Question..kind of tricky

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XtcmeLS

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My LS (2006) runs like a dream. But after i run it for about an hour, let it sit for 30 minutes, then start it again. The idle is REALLY rough, almost like it is missing. The after driving it for a second or 2 the idle is fine.


When car is Completely cold, it starts and runs fine. It is only after running an hour (or more) then letting sit for (30 mins plus) awhile, then restart if misses.


Coils going bad? need tune up?...Im high?



Thanks

Paul
 
I have no idea, so I will guess... IAC valve needs cleaning.
 
what I would do to troubleshoot this -...

the IAC - is dirty or/and slow - so it's not able to adjust fast enough to keep at target idle. This does not usually show on a cold start as the car revs up to 2500 rpm to pre-heat the O2 sensors.

get a vacuum gauge and make sure that you are pulling 18-22hg (~10psi) of vacuum at idle. if not- that's your issue - there are several reasons - but check it first.
 
pektel said:
I have no idea, so I will guess... IAC valve needs cleaning.
Click to expand...

Bad guess, the gen II don't have any IAC.
(Idle is controlled with the main throttle due to the throttle by wire system.)
 
Quik LS said:
what I would do to troubleshoot this -...

the IAC - is dirty or/and slow - so it's not able to adjust fast enough to keep at target idle. This does not usually show on a cold start as the car revs up to 2500 rpm to pre-heat the O2 sensors.

get a vacuum gauge and make sure that you are pulling 18-22hg (~10psi) of vacuum at idle. if not- that's your issue - there are several reasons - but check it first.
Click to expand...

No IAC on 2006.
 
You did say something about being a tweeker some years ago... hahaha

but seriously, does it make any noise? or is it just a rough shake? My LS shakes when it sits still in Neutral, but with the brake on in Drive it doesn't.
 
Is the car turning over and over and then finally starting? Or does it start up immediately (when it is warm) and just have a rough idle?

My V-8 has a rough start. I hold the pedal down to get it started and the exhaust smells like gas. I have changed almost everything (fuel pump, injectors, crank sensor, cam sensor, IAC, MAF sensor, 02 sensors, all 8 coils, etc.) so after checking your fuel pressure be careful of the "its the injectors." One item I haven't replaced is the EGR Valve. Replacing the coils when I got the car helped my LS's trouble between 40-45 mph.

There were a few people that also had issues with the front fuse box and also the fuse box in the truck having a short which caused them starting issues.
 
naw, car starts no problem, just really rough idle. not on a cold start tho, Only after car has been running hour + then shut off for 30 minutes + then RESTARTED, it idles like it is missing.
 
I've been having the same problem lately and my car is starting to "hiccup" during idle. I'm not sure what is causing it but I guess I'll have to take it up to Lincoln...Any ideas?

I've thought about fuel filter since I don't think it has ever been changed and I have 30xxx miles on my car, other than that I am not sure.
 
This is gonna sound stupid, but my car was running rough as well.

All I did was replace the fuel filter, and added a full can of SEAFOAM (not the cheap crap), and it runs like a million bucks!

My mechanic reccomended this, but I was skeptical......long story short he was right :D
 
esalomander said:
This is gonna sound stupid, but my car was running rough as well.

All I did was replace the fuel filter, and added a full can of SEAFOAM (not the cheap crap), and it runs like a million bucks!

My mechanic reccomended this, but I was skeptical......long story short he was right :D
Click to expand...

Did you use your Seafoam in the crankcase, fuel tank or both? I know you can do it in both but I'd like to hear your experience. Was there a lot of fun white smoke as mentioned on a lot of other forums??
 
King03LS8 said:
Did you use your Seafoam in the crankcase, fuel tank or both? I know you can do it in both but I'd like to hear your experience. Was there a lot of fun white smoke as mentioned on a lot of other forums??
Click to expand...

I just ran it through my gas tank. I have read about adding it into the crankcase, but never done it personally.

Also, I did not notice any smoke.
 
How much is Sea Foam around your guys' parts of the world? We sell it at my work for like $6.40 a can.

Im going to replace the fuel filter this week, Im getting HORRIBLE mileage... I drive like a 95 y/o grandpa and do only 15 MPG. I averaged 22 on a 90 miles trip doing 60 - 75... :( A can of foam might do me well :D
 
i dont think it would hurt any. that milage is terroble IMO
I get much better and its combined
Fuel filters are goofy on these puppies. My 02 sen threw a code before i replaced it. kinda odd but it wasnt the o2 it was the filter. goodluck
 
esalomander said:
I just ran it through my gas tank. I have read about adding it into the crankcase, but never done it personally.

Also, I did not notice any smoke.
Click to expand...

The FUN white smoke parade only comes out if you add it in the crankcase or vacuum it in I believe....I'll go buy a fuel filter tomorrow and some Seafoam. I have 4% oil life left so now is a great time to add it in before a change.
 
What is the SEAFOAM and what does it do exactly. I have read a few threads where people talk about using it. It is just basically a cleaner? How / where is it used?

Thanks
 
CrackerJack said:
How much is Sea Foam around your guys' parts of the world? We sell it at my work for like $6.40 a can.

Im going to replace the fuel filter this week, Im getting HORRIBLE mileage... I drive like a 95 y/o grandpa and do only 15 MPG. I averaged 22 on a 90 miles trip doing 60 - 75... :( A can of foam might do me well :D
Click to expand...


I've seen you drive. The only 95 year old you drive like is a 95 year old drag racer! :D

A new fuel filter will help some, but keeping your foot out of it will help more :)
 
King03LS8 said:
The FUN white smoke parade only comes out if you add it in the crankcase or vacuum it in I believe....I'll go buy a fuel filter tomorrow and some Seafoam. I have 4% oil life left so now is a great time to add it in before a change.
Click to expand...

It smokes when its put in the vac.


I would use it in the crank case and vac line. Thats what I do and I add it to the tank every other couple of times I use it.
 
King03LS8 said:
The FUN white smoke parade only comes out if you add it in the crankcase or vacuum it in I believe....I'll go buy a fuel filter tomorrow and some Seafoam. I have 4% oil life left so now is a great time to add it in before a change.
Click to expand...

Let me know if you notice any difference with adding it into the crankcase. I have read about it, and would like to know if it makes a difference.
 
Sounds like a fuel problem. Did you pull any codes? The check engine light doesn't have to be lit and it can still have a value in memory.

I had a problem similar, but more intermittent, and it turned out to be the fuel pump relay, an easy fix, located in the engine bay fuse holder.

Relays could behave like you are describing, but just a WAG...
 
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