My dad has a 1998 Crown vic and the valves have rattled on aceleration since he bought it.He runs 87 octane and would like to continue running the cheaper gas but wants ask you for sugestions to quiet the rattle, Thanks Kenny Campbell
What sounds like valves rattling is actually spark knock (ping). Raise the octane and see for yourself.
Sounds like maybe the EGR valve is malfunctioning. It may need cleaning or replacing or the control system is bad. The DPFE sensor often quits on these engines. It should supply appx 1 volt to the system, and if more it’s a 1/4 volt more or less you’ll get a rich or lean code 41 or 42. Auto Zone should be able to test the system, and if not just go to next higher octane or accelerate slower. LEE
The problem (pinging rather than rattling valves) is more than likely in the EGR system; faulty EGR valve, clogged passageways, faulty EGR vacuum solenoid, etc.
What octane rating does the owner’s manual call for. Frankly cheaping out on the octane can cost more in the long run. Often you end up with less mileage and use more of the cheaper gas so it cost as much or more and you loose performance.
My daughter’s car had the same noise. Turned out to be a bad O2 sensor not telling the ECU to do it’s thing with the timing of the spark. New O2 sensor made all the noise go away. Took me about 30 mins.
It’s not the EGR system or O2 sensors. This is an OBDII vehicle, and if there were a problem with any of these systems the Check Engine light would be on.
But what I want to ask is, was this vehicle bought used?
Tester
Ford Rangers of that time were very prone to that problem and the ECU could be re-calibrated to clear up the problem. Check with the dealer.
If that engine has been “pinging” for 9 or 10 years, those valves might be in very bad shape at this point!
Eh?