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1986 911 Carrera Rough Engine Idle


Vehicle Information: Model: 911 ; Year: 1986; Body Type: Targa; Engine (type, size, modifications): 3.2; Total Mileage: 112000;

I bought my 911 about 9 months ago. During the PPI my mechanic, who is aPorsche specialist, said he didn't like the "feel" of the car as it wasidling. However, he was unable to find anything wrong with the engine,and thought it may just be clogged fuel injectors. He said to run fuelinjector cleaner through a few tanks, and that if that didn't help I mayneed to replace the injectors(worst case). Well I tried about 4 tankfulls with no luck. Basically, the car idles right at 800 rpm withoutfluctuation, but the car shakes from the vibration of the engine. It doesfeel "rough", though I'd probably just assume it was normal had mymechanic not said anything. The car seems to run well, however there issometimes a slight hesitation when I accelerate hard(almost like the caris being held back). In an attempt to correct the "rough feel" duringidle, I have replaced the following: air filter, fuel filter, oil & oilfilter, spark plugs, spark plug wires, distributor cap & rotor, fan belt,fuel injectors, oxygen sensor, and even motor mounts. None of this hasmade any difference in the car's performance. My next move is to get thevalves adjusted(though it's been 15,000 miles). But before I do that Iwanted to get your advice. I've looked through the Bentley repair manual(I handle most of the work myself) and found that the problem may becaused by a faulty cylinder head temp sensor, air flow sensor, or even avacuum/air hose leak. My guess is that the fuel/ air mixture may be toolean and that's what's causing the car to shake. I can get the valvesadjusted, but at this point I'm not very confident it will make anydifference. Do you all have any experience with what else could be theproblem? I'd like to think it may just be an air leak, but which hoseswould I need to check (the manual is useless on that topic, and doesn'teven provide a diagram of the air hoses) and how? It looks like I'd haveto remove the whole air intake assembly to even check the hoses which arebehind it.

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