Motor mounts

Today, while driving from a stop light, our 2000 Siennna did not want to accelerate. We could only make it accelerate very gradually. Aftre 5 more minutes going slowly, we shut it down for about 6 hours, then tried again. Same problem. Also, heard a bit of a clunk when putting car into reverse. Drove it to the mechanic’s place 20 miles very gingerly. The mechanic noticed the problem but, after getting the car slowly to accelerate, he floored it which seemed to make the problem go away. Back at the shop, he hoped to read out the codes, but there were none. He noticed that our motor mounts were not good and I saw the engine really heave and flop back when he hit the gas hard while in park (or did he just oput in in reverse, I forget). Said the motor mount problem and this acceleration problem were absolutely unrelated and, with no codes and the synptoms now gone, could not do anything to identify the cause and just suggested we drive it around town and watch itm to see if it recurred. Thought it might be some sort of vaccum problem that fixed itself.



I did some googling and the quote from Ray about bad motor mounts came up:



RAY: And when the engine is allowed to move around and twist inside the engine compartment, you take the risk of shifting the geometry enough to bind up other components, like an accelerator cable, for example. That could lead to real trouble



How likely is it that the bad motor mounts caused this accleration problem and that gunning the engine, possibly causing it to lurch, could make the problem dissapear?



Thanks so much!

Dean

How likely is it that the bad motor mounts caused this accleration problem

It is certainly possible, but it will not change thee fact that you need to change the motor mount(s). Bad motor mounts can cause all kinds of problems. You apparently have bad motor mounts, therefore you need to change them. They are dangerous as they are!

Changing them should take car of the problem.

I agree with Mr. Meehan. You won’t know for sure until you get the motor mounts fixed, which you should do whether or not it is the cause of your other problem.