Idle Issue - Jim Warman

I put in Jim's name in hopes of getting his attention. It appears to me that
Jim is a professional Ford mechanic.

For three years now I've been dealing with a bad idle. When sitting at a red
light; the rpm's are on the low side, the engine sort of vibrates, enough
that it sometimes causes the exhaust or items in, or on the car to rattle.
It never stalls and runs terrific otherwise.
2000 Explorer XLS, Canadian car, 4.0 SOHC, Auto Trans. 4WD, 116K mi.
This has a "returnless" electric fuel pump. Fuel filter changed about four
years ago. Always Chevron or Shell gas. Located in SW Washington.
No codes set.
So far I've tried, with no success -
New, Air filter, Serpentine belt, Idler pulley, IAC valve, Plugs, Wires,
Fuel Pump, Upper and lower intake gaskets.
Adjusted motor mounts, checked exhaust for looseness, clean MAF with
throttle body cleaner, Inspect hoses for leaks, Checked EGR system - appears
fine. (Idle drops and gets worse when vac. is applied to EGR.) Cleaned
throttle body.
Also I installed long enough ago that I don't remember when, new valve parts
to the trans per dealer recall for trans, no engine braking issue. (DIY)
Anybody have any ideas?

Rick

Rick, offhand I can't think of anything that would cause your concern....
perhaps an out of balance of faulty AC compressor but this would make the
concern predictable.... A code scan might be in order just to see if there
is something that is not critical enough to set the CEL...

If you like, PM me your VIN and I can run OASIS for you.


"Rick Wolford" > wrote in message
. ..
>I put in Jim's name in hopes of getting his attention. It appears to me
>that Jim is a professional Ford mechanic.
>
> For three years now I've been dealing with a bad idle. When sitting at a
> red light; the rpm's are on the low side, the engine sort of vibrates,
> enough that it sometimes causes the exhaust or items in, or on the car to
> rattle. It never stalls and runs terrific otherwise.
> 2000 Explorer XLS, Canadian car, 4.0 SOHC, Auto Trans. 4WD, 116K mi.
> This has a "returnless" electric fuel pump. Fuel filter changed about four
> years ago. Always Chevron or Shell gas. Located in SW Washington.
> No codes set.
> So far I've tried, with no success -
> New, Air filter, Serpentine belt, Idler pulley, IAC valve, Plugs, Wires,
> Fuel Pump, Upper and lower intake gaskets.
> Adjusted motor mounts, checked exhaust for looseness, clean MAF with
> throttle body cleaner, Inspect hoses for leaks, Checked EGR system -
> appears fine. (Idle drops and gets worse when vac. is applied to EGR.)
> Cleaned throttle body.
> Also I installed long enough ago that I don't remember when, new valve
> parts to the trans per dealer recall for trans, no engine braking issue.
> (DIY)
> Anybody have any ideas?
>
> Rick
>

There are a lot of things that can deliver a "bank lean" code... One could
be a lazy O2 sensor but I find it hard to replace one without some empirical
data to make me think that way (watching the O2 activity on a good scan tool
helps). Flip side, some sensors/actuators can be cheaper to replace than to
test.....decisions, decisions....

In retrospect, the 4.0 OHC engine did have about three different intake
manifold configurations.... the only one I am familiar with is the style on
my sons 97 Ranger. Later ones *may* have ported EGR flow.... I'll have to do
some homework there....

Here's why ported EGR makes such a difference.... The DPFE measures only
total EGR flow.... If a motor has ported EGR delivery, and if some of the
EGR ports are blocked, a few cylinders will receive the bulk of EGR flow and
other cylinders none at all... Result will be a very rough idle but only
when EGR is commanded (and this will be decided by computer strategy). The
3.8 has this as a very common concern.

Since total EGR flow isn't excessive, no codes will be set.

Back to the bank lean code.... The PCM is programmed to ignore a specific
number of misfires (either "dead" misfire or poor cointribution misfire -
there can be a difference) in a particular time span. Anytime a cylinder
doesn't consume the bulk of the oxygen it is supplied, exhaust gas oxygen
content will go up. The PCM sees high oxygen content as a lean mixture...
even if the mixture isn't "lean".

