4.0L OHV Rough Idle; Video and Pictures

DjDom · September 2, 2013

Hey guys,

My Ex has had a rough idle for quite a while now.
It's been driving me crazy and I can't find the source.
Recently the engine has started sounding like a diesel. Please don't freak me out that my engine is dying, cause it works great except for idle.

Here is a video, listen to the sound of the engine in the wheel wells and from the exhaust. It just doesn't sound right to me..
https://www.dropbox.com/s/kp25isob0viljos/VIDEO0060-0.mp4

It has a new muffler, new plugs and wires, air filter is clean, MAF is clean, IAC Valve is clean.

Today it finally threw a Check Engine light. This is the first time I was happy to see that little light..

Here's a pic of the screen:

So I assume somethings wrong with the O2 sensor, but when I go to read sensor data, I get this problem:

Notice in the top left, it doesn't give me any data.

Could the messed up sensor possibly be causing my rough idle?

Sorry for the long post, but I really need this fixed..

- Dom

rs2k · September 3, 2013

What kind of vacuum reading does your explorer have?

If your vehicle is truly running in closed loop mode than your sensors HAVE to be outputting a signal. Have you ever seen O2 sensor data with that program on that vehicle?

Does your scanner program show fuel trim like this?

DjDom · September 3, 2013

Never seen the vacuum readings or O2 readings get shown in the program..
Funny, since this program has a General OBDII mode, and 4 Ford Specific modes which still don't read it.
Know of any other programs that should be able to read it so I can try again?

rs2k · September 3, 2013

I use torque for android phones / tablets. It only costs $4.95 and the bluetooth OBDII adapter was less than $15 from Newegg.

http://www.newegg.com/Product/Product.aspx?Item=9SIA2ZZ0ZC2601
https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en

I don't think you can calculate vacuum correctly using OBDII since these vehicles have MAF sensors instead of MAP sensors. You should get a vacuum gauge from an auto parts store or harbor freight for that.

lobo411 · September 3, 2013

DjDom said:
Hey guys,

My Ex has had a rough idle for quite a while now

It doesn't sound bad to me at all. Mine has the same diesel rattle, but it's been going strong for 40k mi (the sound developed at 115k...total miles 155k) and getting 20 MPG on the freeway to boot. How many miles are on it?

If the O2 sensors have never been changed, I'd just go ahead and change them. The longer they go without being touched, the greater the danger that they become seized in the Y-pipe.

DjDom · September 3, 2013

lobo411 said:
It doesn't sound bad to me at all. Mine has the same diesel rattle, but it's been going strong for 40k mi (the sound developed at 115k...total miles 155k) and getting 20 MPG on the freeway to boot. How many miles are on it?

If the O2 sensors have never been changed, I'd just go ahead and change them. The longer they go without being touched, the greater the danger that they become seized in the Y-pipe.

I'm not so concerned bout the diesel sound as much as I am about the rough idle.

I'm at 230k KMs, so.. 143k miles.

The O2s are original. Think they're causing the problem?

DjDom · September 3, 2013

rs2k said:
I use torque for android phones / tablets. It only costs $4.95 and the bluetooth OBDII adapter was less than $15 from Newegg.

http://www.newegg.com/Product/Product.aspx?Item=9SIA2ZZ0ZC2601
https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en

I don't think you can calculate vacuum correctly using OBDII since these vehicles have MAF sensors instead of MAP sensors. You should get a vacuum gauge from an auto parts store or harbor freight for that.

I use a similar scan tool, except it's USB. So I just use my laptop.

lobo411 · September 3, 2013

DjDom said:
I'm not so concerned bout the diesel sound as much as I am about the rough idle.

I'm at 230k KMs, so.. 143k miles.

The O2s are original. Think they're causing the problem?

I think they're rated for like 60-100k, so no matter what you're definitely overdue. Especially since you're getting an o2 code. Hopefully they come out easy, but if not, it might be easier to just drop the Y-Pipe. Then you don't have to worry about getting access to the passenger side upstream sensor.

I replaced my o2 sensors after 150k a few months ago, and it eliminated a check engine light issue I've had for years (catalyst system below efficiency code), so it can make a difference.

