2001 with almost 211,000 miles. Low compression on one cylinder, #3 (40+ psi). Cylinder #2 tested with 135+ psi). Cylinders #1 & #4 have not (yet) been tested.
More than least six months ago my motor seemed like it would occasionally misfire on a cylinder when motor was working under a load.
First problem found around 4 months ago, after frequent (virtually constant) misfirings. Spark plug on cylinder #4 had been fouling, an all black tip! Replaced all 4 plugs with new NGK’s.
3 months later, found spark plug on cylinder #3 has now been fouling, another all black tip! Cylinder #4 did not appear all too bad at this time. Replaced it with one of the good used plugs, removed earlier!
Saturday morning (09/14), while enroute to Keene, NH, continuous misfirings agian!
Upon arriving at Dad’s home in Sullivan, NH, found that plug in cylinder #3 was again fouling!
Chose to do a compression test on cylinder #3. found out the results, less than 50 PSI!
Have been doing some reading about "low compression in Toyota’s 1.8L engines. One suggestion was to do a compression on each cylinder, twice.
Second testing using some oil placed into spark plug holes.
Said that if there was virtually no difference in the readings between each cylinder’s test the problem is said to be a bad valve.
I want to do this last test with my Dad. Car body is in very good shape! We oil undercoat our own vehicles. Wishing to try and save it.