2001 Ford Taurus Emissions Help Needed!!

"Good morning.

I have a 2001 Ford Taurus SEL with the V6 DOHC engine. Recently the emissions light on the dash came on and it's been running rough. I had the following codes show up:

P1506 - Idle Air Control Valve
P1131 - O2 Sensor
P1151 - O2 Sensor
P0171 - System Too Lean
P0174 - System too Lean

Their suggestion was to replace 4 O2 sensors, the IAC Valve and the PCV hose all for nearly $750.

Does it make sense for so many or the emissions system components to go bad all at the same time?

I've made repairs before but I'm not a trained mechanic. Is there something I could check? Is this the type of job a non-mechanic can perform?

Thanks for your advice and insights.

Ken"

No, it sounds like "they" were just planning to shotgun parts in what they hoped would be a worst-case scenario.

The codes would not indicate a reason to replace all 4 oxygen sensors, and the "Lean" codes are likely the reason for the O2 senosor codes anyway.

There have been numerous posts on troubleshooting the P0171 and P0174 codes on this forum. That would be a good starting point. Please use the "Search this Forum" link from the Taurus forum main page and search for P0171. You should find quite a few hits. Most of the time, the P0171 and P0174 are reported together, so you should only need to search for one of them.

-Rod

Thanks, I'll look them up now.

BTW, do you or anyone know where the PCV Valve is located on this beast? I'm trying to get a hold of a repair manual bu haven't had any luck yet. One article on the web mentioned it is possibly on the valve cover on the passenger side closest to the firewall. I've been trying to locate it under what seems to be a air distribution manifold but ther's not much room in there.

Any advice would be a great help.

Have a great weekend.

Ken

Thanks, I'll look them up now.

BTW, do you or anyone know where the PCV Valve is located on this beast? I'm trying to get a hold of a repair manual bu haven't had any luck yet. One article on the web mentioned it is possibly on the valve cover on the passenger side closest to the firewall. I've been trying to locate it under what seems to be a air distribution manifold but ther's not much room in there.

Any advice would be a great help.

Have a great weekend.

Ken
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Hi Ken,
If you have the 24 valve engin (Duratec), I can send you the pdf. file (if your email cliant will except pdf. files? that will show you where the pcv and componets are located.
Rob Roy

Hi Rob Roy. Yup, I have the v6 24 valve DOHC engine. Thanks for sending the PDF along. My email is [email protected].

Have a good weekend.

OK, I've replaced the PCV valve and the faulty hose which was causing a vacuum leak and while it's running a little better, it's still running rough and the emissions light came back on.

Would it make more sense that it's the o2 sensor(s) or the idle air control valve causing the problem?

If it's the o2 sensors would it make sense that all 4 would have gone bad?

Thanks

Ken

OK, I've replaced the PCV valve and the faulty hose which was causing a vacuum leak and while it's running a little better, it's still running rough and the emissions light came back on.

Would it make more sense that it's the o2 sensor(s) or the idle air control valve causing the problem?

If it's the o2 sensors would it make sense that all 4 would have gone bad?

Thanks

Ken
>>>>>>>>>>>>>>>>

Hi Ken, your questions are now beyond my knowledge. Maybe Rod or someone with better knowledge than me will jump in and answer your questions, Good Luck Ken !!
Rob Roy

Does it only run rough at idle, or does it continue as engine speed increases? Has a tune up been performed recently? Are the same codes showing up now as originally?

Verify that all the vacuum lines are connected and in good shape and be sure to inspect the intake air tubes to make sure they are properly connected. Sees like you probably have a vacuum leak somewhere.

-Rod

Thanks to Rob Roy and Rod.

I'll look over the vacuum lines again, but it seemed like they were OK and back where they originally were when I first pulled the codes.

I have just replaced the PCV valve but have not replaced the spark plugs yet; air filter, oil, etc. are in good shape.

I'll bring into a shop to see if the codes are still the same and let you know.

