AustinGT Posted January 11, 2008 Share Posted January 11, 2008 This afternoon as I started the LS (after sitting overnight, inside fortunately!) it kind of coughed around 1000 rpm for a second before something caught and the rpms went back up to 1400 like normal. After I washed it, I fired it back up to move it back into the garage, and it did the same thing, but it was less noticeable this time. This happened once before about two years ago after it sat for 10 days, but other than that it has never done this. The car ran fine once started, but should this be chalked up to a freak occurrence or something that needs to be looked into further? Thanks in advance..... Quote Link to comment Share on other sites More sharing options...
TA in KC Posted January 11, 2008 Share Posted January 11, 2008 This afternoon as I started the LS (after sitting overnight, inside fortunately!) it kind of coughed around 1000 rpm for a second before something caught and the rpms went back up to 1400 like normal. After I washed it, I fired it back up to move it back into the garage, and it did the same thing, but it was less noticeable this time. This happened once before about two years ago after it sat for 10 days, but other than that it has never done this. The car ran fine once started, but should this be chalked up to a freak occurrence or something that needs to be looked into further? Thanks in advance..... 1400RPM sounds like a high idle even if it is cold. At what speed does your car idle at when it is fully warmed up? When was the last time the spark plugs in your car were changed? My car idled close to that speed when cold, and had a similar starting problem, before I changed them. Quote Link to comment Share on other sites More sharing options...
AustinGT Posted January 11, 2008 Author Share Posted January 11, 2008 The plugs were changed by the dealer (what a rip off!) about two and half years and 15k miles ago, so they should still be good. As for the idle speed, it always runs around 1400 when cold, then slows down after about 20-30 seconds. When hot, it idles in Park around 650 rpm without the a/c on, and about 600 in Drive. The idle speeds have stayed constant, it is just the catch right after start-up that caught me off guard.... Could a plug be fouled up or something? Quote Link to comment Share on other sites More sharing options...
aarman4 Posted January 11, 2008 Share Posted January 11, 2008 So much for the old "My car always runs better after it's washed" mantra... Quote Link to comment Share on other sites More sharing options...
AustinGT Posted January 11, 2008 Author Share Posted January 11, 2008 An update- this morning after sitting overnight the same thing happened ... Last night I drove it a little bit, then it sat for a few hours, but it started up normally, so it only "coughs" or chugs for a second or two when it is completely cold. Don't know if this helps to narrow it down... Quote Link to comment Share on other sites More sharing options...
aarman4 Posted January 11, 2008 Share Posted January 11, 2008 An update- this morning after sitting overnight the same thing happened ... Last night I drove it a little bit, then it sat for a few hours, but it started up normally, so it only "coughs" or chugs for a second or two when it is completely cold. Don't know if this helps to narrow it down... Did you check for error codes? Quote Link to comment Share on other sites More sharing options...
AustinGT Posted January 12, 2008 Author Share Posted January 12, 2008 No lights have come on at all... Although my radio cut out randomly (the only way I can hear anything at all is if I crank it up full blast), but I doubt that is related to a cold start issue. Quote Link to comment Share on other sites More sharing options...
90LS400Lexus Posted January 13, 2008 Share Posted January 13, 2008 I think that on both of my LS400s (1990 and 1991), but idle around 1300-1400 when cold. I will check tomorrow. 1400RPM sounds like a high idle even if it is cold. Quote Link to comment Share on other sites More sharing options...
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