Rough Idle, Gen2 V8

JoshMcMadMac

JoshMcMadMac

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I have noticed that the LS will get a "lopey" idle to it sometimes. It seems more prominent in mild temperatures (not so much in the cold) and more so when the car has not warmed up. It is only rough at idle; a slight raise of the RPM to ~800 or so while holding the brake completely smooths it out. It also seems to be intermittent, as sometimes the idle is fine. I honestly do not have much opportunity to notice it, as very little of my driving has be stopped and idling.

It is not the coils, as they were replaced with no impact on the strange idle. Spark plugs were replaced with the coils. MAF sensor was cleaned recently as well, and the engine was Seamfoamed just prior to that...none of which helped. There are no codes, the car runs great, and fuel economy seems to be where it should be for my driving and commute (low 20's). Any ideas what it could be?
 
Nasty gas? I notice a degradation in "idle quality" when I get no-name gas; except Costco. Their gas, out here, seems to be the best.
 
LS4me said:
Nasty gas? I notice a degradation in "idle quality" when I get no-name gas; except Costco. Their gas, out here, seems to be the best.
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Wow, fast response; thanks! No, I do not think it to be the gas. Always 92/93 octane, and not always from the same place. Typically BP, Shell, or Sunoco, occasionally Exxon.
 
JoshMcMadMac said:
Wow, fast response; thanks! No, I do not think it to be the gas. Always 92/93 octane, and not always from the same place. Typically BP, Shell, or Sunoco, occasionally Exxon.
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I had a mechanic tell me once upon a time ago to never mix brands. He said the different additives don't mix well. I get pinging on Chevron, Shell, Union 76, pretty much all the major "Top Tier" brands. So far the only gas that doesn't cause WOT throttle ping is Costco....... Go figure. Oh, we went from 92 octane out here in The People's Republik to 91 in July of 2001. I've been pinging ever since!
 
LS4me said:
I had a mechanic tell me once upon a time ago to never mix brands. He said the different additives don't mix well. I get pinging on Chevron, Shell, Union 76, pretty much all the major "Top Tier" brands. So far the only gas that doesn't cause WOT throttle ping is Costco....... Go figure. Oh, we went from 92 octane out here in The People's Republik to 91 in July of 2001. I've been pinging ever since!
Click to expand...

That is an interesting thought about mixing additives...but I am not sure I would subscribe to that theory. I do get a bit of pinging sometimes at high loads, so that certainly does not help. It is usually about ¼ tank I fill up at, and typically at the Shell.

P.S. - I like it over here on the other coast. ;)
 
JoshMcMadMac said:
That is an interesting thought about mixing additives...but I am not sure I would subscribe to that theory. I do get a bit of pinging sometimes at high loads, so that certainly does not help. It is usually about ¼ tank I fill up at, and typically at the Shell.

P.S. - I like it over here on the other coast. ;)
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I had similar trouble for a little while. I traced it to where I most often was getting gas. I thought that the octane was too low so I had the state go out and test it. Turns out that the octane was okay, but it had very high water content. I stopped getting gas there (it was a Shell station).
 
joegr said:
I had similar trouble for a little while. I traced it to where I most often was getting gas. I thought that the octane was too low so I had the state go out and test it. Turns out that the octane was okay, but it had very high water content. I stopped getting gas there (it was a Shell station).
Click to expand...

I guess I will give that a try, then. It certainly cannot hurt!
 
Can you describe "lopey?" As in a slight vibration?
 
joegr said:
I had similar trouble for a little while. I traced it to where I most often was getting gas. I thought that the octane was too low so I had the state go out and test it. Turns out that the octane was okay, but it had very high water content. I stopped getting gas there (it was a Shell station).
Click to expand...

How did you get the state to go check it out?

LS4me said:
I had a mechanic tell me once upon a time ago to never mix brands. He said the different additives don't mix well. I get pinging on Chevron, Shell, Union 76, pretty much all the major "Top Tier" brands. So far the only gas that doesn't cause WOT throttle ping is Costco....... Go figure. Oh, we went from 92 octane out here in The People's Republik to 91 in July of 2001. I've been pinging ever since!
Click to expand...

I also get pinging at 3/4-WOT past 3.5k, usually do it in 3rd. I've been thinking of trying some 100 octane, unless it's high water content like joe ran into
 
Alax7 said:
How did you get the state to go check it out?
...
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I did a little searching and found that the agriculture department here is responsible for policing the gas stations. I found the right person to e-mail about it. Once there's an official complaint/inquiry, they have to go out, take some samples, and test it. They e-mailed me a report when they were done. I think it took less than a week.
 
Sweet. I might have to do that. I only fill up at 2 chevron's 2 miles from each other around me, I'll get those checked out.
 
I find it odd that there are several people having this problem. I have the same problem but it does it all the time now. On the way home from a night out, I got a CEL. I will update when I figure out what code it is throwing.
 
I had the same problem. I changed the fuel filter and had a fuel system cleaning and it went away. Clould be trash somewhere in the lines, filter, fuel rail or injector.
 
I suppose I do too?.. Slight vibration at idle - raise the RPMs a notch and it's gone. More prominent when cold, but still there even when fully warmed up. Changing gas brands didn't fix it.

I also took the engine cover off and put my hand on the intake manifold, and I could clearly feel the vibration as well. I was planning on running Gumout Regane but decided against it.
 
