TWong350

iTrader: (8)

Good high-octane gas should actually help reduce carbon build-up.

The true issue is poor crankcase ventilation.

I8ABMR

my car does the same thing. Its better than the old school method where we have to hold your foot on the pedal to increase rpm to warm the car faster

TWong350

iTrader: (8)

You should bring it in.

BinaryJay

Did you read the thread? I think you're misunderstanding...

BinaryJay

Lexus has had my car since yesterday. They just called me to tell me that they've had their shop foreman look at my car for my cold start/intermittant rough idle concerns and that while there were absolutely no codes stored in the car but that they did see that there were some "inaccurate o2 sensor readings". I was told that they have "some parts" on order and I assume they are going to replace the O2 sensor. Does the car have multiple O2 sensors? He used the word parts and not part so I'm not sure what else they would be replacing.

O2 sensor wasn't something that came to mind when I was thinking about what could cause this kind of idle hunting, but I suppose it's plausible. I'm happy that because they are doing a repair at all, that they have basically conceded that something is not right with how the car is behaving so I have some confidence that it will get fixed.

Has anybody had O2 sensor problems with their cars? If I was getting bad o2 readings for a while, should I be concerned that the car has been running rich and fouling up other things like the cat or causing carbon buildup? It couldn't have been too big of a fault, though, because the car passed emissions just last October.

Kind of hoping that they decide to run it through an engine/injector cleaning cycle to be thorough.

mr3gs300

yeah mine does a lil rev then settle then rev when warming funny thing I noticed it last nite and it was a bit colder last nite then its been since I got the car so it looks like its a cold start up thing

BinaryJay

Mine does it every time I start the car when the engine is cold, regardless of ambient temperature. I also assume since the dealership went as far as to do a diagnostic and find something to replace, that they must have been able to reproduce it at the shop as well.

The other related or unrelated side effect is a slightly waving idle and some roughness and vibration even when the car is fully warmed up but that only happens intermittently. I thought the vibration was the "cold awd" vibration but it has been happening even though the weather has been consistently warm for quite a while now.

I wonder if this is more of a common thing than I thought, but must people don't think of it as something that is "wrong" and just leave it be until a lot of time has past and finally the computer logs it as an error (after the warranty is done, no doubt).

In any case, hopefully they will call me tomorrow with some good news and I'll have my car back for the weekend. I'll update the thread as it goes.

dubzino

Has anyone else had this issue? Its when you start your car from a cold start and 5-10 seconds after you start it. It revs up as if someone is pressing the gas pedal slightly? And if so, has anyone had it fixed?

BinaryJay

It is totally normal for it to rev up when it's cold, every single car out there does this to help warm the engine faster. What isn't normal is if it goes up and down and up and down... it should start high and slowly drop down to normal idle.

KJSmitty

My GS350 is probably completely normal yet different than any other 21st century car/truck I have owned. When cold, immediately upon starting it will go to about 1500 rpm and like others mentioned slowly come down to about 1200. What's different is it stays there way longer than any other vehicle. It literally takes it until about 2/3rds warmed up prior to dropping down below 1000 let alone to the 650 range when idling/at a stop etc.
What's concerning is it takes more effort to stop the car, it wants to idle at 40mph, and it wants to lurch forward when/if you take your foot off the brake. May be normal yet it acts like an old thermal choke and mechanical high idle setting. Not like the other new computer controlled vehicles that all drop down to normal idle within a minute of starting unless its below 0 etc.. I only experience south central TX winters thus mild and I can attest to 2-3 mpg less during temps in the low to mid 30s. Does my GS have a bad sensor or something? Who knows, yet it's definitely different than any other car we have or have owned in the last 10 years.

Cheers

designo

iTrader: (6)

Your car should not spike up to 1900 after initial start up from 1500. There is something wrong.

You should first target your catalytic converters. Your car idles high because it is trying to get your cats up to operating temperature for your O2 sensors to start reading it's voltage!

Your engine does NOT need to be warmed up in that manner at high RPM. The best way to do it is to wait 30 seconds, and then drive off slowly keeping RPM's low. Never let your car sit there idling as that will clog up your cats and cause moisture build-up in them!

Your synthetic oil today is meant for all this. The last think you need is a cold sludgy oil being revved up to 2000rpm in your engine! That's just not right!

Conclusion: Check your cats!

dubzino

I will have to get my checked then because it has been doing that for quite some time now. It doesn't do it every time. But sometimes I will start and it will go to 1500 as normal then shoot up to 1900 as if someone slightly pressed on the gas. Geese does it ever end with the car? My car just sepnt 6 days at the dealer getting the cam gears changed.

chuckGS350

That's exactly what I have been experiencing with my 07GS350 for many years when outside temperature is below 25F. I didn't have to press the gas pedal much for the first five minutes, at least.