code ps-1406

eddieguy

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#1
1996 buick lasabre. 122,500 mi. my car seems to idle kind of rough at times and today it acted like it wanted to stall- the check engine light came on and i took it to the auto parts store autozone and they scaned for codes with a little handheld scanner and it revealed one code that came up as ps 1406- does anyone know what that code would mean? thanks for replies in advance. as soon as i left the auto parts store after they scaned for codes i noticed my check engine light was no longer on
 
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#2
Hi Eddie,
P1406 Exhaust Gas Recirculation (EGR) Position Sensor Performance
This car has the electronic EGR valves, without having a scan tool I do not know how you would test one. Prehaps another members knows. Since the car is running rough I would think that the valve is not closing fully. I do supose you could remove the valve and see if there is a chunk of carbon holding it open. If I recall correctly a friend of mine said it was a fairly common problem. He even said they made a gasket with a screen on it to prevent this.

Ford_Dude
 

nickb2

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#3
Good call Ford Dude. The torx screw will get build up around it. You can try to clean this valve with combustion chamber cleaner. It sometimes helps. Once this is done, the screen that FD was talking about is good way to go to make sure the carbon buildup doesn't repeat itself. Also pouring down some of that cleaner into the tube may help dislodge some of the build up. Let sit overnight before start up.
 
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#4
Coincidence, stepdaughter comes home this last Sunday driving my 92 DeVille, tells me the service engine soon light just came on. Was an E48 code on this thing, defective EGR valve, but of the vacuum diaphragm type. Pulled it, guess with 120K miles on this car, heat of the exhaust burnt through the valve, was idling rough. Worse yet, the diaphragm was ruptured, no EGR. A panic situation, this can burn up your engine.

Called my parts dealer, said earliest I could get a new one was yesterday morning at 7:30 AM, walked in there, said I am the guy that called about the EGR valve. Got it right here, 220 bucks, what! You said it was 60 bucks on the phone. Opened the box and was one of these.



Stepping motor kind, wrong box. Mine was sitting next to it. The truth of the matter is while all the books state the function of an EGR is to reduced NOx emissions, the reason why you have NOx emissions is that with unleaded gas the combustion chamber temperature compared to leaded gas will increase from 2,100*F to well beyond 2,650*F that will burn out first your exhaust valves, then pop holes in your pistons. Stepdaughter wanted to drive it back to her school, said no way, your mom will have to drive you back and you will have to walk that 1.2 miles to school. Nothing I can do on a Sunday.

Actually you can drive your vehicle that way, if you keep your engine rpm below 1,500 rpm at all times, an defective EGR valve is nothing to fool with.

While I am pretty handy with my machine shop, not a damn thing can I do with a defective stepping motor EGR, that heat melts and corrodes the motor drive shaft, these are strictly throwaway parts. With luck, a bit of carbon will block that weak ass motor, but you are playing with fire.

These things are not easy to bench test either, fed by what is called a quadrature waveform, one phase is fixed, other varies in pulse width modulation that is is shifted 180* to reverse the motor. This motor is constantly opening and closing the valve, really a lot in city driving.

I got that DeVille running smooth yesterday, her mom and I drove it back last night. Just saying, you don't want to fool with a defective EGR. Was not easy parting with 60 bucks, 220 bucks is a lot worse.

If interested in history, Doolittle worked with Shell Oil prior to WWII to develop 100 octane lead free gas, the key reason why we beat the pants of the Germans and Japanese, but with high combustion chamber temperatures, a water injection system was used requiring constant maintenance. Our cars were switched to exhaust gas recirculation to do the same thing, but still not maintenance free with drastic consequences. Was huge problem in the 70's as no sensors were used back then to indicate a fault, shops were loaded with valve and engine overhaul problems.

Never really objected to eliminated lead from fuel, was a constant PITA for lead build up in engines, plus in some people that lead crosses the blood brain barrier, makes them stupid and highly aggressive to do things like run for office or become a dictator. A good explanation for our congress of the last 40 years.
 

Gus

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#5
"my car seems to idle kind of rough at times "......

Yes, it's possible, that a malfunctioning EGR could cause this problem.......but if something is stuck under a pintle, it's more constant, rather than "rough at times".....this code usually means that the pintle position sensor is the problem.....simple way to check is with a scan tool.....with key on, engine off, pintle position should be 0%......if greater than zero, and the pintle is closed, just unhook harness and attach to new one....if it reads 0 %, it's the pintle position sensor......may even find after replacement, the code is gone ,but the rough idle may be caused by something else...