S70 1998 shaking when moving from a stop

BloodyVolvoDriver · Post by **BloodyVolvoDriver** » 09 Jun 2011, 02:07

This is actually the second time its happened to me. I have a 1998 Volvo S70 2.5 20V with 130,000k's on it. The other day, I stopped at the lights and as soon as I took my foot off the brake, the car went mad shaking! (for 4 seconds) I looked at the revs, it was quite stable. Today, the exact same happened again. I have been advised to change the timing belt and idling tensioner 2000k's ago. Any ideas why this is happening? Thanks in advance
*p.s. replaced O2 sensor, catalytic converter (aftermarket) 2000 k's ago

Post by **Ozark Lee** » 09 Jun 2011, 12:52

I think I can understand that.

If you suspect that the timing belt system might be a problem remove the timing belt cover and look at the belt while the engine is running. The belt should not flop around at all. If the timing belt is flopping around park the car until it is repaired. If the timing belt slips it will bend the valves and it can often be Game Over for the engine.

...Lee

mblackwell · Post by **mblackwell** » 09 Jun 2011, 13:26

Shake! That's what they do when you drop a cylinder. I'd check the plugs and wires to make sure they are all tight and firing. After that maybe check that the injectors are all functioning. My daughters 850 did this because of a burnt valve. Yours came back to life so it's probably not a valve. Her's was permanent and terminal. Yours not so much.

Post by **jimmy57** » 09 Jun 2011, 15:47

When you step into throttle to move off a couple of things happen, the engine moves which could be moving the coil wire around to where it can arc if it is bad and the required firing voltage for spark plugs goes up which would make bad spark plug wires arc to ground.