I read on another post that it could also be the EGR valve, DPFE sensor or dirty MAF sensor as well. Any of these could cause the o2 sensors to and 171/174 codes to register. Does this logic make sense?

Thanks again.

It's possible and worth checking into. Worst case, they are all fine and you get that peace of mind. Well, I guess it would be worse to find out they are all bad and need to be replaced.

-Rod

OK I attempted to see if the DPFE sensor and EGR valve were the culprits by connecting the reference and output of the DPFE Sensor (apparently this tricks the PCM into thinking everything is OK which would only work if the DPFE sensor was going bad). This did not improve the idel.

I took it into a shop and discussed everything with a tech there. The good news is that since replacing the PCV Valve and hose, and removing the battery cable, the original codes are not showing up any longer (IE P0131, P0151, etc.). The codes which are showing u now are P0305 and P0306. The tech mentioned it could be as simple as replacing the plugs. He looked at the spark plug wires and said they still looked OK but may also be the problem. What he thought could be causing the codes and the rough idle was leaks in the intake manifold in the two cylinders being referenced. He explained the what the MAF is seeing and what is being delivered could be could be out of sync causing the PCM to act erratic.

Does this make sense?

Does this make sense?

Essentially what he's saying is there may be unmetered air entering the combustion process, ie: a vacuum leak. Per comments made in post #8, yeah, this makes sense. I'd be more prone to suspect plugs, wires, or coil though for the misfire codes.

-Rod

Thanks Rod. I'm going to bring it in to him tomorrow.

I bought some plugs and want to replace the ones in there. This may sound stupid but is there an easy way to replace the 3 plugs located under the air intake manifold? I can't even see the plugs let alone get a tool on them.

Is the a process and/or pictures to get at these?

Ken

I very much appreciate the insights and help so far, but I could really use a little more right now to get this resolved.

I bought some carb cleaner and attempted to spray it into the intake manifold and there were no leaks I could see.

The car is still showing the P0302 and P0305 codes.

I have the plugs to replace the ones in the car and would buy the wires too but I'm not too comfortable right now understanding how to get at the rear 3 plugs and wires. I would appear I need to remove the intake manifold, DPFEE sensor and some other items to get at the rear plugs and to replace the wires, but I'm not sure how involved this is. I stopped in and read through a Haynes manual at an Advance Auto yesterday and thought the descriptions and pictures were really lacking and unclear. They did say the 2001 DOHC engines does not have sparks plug wires, rather they have individual coils.

I called around to a few shops and some wouldn't even consider replacing the plugs and wires and the ones that did wanted over $500! The Haynes manual indicated that if the car backfires at all it could be the EGR system (IE Valve, DPFEE Sensor, etc.)

I have to get this beast back on the road and can't afford to take this in for thousands of dollars worth of repairs. I personally have an issue with having to pay that much to have a tune up done. Does anyone have any more advice? Can anyone send along the shop manual to replace the plugs/wires?

The way to check the intake manifold gasket for leaks with carb cleaner is to spray it around the outside of the manifold/gasket surface with the engine running. If there is a vacuum leak, the leak will suck in the cleaner and cause the engine smoothness to change.

Looks like the way to get decent access to the rear plugs is to remove the right hand cowl grill at the base of the windshield. While you're in there, check for a cabin air filter. If you have one, it's probably due to be replaced. You'll need to disconnect the electrical connector to each coil and remove the 8mm bolt holding the coil in place. Once the coil is removed, use the spark plug socket and probably an extension to get the plugs out. I'd imagine a nice bright light will be helpful too.

-Rod

Here's an update.

Rod, thanks for the advice on removing the cowl. I managed to replace the plugs by doing this...still a major PIA but doable. This did not change the issue.

Also no leaks at the air inlet manifold/plenum either.

The emissions light is still on (and blinks every so often) and the car still runs/idles like it is missing on a cylinder. When you pump the gas some while in the driveway it feels like it wants to backfire.

