Get code P0304 and P0303

Gentlemen: If I accelerate at a slow and steady pace, to "any" cruising speed and maintain that speed I can run smooth, with just a little bit of roughness every now and then forever. BUT, IF I press the accelerator too hard to maintain speed up a grade or to pass out slower moving traffic all hell breaks loose. All power is lost, the engine bucks like a bronco because the timing has been lost and the check engine light blinks. If I pull over and turn off the engine, wait a few minutes ( 5 minutes or so) before I start the engine again the engine runs as before. This sort of episode will happen when it is HOT. I have not yet tried this when it is cold but I imagine it would do something similar when it is cold.

This will happen after coasting down a grade and pressing the accelerator to pick up speed. This will happen from "what ever speed" I start at or drop down to. Once timing has been lost I must stop, turn off the engine and wait before it will run smooth again.

My mechanic tells me the engine is running (timing wise) just fine. I damaged a spark plug because of this activity. I have changed the coils ON EACH PLUG "TWICE" and this loss of timing and power still happens as above. The only codes I get on my $50 code reader are P0303 and P0304 and a smog alert/warning.

I have gotten to the point where I can tell when it is going to happen and have developed a technique of letting off the gas just before the power is lost. This prevents all hell from breaking loose and keeps the engine running smooth.

Does any body have any ideas as to what is causing this problem.????

 

So you replaced the coils but did you replace the spark plugs on those cylinders?

 

Is the CAT stopped up???