1997 ford thunderbird won't pass inspection

raj somaiya

• 2272 Answers
• Posted on Aug 28, 2010

SOURCE: '03 Ford F-150, 5.4 L.

First off, EGR valves seldom fail. Yours probably had nothing wrong with it in the first place. 
DPFE sensors, OTOH, have been a problem for Ford for years. Best results have been obtained with the upgraded Ford replacement. 
Make certain the hoses to the DPFE sensor did not get reversed and are not clogged if you have the non-plug-on version. If the upstream hose is getting blown off or is over-pressurized, clogged cats could be the issue.  
Check the Vacuum line at the EGR valve for vacuum at idle and while reving the throttle. It should not have and vacuum while the vehicle is not in motion. 
It should not have any vacuum while the vehicle is not in motion. 
If it does, you'll have EGR flow at the wrong time which usually causes idle problems and low speed stumbling/misfires. EVR solenoid is either dirty or sticking open. Try popping the cap off and cleaning the filter element and the top of the valve with compressed air. 
It takes a minimum of two drive cycles in which OBDII runs the EGR test for it to turn on the MIL if there are failures.
When the code is cleared typically you have to run through a specific cycle. With Ford a normal driving can take a couple of days to a week or more. There is page that lists the cycle and you can run through it about 45 minutes
Click on the link directly:--
http://www.obdii.com/drivecycleford.html
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SOURCE: 92 ford explorer 4x4 4.0L

That sounds like a possibility. Your engine management system has a cold start circuit. It is equal to a choke. It will keep the mixture rich and limit the engine spark advance. Both affect performance.

Autozone and Oreillys will do a free scan which may pick this up. You would need to change the correct sensor which is usually different than the sensor that operates the dash gauge. A "cold start" condition is a normal occcurence; the duration of the Cold start is something the scanners may not catch.

These types of problems would show up in O2 problems and Rich bank conditions after your Catalytic converter starts complaining. This should not cost much to get you back to 100%.

Jeffrey Turcotte

• 8991 Answers
• Posted on Apr 04, 2011

SOURCE: 1995 Ford Thunderbird, 4.6L. Fuel is pouring into

Hi, the primary sensor inputs used by the computer to establish the appropriate injector pulse width are the MAF snesor and the TPS. I recommend you test these sensors according to procedure pasted below and repair as indicated by test results. Please let me know if you have any questions, and thanks for using FixYa.

MAF Sensor Tests, 1995-96 4.6L Engines

Fig. Fig. 3: The mass air flow (MAF) sensor connector-1995-96 4.6L and 1996 3.8L engines

1. With engine running, use DVOM to verify there is at least 10.5 volts between terminals A and B of the MAF sensor connector. This indicates the power input to the sensor is okay.
   
2. With engine running, use DVOM to measure voltage between MAF sensor connector terminals C and D. If the reading is about 0.34-1.96 volts at idle, the sensor is okay.

TPS TESTING (Note, this procedure calls for a breakout box, but the same test can be accomplished by probing the back of the TPS connector at the brown/white and grey/white wires)

1. Disconnect the negative battery cable.
2. Remove the PCM and connect a breakout box to the PCM and harness.
3. Probe terminals 89 and 90 with an ohmmeter.
4. Slowly rotate the throttle shaft and monitor the ohmmeter for a continuous change in resistance. Any sudden changes in resistance indicates an open or substrate sensor.
5. Reconnect the negative battery cable.
6. Turn the ignition switch ON and using a voltmeter, measure the voltage between terminals 89 and 90 of the breakout box. The specification is 0.8 volts on the 2.3L, 3.8L and 5.0L engines or 0.9 volts on the 4.6L engine.
7. If the voltage is outside the standard value or if it does not change smoothly, inspect the circuit wiring and/or replace the throttle position sensor.