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Discussion Starter #1 (Edited)
I have a 2006 Ford Taurus 3.0L with the Vulcan engine. My check engine light comes on about once a month and stays on for 2 days and then turns off. My engine idles rough and dies sometimes. I took it to the Ford Dealership and they said the computer showed error codes P2196 and P2198 as O2 sensors being stuck. They said the catalytic converter was below threshold and needed to be replaced.

The cost for them to do this was very expensive so I am looking for a less expensive alternative. I have done some research and found there are 2 different catalytic converters, one in the front and one in the rear. I'm not sure which one I need. Could someone please help? I would like to purchase an after market replacement and take it to a local mechanic to be replaced.

Also, does this sound like a likely cause for the engine to idle rough and stall and throw codes P2196 and P2198? I would hate to change the catalytic converter and to continue having the idling problem.

By the way, I had a tune up today and had the fuel filter, spark plugs, spark plug wires, PCV valve, and air filter replaced. I continue to have the idling problem.

Thanks,
Jason
 

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The P2196 & P2198 are O2 sensors stuck rich codes. So, you need to find out whats going on there. Your air fuel ratio has too much fuel in it & that'll make the cat converters over heat trying to process the excess fuel in the exhaust & that can cause them to melt down internally & increase exhaust back pressure & that can cause the engine to run hot & the rich air/fuel ratio & excessive exhaust back pressure can cause really bad gas mileage & driveability problems, all a vicious circle.

Do you have a lit CEL/SES light??? If so, run this puppy by your favorite autoparts store for a no cost computer trouble code scan & post All code Numbers they find + any more the Dealer found, as they can offer up good trouble shooting clues.

Did this problem come about suddenly after some event, or slowly over time????
How long have you had this problem????
 

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Discussion Starter #3 (Edited)
Hi pawpaw,

Thank you for your help. I've only seen the check engine light every once in a while and then it clears after a couple of days. I have taken my car to a local mechanic and he saw the P2196 and P2198 codes. He cleared the codes and I drove it for about 30 minutes and the codes were back. Those are the only active codes. In the history, there had been a transmission error code. It's strange that those codes don't always cause the check engine light to come on. Maybe when the fuel/air mixture passes a certain threshold, then the check engine light comes on?

I have had this problem for about 6 months. I have had the car for about 3 years. I am not aware of any event that could have triggered this problem. It just started happening out of the blue.

So, are you saying that the catalytic converter wouldn't cause these error codes? From your post, it sounds like something else is causing those error codes and that could eventually damage my catalytic converter and cause more problems. If that is true, then changing my catalytic converter wouldn't help, right? Would that just set me up to have another damaged catalytic converter after a while?

Thanks,
Jason
 

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Yes, if you have a air/fuel ratio problem thats overly rich it would cause the replacement cat converter to be damaged also.

So you need to find out why the O2 sensors aren't switching like they're supposed to be doing.

I suppose you could have a vacuum leak, thats causing the computer to have the fuel injectors squirt more fuel to try & make up for the excess air, all to try & get the fuel trim back under control, but the needed fuel to do this is beyond the computers ability to have the fuel injectors do that.

SO, also look for a vacuum leak under hood. Like broken vacuum lines & that would include a damaged/leaking PCV valve rubber hose or stuck open PCV valve, leaking intake manafold gasket, ect.
 
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What happens a lot of times on these is that the o-ring at the IMRC seal on the back passenger side of the plastic upper intake goes bad and causes a lean condition/vacuum leak. The customer ignores the symptoms for a while and it eventually oveheats and melts the catalytic converters internally. I don't know if this is your case, because I don't know what data the dealer saw to lead him to that conclusion. I would look at fuel trims at idle and 02 sensor switching to determine the whole problem.
 

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Get a scan tool on the car and actually read the O2 sensor voltages. If they are showing more 1.0 volt, then you know you have a short to power somewhere in the circuit. With the engine running the sensors should be switching between 0.1 and 0.8 volts on a regular basis.

Is your MAF clean?

