Emissions test failed

PURPLEUNICORN714

MEMBER
FORD ESCORT

I havea 1994 ford escort, I put it though an emissions test and it fail the nox the limit was 583 admy reading was 702, the codes where egr valve opening not present and throttle positioning sensor, I changed the oil and filter, spark plugs and cleaned out with throttle body cleaner stil nothing, the readings were the same, I changed the egr soliiod but still nothing, the egr valve opens if I put direct vaccum on it but doesn't seem to work the way it should can you give me any suggestions, or tell me how to check the egr valve, soliod and such. Thank you

4 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Does it have DPFE ( Differential Pressure Feedback EGR) EGR positioning sensor

The computer gets a sensor input to activate the solenoid to transfer vacuum to the EGR-

When you apply direct vacuum it opens-good-check the solenoid/vacuum hoses going to it and out from it while slowly accelerating to 2k rpm-it should have vacuum going to the EGR.

The purpose of the EGR is to recirculate the exhaust gases back to the engine to be reburn that way it lowers the combustion temperature and prevent the formation of oxides of nitrogen.

NOX failures are usually EGR-related, since the EGR system is primarily responsible for reducing oxides of nitrogen. But NOX emissions can also be caused by a bad three-way converter or a computer control system that remains in open loop

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Thursday, April 12th, 2007 AT 9:00 PM

PURPLEUNICORN714

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3 POSTS

Where do I find the DPFE in a 94 ford escort and how do I check it? I chaded the regualrer synoid for the egr valve? I'm at a lose here

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Friday, April 13th, 2007 AT 5:03 PM

RASMATAZ

MECHANIC
75,992 POSTS

You need to confirm whether it has the DPFE I just threw that in as posibility. Dunno the set up on this model

Did you do the 2k rpm check? When the engine is running at idle it shouldn't have vacuum going to the EGR-if so the solenoid has a problem.

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Friday, April 13th, 2007 AT 10:27 PM

PURPLEUNICORN714

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3 POSTS

I think that is the problem, there is no vacum from silinoid at all, I can only open the egr if I hook it direct, so there would be the problem.I could have gotten another bad silinoid, thanks for te help :D

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Saturday, April 14th, 2007 AT 8:07 AM