Ford is known for problems with their DPFE sensors. These sensors detect the change in manifold vacuum pressure when the EGR is commanded on and off. If you get an EGR code, DO NOT automatically assume that it’s a bad EGR valve! Get a hand held vacuum pump and apply vacuum to the EGR. Check the operation of the valve. It if moves properly and the passages are clean, move on to checking the DPFE sensor. Use the same hand held vacuum pump to apply pressure to the sensor. Check for a change in voltage as you do this. If the voltages are within spec, move on to clear up this very common blockage.
Remove the throttle body and gasket. Behind the gasket you will find a half moon shaped passage with 3 openings into the intake manifold. Most likely you will discover that the passages are clogged with carbon buildup. Clean out the passages with a small pick and some throttle body cleaner. Then, install a new gasket and the throttle body. Your problem should be gone.
This problem is common on the 2.5, 3.0 Duratec, and the 4.6 liter engines.
Sunday, August 19, 2007
Ford EGR codes P0401 & P1408—Fix clogged passages
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16 comments:
OK.....97 taurus throwing a p0401 code. And i followed all of your advice (once i found it, i stupidly replaced the valve when that was not neccessary) but i found that the half-moon port (C-Shaped is how i found it, but i see what you mean) and cleaned it out with some intake cleaner and a piece of metal wire, and a whole bunch of paper towels. Started the car up after doing this, and got horrific results. bad idling, stalling, surging. Please help me. what did i do wrong? I didn't try to start it again after i got back into a parking space, but it feels dangerous to drive. Please advise. Is it simply the throttle body cleaner burning off in the engine? i saw someone with a sable asking this same question today on a ford forum you post on. please help.
dumping a lot of intake cleaner into the manifold can cause it to run poorly until it's all burned off. To avoid that, place a brick on the gas pedal to keep the throttle plate wide open. Also keep the air duct off the intake to let the solvent evaporate.
Ok...I'll try that. By the way, you were right on about the channel in between the throttle body and the intake. Right on. Couldn't even get a wire through it to the egr valve...took almost 1/4 a can of throttle body cleaner for that tiny little spot.
I really appreciate what you do here...i'll keep you posted as to my progress.
Thanks,
Michael
OK....aired out the throttle body and air intake to very little avail. I took the opportunity to clean off my battery while the throttle was open. when i had it hooked back up, the engine started much more smoothly than it had the night before (see earlier comment) and after some pinging and surging, the engine ran at a constant rpm (still lower than it used to). However, a sputtering developed from the exhaust, and it began 'choking'the engine. pulling on the throttle control (just as accelerating would) raises rpm's and makes the engine and the exhaust both sound like normal accelleration before any problems arose, and a drive around the block confirmed that the problem only seems to exist at idle.
I'm stumped again, looked all over for an exausht leak anywhere i was working, and didn't find any. all of the egr hoses are still intact and functioning properly.
my neighbor, who does alot of auto body work, suggests that is sounds as if the engine is 'running lean' or as he explained to the layperson like me, too much air and too little gas.
So it was playing with the throttle body that could have caused this? Is there a way to adjust it to make it run properly again? or is there another diagnosis you can give? I'm starting to think i messed up the throttle body when i took it off and cleaned it out.
please advise, you give the best advice of all those i have found online.
Mike
Did you remove the Idle Air Control (also called bypass valve) from the throttle body before you cleaned?)
When the car is at idle, the throttle plates are completely closed. But the engine needs air to breathe. So the IAC literally "bypasses" air around the throttle plate. The valve itself is an electric solenoid that moves a tapered pintle in and out of an opening. The computer pulses an electrical signal to the coil in the IAC. The longer the pulses, the more air that can pass. The IAC valve gets crudded up with carbon and can be cleaned with throttle body cleaner. BUT, you cannot let any of that cleaner into the actual solenoid, or coil area or it can damage the windings on the coil.
First, remove the electrical connector from the IAC valve while the engine is running to see if it changes idle speed. If it doesn't, then the IAC has usually croaked. If it does change the idle, you may want to remove the valve to see if there's any carbon buildup in it.
Also, was there a gasket on the throttle body when you put it back on? Was it in good shape?
A vacuum leak would cause a lean running condition.
ok...i did take to iac valve off to check it, but it was after i had cleaned the throttle body. I suppose i could have gotten throttle body cleaner into it. it is on top of the manifold just after the throttle body, i think, and i did get some cleaner in that area.
