Rough Idle?

The idle on my 86 carrera seems to be getting increasingly rough lately. It always starts fine and runs great except that every now and then it will sputter around 2-3,000 rpm while under a light acceleration. Cold or hot seems to make little difference although I would say the idle is definitley better while hot, but still not quite right. Any ideas on where I should start looking? Thanks to all for your help...this board has been a wealth of onformation to me. Thanks!

Check your intake manifold. The gaskets that are on both sides of the heat blocks will push out and cause vacuum leaks. It may just need to be tightened!

You don't by any chance, happen to be using a K&N air filter, do you? They have been reported as linked to idle and driveability problems on Motronic-controlled engines!

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Warren Hall
1973 911S Targa

I did re-torque the intake a few weeks ago..I was suprised how loose it was. It helped somewhat but it is still not quite right. Maybe I should replace the gaskets? And no, I'm not using K&N..and won't be after reading all the posts on this board!

My 86 Carrera would buck or judder under light load at 2200rpm. Is this the same as what you describe a sputtering between 2 and 3,000rpm?

No experience with Motronic systems here, but I do have a Mopar DME-type engine in my V8 Dakota, and I changed the sparkplugs last year after noticing the around-town gas mileage had dropped about 2-3 mpg. The idle was fine before and after the new plugs, but the mileage picked back up again after the change, so my question is, has your gas mileage been affected???

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Warren Hall
1973 911S Targa

Warren, I have noticed mileage suffering a bit lately (not good with these prices!), so I think I'll take your advice and change plugs. STLRJ, yes this sounds exactly like what I am experiencing.

Unfortunatly, while testing the limits of tire adhesion over the weekend on a very narrow, twisting back road, I experienced the dreaded 911 tail spin for the first time ever and suffered some minor damage while sailing into the woods backwards. Luckily, very minor damage, but I am now having this repaired and will focus on the idle when I get the car back.

Paul,
This is kind of off subject, but what was the tailspin like? Do you think you made a driving mistake, or was it sort of out-of-the-blue? I worry about this, and I'd love to hear the experience of an actual 'survivor'.
Brad

Brad, it was definitely my mistake. I was going into the turn real hard and then suddenly lifted off throttle right at the apex of the turn. A textbook example of what not to do. At least I learned a lesson (the hard way as usual).

Fortunately, I've never done that in mine, but I do know what it feels like, as I did a complete 360 in my Beetle on a slick off-ramp about 28 years ago! Luckily, the off-ramp wasn't lined with concrete, just gravel. The Beetle had Konis and sticky tires, and was decambered for autocrosses, or it would have rolled! Nothing damaged but ego. Glad yours turned out to be only minor damage!

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Warren Hall
1973 911S Targa

Okay, since none of you know who I really am (I'm not really Superman) I'll admit I made a similar mistake. I'll even admit I had recently consumed two beers. I will never stop being angry with myself. Please be careful with these cars, they are not to be trifled with.

I also let off, and even braked. Front slid a little. Fortunately no cars coming. I fought it through the outside of the corner (suprized it ended with no body damage). Then, at much slower speed, the rear finally kicked out and it slowly came around 180 degrees. This was with Michelin Pilots. Your (car's) rear end is very heavy! One more time.....Do not be stupid in these cars like I was. I am a first-time Porshce owner and very excited, and I wish I had been driving them all along. But if I had owned one as a younger man, I might be dead.

I think a lot of 911 owners have experienced LTO
In my first 911 a 75 silver anniversary edition I did the same thing about 10 years ago while driving on a onramp on the freeway I lifted and spun caught it and fishtailed one way then over corrected the other several times at 85+mph I was totally out of control the only thing that saved me was that I punched it at the last second which tranferred the weight back to the rear and brought it back in control
I quickly learned never lift no matter what

It's comforting to know others have had similar experiences...

[TSwede]

I notice someone on the board had a similar problem... it feels as though my gearbox (or teeth) will fall out.... did you get it solved - if so how?... Has anyone else had this (1975 2.7s)

Regards

[Superman]

Now this is an OLD thread. I was a "guest." Nearly 3000 posts ago!