I tried mixing a few gallons of 100 octane with some 91 to get 93+, no pinging at full throttle. It was a real nice pull with no pinging, never felt that before today. thanks california! :mad:
 
Just found out I had two bad coils. Stealership got their asses handed to them this time though. I had went to the dealership last week to see what I could do about this miss. The mechanic said he drove it and had no problems. I asked if they hooked their machine up to it to test the coils. they said yes. Knowing that the only way to really test the coils is to bench test them, I asked the mechanic if he could be sure the coils are fine and would not give me any problems. The mechanic assured me that the coils would not fail for some time. Today I went in there, had a mechanic go with me on a test drive with the machine hooked up, and he still tried to say that it was not an ignition coil problem. I insisted (My way of demanding something) that they bench test the coils that were from the pistons that were missing. I was then told if the coils do not fail, I will have to pay for the diagnostic fee. I already knew this and I was pissed so I told them to go for it. 5 minutes later, the service desk attendant came into the waiting room and told me my car was done. I asked him what was wrong. He told me two coils had failed the bench test. My car now drives like it should after two idiots claiming to be mechanics were proven to be wrong by some a-hole. Made my day. All I can say is, if it is a stumble and you get it after a fuel filter and a fuel injection treatment, get the coils bench tested. It will save you some time and gas money.
 
rwurst918 said:
Just found out I had two bad coils. Stealership got their asses handed to them this time though. I had went to the dealership last week to see what I could do about this miss. The mechanic said he drove it and had no problems. I asked if they hooked their machine up to it to test the coils. they said yes. Knowing that the only way to really test the coils is to bench test them, I asked the mechanic if he could be sure the coils are fine and would not give me any problems. The mechanic assured me that the coils would not fail for some time. Today I went in there, had a mechanic go with me on a test drive with the machine hooked up, and he still tried to say that it was not an ignition coil problem. I insisted (My way of demanding something) that they bench test the coils that were from the pistons that were missing. I was then told if the coils do not fail, I will have to pay for the diagnostic fee. I already knew this and I was pissed so I told them to go for it. 5 minutes later, the service desk attendant came into the waiting room and told me my car was done. I asked him what was wrong. He told me two coils had failed the bench test. My car now drives like it should after two idiots claiming to be mechanics were proven to be wrong by some a-hole. Made my day. All I can say is, if it is a stumble and you get it after a fuel filter and a fuel injection treatment, get the coils bench tested. It will save you some time and gas money.
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JoshMcMadMac said:
It is not the coils, as they were replaced with no impact on the strange idle.
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:shifty:
 
I read that. I just said I would post what had happened since others have had a similar problem in this thread.
 
To be honest your post gave me the motivation to call my dealer and get all of my failing and marginal coils replaced. Last time they refused to do a bench test, this time I called the warranty company first. Called Lincoln after and now they will be doing a bench test on every coil and replacing as necessary.

Josh I hope you figure your issue out. I also have a rough idle on my Gen1 V8. Its more noticable within the first couple minutes of start up. The symptoms you described are dead on for how my car is acting. After the coils are replaced, I'll reset my transmission as Frogman has posted. I'll be tackling this rough idle. Could it be vacuum related possibly?
 
diskfunktional said:
To be honest your post gave me the motivation to call my dealer and get all of my failing and marginal coils replaced. Last time they refused to do a bench test, this time I called the warranty company first. Called Lincoln after and now they will be doing a bench test on every coil and replacing as necessary.

Josh I hope you figure your issue out. I also have a rough idle on my Gen1 V8. Its more noticable within the first couple minutes of start up. The symptoms you described are dead on for how my car is acting. After the coils are replaced, I'll reset my transmission as Frogman has posted. I'll be tackling this rough idle. Could it be vacuum related possibly?
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i am also going to try the transmission reset as my shift points have fealt a bit off
 
Did anyone ever figure this out? I'm getting very slight vibrations/shaking just at idle. It seems to happen more in the cold and I don't feel it in gear. Its hard to explain, but its not constant and you wouldn't be able to feel it if you had the radio on. I just had all my coils and plugs changed (dealers expense).

I looked for any cracks or leaks and I found that plastic tube that connect to the intake and valve cover is cracked at the base of the valve cover fitting. It still seems to seal but could this cause it?
 
I was just under my car putting new cats on for a PO420 low efficiency code. My car was idling roughly before, and it has since smoothed out considerably. There is however a very small vibration I feel at idle from time to time. I'm wondering if it's because of my engine mounts, while I was under the car I saw what looked like old dried fluid that had been leaking from the engine mounts, black in color and not a lot, I'm wondering if my engine mounts are not isolating engine vibration as they should, and contemplating making it my next project...
 
rallyusa said:
I was just under my car putting new cats on for a PO420 low efficiency code. My car was idling roughly before, and it has since smoothed out considerably. There is however a very small vibration I feel at idle from time to time. I'm wondering if it's because of my engine mounts, while I was under the car I saw what looked like old dried fluid that had been leaking from the engine mounts, black in color and not a lot, I'm wondering if my engine mounts are not isolating engine vibration as they should, and contemplating making it my next project...
Click to expand...

I'd think if it was the mounts it would be more constant vibration. I feeling this is a miss. I'm contemplating taking it back to the dealership its been there twice this month, overnight for both. Pain in the a**
 
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