View Full Version : vibration and no boost

07-14-2003, 01:45 PM
I just bought a 91 sc and I am having 2 problems with my car and hope you guys can help me out. When i start the car up there is a slight miss but the car idles perfect. once i put the car in gear there is a very bad vibration also when driving it. I checked the 4 bolts from the drive shaft and they are all tight. I also checked the vacum lines the best that I could but they all seem to be in good shape. With the car running i checked to see if the harmonic balancer was wobbling but it also looked to be ok. My second problem being that when the car is ideling i have no vacum on my boost gauge or when driving the car i have no boost. I checked the vacum line that goes from the motor to the boost gauge to see if it fell off but it is on there securely. I then checked the supercharger oil and it is low. I will pick up 2 bottles this weekend. I do not drive the car in fear that i will do more damage to the car. I only drove the car around the block several times. When driving the car ( very short distances) the check engine light does not come on but then again keep in mind very short distance in driving the car. It is very hard to have just bought a sc and it just sits in the garage. Any help you guys can give me would be greatly appreciated. Thank you.

07-14-2003, 02:18 PM
For the vibration, check to see if your motor mounts are broken.
For the no boost, check to see if the vacuum line to the gauge is cracked or broken, which may require you to remove the cluster. Good luck

07-14-2003, 02:43 PM
If you have bad wires, the car will jerk and sputter under load, also bad plugs will cause the car to run like [email protected] Could be that the previous owner used cheapo (bosch) plugs. If you change the plugs, use Motorcraft or AutoLite Double Platinums and you won't have any plug related problems. (Best to use MotorCraft wires too, unless you are looking at some sort of race related big horsepower modifications).

For the "No VAC/ Boost", that is probably related to the little line that connects to the guage. You may be able to hear the air whistling out of the hole, if it is behind the guage panel.

You may also want to check the connections on the IC tubes at the SC and the IC, leaks here won't cause the guage to quit working, but could have something to do with your performance problem.

07-14-2003, 04:11 PM
Thanks for the info. I will do the plugs and wires this weekend. looks like this will be a job to do. My car does not sputter or jerk though. Just vibrates real bad. Bad enough to shake the dash board. Will do all the things that you guys did suggest and let you know this weekend. Thank you.

07-19-2003, 11:21 PM
Well I had my friend come over and he looked my car over and he said that it is my harmonic balancer. Does anyone know where I can locate a BHJ balancer? Any info would be appreciated. Thanx.

07-20-2003, 12:01 AM
that's what I was going to think. That the balancer had failed. If it fails bad enough the belts will slip not allowing the SC to be driven enough to produce meaningful boost.

You can try BlueTongueMotorsports for the balancer.


07-20-2003, 09:56 AM
Thanx mike. I went to that site you gave me and will be ordering a BHJ HB but it is going to take me about 2 weeks to save up for it. They are costly but well worth it. Thank you.