if all 4 cylinders are misfiring, is it likely that it is something other than the spark plugs

I don't know what the code was. We are selling the vehicle and a potential buyer used the OBD and told us it said all cylinders were firing. We just replaced the valve cover because of a leak and know that the timing belt cover has a leak as well. We have not replaced that cover. Could it be the timing belt? As I was told the timing belt might be covered in oil, although it is not due for changing for another 60k kms

The fellow said that all four cylinders were firing so I can only assume that all four codes were showing.

Seems we need to know the exact numerical ID of any and all coded set in the computer. When the Engine is running...does it run rough? When driving down the road....does it run rough?

Thank you for your help. I drive a 1999 v6 camry, and in comparison to my car, I think it runs rough, although I don't notice the misfires. It is my brother's car so I only drive it occasionally.

Suggest you have the computers re-Scanned and provide us with the exact ID of the codes. Numbers and letters. Some Auto Parts stores do this for Free.

Jabar....any updates concerning the issue with this vehicle?

all 4 of my clinders are mmisfireing sending coes p0300, p0301 p0302 p0304 and p0303. I have 97 camry le 2.2 l 4cyl

Guru9k4cp Did you find out what those codes were for. Or maybe I should rephrase my question to ask you if you found out what the problem is because I have a Toyota Camry 2005, 2.2 liters 4 cylinders and I also have those same codes along with a P0172 and a P0136

Babybluz64....lets start fresh. Clear all codes...take it for a ride. How does this vehicle run? Any warning lights on or flashing? Do you smell Gas inside or outside the vehicle? Pull the engine dipstick. Smell the oil on the end of the DS. Does it smell like gasoline?

Baby bluz......did you ever solve the problem with your vehicle?

Hey guys i have a 2006 kia rio and about coupke weeks to a month ago my check engine light came on then couple days later check engine light went off and now i left work everything was fine nothing wrong with the car next day i started my car and check engine light is blinking and its idleing kinda rough and drive kinda rough like it lost horse power So i changed spark plugs and that wasnt the problem its still doing the same thing but when i started it after i changed plugs it threw out a big white cloud of smoke and did it couple time after that im thinking water might be in my fuel somewhere or ignition coils are bad whats chances all ignition coils going bad all at once i got my codes and they are from p0300 to p0304 which is all cylinders are misfiring does anyone know what this could be where should i start from ignition coils or fuel or vacuum its driving me crazy

We would start the diagnosis by checking the engine oil. We smell it. Does it smell like gas? We feel it. Does it feel thin like water. What color is it. Is it milkey. We check the coolant level. If its low....you may have a leak in the Head Gasket.. We check for vacuum leaks by inspecting for cracked vac. lines. What did those spark plugs look like? Did they look black and carbon fouled?

I checked the coolant it was full the spark plugs was looking alright but they smelt like straight gas really bad and I will check the oil when I get home if gasket leaking wouldn't the head leak oil someone told me it could be my mass flow sensor??

MAF....indeed. Thats usually sets a MAF code. Smell of gas at the SP means the engine is over fueled.......very rich mixture. Where is the fuel pressure regulator on this engine. Is there a small vacuun line...rubber hose attached?

Ru.....what is the latest and greatest concerning this vehicle?

I was wondering if the fuel filter would do this to my car or could it be the head cause this

IMO a fuel filter or head gasket does not explain why the SP have gasoline(smell) on them. The Fuel Pressure regulator is my prime suspect. Go to NAPA ONLINE and find a listing for a FP regulator for your make model year. There you will find a picture displayed. Now you will know what it looks like....look under the hood for same....pull off the rubber vacuum line attached to the FP reg....and smell the end of the hose. if you smell GAS....you have a bad FP reg. Get back with results.