Unless you had a P0420 and P0430 codes or have symptoms of an exhaust restriction (like severely limited power), I don't see why your catalytic convertors would need replacing without further evidence.
 

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Discussion Starter #7
Well, I took the car to an auto parts store this morning and the only error code that showed up was P2196. The P2198 code had cleared. I purchased propane with a torch and a hose. With the engine running, I put the propane all over the intake area including the IMRC, PCV Valve, MMF, and all the vacuum hoses I could see. The engine never accelerated or stalled. The engine light was on before I went to the auto parts store but it went off after I left. Also, my gas mileage increased dramatically after leaving the parts store and the engine wasn't idling rough any more.

Could the tune up I had done yesterday have fixed the problem and I just had to drive it a while for it to idle correctly? The check engine light came on after the tune up yesterday and it started idling worse after the tune up. Now I'm thinking that it took a while for the PCM to recognize that the fuel/air mixture was correct and to recompensate. During the tune up, they changed the valve cover gasket, spark plugs, spark plug wires, and the fuel filter.

I'm going to continue driving it and I'll take it back to the auto parts store to see if all the codes have cleared. I'll let you guys know the outcome.
 

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If the fuel filter was clogged & thus limiting fuel volume flow, it'll cause a lean mixture when driving & confuse the computer so it'll want to enrich the mixture by causing the injector to squirt longer, again its all a vicious circle.

Try disconnecting the battery B- cable for say 15 min, to wipe the corrupt fuel trim tables, so the computer can begin to build new tables with all the new parts. Also perform the cold & warm idle strategy relearn routine, to prevent idle problems, as that too gets wiped with a battery cable disconnect.
http://www.taurusclub.com/forum/1358165-post4.html
 
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Yeah, try resetting the codes or disconnecting the battery to clear the memory. That way you start with a clean slate. If it still runs rough and you have the same codes after resetting it, then you know you still have the problem.
 

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Let us know how your trouble shoot goes.
 

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Discussion Starter #11
Well, my Taurus has continued to have the idling problem so I took it to another Ford dealership yesterday to get another diagnosis done on it since the 1st diagnosis by another dealership was incorrect. They called me today and said the problem was a faulty cam synchronizer. I am skeptical because 2 other mechanics have been incorrect so I told them the history on this car and now they want to take a 2nd look at it and they will call me tomorrow. Does anybody know if a faulty cam synchronizer would cause the car to idle rough and to die sometimes when at a stop sign or stop light? They said there weren't any active error codes now so maybe the tune up I had done a few months ago fixed the P2196 and P2198 codes?
 

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You may have more than one problem.

When its idling rough, or about to stall, what happens if you quickly shift into "N", does idle get better, or stay the same???

What happens if you switch the AC on when its in gear & idling rough, does the engine rpm drop, idle get worse, or stall??? If so, I'm thinking maybe an acting out IAC on the idle woes.

An acting out/sticking open PCV valve or rubber plumbing problem to it, can cause intermittent idle woes & fuel trim problems.
Same for leaky/sticking open fuel injectors.

If you come to suspect the IAC, perhaps consider removing & cleaning it inside with a plastic safe spray cleaner, like CRC QD, or CRC or Valvolene MAF spray cleaner & keep the IAC little black cap & electrical connector end up, so the solvents don't run in & cause other mischief. Cleaning the IAC may not last & is probably why Ford recommends replacement when they begin to act out, cleaning it didn't last for me on my 99 Ranger, but was a good trouble shooting step.

Seeing as you don't have cat converter efficiency trouble codes, or driveability or wimpy engine power output, signs of a clogged cat, I'd put that lower down on your suspect list.
Also seeing as how you don't have any trouble codes associated with the cam sync, I'd hold off on that too, unless you can hear it squeeking, then its time to replace the assembly.

You did have some O2 sensor switching trouble codes that seemed to be coming & going, that might be suggesting the O2 sensors may be near the end of their life, which is usually around 75-100K miles, so I agree with getting a scantool on the vehicle & driving it while monitoring the pre cat O2 sensors switching speed & range & monitoring both cyl banks short & long term fuel trim numbers & post any scan tool trouble code numbers & values for O2 sensor switching speed & voltage range & the fuel trim numbers.