HTH

"Ashton Crusher" > wrote in message
...
> If you guys figure it out a friend of mine would like the answer too.
> He just spent $900 at a shop for manifold gaskets that they said would
> fix it and it's not fixed. The only thing I didn't see listed that
> you might replace is the O2 sensors. The code he gets is left bank
> lean.
>
>
>
> On Sun, 29 Apr 2007 17:30:41 GMT, "Jim Warman"
> > wrote:
>
>>Rick, offhand I can't think of anything that would cause your concern....
>>perhaps an out of balance of faulty AC compressor but this would make the
>>concern predictable.... A code scan might be in order just to see if there
>>is something that is not critical enough to set the CEL...
>>
>>If you like, PM me your VIN and I can run OASIS for you.
>>
>>
>>"Rick Wolford" > wrote in message
m...
>>>I put in Jim's name in hopes of getting his attention. It appears to me
>>>that Jim is a professional Ford mechanic.
>>>
>>> For three years now I've been dealing with a bad idle. When sitting at a
>>> red light; the rpm's are on the low side, the engine sort of vibrates,
>>> enough that it sometimes causes the exhaust or items in, or on the car
>>> to
>>> rattle. It never stalls and runs terrific otherwise.
>>> 2000 Explorer XLS, Canadian car, 4.0 SOHC, Auto Trans. 4WD, 116K mi.
>>> This has a "returnless" electric fuel pump. Fuel filter changed about
>>> four
>>> years ago. Always Chevron or Shell gas. Located in SW Washington.
>>> No codes set.
>>> So far I've tried, with no success -
>>> New, Air filter, Serpentine belt, Idler pulley, IAC valve, Plugs, Wires,
>>> Fuel Pump, Upper and lower intake gaskets.
>>> Adjusted motor mounts, checked exhaust for looseness, clean MAF with
>>> throttle body cleaner, Inspect hoses for leaks, Checked EGR system -
>>> appears fine. (Idle drops and gets worse when vac. is applied to EGR.)
>>> Cleaned throttle body.
>>> Also I installed long enough ago that I don't remember when, new valve
>>> parts to the trans per dealer recall for trans, no engine braking issue.
>>> (DIY)
>>> Anybody have any ideas?
>>>
>>> Rick
>>>
>>

After you mentioned V8, we were going to head there.... There is an elbow at
the back of the intake manifold that can get mushy, rip and create some
grief.... This would normally affect both banks but there is a bit of a
rub..... One would need a very capable scan tool to access the fuel trim
PIDs to see if the other bank might be close to setting a code but hadn't
yet "gotten around to it".....

My bad for not even thinking of it earlier but, in my defence, I don't work
on anything with spark plugs very much. Those times I am given a gas
drivability concern, I always check the 4 fuel trim PIDs..... It is one of
those things that is "too" natural and gets lost in the system..... If
someone were to ask me to list the first 12 things I do in the morning after
getting up, I would probably forget to list "put on my socks"......

Nah.... I still had a brain fart.... glad to hear that your friend found the
concern.....


