1998 Ls400 sluggish throttle response
#1
Pit Crew
Thread Starter
1998 Ls400 sluggish throttle response
98 Ls400
160K miles
over the last few weeks ive noticed the acceleration has been getting sluggish. This is most noticble when accelerating from a stop, or when accelerating to pass. The best way to describe it is that the throttle response is not as instant anymore. It seems to bog down for a second before the power really kicks in. Ive also noticed the idle is around 450 RPM with a/c off in D4. With a/c on around 650 RPM. Ive been reading alot on this site and it seems like my spark plugs could be an issue. I am unsure when they were last replaced. My best bet would be they have nearly 100K miles on them. I am ordering NGK IFR6T-11 plugs and also a new PCV valve and grommet. Anything else i should be considering to replace.
thanks
160K miles
over the last few weeks ive noticed the acceleration has been getting sluggish. This is most noticble when accelerating from a stop, or when accelerating to pass. The best way to describe it is that the throttle response is not as instant anymore. It seems to bog down for a second before the power really kicks in. Ive also noticed the idle is around 450 RPM with a/c off in D4. With a/c on around 650 RPM. Ive been reading alot on this site and it seems like my spark plugs could be an issue. I am unsure when they were last replaced. My best bet would be they have nearly 100K miles on them. I am ordering NGK IFR6T-11 plugs and also a new PCV valve and grommet. Anything else i should be considering to replace.
thanks
#4
Moderator
I assume your idea will be improving the acceleration some but not fully. I don't think your idle would be improved by that.
My bet is 2 other different items that cause your problem rather than yours. But I'd better not interrupt you and I dare wait until your result will come up before insisting my bet. Since 100k miles sure is the time to change spark plugs and the grommet. You have been reading the site a lot and you might have already noticed those 2.
My bet is 2 other different items that cause your problem rather than yours. But I'd better not interrupt you and I dare wait until your result will come up before insisting my bet. Since 100k miles sure is the time to change spark plugs and the grommet. You have been reading the site a lot and you might have already noticed those 2.
#6
It seems the 5-speed transmissions up shift very early in these cars, put your car in PWR mode and see if the acceleration improves
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#8
Pit Crew
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#9
Pit Crew
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thanks
#10
Pit Crew
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#11
Pit Crew
Thread Starter
I did find this interesting thread:
https://www.clublexus.com/forums/mai...ntial-fix.html
anyone have any experience with these Fuel injection cleaners ? Do they work ? any chance they do more harm than good ?
https://www.clublexus.com/forums/mai...ntial-fix.html
anyone have any experience with these Fuel injection cleaners ? Do they work ? any chance they do more harm than good ?
#12
I would start with the simple things that may need to be addressed anyways. If spark plugs are old then replacement is due. As well, the PCV and grommet and hose are easy items.
My own experience, with my now replaced 95, was low idle after long stretches on the highway... so low that it would die when I came to a complete stop. It would start right up no problem. Replacing the plugs and a thorough cleaning of the throttle body resolved my problem. The TB can get pretty sticky and gummed up in there and it needs to be cleaned out on a regular basis. After I completed those two items, my low idle issues went away completely.
Just my experience, yours may differ.
My own experience, with my now replaced 95, was low idle after long stretches on the highway... so low that it would die when I came to a complete stop. It would start right up no problem. Replacing the plugs and a thorough cleaning of the throttle body resolved my problem. The TB can get pretty sticky and gummed up in there and it needs to be cleaned out on a regular basis. After I completed those two items, my low idle issues went away completely.
Just my experience, yours may differ.
#13
I did find this interesting thread:
https://www.clublexus.com/forums/mai...ntial-fix.html
anyone have any experience with these Fuel injection cleaners ? Do they work ? any chance they do more harm than good ?
https://www.clublexus.com/forums/mai...ntial-fix.html
anyone have any experience with these Fuel injection cleaners ? Do they work ? any chance they do more harm than good ?
I changed my fuel filter and my car accelerates so much better, I also did a diff drain and fill, idk if that would help