Ford escort engine knock

My 97 Escort makes an engine knocking noise when I excelerate. It gets worse when I,m going up a hill or excelerate hard. It has the 2 litre motor with 140,000 KM's. It only started doing this recently right after I had it tuned up at the shop. If I put a higher octane gas in it it goes away. I'm not positive but I don't believe I should have to put mid-grade or supreme gas in it. It seems to have lost power and works hard getting up hills, I'm also getting bad fuel mileage. I thought a tune up was supposed to make it run better. Any suggestions would be appreciated.

I have the Haynes Repair Manual for 1991-2000 Escorts. In the Trouble Shooting section, under Engine Symptoms, it says that there are 6 things that could cause the engine to ping or knock during acceleration or uphill.

These Are:

1. Incorrect grade of fuel. Fill the tank with fuel of the proper octane rating.
2. Fault in fuel or electrical systems
3. Ignition timing incorrect
4. Improper spark plugs. Check the plug type. Check the plugs and wires for damage.
5. Faulty emissions system
6. Vacuum leak

I don't know everything about cars, and I did copy those out of the book, but I do know that you should take it back to the place you had it tuned up at. It sounds like it was a mistake they made.

If you were interested in getting the book, you can buy it at Autozone or Pepboys and I think its only like $20.

-Brian

Look in the owner's manual and see if it isn't supposed to run a higher octane. About all they do on 'tune-ups' these days is replace the spark plugs. Have you tried gas from a different station?