Is your LS able to get 3000+ rpm while idle?

[Tony_1992]

Hey guys, I just replaced the spark plug of my Lincoln LS V8 3.9L. And after that I drove the car on the highway for a test drive. Everything works fine. No Engine warning, rpm in normal range, same or even better fuel performance(17.5mpg in city and 26mpg on highway). Only one little problem that haunts me now.

When the car is in idle, I tried to floor the pedal to the end but the maximum rpm that I can get was about 3000rpm, no matter in P or N mode. This phenomenon disappears in D4 and D5 mode, in which I can easily get 5000+ rpm when accelerating.

Is that normal and the same to your car? Or, is this a huge problem?

Also, I was a little worried about the potential missing fire problem before replacing spark plug. How to eliminate the possibility of that?

Thank you!

 

[joegr]

...
When the car is in idle, I tried to floor the pedal to the end but the maximum rpm that I can get was about 3000rpm, no matter in P or N mode. This phenomenon disappears in D4 and D5 mode, in which I can easily get 5000+ rpm when accelerating.

Is that normal and the same to your car? Or, is this a huge problem?
...

Works as designed. Neutral limiter.

...Also, I was a little worried about the potential missing fire problem before replacing spark plug. How to eliminate the possibility of that?

Thank you!

I am a little confused by the question. Trying to eliminate the possibility of future misfire? Did you have a misfire and you are unsure that you fixed it?

Note that misfires on the LS are usually due to COPs (ignition coils) becoming marginal. Usually if one is bad enough to detect, then all need to be changed. So far, only OEM (Motorcraft) coils have proven to be safe replacements. When changing a coil, it is very important to change that spark plug at the same time, not a month before or after. When changing spark plugs on the V8, it is very important to check and set the gap on each to exactly 1.0mm.

 

[Tony_1992]

Works as designed. Neutral limiter.



I am a little confused by the question. Trying to eliminate the possibility of future misfire? Did you have a misfire and you are unsure that you fixed it?

Note that misfires on the LS are usually due to COPs (ignition coils) becoming marginal. Usually if one is bad enough to detect, then all need to be changed. So far, only OEM (Motorcraft) coils have proven to be safe replacements. When changing a coil, it is very important to change that spark plug at the same time, not a month before. When changing spark plugs on the V8, it is very important to check and set the gap on each to exactly 1.0mm.

Hi, my car does not have any sign of missing fire for now. Just a little bit unconfident of my skill, cause I'm not a professional mechanist.

And you mentioned the exactly 1.00mm thing, I'm not aware of that. Just bought some Denso spark plug from Amazon. Is that extremely important?

 

[joegr]

...And you mentioned the exactly 1.00mm thing, I'm not aware of that. Just bought some Denso spark plug from Amazon. Is that extremely important?

It seems like it could be a factor for coil life. The plugs are supposed to come preset to the correct gap, but my experience is that one or three will be wrong in any set of eight. You have to use the right tool and be careful when setting (and even when checking) the gap or you will damage the center electrode. There are youtube videos on how. NGK is the OEM plug for the LS, but this is not to say that the Denso aren't fine.

 

[Tony_1992]

It seems like it could be a factor for coil life. The plugs are supposed to come preset to the correct gap, but my experience is that one or three will be wrong in any set of eight. You have to use the right tool and be careful when setting (and even when checking) the gap or you will damage the center electrode. There are youtube videos on how. NGK is the OEM plug for the LS, but this is not to say that the Denso aren't fine.

OK, confusion resolved. Thanks a lot

 

[joegr]

I would probably just leave them as they are now, since they are installed and seem to be doing okay, but next time...