97 Taurus P0303 code


Good day to all…

I have a 97 Taurus 3.0 OHV that has aprox 25k on a new crate engine. Recently I have developed a P0303 code. Cyl #3 misfire. The MIL is on, engine idles rough and smoothes out aprox 1500 RPM. Code appears when warmed up at idle or hi-way speed. Engine Vac is 15-16. I travel aprox 60 miles a day and MPG appears to not be affected.

Here is what I have done to this point. Replace Cyl #3 injector w/new, swap plug and wire from another cylinder, changed Ign coil and still no resolution. The EGR and Pipe was replaced because It broke when trying to remove it.

A compression ck has not been completed at this point.

What am I missing here? You assistance is appreciated.



Check the compression in that cylinder.


With the vacuum reading of 15-16 I would suggest a vacuum leak probably at the intake manifold near the #3 cylinder. Spray some carb cleaner around the intake and listen for an rpm change.


I sprayed carb cleaner around the intake area again with no signs of a vacuum leak.
After the Compression check on Cyl #3, I found only 60psi pressure compared to 160 psi in other cylinders. Since the engine is covered under warrenty, I will let the shop who installed it take it from here. Thanks for the follow up. Brian