High Idle on N/A engine

2JZ N/A engine (Lexus GS300 Auto UK spec)

I'm getting high idle - just over 2000 rpm on cold start and about 1000-1100 when hot/

I will renew the air filter. Should I also remove and clean the intake manifold???

I will clean the MAF and air temp sensor - is brake cleaner (spray) ok?

Also can exhaust leak cause high idle?

Thanks,

Ro

N/A's rev slightly higher than TT's anyway, but 2K is a tad much. Have you adjust the idle screw yet??

Have you adjust the idle screw yet??

I thought that was a no no and screws up the TPS sensor or something?

Intresting, but if it does why would it be there to adjust?? You could be right just playing devils advocate.

http://www.mkivsupra.net/vbb/showthread.php?t=43611&highlight=idle+screw

Also kind of related - http://www.mkivsupra.net/vbb/showthread.php?t=13979&highlight=idle+screw

The worst thing is i don't even remember it

2k cold is normal and 1k hot is normal under load (ie lights aircon etc on) mike normaly sits at 800-900

Thanks guys

I will clean the Maf sensor just in case - Is brake cleaner spray ok?

No! The idle is within the limits, dont forget at the start the idle is rich, when hot it should be 1200rpm - same as an NA Supra.

No! The idle is within the limits, dont forget at the start the idle is rich, when hot it should be 1200rpm - same as an NA Supra.

Oh! OK!

Cheers Darren.

Have you received the log book back?

Ta,

Ro

Got it today so posting out tommorow!

It actually drinks more fuel than my BPU TT by the way! Hence thinking the Idle speed may be contributing to this. I'll get the spark plugs changed.

Got it today so posting out tommorow!

Cheers

No! The idle is within the limits, dont forget at the start the idle is rich, when hot it should be 1200rpm - same as an NA Supra.

Faye's NA idles at about 600 or so when hot! Certainly not 1200!

600 - 650 is right for my TT also. With A/C on it's close to 1,000.

Cold start is 2,000rpm, as we already know, due to the fast idle procedure.

Are you sure A/C isn't switched on?

600 - 650 is right for my TT also. With A/C on it's close to 1,000.

 

Cold start is 2,000rpm, as we already know, due to the fast idle procedure.

 

Are you sure A/C isn't switched on?

Nope - the AC is off.

Fuel consumption is high too (Higher than my BPU Supra, even when giving it a thrash!)

Faye's NA idles at about 600 or so when hot! Certainly not 1200!

I don't know the NA engine at all - but I would have thought what I'm getting is a little high. Obviously the relatively high Idle (compared to my TT anyway) is quite load and a cruiser like the GS300 doesn't seem to be right being that loud

Firstly a big thanks to Absxxxx, who was kind enough to check and diagnose the car.

The car is indeed running high Idle - the throttle cable has been tightened. This is masking the underlying issues. I knew there's bit of a misfire and slight exhaust leak but it's worst than I thought. The fuel consumption is higher than my BPU TT because it's running on 5 Cylinders!!!

Abs colleague stepped in and this guy is a genius - By standing next to the car he said "the misfiring is not because of a ignition or exhaust leak issue - it's a vacuum problem"!! And indeed he was right!

They then sprayed a special fluid over the vacuum pipes (This is a Maf sensor based N/A engine) and found out that it's coming from the throttle body to intake manfold gasket. Hopefully it's just the gasket and not a crack somewhere.

So it's time to get my hands dirty and start fixing her up.

Cheers Abs and everyone who posted,

Ro

Reviving this thread as it sounds similar to my problems, to clarify the reason your engine was rich was cause it was running on 5 cylinders and the high idle was due to an air leak...?

Thanks Carl