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Discussion Starter · #1 ·
So, just about 2 months ago we discussed the odd misfire issue with my 2001 Duratec. Here's that thread:

http://www.taurusclub.com/forum/82-maintenance-repair/160666-strange-misfire-my-01-duratec.html


To recap for those that don't want to click the link, my 2001 Duratec (162k miles) is acting up. I've had the car 8.5 years, and have done a lot of maintenance over the years. The issue is that when the car is cold, it runs really rough both in Park/Neutral and in gear. After the car reaches the normal operating temp range, the problem goes away. The plugs/wires were replaced around 105k with Motorcraft wires/platinum plugs, and at that time, the upper intake manifold gasket was replaced with a gasket set from the Ford dealer.

I had a smoke test done, and there was a small vacuum leak detected (which was fixed). My son took the car back to college, but reported the same issue the next time he started the car. Now he's back home, and I need to get this issue fixed.

I figured I would start with the upper intake manifold gasket. The symptoms really go away when the car heats up, and Sheila posted that it sounded like a gasket issue. My question is this: is it possible to have an issue with the manifold gaskets but not have any other issues? (meaning that the gaskets themselves did indeed go bad). The car's gas mileage has not varied in years, and it doesn't use any appreciable amount of coolant. Also, is it worth simply replacing both the upper and lower intake manifold gaskets? I won't be doing this repair myself, but the gasket set is pretty inexpensive, and I'm tired of messing with the problem!
 

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I read my replies in the original thread and cant think of any other possibilities or suggestions. Sorry, im at a loss.
 

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If it's inexpensive, do it. Best case, problem solved. Worst case, you know your intake gaskets are good for a while.
 

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I would tend to agree. I have some of the same symptoms, and I am considering pulling it all apart and replacing both upper and lower gaskets. I only replaced the upper last time. I will also replace all the injector o-rings, because any of them could cause the same issue.
 

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This is the same problem I'm encountering right now as well.
 

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Have you cleaned the injectors? If they have poor atomization, the fuel may just puddle in the intake until it is warm enough to vaporize on the intake surfaces.
 

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Discussion Starter · #7 ·
I would tend to agree. I have some of the same symptoms, and I am considering pulling it all apart and replacing both upper and lower gaskets. I only replaced the upper last time. I will also replace all the injector o-rings, because any of them could cause the same issue.
Should I look in to doing the o-rings at the same time? Are they going to be uncovered when the upper and lower intake manifolds are off?
 

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Discussion Starter · #8 ·
Ok -- just got off the phone with the local Precision Tune. I've had some of the maintenance done by them over the last 8 years or so. They let you bring your own parts in, which is nice. They quoted me the following:

Replacing o-rings for the injectors: $153
Replacing upper and lower intake gaskets: $340

They are claiming 4 hours on the gaskets, and almost 2 hours on the injectors. Sound about right?
 

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Maybe you have more than one problem.

Since you don't have any pending or set trouble codes, it seems to me that indicates it's something the computer isn't directly monitoring, so that in itself is a small clue.

I like all of the ideas put forth, but if replacing the intake manafold gaskets passed the smoke test & didn't fix the problem last time, it doesn't seem to me they've earned a high up place on the suspect list????

In the other thread it wasn't clear if the PCV valve has Ever been replaced???? If not, it's Way past due!!!!
The rubber elbow to it is also prone to dryrotting & leaking in it's bend, so if you decide to replace the PCV vlave, give it's connecting rubber elbow a close inspection.
I know you had a smoke test done, but that doesn't mean the PCV valve has earned a pass!!!!
The PCV valve is a calculated for vacuum leak & if it's stuck closed when cold, it'll upset the programmed for, open loop fuel trim value.

Have you done a fuel pressure leak down test????

Have you hooked up a scantool that'll read PID's & monitored long & short term fuel trim????
Have you monitored the O2 sensors switching speed & range????
Have the O2 sensors ever been replaced????

The IAC, probably belongs on your suspect list too, for the rough cold idle, especially if engine rpm is low.

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

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Discussion Starter · #10 ·
Maybe you have more than one problem.

Since you don't have any pending or set trouble codes, it seems to me that indicates it's something the computer isn't directly monitoring, so that in itself is a small clue.

I like all of the ideas put forth, but if replacing the intake manafold gaskets passed the smoke test & didn't fix the problem last time, it doesn't seem to me they've earned a high up place on the suspect list????

In the other thread it wasn't clear if the PCV valve has Ever been replaced???? If not, it's Way past due!!!!
The rubber elbow to it is also prone to dryrotting & leaking in it's bend, so if you decide to replace the PCV vlave, give it's connecting rubber elbow a close inspection.
I know you had a smoke test done, but that doesn't mean the PCV valve has earned a pass!!!!
The PCV valve is a calculated for vacuum leak & if it's stuck closed when cold, it'll upset the programmed for, open loop fuel trim value.

Have you done a fuel pressure leak down test????

Have you hooked up a scantool that'll read PID's & monitored long & short term fuel trim????
Have you monitored the O2 sensors switching speed & range????
Have the O2 sensors ever been replaced????

The IAC, probably belongs on your suspect list too, for the rough cold idle, especially if engine rpm is low.

More thoughts for consideration, let us know what you find.
pawpaw -- good thoughts here. Unfortunately, the smoke test was actually done when the engine was at full operating temperature (why I didn't drop it off the night before I don't know, because I should have), so the "miss" wasn't there when they performed the test. I'm more suspicious of the lower intake manifold gasket, since I know it is the original gasket. I'd like to think the OEM upper intake gasket that was installed 5 years ago is still good, but you never know.