As far as the gaskets...what was strange about this was that the new throttle body gasket is fiber, while the old one was metal. I think i could still use the old one, as it came off easily, and with a little cleaner, it would be in normal condition. Everything i have seen says no, that the old gasket is always shot. I'll check the iac tonight, and post my comments again.
Thanks,
Mike
OK....reviewed the aic valve, there was nothing wrong with it, I cleaned out the bypass port, although it is doubtful that it was necessary, and cleaned alot of the junk off of that spring at the base of the aic. This was not the problem.
The problem was a vacum leak around the base of the throttle body. apparently, a certain discount auto parts store, who shall not be named at this time (It shall suffice to say that I will never trust this place in southern Illinois who features the name of my favorite irish pub), did not realize that the taurus has 2 possible engines. Although it appeared as if the gasket between the throttle body and the intake manifold were the same, the slight differences were enough to let dirty air pass the throttle plate and enter the engine straight through the intake manifold. A cleaning and reattatching of the old gasket proved this to be the problem, and a trip to trusty ol autozone (filled with a lot of baffled head shaking by the autozone staff that a certain discount auto parts store has a complete lack of competence or listening skills) got me a new one that was an identical match to the old one.
Now you should hear the old kitty purr. still, kinda sounds like a wretched, sick, dying cat, but the ses light is off, and it idles normally. I will be going to the epa station this afternoon to hopefully pass my test. Keep your fingers crossed for me.
I owe it all to you, Rick, and if you are ever in need of a journalist or web copywriter with rudimentary knowlege of html practices and search engine optimization, feel free to let me know.
Rock on.
Mike
I PASSED I PASSED I PASSED!!!
Chalk one more sucessful repair up to the Rick man, nobody rocks like Rick.
I think i'll name my first child, boy or girl, Rick.
Rock on!
mike
And the saga continues...
So now something new has developed, another problem with the egr. To recap:
New valve, new sensor, clean hoses, clean port in throttle body, no vacum leak (that i know of, none apparent)
now it isw p0402. excessive flow. Any ideas?
Passed emissions, an got my sticker, so no rush this time. Much less panicked.
Mike
Looking at other technician's postings it looks like the EVR vacuum regulator can stick open, causing the EGR valve to remain partially open and provide too much flow. Not a common problem, but a few techs have had to replace them reported the problem gone.
The only other possibility is a wiring problem to the EVR that's intermittent and providing power to the regulator when the PCM isn't calling for it.
The code actually turned off shortly after. Techs at autozone suggest calling up the warranty on the dpfe, since there seem to be conflictoing signals about the amount of pressure in the system. and cleaning our the electrical connections on the little gray clip that runs power to it. I'm trying a new sensor and electrical parts cleaner. Don't get me wrong, i love my old car, but come janurary, i can't wait to move on to the focus.
mike
Thank God for this site. I just spent $300.00 having EGR, DPFE, and solenoid replaced, only to throw a 0401 code again. After reading this blog, I cleaned the port in the throttle body, cleared the code and have been DTC free since. Wish I'd read this first.
Thanks Rick!!
Thanks for this help!!!!! My daughter's '97 Sable CEL was on, posted a 401 code. Rem throttle body and that channel was absolutely clogged. While everything was off, I went ahead and repl the DPFE sensor since its such a pain to get to. One more point tho' - The rubber elbow that attaches to the rear of the intake manifold (where the the 3 other red vac lines connect) was very loose. I placed a zip tie around it where it slips on to the manifold nipple. I have to believe there was major vac leakage going on there.
Zip ties won't work!. Replace the lines with rubber vacuum hose and adapter fittings. You can get them at any parts store. Ford doesn't sell replacement rubber connectors for those plastic tubes.
I'm pulling my hair out trying to diagnose a 5.8L F-250. Code reader says egr voltage too high/low. Replaced sensor, still get engine light and egr code. Don't think the valve is the problem, but don't know what is. Also getting intermittent kind of rotational scraping or rubbing sounds coming from the undercarriage of the truck. whatever it is, the faster I go the faster it goes. Like I said it doesn't do it all the time but when I hear it and step harder on the throttle, the sound increases in intensity. Very wierd. Can't tell if it's brakes or tranny or u-joints or what.
Ok..before I take my throttle body off and clean it up...will this work for a 2.0 SOHC 98 Escort?
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