Strange noise from engine when at operating temp. Occurs between 1500 and 2800 rpm. 1993 with manual tranny and complete tune up.152k. Timing is correct. EGR ports have been cleaned twice. FITV and throttle body have been cleaned. Smell is kind of like propane coming from exhaust and can be re-produced by sitting in driveway uphill and riding the clutch within the rpm range described. Sounds like spark knock. No, the smell is not clutch . Exhaust has been inspected and nothing is loose. Please help.

 

Have you ever re installed a knock sensor and the 02 sesor on that car since you'v had it? Cat Converter can be checked at a exhaust shop..they should have put a sniffer in the pipe when they looked at your muffler..

Good Hunting...

 

Have not changed those out yet. Guess I am just used to OBD2 cars telling me to do so. Would these not throw a cel? Also the fuel mileage is averaging 24 with 50/50 driving. Is this normal for a 1993?

 

Found the timing was set too high. Runs great and gets better fuel economy now. Hope this helps someone else.