lexus_ls

I have a 99 LS400 with 130k, oil changes ever 3k, well maintained, new power steering pump, timing belt etc. I am noticing under hard acceleration theres smoke coming out of the exhaust, under any other acceleration theres no smoke and no smoke at start up. No issues with the car, runs fine. Any ideas? Thanks!

RA40

iTrader: (6)

Any codes? Color of smoke? How is the oil regarding consumption?

dicer

Maybe just the tires.

PureDrifter

iTrader: (10)

We need more information, this is toov ague. Could be everything from serious issues to simple condensation.

YODAONE

Have experienced this phonomenon as well on 1999 LS400 with 150k.

It occurs only during pedal to the metal acceleration.

Not burning oil...the 0W-30 Mobil 1 synthetic has not budged from full on dipstick for 2,000 miles now.

Neither has the coolant level diminished .

Thought I read somewhere on this site that upon full throttle the ECU directs the fuel system to slightly over rich to prevent engine damage from detonation....resulting in unburned fuel the catalytic converter cannot fully catalyze, coupled with condensate....whiteish smoke.

If this is not normal (has anyone asked Lexus) then perhaps fuel system components; fuel pressure regulator, injectors are tired, or marginal ignition coils, detonation sensors (will signal ECU to enrich fuel charge and retard timing-what octane fuel are you using?)

Valve lash adjustment?

Ours is a solid lifter engine. Excessive lash will increase valvetrain noise which could be picked up by detonation sensor.

Detonation sensors and connectors?

Are all cooling system components operating at peak performance? thermostat, waterpump, radiator, system pressure?
Coolant temperature sensor?

What is the condition of the engine to frame negative grounds?

Are fuses original? (17-18 year oold fuses may have tarnished contact area resulting in increaed resistance-see my blog on subject)

Have you tested each ignition coil?

Are the ignition coil connectors tight to the coils? These connectors are notoriously susceptible to age and heat related embrittlement(Lexus went cheap and did not use rubber shrouds over this and other connectors, allowing engine heat to fry plastic) and if spark plugs have ever been changed, then the fragile locking tabs on the coil connector on the harness side are likely compromised or broken...but available from Lexus.

What is the condition of the fuel injector seals (o-rings and grommets)?

Are your emmissions system hoses holding vacuum?

The ECU will compensate for vacuum leaks...probably more so at higher RPM.

PCV valve and grommet?

Both hoses on PCV system are likely leaking vacuum (and oil) if original.

Valve cover gaskets?

Spark plug tube seals? (Dry and brittle from age alone, if not by use. ..see if oil in tubes)

Spark plugs?

Idle up control valve on power steering? Check that no power steering pump fluid in vacuum lines.

Probably a few more items that can be added to the list.

Let us know how you resolve this.

LSpho

I've yet to see any petrol motor NOT smoke when wide open throttle or heavy acceleration...

YODAONE

Granted this is a "petrol motor"...it is arguably one of the best gasoline engines used in a production automobile...and so the question is not whether other engines smoke at wide open throttle, but whether the 1998-2000 1UZ-FE VVTi engine normally smokes at WOT. Anyone care to report results?

Stroock639

there should never be any 'smoke' but if it's cold and humid enough you'll see some clouds out of the exhaust but that's with every car

YODAONE

OK. So anyone experience WOT exhaust "smoke" on a 1998-2000 U.S. LS400 not related to coolant, power steering fluid or engine oil in the exhaust stream, in temperate weather?

If so, what steps were taken by you and, or, your mechanic to diagnose and remedy this problem?

sndlight

Are you seeing the smoke in your rearview?

YODAONE

Yes, while driving Exressway then going WOT for a stretch.
If someone has already performed diagnosIs and solved this problem (if it is abnormal) then feel free to respond how.

Scraape

you get any smoke on cold startup? I get it on my 98 at times and assumed valve stem seals

Schramm

Lexus_LS,

Get the car on a hoist and fully inspect the exhaust system. Check for rust and corrosion, especially where the stainless steel pipes fore the catalytic converters mate with the cast iron exhaust headers. The mating gasket and flange is a potential weak point, especially if you live in northern climates. Cold weather can cause increased condensation and salt for deicing roads accelerates rust. Also look for oil leaks. Oil leaks from valve cover gaskets are pretty common on high mileage vehicles and can drip on the hot exhaust system. Such condition will be most notable when car is parked and running. May be able to smell oil burning. That was the case with my 1996 LS400. Replacing the valve cover gaskets solved the problem. Otherwise, if you see smoke out the tailpipe under hard acceleration, that could simply be engine piston ring wear. Does the engine burn oil?

YODAONE

The engine does not burn oil or consume coolant. At operating temperature this condition only occurs at W.O.T. It appears similar to vaporous cold start enriched fuel odor in the exhaust which disappears once the catalytic converters warm up. This is either a.)Normal...asked if anyone else experiences this at W.O.T... no responses yet. or; b.)The fuel/emissions system requires attention or; c.) possible exhaust leak, ( causing O2 sensors to compensate) although I do not hear it or; d.) Weak ignition components.

billydpowe

iTrader: (1)

I only do WOT at cruise speeds and I see no smoke at all, am I doing it wrong, or have a good one.. maybe 200k+ limits my ability to make smoke