Hi All,
I have a great 89 Olds Custom Cruiser wagon, 66K miles, awesome car. Just today, it started loosing acceleration power (was fine yesterday). When I depress the accelerator, it sounds like a large diesel truck is accelerating (sound comes from under the dash), very loud. When foot comes off accelerator, quiet as a church mouse. What could be causing this? If I depress accelerator enough, it will go in to overdrive, but getting up hills is quite a chore if there is not enough momentum.

Any thoughts? I had the same issue with my Pontiac Parisienne wagon with acceleration, ended up being the carburetor, but that didn't make any noise like the Olds is. ? vacuum line issue? Any ideas would be helpful.

Thanks,

Ryan

 

A couple of things, but first some terminology. When you fully depress the accelerator, the trans should shift OUT of overdrive, into a lower gear. That's called downshifting.

Second, be sure there are no leaks in the many miles of vacuum tubing on the engine, and that they are all connected properly. Any one of them either leaking or being misconnected will cause loss of power and poor gas mileage.

Third, get a Chassis Service Manual and either fully understand the CCC adjustment procedure or insist that your mechanic do the same. Few people have the skill or patience to adjust these systems properly, especially in today's environment of "read the code and replace the part". Most of the problems with the CCC system will not set a code.

Fourth, check the A.I.R. tube that runs to the catalytic converter. This is a rubber hose from the air switching valve on the forward passenger side valve cover that connects to a check valve and metal tube at the rear passenger side of the engine. The metal tube runs down along the bellhousing and connects to the converter using another short rubber hose. The rubber hose gets burned and leaks, and the metal tube eventually rusts out. Either will cause the noise you describe under acceleration and will sound like it's coming from under the dash.

 

Thank you for the information, Joe. I love these cars but don't yet know the inner workings as well as I would like.

I will look into 1. vacuum line issues, 2. CCC, and 3. AIR tube. It does sound like it is coming principally from the passenger side under the dash area. The major symptoms I have are poor gas mileage (not new), the loud sound (new) and loss of power going up hills (new). Like I said, there were NO symptoms yesterday and all of a sudden it started today. I can check the vacuum lines, but I don't have the know-how to adjust the CCC.

Thanks,

Ryan

 

It ended up being the catalytic converter; she's now back on the road.

Thanks again,

Ryan

 

Great - glad you got it fixed.
I did not know a bad cat would cause such sudden noticable problems from popping up.
Maybe the computer finally ran out of adjustment span....

 

I was leaning toward vacuum leak myself because of the sudden acuity of the problem. I was surprised to find the converter completely plugged. All toll it was about 250$ repair, not too devastating!

 

250 is pretty cheap for a cat. I remember seeing one for a nissan sentra for over 900, and there were two cats on the car!
Your new cat will last a long time as long as the car is running well.

 

The cost for a cat depends on the type of cat and extent of "direct fit" you want to pay for. In my case I've simply bought a $50 universal cat and welded the end piped into place myself. The hi-flow aftermarket cats pose no more restriction than a piece of straight pipe.