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Discussion Starter · #1 ·
Could a faulty EGR solenoid cause a lean condition in bank one, and a cylinder misfire?, I have a 2001 taurus 3.0 DOHC and after I start the car and let it idle for a while the RPMs will drop low and idle rough and try to die and my gas milage has been cut down. I have changed the spark plugs, PCV valve, and the collapsed PCV valve elbow connector to the Intake. I think that the EGR solenoid is going bad because the vacume hose that plugs into the EGR valve has poor and inconsistent vacume, could that be the problem?
 

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You should be able to clean the EGR out with some parts cleaner, the EGR can Deffinately cause this (the same thing happened on my 96 T-bird 4.6L) it would randomly misfire and then it was fine, then it would misfire again as well as get poor gas mileage. I found a VERY clogged EGR (Full of carbon) The reason this can be caused is because when the EGR is stuck open it is pumping HOT exhaust gasses that contain unburnt fuel, if the EGR cannot properly "Pulse" and is stuck open your vehicle is not adjusting for the aditional unburnt fuel that the EGR is letting in the intake manifold causing a rich condition misfire.
 

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Discussion Starter · #4 ·
I appreciate the help ill try cleaning the EGR valve this weekend and then check back in and keep you posted on the progress....thanks for the idea.
 

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Discussion Starter · #5 ·
Ok so as an update, this weekend I cleaned the EGR valve and im still having the idle rough issue, when it gets to operating temp it runs like a dream, but untill then it runs very rough and tries to die still at the moment it hasent thrown a code yet but im just waiting for it ahaha...I also checked with starting fluid for vacume leaks and I could find none even at the intake gasket. My next question is the vacume hose that runs from the EGR Solenoid to the top of the EGR valve has a light fluttery vacume to it, should that be light and fluttery or a strong constent vacume like all the rest?
 

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light vac. pressure at the EGR diaphram, I would suggest the IAC valve next. It might be sticking causing poor idle when cold, the IAC opens the most when the engine is cold and closes as the engine gets warmer. If the valve is stuck It can cause the engine to stumble when cold. The IAC is easy to get to so it will be easier to do for sure.
 

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The EGR valve should not open at idle, only under moderate load and rpm and at operating temp. My 1998 Taurus GL 3.0L also had a rough idle. Ran a compression check, looked for vacuum leaks, everything checked out. Put a vacuum gauge to it and found it had only 12inches of vacuum. Started pulling vacuum lines and found vacuum supplied to the EGR at idle causing the valve to open. According to the Ford service manual it only takes 1.6-in. to open the EGR(fully open at4.5-in). I installed EGR vacuum regulator solenoid from my 1999 Ranger 3.0L. No more vacuum to the EGR at idle. The manifold vacuum is now at 17-in.
 

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^^ I was blind, now I see the light - Thank you lats007 so then it is possible that the OP has a faulty EGR vacuum control solenoid ?
 

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Both of my tauri do what you describe. One running perfect. Still slight pulsing vacuum on the egr vacuum line at idle. I don't think this is enough to open the valve.
 

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It could be a faulty EGR vacuum solenoid. Manifold vacuum is always supplied to the EGR vacuum solenoid but is vented to atmosphere at idle, and not at operating temp. The EGR should only open under a load. It's only job is to reduce combustion chamber temp thereby reducing NOX. If the EGR doesn't operate, you'll notice a lot of pinging. On my 1998 Taurus(130,000 miles), I just pulled vacuum lines until I found vacuum at the EGR, which shouldn't have been there at an idle. Fortunately, I've got 4 Fords to pull parts off of and experiment with. After replacing the EGR vacuum solenoid, it doesn't have the rough idle all the time, now it's only when it's cold and only lasts about 2 minutes. Just enough time to get to operating temp. I'm starting to think I've got a bad injector. Fuel pressure's at 35psi, also new plugs ,new wires.
 

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When the car is stationary, I think it's normal to feel very light, fluttery vacuum at the end of the hose that connects to the EGR valve (from the EGR valve solenoid)--for some reason, under normal conditions, the EGR solenoid lets a tiny bit of vacuum through (well below even a half inch/hg) even when it's not being told by the PCM to open, but not enough to open the EGR valve. In my experience (1994 Taurus 3.8), the EGR solenoid properly opens, and thus supplies sufficient vacuum to open the EGR valve, only when the car is being driven (and thus under load, as lats007 points out), and mostly (only?) when accelerating. You can't properly test the EGR solenoid by trying to get it to open and supply vacuum to the EGR valve by opening the throttle while the car is stationary (at least that's been my experience). The amount of leakage vacuum through the solenoid must be very low, since I've found that applying just one inch/hg to the EGR valve, while idling, will open it enough to cause the car to start to stall.

As part of a complete checkout I'm doing on my Taurus, I recently focused on the EGR solenoid, EGR valve, DPFE, etc. I hadn't done this before, so I didn't know what kind of behavior I was supposed to be seeing from the EGR solenoid. I learned the most about it when I teed a vacuum gauge into the line running from the EGR solenoid to the EGR valve, using a hose long enough to let me put the gauge inside the car on the dash, and then I drove around and watched the gauge. It shot up to 4-5 hg often, but not always, only when I accelerated from speeds starting around 20 MPH or higher, after which vacuum would usually drop quickly back to zero on its own, but taking my foot off the gas always immediately dropped hg to zero. Some acceleration caused only about 2 hg of vacuum. The 4-5 hg vacuum periods usually happened during shifting periods during acceleration. When the vacuum would rise and drop, it happened fast--no lag. This implied to me that my EGR solenoid was responding quickly to the duty-cycled (variably pulsed, to pass different amounts of vacuum) 12VDC that the PCM supplies it with, and that my EGR valve was responding quickly to the different amounts of vacuum the solenoid was passing through to it.
 

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lats nailed it. Same problem I had with a 99 Vulcan, three years ago. First, least expensive part I changed out, was the solenoid, upon finding its resistance was out of range, as per the Ford Factory Manual I have on CD. It won't let me copy and paste, but your situation smacks of it. Solenoid was $25, and DFPE was $55 at the time. Paid for the solenoid valve, and that was the problem. That made sense, as the solenoid is a modulating gizmo, and the DFPE sensor is solid state.
 

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So my 2001 Taurus with the 3.0 Vulcan is throwing P0402 (excessive EGR Flow?) but the only performance issue I notice is when travelling at low speeds most often 15-35 an a time or two between 35-50. I haven't replaced anything yet or tested it in anyway. Just driving around when I accelerate slowly the engine hesitates or if I feather it at a constant speed it will randomly feel like the car is not getting gas for a split second. My solution so far is just accelerate faster an try to coast as much as possible.
On a cold start when stationary the car idles like new an needle stays put at around 650-700 RPM I think. If I drive far an don't stop for about 2 or so hours it seems the symptoms fade away an happen way less an not as bad. Just not sure what to replace first.
People on here have said DPFE but I'm not sure I gave a good enough description the first time. So any advice? How much would a completely new EGR system cost roughly?
 
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