they were pretty oily and smelled of gas. Replaced them with new and took it out for a short drive. No change and finally, when I brought it back, I could not start it.

History: daily driver, Total 140k, top end at 80k, new injectors, crank sensors, and oxs at 110k. Cly head temp sensor three months ago.

Car is an 84 and usually runs very well.

Thanks for your comments and thoughts

Groesbeck Hurricane 07-13-2010 07:33 AM

Random thoughts: have you checked the sparkplugs since you replaced them?

Can you check the spark plug wyres and make sure you have them in the correct positions on the plugs and on the cap? (Yep, but you'd be surprised how many of us make that mistake)

Does the dipstick show fuel in the oil? How old is the oil? are you running dino or syth?

I am NOT an expert at these things. My gut feel is the timing or swapped spark plug wyres. Do the new plugs have the correct gap?

The hot drive should not have caused a major issue, IMHO. I've done that many a time with my '83 and it is still going strong.

jimbauman 07-13-2010 07:44 AM

Possibly one of the usual suspects: cylinder head temp sensor? Could have gone bad, even after three months... If you have a multimeter you can test it...

JB

rusnak 07-13-2010 10:47 AM

We've seen a strange number of CHT failures. You can ground the sensor harness to check the cht and eliminate that as a problem.

SVKarl 07-13-2010 10:55 AM

Thanks guys, some preliminary feedback:

Wires are not mixed up, never removed more than one at a time from the individual plugs and did not remove any from the distributor, but rechecked anyway and they are oriented properly.

So far OXS seems to test out fine and we are now looking at the CHT. Also going to make sure nothing strange happened at the distributor, like cracked cap, etc.

Starting to wonder about a massive vacuum leak but without disassembling the entire intake and checking all the boots, hoses and fittings, pretty hard to tell. Have visually (and with mirror) inspected as much as we could see though and nothing looks amis.

More comments and suggestions welcome.

Karl

Drisump 07-13-2010 05:10 PM

IMHO it seems to me that if ALL your plugs show evidence of improper combustion, two places to look are at the sensors, (which you are doing) (the quality of information that the DME is receiving) or the DME itself may be timing improperly (fuel or spark) despite being supplied with the proper information. I don't know of any reason that sitting in hot traffic could result in your symptoms.....it may not be related. Does it start well but starts to have problems while warming? Or are there problems all the time? Good luck

mackskibum 07-13-2010 05:43 PM

Sounds like a disconnected CHT sensor. Check the wires on the left side of the engine to make sure they are connected.

SVKarl 07-13-2010 09:07 PM

Drisump,
I agree about the sitting in traffic perhaps not being connected with the symptoms. Each plug, admittedly having been in the car for over a year looked pretty similar, really smelled of gas and pretty gooey (sp?). I had to stop working on it but will be back on it tomorrow. Next stop is checking CHT function; it it definitely still connected. Trying to put off checking the DME for last, trying to make sure all the various sources for its information are all working correctly.

Really seems like its getting waaaaay too much fuel. From the instant it starts, this condition occurs and remains basically no matter what, part throttle, full throttle, idle all rough the more throttle, the more smoke smelling of unburned gas.

Still puzzled.

Karl

DanielDudley 07-14-2010 01:06 AM

How do the cap and rotor look ?

SVKarl 07-14-2010 06:53 AM

One of the next stops later today; cap appears fine from the outside.
Karl


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