EGR test

[rcolosi]

Is there a test to check whether the EGR system is operating correctly, or is everything assumed to be good if the check engine light is not on. I'm getting some pinging.. on good gas and all.. and was wondering if this might be the culprit.

Thanks! (2004 Ranger 4.0)

 

[almostclueless]

I can't guarantee the light would come on....


There is a DPFE sensor on my 98...it's a box the size of a big pack of chewing gum bolted to the front of the intake plenum, with two slightly different sized vacuum hoses and an electrical connector.


It provides feedback to the PCM on EGR flow. I did a test where I hooked a vacuum guage to one port of the sensor and monitored the output while drawing a vacuum to various vacuum levels.


I wasn't having pinging probs, just did it for kicks. But pinging can definitely be caused by insufficient EGR.

 

[MAKG]

Yes, the EGR can cause pinging and yes, it can be tested like almostclueless said.

However, a commonly overlooked cause of pinging is mild oil consumption. You can try to put synthetic in the crankcase and see if it cures it.

Inspect your spark plugs. You might see ash from mild oil consumption or oil fouling from severe oil consumption. Maybe some glazing from lean mixtures.

Do make sure it's actually pinging. Other taps -- especially valve noises -- can sound like pinging. Pinging is characteristically worse at high engine load. Valvetrain noises are strictly RPM dependent. Note that pinging is in some sense normal when the tach is too low (on a 4.0L, below about 1500 RPM -- note the engine will run much better over 2000 RPM) and the throttle is high.