88 3.8 running rough( timing?)

78K miles
Friend i bought it from said he thinks it is out time due to the chain jumping a tooth. I was told that these engines have computerized timing correction up to 20 degrees, but if the chain jumped a tooth, wouldn't that be approx 25-27 degrees? The few things i could think of to cause that would be a worn out tensioner or a stripped gear in there somewhere. Has a new crank sensor, plugs and wires. The car started running bad 2 years ago and the old lady that owned it just parked it.

Fully loaded with minor body scratches for $400 isn't bad!

Thanks

have you tryed changing fuel filter and injector cleaner in tank, if an old ladies driving maybe needs a good highway run, cheaper than a timing chain
unless of course it goes while on the highway

I think if the chain jumped, the valves would bend. You might check the compression on the cylinders to see if they are about equal (I think about 150psi). My 87 died at idle at 93K and the timing gear was shot, but the pushrods were bent also.

If the crank sensor was replaced, I might double check the installation. You also have a CAM position sensor that is located just to the left of the water pump. It is also used to set the computer corrected timing. Both the crank and cam sensors suffer from prolonged exposure to intense heat and oil bath. After those have been replaced, make sure your ignition module is not becoming faulty, and that your plugs are gapped correctly. Last, after changing the fuel filter I would have the fuel pressure checked. You could have a bad fuel pressure regulator or even a shorted out fuel injector. So many things to check. Hope this gives you some ideas. -Chris

what is wrong depends on what you mean by running bad. If the car backfires, especially when you manually downshift going downhill, it is the timing chain. The chain had plastic gears put in when the factory builds it. With the mileage it has, you should probably replace the timing chain, anyways. B/c, IF IT JUMPS A NOTCH, THE VALVE HEAD WILL HIT ON THE CYLINDER HEAD, AND IT WILL NOT RUN AT ALL. I speak from experience.