I did not change out the wires/coils yet primarily because Ford wants ~ $150 per wire to replace. The parts guy I spoke with said they really should only be replaced when needed.

Is there anything else that comes to mind I can check next?

If you've managed to replace the plugs, it's not much of a stretch to think you could replace the wires as well. However, the manual implies that your model year uses the Coil on Plug (CoP) so you shouldn't have plug wires. Maybe that's where the $150 per comes from, that's the cost to have a dealer replace all 6 CoPs. Since you did the plugs, was it spark plug wires or a CoP that you had to remove to get to the spark plug?

-Rod

They looked like regular wires to me with boots on both ends coming from the plug and leading back to looked similar to what used to look like a distributor cap.

Would after market wires be OK here or do I need to remain consistent with what Ford offers? I double checked with the dealership and this time they quoted ~ $100 for the wires versus ~ $40 in an auto parts store.

You may want to consider spending the extra $60 for the dealer wires if you plan to keep the car awhile. Also, there maybe a parts house in your area that deals in Motorcraft parts and would sell the wireset for less than the dealer.

-Rod

Thanks again Rod.

I went to NAPA and bought some OEM replacements and put them in the car. It didn't improve my situation.

Is there anything else I can troubleshoot?

Since you're finding that you do not have CoP configuration, you may have a bad coil. I'll see if I can dig up a diagram showing if cylinders 2 and 5 (relating to your P0302 and P0305 codes) share a coil pack. In the mean time, make sure the wiring connector to the coil packs is seated firmly.

-Rod

I'm not having any luck finding if cylinders 2 and 5 share a coil in the coil pack. The coil pack is laid out though with three coils, A, B, and C. I'd suggest you trace the spark plug wires for cylinder 2 and cylinder 5 back to the coil pack and see if they are on the same coil. If so, and the wiring to the coil looks good and is connected securely, you may want to consider replacing the coil pack.

If you have a spark tester, you could check the spark from those two wires and coil towers. If you didn't have good spark from the towers, using an oscilloscope, you could test the drive to the coil to make sure the PCM is telling the coil to fire.

-Rod

A FINAL update... I replaced the coil and she's running fine again. I highly recommend making sure you connect the correct wires in the correct sequence once completed though :(

Rod, thanks again for all of your help you have been absolutely wonderful.

Glad to hear that you probably got this issue solved. The other good news is you won't have to worry about needing spark plugs or wires for sometime, and you were able to do most of this on your own, saving some money and hopefully gaining more of an understanding of the underhood of your car. Great work, and thank you for the follow-up post.

-Rod

Klnaco, the things to check on the codes you mentioned is definitely the EGR system, the oxygen sensors, the PCV valve, the MAF, and the air filter. You mentioned needing details on the back plugs. The only way to get at those rear plugs and coils is to remove the air intake manifold. It's actually quite simple. Just take off the bolts holding it in place. They're right on top. I think there's 10 (5 across the front and 5 across the back) and I think they're 10mm bolts. If I remember correctly you have to disconnect it from the MAF and air filter connection, but once you get those off you have plenty of room to get at the rear plugs. I was surprised to see that the DOHC uses individual coils and yeah each of those is almost 100 each without tax. Once you get the coils off though, be sure you have some long extentions on your sockets because they're pretty seem. I think it was 10" to get at mine. I can't be sure because I used a few smaller ones and joined them together. Each coil should be labeled for the cylinder it's on but honestly the coils are all identical so there's no real order to put them in. I'd keep them in the order they were pulled out though so you know which plug coil is having trouble if any. Just pop everything back on and check that the connections are all tight to make sure the vacuum is good. Like I mentioned in another post, at worst case it's a catalytic converter on the too lean codes, but check the smaller stuff before you jump to that as that can get expensive as not many mechanics also do exhaust work. They'll usually send you to someone else and from what I'm told some places won't even touch the exhaust on a Ford.