P1407 (No EGR Flow) Fix - 95 LX 4.6
1995 LX w/4.6 engine and 232K miles. Basically stock with original EGR valve, never been removed. Daily driver for the last twelve years. County/state requires the vehicle to pass an emission inspection every two years for registration renewal, until the vehicle is at least 25 years old.
Decided it was finally time to clean out the EGR tube after a series of codes over the last few years related to the EGR system. I've read on this site that some have had luck removing the EGR tube by first removing a/c components, but having a good working a/c system I decided to attack it from below. Ford Thunderbird/Cougar Service Manual helps a lot. I typically use their nomenclature for most descriptions here. I disconnect the battery before working any electrical connections, especially to the emission control system.
Had to first remove the Dual Three-Way Catalytic Converter and Pipe (Y-pipe). Couple possible approaches: just bust the bolts and replace and drill/retap as needed to maybe save time, or use plenty of rust penetrant (PB Blaster), heat, and repeat as needed until getting the nuts to budge. I used the latter approach.
Disconnect the exhaust pipe from the resonator by removing two nuts holding flange to resonator. Rubber exhaust hanger insulators can be difficult to remove and replacements are not quite the same design as original, but easiest to just cut the old one near the rear differential off and get a new one. Remove the sub-frame center support member and place the exhaust pipe inlet out of the way of the resonator.
Remove the resonator. I could not get the Y-pipe off with the resonator connected to it. After removing the clamp, liberal heat and oil on the resonator inlet and applying hammer blows to a block of wood pressed on the front of the resonator and I was able to remove it without damaging it. It's a straight shot from the Y-pipe to exhaust pipe so the resonator could be replaced by a straight piece of pipe, but I have read some people didn't like the sound of the exhaust with the resonator removed.
Disconnect O2 sensor wiring. Two front ones are easy. Two rear ones are tight. On the right rear sensor I first unplugged the electrical connection to the transmission for clearance. It unclips by applying pressure on the rear of the connector. It will leak transmission fluid so clip it back in after disconnecting the O2 sensor. On the O2 sensors with tight clearance I used a small screwdriver to push in the catch tab on the side, then another screwdriver for leverage to separate the two connectors. I could not reinstall the Y-pipe first try due to interference between the two rear O2 sensors and the transmission. Get an O2 sensor wrench and remove the two rear O2 sensors.
Remove the four 15 mm nuts holding the Y-pipe to the exhaust manifolds. I used a swivel socket (Sunex SUN215MD) the two outboard nuts. For the two studs that I broke, I drilled and retapped with a 10 mm - 1.50 tap. I had best luck using the expensive drill bits labeled Hard Metal to drill out the broken studs after cutting flush with a dremel cutting wheel. For replacement studs I used Dorman 03133 exhaust flange kit, even though it comes with six studs/nuts. I used new nuts on all four studs.
Remove the EGR Tube. Patience is a must as replacement tubes are not available. Use plenty of PB Blaster, heat, apply a few sharp hits to the wrench with a hammer, and repeat as many cycles as needed until you get the lower EGR tube nut to budge. Took me four cycles before the nut loosened. And I squirted PB Blaster on it when I first started the job. Nut is 27 mm (1 1/16"). I forced a piece of 1 5/8" pipe on to a 27 mm combination wrench to give me something to hit. Flare nut wrench would be better, but I don't have one that size. Unscrew nut from exhaust manifold.
Complete removal of EGR tube from under hood.
Basic: Remove wipers and cowl for clearance. Remove air cleaner outlet tube ("violin case"). Unplug throttle position sensor, disconnect throttle body from throttle body adapter ("elbow"), disconnect throttle body cable bracket from intake manifold, and place out of way. Remove vacuum hose from throttle body adapter and vacuum tree against cowl.
Disconnect electrical connections from EGR vacuum control solenoid (EVR) [clip out from top] and Differential Pressure Feedback Electronic (DPFE) sensor (compress sides of clip while pulling back]; vacuum tube assembly connections to intake, EGR valve, fuel pressure regulator, and EVR; DPFE hoses, and bracket holding EVR and DPFE to throttle body adapter (10 mm hex head screws).
