Engine Reving When Cold And Warm.

[Gareth Rose]

Ive noticed that when I first start my car it revs quickly and the revs drop off nearly instantly when I take my foot off. But after a few seconds when it starts warming up it revs up then the the revs take a few seconds to drop back down. Is it supposed to be like that. Its as if theecu changes when its starts warming up. It just sounds a bit strange when you rev it wen its warm, it makes it sounds like my girl friends old KA,lol. Should I try resetting the ecu? Its going in for its 60000 mile service on thusday so I might wait and see what its like after that.

Hope other peoples cars do the same

Cheers

Gazza

[Scorps01]

Er no, mines never done that and i never start it by using the accelerator.6Ok service will include spark plugs so i guess that will have an affect on good starting.

[Mark W]

May be worth checking the throttle body too - I eventually got to the bottom of my GS problem - sounded like missfiring sometimes but noticed the revs were also very high at startup and wavered (is that a word!?!) around a bit - particularly at idle.

Cleaned the throttle body out and took off the little plate on the throttle body that covers a little chamber with about 8 holes in - gave them all a good clean too (all with carb cleaner) and they were well mucky....not sure if the little chamber is common on all lexus - maybe just the GS....

After done, went to start thecar - thought I'd broke something as didnt think car would start - Turns out that it had actually started and was that smooth I couldnt tell !

[Gareth Rose]

I dont mean that I start it using the acc, just if I start it and pull straight off my drive it revs and drops quickly. If I wait a few mins, it revs fine but takes longer to come back to idle. Its almost as if theres a bigger fly wheel on it. Il see what its like after its service.

Cheers for the replies

[Steve_D]

I dont mean that I start it using the acc, just if I start it and pull straight off my drive it revs and drops quickly. If I wait a few mins, it revs fine but takes longer to come back to idle. Its almost as if theres a bigger fly wheel on it. Il see what its like after its service.

Cheers for the replies

I know that my IS200 revs at about 1500 RPM when its cold, revs go down as the engine warms up to 700rpm (anyone elses?), but its different than what your experiencing.

[KnightUnit]

Never had a problem like this with my IS and its upto 130,000 from 60,000 (when I got it). Cold or hot, always ticks over at just under 1,000 rpm.

[VVProtocolVV]

Mys the same, when its cold it revs at about 1500rpm idle then slowly over a minute or so to under 1000rpm, it idles at about 700-800 when warm. I always let my car run idle until revs drop before i start moving. let the oil circulate a bit round the engine.

[redz_UK]

isnt that some kind of automatic choke system? sounds normal to me...

[Gareth Rose]

My idle rpm is the same as everyone elses when warm and cold. I mean the rate of rise and fall of rpm when i use the accelerator. When cold, if i blip the throttle the revs rise quickly then quickly fall back to idle (about 1500 rpm). But after a few minutes when its warmed up, if I do the same, the revs don't rise with the same vigourur, its then takes longer to fall back to idle. Like I said, when cold, it revs and sounds like a sports car, but as soon as its warm its like its got a big heavy flywheel.

Im trying to describe t the best I can, sorry if any one misinterpretted me last time.

Cheers for the replies

Gazza

[edeath]

I think what the guy is trying to say is that he is getting better throttle respose when his car is cold. i.e: his revs drop off much quicker from a blip of the throttle when he has just started it than when it is warm.

Can't say i've noticed in mine but ill check later.

[Rob]

it does take longer to drop down than to increase and is quite normal.

[Gareth Rose]

I think what the guy is trying to say is that he is getting better throttle respose when his car is cold. i.e: his revs drop off much quicker from a blip of the throttle when he has just started it than when it is warm.

Can't say i've noticed in mine but ill check later.

Thats exactly what I was trying to say. Guess Im not very good at writing what im thinking.

If you could check it would be great. Just seems a bit strange that when cold you can blip the throttle and the revs jump up and down and it sounds awesome, but when warm it sounds a bit, well sh*t, lol.

Cheers for replies

Gazza

[edeath]

damn i forgot to check. My engine note doesnt really change with temperature. Just i whine untill 4-4.5 then a kind of scream untill the limiter. i'm gonna leave work soon i'll check the rev drop off on the way home.

However as a side note my old focus used to make an awesome sound when cold with a k&n but when warm was quite timid sounding.

Ed

[edeath]

damn i forgot to check. My engine note doesnt really change with temperature. Just i whine untill 4-4.5 then a kind of scream untill the limiter. i'm gonna leave work soon i'll check the rev drop off on the way home.

However as a side note my old focus used to make an awesome sound when cold with a k&n but when warm was quite timid sounding.

Ed

Just had a quick test on the way home where the engine is only warm for a couple of minutes before home. It did seem a tiny bit quicker to drop off the revs when it was first turned on but thats peobably because i was looking for it. It's nowhere near any different to affect performance if it is different.

Deff no change in engine note either.

[Gareth Rose]

Thanks for that.

Maybe Im just being picky.

Maybe one day If I get round to it Il do an ECU reset.

Cheers guys

Gazza

[Diapason]

Gareth, I think I know what you're talking about, and I've mentioned this on the forum before.

When the car is cold, it doesn't seem to "freewheel" very well. You take your foot off the accelerator and it's almost like you've applied the brakes, the revs drop so quickly. When warm, it seems to freewheel much better. Is that the kind of effect you're talking about?

[Gareth Rose]

Yeah thats the kind of effect I mean. Just find it a bit strange.lol

[Skotte]

I have never noticed this but I would say it sounds normal from a logical point of view. When the car is cold there is less lubrication in the engine and thereby higher friction making the pistons or whatever slow down faster. Sorry, I am not a mechanic but I was just thinking out loud