I have a 1997 f-150 with a v-6. I havea flashing check engine light andcode po302. I have replaced coil ,plugs ,wires and injectors. I have checked ccompression, maf, egr IAC. No vacuum leaks. It idles rough , but seems fine on highway. It only flashes check engine light when setting at a red light. PLEASE HELP.

 

Have you cleaned your EGR ports? if i read correctly p0302 is a misfire on cyl #2. Did you get all your plugs tight and boots on plugs properly?

 

Yes plugs are tight and the boots are securely on plugs and coil. No have not cleaned egr ports. How do I clean them.

 

What brand plugs, wires, injectors, and coil did you use? Does it use ANY coolant at all?

 

I used all motor craft parts. It uses no coolant at all. The problem is only at idle speed. I cleared codes and drove it 500 highway miles with no issues.

 

I would hook it up to an OBD-II scanner and see what your SHRTFT (short term fuel trims) are on banks 1 & 2. They should be similar, and if its runs like mine, they should bounce between -3 and +3 at idle. Also on the OBD-II scanner check the voltage graphs on your front two oxygen sensors. They should bounce between .2V and .8V at idle, if its running anything like mine.

If you have a vacuum leak, these numbers will be all out of whack at idle, but will be fine at higher speeds, on the highway.

Cleaning the EGR ports is a matter of removing the intake plenums from the top of the engine and physically cleaning them with a dental pick... very carefully. Just did this about 3 weeks ago, and mine were 99.9% plugged with oily gunk. Then blew them out with an air compressor (intake ports were filled with rags obviously) I don't know that it made much of a performance improvement, but it was good to do since I had it apart anyway.

 

Fought this problem for months myself on my 2000 4.2L. Final fix was replacing the Camshaft position sensor and synchronizer. It was the sensor that went bad, I replaced the whole assembly since the magnet dislodged.

Was a trick to align, but solved everything- I too went through all the replacing of other items with no luck- but it was done and out of the way.