Contour Enthusiasts Group Archives Forums General Troubleshooting CA NO emissions problem fix

I recently moved back to northern CA from FL. Before when I was in CA the dyno smog test (simulated driving) didn't exist; testing was done while the wheels were stationary. Part of registering the vehicle was doing a smog test. My Connie failed the NO (nitrogen oxides) ppm emission test.

1/05/06 CA NO(ppm) emissions test results:
@15 mph 935ppm (437 max)
@25 mph 678ppm (724 max)

2/06/06 CA NO(ppm) emissions test results:
@ 15mph: 44
@ 25mph: 341

Right away the shop wanted to charge $99 to diagnose the problem. Not fix - only diagnose. I said I would come back later. The smog tech also asked if I had recently changed the battery because the OBD self tests also failed. I said the battery was disconnected before I left FL, but that was over 3000 miles ago.

I did some searches and found that the DPFE (Dynamic Pressure Feedback EGR) sensor was the likely culprit eventhough a CEL light wasn't present. The search also pointed out that the OBD self tests couldn't complete because all the IM (?interval monitor?) tests weren't done. It's possible for a DPFE to be so broken that it doesn't cause a CEL. So here's what I did:

* UIM/LIM rebuild
found 1 injector-to-LIM seal was cracked
cleaned carbon deposits from UIM, LIM, and throttle body
Replaced:
PCV valve, tb gasket, IAC & gasket, EGR gasket,DPFE, spark plugs and engine oil & filter
1)PCV - used clamps to insure PCV valve was secure
2)IAC - bought it long time ago but never put it on
3)plugs - used trusty APP764's
3)DPFE - pricey ($111, ouch)

Things I didn't change:
UIM & LIM gasket - replaced them 2 years ago, gave them a good soap and water bath
injector oil rings - replaced them 2 years ago.

Congratulations.

There are two devices that control NOX. EGR and reducing cats. Oxydizing cats cut CO an HC while reducing cats cut NOX. Most cats today do both.

The EGR cuts NOX by reducing combustion chamber peak temperature. So make sure that the EGR is fully functional. Apply vacuum directly to the vacuum nipple on the EGR valve with the engine at idle. The engine should degrade in idle quality, and probably stall. If it doesn't, remove the throttle body and clean the EGR passages behind it (good idea anyway, this is a common problem on these engines). Also make sure that the valve itself isn't plugged or the diaphragm ripped.

Have you altered any of the three cats? Are the pre cats removed (headers installed) or gutted? Do you still have the original main cat or did you swap it out for a high flow cat?

Also, were the cats propely warmed up prior to the test? Not just a well warmed up engine, but warmed up cats. About 15 minutes of spirited driving immediately before testing often does wonders to test results.

Sometimes if the cats are coated, it helps to run some injector cleaner or something similar through them along with some spirited driving. Berryman's from a "vacuum suck" often brings lazy cats back to life.

Good luck with getting it resolved.

So that's the acronym - NOX vs. NO, cool. I believe I have reducing cats. I replaced both original precats 4 years ago when I had a CEL. I can't remember, but I think the DTC was P0402. I was lead to believe that Ford skimped when the cat honeycombs were dipped in the chemical bath so they were prematurely failing. Before the replacement, I swapped the downstream O2 sensors around to see if the problem went away or followed a sensor, but the code persisted. The precats were replaced with OEM equipment. Later various posts suggested the problem could have been fixed with a PCM flash upgrade, but I had already replaced them. I still have the original main cat.

During the UIM/LIM rebuild I applied vacuum to the EGR valve and watched the valve stem move. I never did any tests while the engine was idling.

For the first smog test I drove the car to the shop using surface roads and revved (2000 - 2500 RPMs) the car for 10-15 minutes while waiting my turn. For the second smog test I drove the car on the higway and never shut it off before the test.

Do you think the OBD self tests not completing was a result of the precats/cats not being sufficiently warmed? I was told that even if the car passed emissions wise I would have still failed because the self tests didn't complete. This is what drove me to replace the DPFE since its voltage is input to the PCM wherease other EGR components like EVR and Air Pulse are controlled with PCM outputs.

Thanks for the input, hopefully this discussion will help others.

The P1000 code means that the self test monitors have not all completed sice the last time the battery was disconnected or the codes were read. On many cars, the monitors will run fairly soon (maybe a half hour of driving). Our cars, as well as many Fords, take longer. Sometimes, depending on driving habits, it may take a couple of weeks or more.

So, no, the P1000 had nothing to do with a weak cat.

I appreciate both of your replies. I didn't use my OBD II scan tool when diagnosing the emissions failure. I looked at the report and assumed the OBD self test failure was EGR related. Can all OBD II scanners detect/display P1000 code? Either way since I drove the car over 3,000 miles in 5 days all monitors better of run. Heck, after doing the UIM/LIM rebuild I only drove the car a day before smogging it a second time.