Well, like I have said before this car is turning out to be a failure in progress. Since I have put in the new engine there are just problems after problems. Right now I am dealing with a .........well........I don't know what and that is the problem. When driving my car there is a certain spot on the throttle that the car will jerk back and forth almost as if there is being towed by another car. It does this only around 1500 RPM and it doesn't matter if the engine is warm or cold. You can reallllllllllllllly notice it when going up hills at the speed limit. The tach. will show that the engine is jumping around, starting at 1500 dropping to 900 and then peaking to 1700, up and down, up and down. It doesn't matter what gear it is in either. Since putting in the engine I had to rebuild the tranny, and I am thinking that this might be the differential. It is the stock one that came with the car. I haven’t done a single thing to it since owning it except change the fluid after I bought it(about 10k mi ago). Any suggestions on what it might be? I still think that it might be a vacuum leak but I know the carb. and intake are good so it would have to be internal, but it is a stock motor. Has anyone ever experienced this?

 

engine surge is mostly caused by vacuum leak via a vacuum hose, carb gasket, or intake gasket. Sick

 

I have replaced the intake and carb gaskets along with all of the hoses when i was first having the problem and it still has the same problems.

 

Sounds like a vacume leak. If the gaskets are good check the carb. Also replace the fuel filter soon. What shape is the dizzy in? Sometimes the mechanical ones will have a 'dead' spot at certain rpm's and builders will go back to the origional vacume advance distributors. Get some starting fluid or ether, crank up the mill and spray some around the intake manifold (or around any intake related gasket area for that matter). If you get a surge in the motor that means you have a leak as the starting fluid in seeping into the cumbustion chamber through the 'leak'. I would start with the fuel filter - cheaper and simpler than most other new parts. You said that you put in a new engine. was that 10k miles ago? is there a warranty on it? Also you rebuilt the tranny. Try tranny conditioner. You also said you havent done anything to it since you bought it, might be time for a good once over; timing, plugs etc. Until all the simple things are ruled out you wont know what real problems you might have.

 

do u have an egr valve? i have seen those cause that kind of problem that is if you have one

 

Purchase a vacuum gauge, disconnect everything, and plug all the holes, and study what it does, as you plug the stuff back in

You can learn alot from this website

http://www.earlycuda.org/tech/vacuum2.htm

 

if the vacuum stuff dose not work try looking at your Torque Converter