I just changed the timing set and car ran for 1000 miles no problems. Then I started losing power especially after 4000 rpm's. So I changed spark plugs and the car ran worse. Put old ones back in and it ran just as bad. Took valve cover off and had slack in the chain again. Took it all apart and re-timed, put the old tensioner back in, got the slack out of the chain, new chain was still shorter than old chain. Put it back together and still runs bad. Compression test shows everything is good, 180 pounds all 4 cylinders. The weird thing I noticed at wide open throttle is that I have air coming out the throttle body and valve cover. Is the cat plugged causing pressure in the intake ?

are u getting poor gas mileage?. Best thing I can recommend is take the cat off and inspect it. also if there is power with it off then thats the problem for sure.

good luck.

easiest way to test is to take the 1st O2 sensor out of the exhaust pipe. Opening up a hole pre-cat. Go drive it quick and see if that makes it not feel like its falling off. And yes, it will be super loud. If it feels like its not falling off then the cat is plugged. Plug the O2 sensor back in and get the cat replaced.


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It turned out the problem was a plugged cat.

Should the car get worse MPG if the cat was removed ?

well if its gone i imagine your downstream o2 if throwing a fault code. So yes it probably in limp mode of somekind.

No it will not put it into any limp mode.... Nor get worse gas millage

No it isn't throwing a code, the anti fouler trick was used and the computer is perfectly happy running in closed loop.