Strange Vibration
10-29-2007, 08:30 PM
#1
Rennlist Member
Thread Starter
Strange Vibration
Hi all!
Just started experiencing a strange & inconsistent vibration when the car is at idle. It shakes a bit (very slightly) then stops - over and over again in a very inconsistent manner.
It feels more like a transmission/gear linkage shake than an engine induced shake... If that makes any sense.
Under throttle at any amount the car runs like a top.
You guys are smart - any ideas?
thanks,
--JC
Just started experiencing a strange & inconsistent vibration when the car is at idle. It shakes a bit (very slightly) then stops - over and over again in a very inconsistent manner.
It feels more like a transmission/gear linkage shake than an engine induced shake... If that makes any sense.
Under throttle at any amount the car runs like a top.
You guys are smart - any ideas?
thanks,
--JC
10-29-2007, 10:07 PM
#2
Seared
Rennlist Member
Rennlist Member
How many miles does the car have? It could be one or more worn plugs - have they ever been changed?
My early '95 now has 46,000 miles. I purchased it with 34,000 on the clock. It's always had a somewhat rough idle - when compared with a run of the mill Toyota, etc. I changed plugs and hardly noticed a difference.
What you are feeling may simply be normal for the 993 - a very raw machine.
Andreas
My early '95 now has 46,000 miles. I purchased it with 34,000 on the clock. It's always had a somewhat rough idle - when compared with a run of the mill Toyota, etc. I changed plugs and hardly noticed a difference.
What you are feeling may simply be normal for the 993 - a very raw machine.
Andreas
10-29-2007, 10:27 PM
#3
Rennlist Member
i am glad this has come up again. i love my car but i hate the shaking idle. i know it is not lexus smooth but i also know from previous cars that it is not right.
done the usual:
-new plugs
-new caps
-new rotors
-cleaned isv
-cleaned maf.
-no arcking in the dark under the hood.
-no vacuum leaks.
-found a swopped plug wire which smoothed it out somewhat.
-run techtron in gas tank
-un-plugging the injectors while car is running seems to be consistand on all cylinders.
i read here about the motor mounts where 1 person found it smoothed out the car.....thinking about that next.
hoping someone has the magic solution
done the usual:
-new plugs
-new caps
-new rotors
-cleaned isv
-cleaned maf.
-no arcking in the dark under the hood.
-no vacuum leaks.
-found a swopped plug wire which smoothed it out somewhat.
-run techtron in gas tank
-un-plugging the injectors while car is running seems to be consistand on all cylinders.
i read here about the motor mounts where 1 person found it smoothed out the car.....thinking about that next.
hoping someone has the magic solution
10-30-2007, 10:28 AM
#4
Drifting
i am glad this has come up again. i love my car but i hate the shaking idle. i know it is not lexus smooth but i also know from previous cars that it is not right.
done the usual:
-new plugs
-new caps
-new rotors
-cleaned isv
-cleaned maf.
-no arcking in the dark under the hood.
-no vacuum leaks.
-found a swopped plug wire which smoothed it out somewhat.
-run techtron in gas tank
-un-plugging the injectors while car is running seems to be consistand on all cylinders.
i read here about the motor mounts where 1 person found it smoothed out the car.....thinking about that next.
hoping someone has the magic solution
done the usual:
-new plugs
-new caps
-new rotors
-cleaned isv
-cleaned maf.
-no arcking in the dark under the hood.
-no vacuum leaks.
-found a swopped plug wire which smoothed it out somewhat.
-run techtron in gas tank
-un-plugging the injectors while car is running seems to be consistand on all cylinders.
i read here about the motor mounts where 1 person found it smoothed out the car.....thinking about that next.
hoping someone has the magic solution
BTW: what color is the interior?
10-30-2007, 11:53 AM
#6
Drifting
Have you checked all your induction system band clamps? It sounds like a vacum leak that the dme is trying to reconcile, but can't. Hrd to find vacum leaks, but it will be an "Ah-ha" moment when you do.
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10-30-2007, 01:53 PM
#8
Rennlist Member
have been spraying carb cleaner around intakes and no difference. will keep on checking though....
10-30-2007, 01:56 PM
#9
Rennlist Member
i made a difference after that but still is bad..
10-30-2007, 02:03 PM
#12
Racer
I too have similar vibration issue/concern on my 97 C4S. Although, at times I feel it is a normal vibration (as Andreas mentioned). It is quite annoying at times, but tolerable.
10-30-2007, 02:12 PM
#13
Three Wheelin'
This seems to be a normal occurrence on some if not more and more 993's. I have 40K on my 96 C2 and have the same described vibration. I sat in my friend's 95 C2, same mileage and noticed the exact vibration. I changed the fuel filter, cap, rotors, cleaned the ISV, added Redline injector cleaner. I did not change the plugs and wires - I will embark upon that journey over the winter months. All in all it helped only a little but the vibration at idle persists. I had my P wrench look at it and he confirmed that it is a characteristic of my 993. All that matter is the car performs flawlessly otherwise! 
10-30-2007, 04:57 PM
#14
Drifting
This seems to be a normal occurrence on some if not more and more 993's. I have 40K on my 96 C2 and have the same described vibration. I sat in my friend's 95 C2, same mileage and noticed the exact vibration. I changed the fuel filter, cap, rotors, cleaned the ISV, added Redline injector cleaner. I did not change the plugs and wires - I will embark upon that journey over the winter months. All in all it helped only a little but the vibration at idle persists. I had my P wrench look at it and he confirmed that it is a characteristic of my 993. All that matter is the car performs flawlessly otherwise!
Yes - one way to look at it is that your car will not win any performance points for a Prius-smooth idle. Everything good with the 993 happens post-idle
10-30-2007, 06:45 PM
#15
Rennlist Member