"Ashton Crusher" > wrote in message
...
> He fixed it himself. Don't have the exact details but something about
> the hose to the PCV leaking.
>
>
> On Sun, 29 Apr 2007 23:23:50 -0700, Ashton Crusher >
> wrote:
>
>>See if you think these symptoms add up to anything, keep in mind he
>>just had the manifold gaskets replaced. I think it's a 98 Expedition
>>with a V8, 180K miles. I drove to lunch with him and at times it
>>idles properly but then while you are sitting at the light the speed
>>will suddenly drop about 150 rpm and the idle gets rough. Often after
>>15 seconds of that it just stops running. Starts right up.
>>
>>
>>On Sun, 29 Apr 2007 19:22:41 GMT, "Jim Warman"
> wrote:
>>
>>>There are a lot of things that can deliver a "bank lean" code... One
>>>could
>>>be a lazy O2 sensor but I find it hard to replace one without some
>>>empirical
>>>data to make me think that way (watching the O2 activity on a good scan
>>>tool
>>>helps). Flip side, some sensors/actuators can be cheaper to replace than
>>>to
>>>test.....decisions, decisions....
>>>
>>>In retrospect, the 4.0 OHC engine did have about three different intake
>>>manifold configurations.... the only one I am familiar with is the style
>>>on
>>>my sons 97 Ranger. Later ones *may* have ported EGR flow.... I'll have to
>>>do
>>>some homework there....
>>>
>>>Here's why ported EGR makes such a difference.... The DPFE measures only
>>>total EGR flow.... If a motor has ported EGR delivery, and if some of the
>>>EGR ports are blocked, a few cylinders will receive the bulk of EGR flow
>>>and
>>>other cylinders none at all... Result will be a very rough idle but only
>>>when EGR is commanded (and this will be decided by computer strategy).
>>>The
>>>3.8 has this as a very common concern.
>>>
>>>Since total EGR flow isn't excessive, no codes will be set.
>>>
>>>Back to the bank lean code.... The PCM is programmed to ignore a specific
>>>number of misfires (either "dead" misfire or poor cointribution misfire -
>>>there can be a difference) in a particular time span. Anytime a cylinder
>>>doesn't consume the bulk of the oxygen it is supplied, exhaust gas oxygen
>>>content will go up. The PCM sees high oxygen content as a lean mixture...
>>>even if the mixture isn't "lean".
>>>
>>>HTH
>>>
>>>"Ashton Crusher" > wrote in message
...
>>>> If you guys figure it out a friend of mine would like the answer too.
>>>> He just spent $900 at a shop for manifold gaskets that they said would
>>>> fix it and it's not fixed. The only thing I didn't see listed that
>>>> you might replace is the O2 sensors. The code he gets is left bank
>>>> lean.
>>>>
>>>>
>>>>
>>>> On Sun, 29 Apr 2007 17:30:41 GMT, "Jim Warman"
>>>> > wrote:
>>>>
>>>>>Rick, offhand I can't think of anything that would cause your
>>>>>concern....
>>>>>perhaps an out of balance of faulty AC compressor but this would make
>>>>>the
>>>>>concern predictable.... A code scan might be in order just to see if
>>>>>there
>>>>>is something that is not critical enough to set the CEL...
>>>>>
>>>>>If you like, PM me your VIN and I can run OASIS for you.
>>>>>
>>>>>
>>>>>"Rick Wolford" > wrote in message
>>>>>news:ruKdnZdVpOgIY63bnZ2dnUVZ_oSnnZ2d@comcast .com...
>>>>>>I put in Jim's name in hopes of getting his attention. It appears to
>>>>>>me
>>>>>>that Jim is a professional Ford mechanic.
>>>>>>
>>>>>> For three years now I've been dealing with a bad idle. When sitting
>>>>>> at a
>>>>>> red light; the rpm's are on the low side, the engine sort of
>>>>>> vibrates,
>>>>>> enough that it sometimes causes the exhaust or items in, or on the
>>>>>> car
>>>>>> to
>>>>>> rattle. It never stalls and runs terrific otherwise.
>>>>>> 2000 Explorer XLS, Canadian car, 4.0 SOHC, Auto Trans. 4WD, 116K mi.
>>>>>> This has a "returnless" electric fuel pump. Fuel filter changed about
>>>>>> four
>>>>>> years ago. Always Chevron or Shell gas. Located in SW Washington.
>>>>>> No codes set.
>>>>>> So far I've tried, with no success -
>>>>>> New, Air filter, Serpentine belt, Idler pulley, IAC valve, Plugs,
>>>>>> Wires,
>>>>>> Fuel Pump, Upper and lower intake gaskets.
>>>>>> Adjusted motor mounts, checked exhaust for looseness, clean MAF with
>>>>>> throttle body cleaner, Inspect hoses for leaks, Checked EGR system -
>>>>>> appears fine. (Idle drops and gets worse when vac. is applied to
>>>>>> EGR.)
>>>>>> Cleaned throttle body.
>>>>>> Also I installed long enough ago that I don't remember when, new
>>>>>> valve
>>>>>> parts to the trans per dealer recall for trans, no engine braking
>>>>>> issue.
>>>>>> (DIY)
>>>>>> Anybody have any ideas?
>>>>>>
>>>>>> Rick
>>>>>>
>>>>>
>>>