More thoughts for consideration, let us know what you find.
 

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If you have a bad cam syncro you would probably notice it at higher RPMs before it causes an idle problem. Does the engine buck above 3500 RPM?

I'm not so sure on the cam syncro either. I feel like the mechanic is guessing unless he hooked up a scope and everything to test it (doubtful).
 

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Discussion Starter #14
I just spoke with the mechanic again and now they are saying that their testing was inconclusive. They said that the cam synchronizer was making a noise and they thought that could possibly be causing the problem, but they weren't sure. They said it would be $677 to replace that but they couldn't guarantee that it would fix the problem. Since they couldn't guarantee that, they said they wouldn't charge me for the diagnostic fee. They again said that there were no active codes in the computer.

So now I'm back to where I started. I have only noticed a problem with the car while it is idling. When the engine is accelerating, it runs normally. I have tried 2 Ford dealerships and another mechanic and nobody has been able to find the problem. It has cost me a lot of time and money so I think it would be best for me to sell this car and buy another one unfortunately.

If anyone can recommend any easy tests that I could perform myself, I would be glad to try them. After I pick up the car, I am going to try putting it in neutral when it idles rough to see what happens. I'll also try turning on the a/c to see what happens when it idles rough. I'll let you guys know what happens.

Thanks,
Jason
 

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Well, if the cam synco is making noise I agree it should be replaced. I also concur that it might or might not fix your idling problem, so it's a gamble. However $677 seems very steep for just the cam syncro replacement. The part is $80 and I would think it would only take about an hour of labor. So that job should cost more like $300.

All the easy tests would have been done by the techs already. You're into scan tool and oscilloscope territory I think.
 

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While your doing the IAC tests, also try disconnecting its electrical connector, the engine rpm should drop, it may run rough or stall, this is a sign that the IAC is working. If nothing happens, its a sign it isn't working. Could be a bad IAC, or maybe a wiring, or electrical connector problem preventing its computer controlled voltage pulses from reaching it.

EDIT: If the cam sensor is noisy/squeaking, its time to replace the assy, as the oil pump on the Vulcan is driven through it & if that fails at the wrong time you could damage, or loose an engine for lack of lube & it shouldn't cost as much as quoted to replace the cam sensor assy.
 

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Same codes, same symptoms here. Replaced IAC, upper intake manifold gaskets, new plugs and wires, new PCV valve, etc. etc. etc.

I found another thread that went on for 10+ pages where someone chased this problem for awhile until they replaced the fuel injectors, which cured it. Does it take a few more cranks than normal first thing in the morning to start the car?
 

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Discussion Starter #19
Pawpaw,

The idling problem seems to be worse when the car is in drive. When I shift to neutral, it does seem to get a little better but the car does idle rough and sometimes will die while in neutral. When I shift to drive from neutral, it gets worse and will almost die or will die. Turning on the air conditioner does seem to help a little but it still idles rough with the air conditioner on.

Disconnecting the cable from the IAC causes the engine rpm to drop and almost dies as a result. I don't have any cleaning fluid to clean the IAC, but I do remember the mechanic taking off the IAC and cleaning it with no improvement.

I purchased a motorcraft cam synchronizer with a sensor off of ebay for $65 that came off of a crate motor and is in new condition. I don't really feel comfortable changing it myself due to the timing issues that could happen if installed wrong. I made an appointment with the Ford dealership for next week to change it and they quoted me $312+tax for the labor. They said it would be 2.5 hours @ $125/hour. If I get brave enough, I may attempt to change it this weekend myself. I don't have the alignment tool though.

Before I had the tune up, I do remember that the Ford dealership had said that the catalytic converter was below threshold and needed to be replaced. Could that be causing this idling problem?
 

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Discussion Starter #20
15951,

The car always starts up fine on the first try. When the engine is cold, it idles a little faster and I don't have the idling problem then. When the engine warms up and starts to idle down, that's when it starts to idle rough.
 
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