I just looked back through my records, and don't show where I purchased a PCV valve, so it IS time for that to be replaced. Not sure how I missed that one along the way. Should I also replace the hose and connector, as they are original?

I haven't had the fuel pressure leak down test done -- would that detect a problem with the injectors/o-rings?

The O2 sensors were replaced shortly before I bought the car, but that was about 76,000 miles ago (and 8.5 years). I read recently that the O2 sensors often go bad AFTER the problems show up. Should they be a regular maintenance item at a certain mile interval, kind of like the spark plugs? And are there 4 on this car?

Is the IAC the part that can be removed and cleaned? Or is that the MAF sensor? I'm sure it's the original part that's on the car, as I have not replaced it.
 

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Discussion Starter · #11 ·
Have you cleaned the injectors? If they have poor atomization, the fuel may just puddle in the intake until it is warm enough to vaporize on the intake surfaces.
I've never actually paid to have them cleaned, but in the last 8 years, I have probably run at least 25 bottles of Techron Injector cleaner through them.

Would poor atomization show up as reduced gas mileage? The gas mileage on this car has been amazingly consistent over the last 8 years, so I've always figured that the injector cleaner was doing its job.
 

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If you've been cleaning them regularly with Techron they're probably OK. If the engine is hot during most drives you may not notice a decrease in mileage even with fouled injectors.
 

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Yup the MAF & IAC can be removed & cleaned with a non residual, plastic safe spray, like CRC QD, or CRC MAF sensor cleaner, ect, but if the IAC is acting out, cleaning it may not last, it didn't on my 99 Ranger 4.0L, but was a good trouble shooting test for me.

If you decide to remove & clean the MAF sensor too, make sure to keep it squeeky clean, let it cool first if the vehicle has recently been driven, don't touch the sensor with the spray wand & be sure to use a non residual cleaner like CRC MAF cleaner. Anything drying on the MAF heated sensor element, will bake on & corrupt it's calibration & cause it to send the computer bad PID info & that'll have the computer get confused about true air flow into the engine & cause it to mess up fuel trim, all a vicious circle!!!!

A fuel pressure leak down test might indicate a problem with leaking fuel injectors, or a pump problem.

If your going to replace the PCV valve, why not consider replacing the connecting rubber hose too, it's served it's purpose with 162k on it.

Well with 76K on these O2 sensors they're sorta coming on the suspect list mileage wise, as most folks consider replacing them around 75-100K.
It would probably be worth getting a reading on their switching range & switching speed, to see if they're geting lazy & if so, replace them.
They're not on line yet, when your having your cold start up problem, but being heated O2 sensors, they're likely on line within the 5 minute period you say it's acting out.

Edit: I'm talking about the two up stream O2 sensors, that the computer uses to help it figure out what to do about the fuel injector squirt time, in controlling fuel trim.

The two down stream cat monitoring O2 sensors don't figure in on fuel trim & if you don't have any trouble codes for them, no need to replace.

Well I suppose with the smoke test being done on a warmed up engine, the intake gaskets still belong up there on the suspect list.
Maybe consider checking the torque on the upper & lower intake manafold fastners & replacing the PCV valve & maybe try cleaning the IAC valve & see if you get positive results, before tearing into the manafold gaskets.
 

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Discussion Starter · #14 · (Edited)
Heard back from the mechanic. It turns out that the upper and lower intake manifold gaskets were bad, and there was a crimp in a vacuum line under the intake manifold.

But that wasn't all. They also said that the coil pack and MAF sensor were bad. The coil pack I can understand, as it is the original and is now 10 years old (and 162k old, too). However, can I not just clean the MAF sensor? Or does it actually reach a point where it needs to be replaced?
 

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The MAF sensor can be cleaned as I outlined above.

Since you didn't have a trouble code for it, I'd at least question more closely Why the shop thinks it needs replacing.

It's easy to do, so you can replace it if need be.

If you decide to have them replace it, ask if they're using a new OEM MAF sensor, a reman, or an aftermarket part.

Since the MAF sensor only sees filtered air, If it's dirty, you need to look upstream to the air box, air tube & air filter, to find out Why it got dirty.
 

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Discussion Starter · #16 ·
pawpaw,

Forgot to add in my post above that the mechanic said he pulled a code off the OBD that indicated a bad MAF. I figured I could replace that part myself using an aftermarket part. I'm willing to bet that it's dirty because the area that my son is living is under serious construction, and there is a LOT of dirt in the air. I replaced the air filter last year, but something tells me it's filthy again.

Am I correct in assuming that if there is a code pulled for the MAF that it should be replaced and not cleaned?
 

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If the MAF sensor needs replacement or not, depends on whats wrong with it, so post the trouble code number.

Check the air filter, replace if needed, make sure it's sealing well, button the air box & air tube up correctly & show that youngster how to do it, so he can keep tabs on things.
 

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Discussion Starter · #20 ·
pawpaw -- I'm definitely going to show my son how to change this air filter. As luck would have it, I bought 2 last time and the other one is about to be installed. I'm picking the car up in about an hour, and I'll post the code that they pulled from the MAF.

sheila -- I'll pick up some CRC at the parts store and clean the MAF. It would be nice if I could get by without replacing the MAF -- I've priced it at $60 locally.
 
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