DjDom · September 3, 2013

lobo411 said:
I think they're rated for like 60-100k, so no matter what you're definitely overdue. Especially since you're getting an o2 code. Hopefully they come out easy, but if not, it might be easier to just drop the Y-Pipe. Then you don't have to worry about getting access to the passenger side upstream sensor.

I replaced my o2 sensors after 150k a few months ago, and it eliminated a check engine light issue I've had for years (catalyst system below efficiency code), so it can make a difference.

Great. How expensive are they and how do I change them..

lobo411 · September 4, 2013

DjDom said:
Great. How expensive are they and how do I change them..

About $30-$40 at Rockauto. They're basically just like a big spark plug, but the problem is that they tend to seize and get welded to the pipe due to the exhaust heating/cooling cycle + rust. The first thing I'd do would be to try a 22 mm or 3/4" box wrench. If you're lucky, it'll just turn and come out like a dream, but that's unlikely so don't try very hard. If it doesn't come easy, then get an oxygen sensor socket at PepBoys or Amazon or whatever. You might have to try tricks then....heat the bung with a blowtorch, try PB Blaster and let it soak in, cheater bar, etc...

I did all of the above on mine and I got the driver's side one out fine, but the passenger side ended up tearing out the bung threads. Not a big deal if that happens...you can grind off the old bung and weld in a new one, or have an exhaust shop do it for $20 or so.

DjDom · September 4, 2013

lobo411 said:
About $30-$40 at Rockauto. They're basically just like a big spark plug, but the problem is that they tend to seize and get welded to the pipe due to the exhaust heating/cooling cycle + rust. The first thing I'd do would be to try a 22 mm or 3/4" box wrench. If you're lucky, it'll just turn and come out like a dream, but that's unlikely so don't try very hard. If it doesn't come easy, then get an oxygen sensor socket at PepBoys or Amazon or whatever. You might have to try tricks then....heat the bung with a blowtorch, try PB Blaster and let it soak in, cheater bar, etc...

I did all of the above on mine and I got the driver's side one out fine, but the passenger side ended up tearing out the bung threads. Not a big deal if that happens...you can grind off the old bung and weld in a new one, or have an exhaust shop do it for $20 or so.

Which O2 sensor is that code for? So I know which one MUST be changed.

rs2k · September 4, 2013

Change both pre cat sensors. They really should have been changed a while ago.

Changing both will end up paying for themselves after a few fuel tanks.

DjDom · September 4, 2013

rs2k said:
Change both pre cat sensors. They really should have been changed a while ago.

Changing both will end up paying for themselves after a few fuel tanks.

Easier said than done. Knowing my luck, I won't get them out.

sloop · November 1, 2013

did you get them changed?

DjDom · November 1, 2013

No, I did not.

If I can pass emissions with them bad, I'll leave them be.
I don't notice a change in gas mileage/performance. Just the rough idle.

deweyville65 · November 1, 2013

Mine sounds similar. I have replaced the rocker arms and pushrods on the left bank. Have to do the right bank though. I can definitely hear the rocker arm clatter in the video. FYI I had a bad 02 sensor on the left bank, replaced it, now the fuel mileage runs around 18 instead the nearly 20 I was getting.

DjDom · November 10, 2013

deweyville65 said:
Mine sounds similar. I have replaced the rocker arms and pushrods on the left bank. Have to do the right bank though. I can definitely hear the rocker arm clatter in the video. FYI I had a bad 02 sensor on the left bank, replaced it, now the fuel mileage runs around 18 instead the nearly 20 I was getting.

Guess I'm not gonna change the sensor then.

1992fordgreen · November 10, 2013

I bet your PCM is taking a dump. Akward minor issues always peer when the PCM craps. GL

DjDom · November 11, 2013

Nah, my PCM is good. I'm able to access all data and preform Ford OBDII tests.

1992fordgreen · November 12, 2013

Doesn't matter, capacitors leak over time. Wear in old cars and parts, part of life.

4.0L OHV Rough Idle; Video and Pictures

DjDom

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lobo411

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