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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / April 200695 Mercury Cougar - EGR Bad?
Ok, let's try this again - I apologize for my original vague posting. You guys have helped me out a lot in the past, hopefully you can again. 95 Cougar, 4.6 V8, 119,212.7 miles My check engine light came on after the car had just been sitting for a couple of weeks. I got Auto Zone to read the code, which turned out to be: P1407 EGR No Flow Detected Does this actually mean the valve itself is bad, or just that a sensor SAYS it is bad? How would I diagnose / repair this - it is making the car run kinda rough. The AZ guy said it could be something as simple as the gas cap being bad, but that P1407 code sounds a lot more specific than that : ) I have located the EGR, it is conveniently located behind the intake crammed into a tiny space against the firewall. I am really hoping I don't have to remove it : ) Thanks, Libby In article <1143999924.230977.269770@g10g2000cwb.googlegroups.com>, > Ok, let's try this again - I apologize for my original vague posting. > You guys have helped me out a lot in the past, hopefully you can again. [quoted text clipped - 8 lines] > > Does this actually mean the valve itself is bad, Not necessarily. > or just that a sensor > SAYS it is bad? Could be the sensor or the hoses that attach it to the exhaust system. Could be plugged passages in the intake manifold. Could be a problem with the EGR vacuum control. > How would I diagnose / repair this - it is making the > car run kinda rough. All trouble codes have a published diagnostic procedure. > The AZ guy said it could be something as simple as > the gas cap being bad, but that P1407 code sounds a lot more specific > than that : ) The AZ guy is an idiot, that's why he works at AZ. > I have located the EGR, it is conveniently located behind the intake > crammed into a tiny space against the firewall. I am really hoping I > don't have to remove it : ) Most common problem on the early 4.6s is carbon plugging the passages in the intake manifold. Cleaning requires removal of the upper plenum (the elbow behind the throttle body) and digging the carbon out of the passages in the lower intake manifold. The EGR valve itself is decidedly low tech and not all that failure prone. The DPFE sensor and the hoses that attach to the EGR pipe are high failure rate parts. > How would I diagnose / repair this - it is making the > car run kinda rough. > All trouble codes have a published diagnostic procedure. Ok, now we're getting somewhere. And the procedure to diagnose this problem would be.... The first thing you should do is apply vacuum to the EGR valve while the engine is running. If it starts idling rough or stalls then you know the valve is working. If the engine continues to run smoothly chances are very good that the passages in the intake are clogged with carbon. Bob >> How would I diagnose / repair this - it is making the >> car run kinda rough. [quoted text clipped - 3 lines] > Ok, now we're getting somewhere. And the procedure to diagnose this > problem would be.... >> How would I diagnose / repair this - it is making the >> car run kinda rough. [quoted text clipped - 3 lines] >Ok, now we're getting somewhere. And the procedure to diagnose this >problem would be.... Listen to the 'cuda. IIWM, I would start doing the near free cheap things like removing the throttle body and cleaning the EGR ports. Mine uses a bit (lots) of oil and needs the EGR ports cleaned regularly. This requires removal of the throttle body which gives me an opportunity to clean the IAC and the throttle body as well as check/replace as necessary, the hoses that attach to the DPFE sensor and the PCV system both of which frequently require attention (relatively, of course). Cleaning the IAC may require that the valve end be soaked overnite in TB cleaner to loosen the sludge. This will help it idle better. New TB, IAC gasket and TB cleaner is well under $20US. If the cleaning doesn't do the trick, the next step would probably be replacing the DPFE sensor itself. The last thing you want to tackle is the EGR. You should open it using a vacuum pump at idle before removal. If the engine starts to run like crap as you do this, the EGR valve is working. If the engine does not respond to this, it is a sort of a b***h to get at and remove. Also, a lack of response can be plugged EGR ports if you have not already cleaned them. It is usually well rusted after a few years and will resist your attempts to remove with gusto. HTH Lugnut In article <1144005970.382066.15100@z34g2000cwc.googlegroups.com>, > > How would I diagnose / repair this - it is making the > > car run kinda rough. [quoted text clipped - 3 lines] > Ok, now we're getting somewhere. And the procedure to diagnose this > problem would be.... More than I'd care to type here. In a nutshell; 1) Visual inspection of EGR vacuum lines, solenoid, DPFE sensor and hoses. 2) Verify EGR passages by manually opening EGR and noting RPM drop. 3) Tee vacuum gauge into EGR vacuum line, run self test and watch for vacuum at appropriate stage in self test. 4) Observe DPFE voltage with scan tool while manually opening EGR valve. |
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