View Single Post
  #2  
Old 10-30-2004, 12:25 PM
avatar307's Avatar
avatar307 avatar307 is offline
AF Regular
 
Join Date: Mar 2004
Posts: 259
Thanks: 0
Thanked 0 Times in 0 Posts
Re: '89 LeSabre with a vibration problem stumper

Why is it problems in this forum always seem to occur at the same time? 2 weekends ago, it was water pumps, like 5 threads, the day after I had to change mine. Last weekend it was transmissions. This weekend... this weird vibration problem.

I don't know... occilation you mention, of the car almost bouncing up and down, makes it unlikely that it is the engine. Due to the fact that it's side mounted, occilations from the engine would more likely make your rock.

It almost sounds like the transmission is surging. Providing power hard to the wheels, then dropping out for a couple seconds, and repeating. That could cause the car to hop, similar to pumping the brakes when coming to a stop, but in the opposite direction.

Bouncing a car from inside the frame takes a lot of force... it takes a lot of force just to over-ride the dampening effect of the shock absorbers. Power surging on and off the wheels is the only thing I can think of.

I take that back. Have you checked the fuel filter and the fuel pressure to the fuel rail. If your engine is getting fuel in surges (as often happens with a dying fuel pump or a clogged filter), then it's RPMs would bounce up and down. That would in turn cause uneven power to the transmission and thus to your wheels.

This may not be noticed when idling in the driveway with the hood up, because the engine does not need that much fuel. However, after driving down a road at 45 MPH and slowing to the stop, the engine would have more problems getting adaquate fuel to maintain idle, as it had been subjected to driving requiring greater fuel consumption.

In addition, if ports on the fuel rail are clogged, a fuel injectors is bad, a spark plug or wire is bad, then you would only be getting power from certain cylinders. Thus your engine would spin fast when pistons fired correctly, and choke when other pistons did not.

To amplifly this effect to the level you are suggesting, I would expect it would need to occur in common TDC (top dead center) pairs or triplicates. Such a pairing would be most likely if one of the modules of the Ignition Control Module fried. (I.e. Where are the spark plugs connect in pairs.)

Now the other guys vibration problem... that sounds more like... the whole car shakes and rattles like it's going to come apart. Coupled with stalling out, that's almost certainly a sensor problem or a fuel supply problem. IMHO, whenever an engine stalls it's oil, gas, electrical, coolant, sensors, in that order. LOL

Anyway, anyone else have opinions on my opinions? Anyone wanna tell me I'm full of bull, because there's probably a good chance I am.

Anything that involves a transmission, I hate automatic transmissions, I can never tell if they are working or not. I also hate glue, just so you know.
__________________
"Sleeping is the only thing keeping me from killing all the stupid people on this planet."
"Of one that loved not wisely but too well;" (Othello, Act 5, Scene 2, Line 344)
Reply With Quote