so I bought this 1991 geo prizm (toyota camry/corola) (geo-ota)... 16 valve r22 ??... It has 45,000 miles on it and it ran great until today. I was trouble shooting it and noticed it had dog food in the air filter box (luckly outside part of the filter) but still crazy to have found! so it didnt get in the manifold I cleaned the manifold thoroughly anyway, changed the spark plugs put sea foam in gas tank and oil, checked the spark plugs to make sure they were firing and they seemed to be working properly. The car has very little power, and makes a ping/tick noise at high rpms, It did foul the plug in cylinder 4, has poor acceleration, and a rough idle and will not easily go over 35mph, so i checked the compression it had 165 on cylinder 4 and 150 on cylinder 3 and no compression on 1 and 2... I removed the valve cover and turned the engine over manualy to watch and to make sure the valves werent stuck or something... Would you have any ideas to what is wrong with it? Please email me back and thanks for your time.

 

If only one cylinder was low would state a valve issue, burnt, stuck, etc.

If two cylinders side by side this suggests a blown head gasket.

You checked the valve action which was OK.

If two cylinders have no compression the engine will have little horse power, the results are what you are experiencing.