2004 Lincoln LS Rough idle

joeym427

joeym427

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Hi All,

I’m having an issue where my Lincoln is idling rough when initially starting it. Just started happening this week, just as it has started getting cold (I live in Ohio). My car is an 04 v6 and has 155k. I replaced all of the coils and plugs at ~125k and the plugs again at 140k when doing the valve cover gaskets. It appears that the PCV valve hose was changed earlier on a previous job.
My big take away is that after doing an Italian tune up the issue goes away. I’m able to put the car back in park and I have no issue. Has anyone else experienced this issue?
In the past I had a shop clean out my throttle body (seemed random at the time)
 
Here’s some more info: essentially the car idles until it dies. I watched yesterday as the car idled at 400 rpm , I planted my foot on the gas and it didn’t change. After dropping it into gear it came to life and the car was fine. Just seems odd.
 
**Update**

Decided to go with cleaning the throttle body as it was simple and cheap. Took about 25 minutes. Car appears to be alitlte more responsive, we’ll see what happens when it’s sits over the weekend in the cold.
 
*update* drove car after it sat for two days. No difference. Very jerky idol when started , had to drop it in gear and plant foot on gas to keep it from stalling. Planting foot on gas while in park is not enough.

any ideas on what would cause this?
 
The PCV elbow comes to mind as a possible issue. Unplug the electrical connector to the MAF and start the car. If it does better, then it could be an intake leak (such as a torn PCV elbow), or a dirty MAF.
 
joegr said:
The PCV elbow comes to mind as a possible issue. Unplug the electrical connector to the MAF and start the car. If it does better, then it could be an intake leak (such as a torn PCV elbow), or a dirty MAF.
Click to expand...
I’ll give the MAF a cleaning over the weekend. Will update with results. Thanks!
 
So I have the same problem and I have a lincoln ls 03 v6 and I was throwing codes for my break booster and I decided to switch that out yesterday (which was a pain in the) but I started it up today from a cold start and it started up just fine. I was thinking maybe a had a bad vacuum leak in the booster which replacing it helped.
 
01V6 always a vac leak somewhere or the IAC valve. I don't believe the 03 has an IAC valve. check all hose connections are tight.
 
joegr said:
The PCV elbow comes to mind as a possible issue. Unplug the electrical connector to the MAF and start the car. If it does better, then it could be an intake leak (such as a torn PCV elbow), or a dirty MAF.
Click to expand...
PCV elbow looks pretty good. The MAF looked very very clean, didn’t even bother cleaning it. We just had a brief weather change in Ohio, it’s been in the 60s this last week and I’ve had no issues with the car. It seems like I only have issues during cold starts. Also started running 93.
 
6ix5ive1ne said:
So I have the same problem and I have a lincoln ls 03 v6 and I was throwing codes for my break booster and I decided to switch that out yesterday (which was a pain in the) but I started it up today from a cold start and it started up just fine. I was thinking maybe a had a bad vacuum leak in the booster which replacing it helped.
Click to expand...
What’s odd is that I don’t have any codes that are being thrown. I just have the feeling that my coils are starting to go prematurely causing a misfire ? What’s unique is that I have no codes.
 
Use Forscan or another tool to get the mode 6 misfire data. That will show misfire counts that are below the threshold to trigger an actual misfire code. You can also look at short term and long term mixture adjust to get a hint about air leaks (look at cold idle, at warm cruise, and while accelerating).
 
joegr said:
Use Forscan or another tool to get the mode 6 misfire data. That will show misfire counts that are below the threshold to trigger an actual misfire code. You can also look at short term and long term mixture adjust to get a hint about air leaks (look at cold idle, at warm cruise, and while accelerating).
Click to expand...
Alright. So I just ran a mode 6 misfire data scan. All cylinders look good but under misfire general data I exceded the maximum emission threshold misfire data rate. See attached picture. Do you know what this may mean? Thanks for the help!

Capture.PNG
 
joegr said:
Use Forscan or another tool to get the mode 6 misfire data. That will show misfire counts that are below the threshold to trigger an actual misfire code. You can also look at short term and long term mixture adjust to get a hint about air leaks (look at cold idle, at warm cruise, and while accelerating).
Click to expand...
Also it’s worth noting that when using Forscan I came across several additional codes. P0660, U1041, U1262. Are one of these codes more likely the culprit ? I read that a faulty IMT valve could cause a rough idle when cold.
 
joeym427 said:
Also it’s worth noting that when using Forscan I came across several additional codes. P0660, U1041, U1262. Are one of these codes more likely the culprit ? I read that a faulty IMT valve could cause a rough idle when cold.
Click to expand...
I just downloaded forscan also, do you run this mode 6 test with engine running? Or it saves all the log info? Here's what it said with engine off. Reason I ask is all my individual cylinders are identical data and the evap section said not ready. I guess yours are too, but our numbers are different.

I have code p0108 which Auto zone says I need a new EGR valve but info on here doesn't mention EGR at all, but it mentions misfires and other stuff. Thanks.
16102303596115232737114044612663.jpg
 
Last edited:
SultanGris said:
I just downloaded forscan also, do you run this mode 6 test with engine running? Or it saves all the log info? Here's what it said with engine off. Reason I ask is all my individual cylinders are identical data and the evap section said not ready. I guess yours are too, but our numbers are different.

I have code p0108 which Auto zone says I need a new EGR valve but info on here doesn't mention EGR at all, but it mentions misfires and other stuff. Thanks.View attachment 828575152
Click to expand...
Found a forum that spoke about your p0108 code, check this out P0108: Manifold Absolute Pressure/BARO Sensor High Input - anyone know what this is?. Also I ran the mode 6 test while the car was running. I cross posted this on the FB page. Will update if any progress is made.
 
Please note that the MAP sensor is an integrated part of the EGR valve assembly on the 2nd Gen LS.
 
Guess he says it was an egr valve, thanks a million. Guess autozone is legit after all!
 
04_Sport_LS said:
P0108 is fairly common on a Gen 2 LS at around 150k miles. P0408 also.
Click to expand...

The two times I have seen it both came down to the plastic of the EGR assembly cracking and leaking vacuum. I'm sure they all will eventually.
 
04_Sport_LS said:
I haven't had the pleasure of changing the EGR on a V6. :eek: The V8 is pain in the ass enough. :rolleyes:
Click to expand...
yeah I got a v8, it doesn't look fun, that's why I was hoping AutoZone was wrong and it was something else, no such luck, lol
 
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