jk1105

Ok, my 92 LS 400 (85000 miles) let me down this morning, and I am trying to figure out the problem. Any help would be greatly appreciated. The LS400 has been a great car in the 5 months I have owned it, but not this morning! When I accelerated onto the main road from my neighborhood, the car would not accelerate past 15/20 mph. It felt like the car died, as the engine was lugging badly. The rpm level wouldn't go over 2000 either, which makes me think this is not a transmission issue. In drive, the car just won't surpass 2000 rpm or 15/20 mph. Strange, I think? Nothing is leaking, but there was a smell coming from the car once I pulled back into the driveway.

Does anyone have any ideas of what this may be? I heard that these cars may have a built in Engine defense where if the Engine has issues, the car won't let you accelerate past a certain speed, to protect the engine of sorts? Any help would be greatly appreciated. Thanks!

SharpLS-96

Hi and welcome to CL!!!

See if the following thread helps you.
https://www.clublexus.com/forums/sho...d.php?t=100803

In most cases it's either a bad Throttle Body Sensor (TBS) or bad spark plugs and/or wires.
When was the last time the car was tuned up?

jk1105

Thanks for the reply! Actually, the car was tuned up very recently, with new spark plugs, filters, and belt. So that shouldn't be the problem. I was just told by a friend that what the car did was go into what is called "Limp Home Mode", where the car will diagnose there is an issue, and will protect the engine from further damage by not letting you accelerate past 20 mph. He said several things could cause the car to go into this Limp Home Mode, including transmission and electrical problems the most common. I guess I will have to go to the Mechanic and have him hook up to the car's computer. Any other ideas?

SharpLS-96

Could be due to a transmission solenoid failure or a dirty and/or corroded electrical connector to the tranny. Any number of sensors could be dirty.

Good luck.

Christian

Hello,

had a same problem many years ago. Check what the the economy light does. If it stays green, the engine will get no air, probably the inside cover of the hood is getting loose right in front of the air intake. Just use a carpetknife and cut some of it off.

Chris

JDMFreak

can you tell me where these sloenoid is located at?

Lexushead

I don't have a solution for you but I have similar problem this morning coming to work and I'm hoping that someone here can help me.
I entered the highway and the car hesitate then accelerate. It hesitate everytime I accelerate but the car speed up to 65 mph without a problem. No Engine lights. What could cause this hesitation?

History:
92 LS400 with 247,000 miles.
Last Fall:
Replaced air filter, cleaned TPS but did not adjust it.. Engine lights went away and the car ran great until now.
AT around 225K:
Replaced plugs and used wires . Bought new Bosch wires but it was bad from parbins.com and they won't take it back so I got a used one from a Junk yard. One of the old wires were bad, arching to engine. I wonder if this is the same problem...
Replaced alternator brush, cap and rotor, 8 used injectors with new kits(dealer told me one injector was bad, they wanted $3k and they were wrong. It was the wire) , radio, antenna, battery, used front shocks, fan clutch, headlight bulbs, tires, driver door lock&unlock spring, and lots of oil changes.

nthach

the solenoid is part of the valve body in the tranny. You can see some of it when you drop the fluid pan.

The TPS sensor is a small circular piece on the throttle body, it says TOYOTA Aisan on it.

Lexushead

Don't hesitate to put your result here.

lorenzo816

What "kind" of hesitation?

Does it hesitate in neutral?
Does it slip and catch?
If so, could be the tranny.
Try and drive it in all the gears and describe your results.


Or
Does it hesitate in all gears equally.
If it just doesn't want to go and the engine is not "breathing" right... could be the intake or exhaust.
Does the check engine light come on?
If so, learn how to read it Here
Could be any number of sensors: crankcase, Oxygen, TBPS.....

I've read here in these forums that some LS and SC owners have experienced some ECU problems. Rare though.
Run thru some of these to find out what is wrong and if you do a Search Here you may find the answer.
Good luck!

Lorenzo
92 LS400 174k

Lexushead

Thanks for the reply.
The sympton is similar to ONe21's SC300.
When I would accelerate the car would hesitate (jerking), as if it were going to shut off, and then it would start to accelerate. It's doing it when you begin to accelerate from a stop or if you are cruising and let off the accelerator, then press it again. It will jerk for a couple of seconds then assume it's normal acceleration. Everytime I accelerate, it hesitate (jerks). Step on it hard, it eventually pick up speed but jerkingly (is that a word?).

Air Filter is fine.
Cleaned TP area and butterfly. Did not adjust TPS. Afraid I might mess it up.

Plan to change plugs and some wires this weekend while the kids are out chasing eggs.

lorenzo816

sounds like jk1105's issue is maybe the car is in limp mode.

and Lexushead's issue could be the tranny or Fuel Pressure regulator.
Have you cleaned the Throttle Body lately?

Try that and I hope you pinpoint your problem.

My 2 ¢

Lorenzo

92 LS400 174k

Lexushead

I think it was either spark plugs or wires. I changed both and hesitation is gone........for now.
I still have a miss (hiccup) once in a while while idling.

Gabe M

Check your coils. I had a bad one on a '91 LS400. It would run but very poorly. If you floored it the revs wouldnt go over 2,000. If you were real easy with the gas I could get it up more.
-Gabe

NisAznMonk

I've got the same problem

https://www.clublexus.com/forums/sho...ight=ls400+ecu