Remove vacuum tube assembly between fuel pressure regulator, EGR valve, EVR, and driver side of intake manifold. Remove vacuum hose assembly between PCV valve and two ports on intake manifold. Remove throttle body adapter from intake manifold. Tape over throttle body adapter hole in intake manifold.
Remove two 10 mm hex head screws holding EGR valve to intake manifold and remove EGR valve and EGR tube assembly. Remove the EGR valve from the EGR tube (also 27 mm). I attached bolts to EGR valve mounting holes and placed in vice for several cycles of PB Blaster, heat, and hitting wrench with hammer until it loosened. When separating I found the two completely clogged with carbon.
I cleaned the EGR tube with carburator cleaner and mechanics wire. Took several hours of soaking, poking, and repeating. Clean the ports in the intake manifold between the EGR and the throttle body adapter. I've read mixed reviews about cleaning EGR valves, so instead I bought a new Motorcraft one.
Reassembly. Most of the gaskets looked OK during disassembly, but I use new ones anyway.
Install EGR valve and gasket. I used a socket and extension to get the bolts finger tight, then tightened with a combination wrench on the inboard screw and socket/extension with ratchet on the outboard screw.
Attach DPFE hoses to EGR tube. Set EGR tube in place from underneath and loosely tighten EGR tube nut to exhaust manifold. Tighten upper connection to EGR valve as much as possible by hand, complete with crowfoot wrench on extension(s) from below. I had good luck with 3/8" drive flarenut crowfoot Armstrong 11-849. After tightening upper connection, tighten lower connection with wrench. Initially I thought I was going to reinstall the EGR valve and EGR tube as a single unit, but I could not get the proper angle of the tube to avoid what I thought would be putting too much stress on the tube.
Remove tape and reinstall throttle body adapter and gasket (Felpro 94800). Attach vacuum tube assembly. Use a new Dorman 47072 emission T on the rear port of the intake manifold.
Verify operation of the EVR and DPFE and replace as needed. Attach EVR, DPFE and bracket to throttle body adapter as assembly, then connect DPFE hoses, electrical connections to EVR and DPFE.
Attach vacuum tube assembly to EGR valve, EVR, fuel pressure regulator and intake manifold. Green tube from EVR to EGR valve will likely be brittle and break, especially since location of the vacuum port on the new EGR valve will likely be different than the original one. I used black 1/8" plastic tube (Vacu-tite 47417) with 7/64" rubber hose to repair the broken section of green tubing, replacing all the way into the original rubber EGR valve connector. If I thought of it earlier I would have gotten some green heat-shrink wire wrap off ebay for the replacement plastic tubing.
Reinstall throttle body and gasket. Clean Mass Air Flow (MAF) sensor with MAF cleaner before reinstalling air cleaner outlet tube on throttle body. Install vacuum hose on throttle body adapter and vacuum tree, reinstall cowl and wipers.
Reinstall Y-pipe. I used 3/8" drive and torque wrench to 20 lb-ft per specifications so as not to overtighten and break studs. Reinstall two rear O2 sensors and reconnect all four O2 sensors. Re-attach resonator, exhaust pipe with new exhaust hangar insulator, and sub-frame center support member.
Reconnect battery, check for leaks.
After going through a drive cycle I did an oil change, brought it in for emission inspection, and it passed.
Disclaimer: Not saying this is the best way or the only way, just this is the way I did it and it worked for me.
Acknowledgements: Many thanks to the good advice I got from posts about the EGR system on this site from Tbird Bob, T6Rocket, XR7-4.6, Grog6, tbirdguy, Rayo, S4gunn, Black_Cat, Rodeo Joe, etc., etc. And especially who came up with the saying, "It's not a bolt-on, it's a challenge" which helps motivate me to fix it myself.
Last edited by Jim3inVirginia; 02-09-2017 at 12:10 PM.