account2x

iTrader: (5)

I really wish people would stop giving advice on engines they didn't work on. The 1UZ-FE VVT-i does NOT have an Idle Air Control Valve.

Search the Second Generation GS400/430 section for yourself. You'll see low idle / rough idle threads going back over half a decade.

Here are some nice quotes.

blacksc4

iTrader: (1)

as stated above, how low?
cleaned the IAC(1uz-fe 92 sc400)
air filter,
make sure to check your ignition coil,
run by an autozone and have them check your alt and battery,
plugs and wires,
make sure ur maf is good,
TB is clean,
tps is fully functional
02 sensors are good
try running some sea foam and clean everything (good to plugs after seafoam)
cap and rotors
coolant temp sensor

all very cheap and easy checks and fixes

i had a low idle, turned out my battery was bad, only read at 10v replaced it an im good but those are just a few things to check... i havnt heard of the mount problem before

OBEY414

dude fuel pressure regulator is probably bad

GSteg

iTrader: (15)

The 98-00 1UZ doesn't idle as smoothly as the pre-98 1UZ. New mounts will reduce idle vibration, but when they're worn, the vibration is MUCH more noticeable. Technically the idle speed does not change..but you feel a difference because the new mounts are masking the problem. And yes, even new GS back then had the same problem. Owners didn't notice it until the engine mounts were a few years old.

I would like a higher idle speed, but I can't do anything to change that, at least in a feasible way. As long as it doesn't die, then I'm okay with that.


Now the question....has you idle speed changed dramatically? What does it idle before vs now?

Ali SC3

iTrader: (10)

really, learned something new again. If it doesnt have an iac valve that worries me that he paid his mechanic to clean one.
I still can't believe this thread is several pages and we still dont know how many rpm's the car idles at.

scENFORCER

Where it is:

scENFORCER

Where it should be (with lights on):

Luxor

iTrader: (15)

That is definitely where it should NOT be. It looks like your idle is about 300-400 RPM in this picture.

Idle for your 1UZ-FE engine is supposed to be at 750RPM (+ or - 50 RPM).

In other words, the needle should be at around the middle tick mark between 0 and 1,000 RPM.

BLK13X

How long ago did this happen (low idle)? Is/how is the vibration at idle?

In the photos posted it looks like the car has had the ECU fuse or battery terminals pulled and the ECU is re-learning. Constant idle speed should be around the 700RPM in park at operating temperature as stated above.

You say CEL comes on occasionally, do any other lights turn on as well (overheating catalytic converter for example)?

flux702

I have the same problem here.
@scenforcer: Just curious, but when you start your car up where is your idle? Mine is around 1250 sometimes going to 1500rpms.

I plan to change my mounts fairly soon as my car is at 236k and I highly doubt that they have ever been changed.

Ali SC3

iTrader: (10)

Wow I can't believe the motor can even idle that low.
after reading more about the vvti the electronic throttle body on these control the idle (as well as cruise control). maybe there is an adjustment on it, or it has gone bad. you mind snapping a close up picture of that area.

give this a read page 91 and on
http://www.toymods.org.au/~rod/Techn...comparison.pdf
There is an idle control motor in the throttle body.

scENFORCER

It has been like this since I got the car over 2 years ago, always thought it was normal till I started reading another 'low idle' thread. My old '95 sc400 also had a low idle which further made me think it was normal.
There is also absolutely no vibration in the engine, as mentioned before. I've also replaced the spark plugs with NGK laser iridiums, and installed a new tranny mount all within the past 6 months. Those definately made the car run better/smoother, but did not affect the idle at all.

Please note that the pictures are when the car is idling in Drive, not in Park. When in Park the car idles closer to the 750rpm range.

Yes, I have a CEL is for a bad front cat. Have the CEL on for 2-3 days, then it turns off for 2-3 days. No other lights, and the temp is normal (as per the picture above).

scENFORCER

When I first start the car its just above 1000rpms, about 1250 I'd say. Then it goes down once warmed up (or once it goes into closed-loop mode? If I'm correct?).

scENFORCER

Where exactly am I looking for this picture?

enigma65

I had a low Idle in my 93 gs it was coming from a clogged EGR system. After checking everything else IACV, throttle body and intake system. Try to clean EGR 1st then move on. good luck It can be a pain in the neck figuring out exactly what the issue is.