Are you another one that has to run their A/C all the time to keep it from dying? My 2000 will be screwed if the A/C ever craps out.

 

no...something is wrong with your car. i rarely if ever use my AC since i tend to drive with my windows down a lot in this cali weather.

 

I have a check engine light on code 41. The car runs and idles perfectly. The check engine light goes on and off every so often. Does this mean 100% for sure its the TPS or could it be another issue?

 

No, running the A/C, lights, etc., doesn't make a difference in the idle. It's a little low, but the car never acts like it's going to stall. I've cleaned the throttle body and it didn't change anything. There are a lot of variables, so it's a process of elimination.

 

well I took the TPS out and sprayed contact spray in there. I assume there is a seal in the shaft but maybe some got through. Anyways so far so good, no engine light. Lets see how long it lasts

 

im getting a code 41 as well even though i changed the tps already. im figuring either a bad wire or the plug for the tps itself. gonna get out the continuity tester when i get home. ive got a spare tps plug i cut from a car in the junkyard but im guessing ill end up running wires to the ecu itself. time will tell.

 

still working good no engine light

 

well, checked all the wiring. its fine, so checked all 3 of the tps's i have which includes the origonal. none of them have continuity from the vc to gnd. only one had continuity to the vta and idl pins. so looks like i need a new tps. grrrr

 

installed new tps, toyota part. Much better than before, I am able to press down on the gas more than before, before the bucking starts up again.

I adjusted the sensor itself a bit to be 'centered' with the screws and the oblong opening. For 5 glorious seconds, I was able to go full throttle and step on the gas without any bucking or symptoms whatsoever. However, it returned shortly afterwards. Sigh

edit: went back outside 3 hours later, took it for a spin 3 times up and down the block... pedal mashed to the floor and its fine.. i wonder if this will hold up

 

how do you tell which is vta, idl, vc, gnd. I saw my is the color wires. could you specify the color of vta, idl, vc, gnd? thx

 

btw, i found out the continuity tester said open because the resistance from vc to gnd is 4.25-8.25k. looks like the tps is in fact good. so not sure why im still getting a tps error code. it doesnt make any sense. ecu has been rebuilt, wiring is good and tps is good. even tried one from a car with no issues to test. same prob. error 41. also checked to make sure the proper wires were jumped for the sub tps sensor as my car doesnt have traction control. they were jumped correctly. would a vacuum leak between the maf and tb cause this error code?

edit: i bought a new meter today as mine is old and not all the functions worked properly. tested the tps sensors with the new meter and confirmed again they are in fact good.

edit 2 7/27/10:well, i found a replacement ecu last week. bought it, and it arrived yesterday. put it in and the car runs perfect now. no engine codes at all, and i can floor it and it goes. no more bucking. now to contact ati for my refund.

 

I've been trying to trace the problem with the 'higher' than I think to be normal idle, which is about 15-1650 rpm for about 5 minutes on a cold start on a 1995 ls400 with 190k, and I'm thinking this could be the culprit...any thoughts on this? As soon as the car is warm, the idle is very smooth, and about 4-500. I just hate it when I don't have the time to warm the car up for 5 minutes because I feel like I'm 'slamming' it into gear....

 

the idle should not be that high when cold nor that low when warm

the factory spec for idle speed on your car is 650 rpm when warm

IDLE SPEED INSPECTION
EG5FW–01

INITIAL CONDITIONS
(a) Engine at normal operating temperature
(b) Air cleaner installed
(c) All pipes and hoses of air induction system connected
(d) All accessories switched OFF
(e) All vacuum lines properly connected
HINT: All vacuum hoses for EGR system, etc. should be prop-
erly connected.
(f) SFI system wiring connectors fully plugged
(g) Ignition timing set correctly
(h) Transmission in neutral position
(i) Air conditioning switched OFF

INSPECT IDLE SPEED
(a) Race the engine speed at 2,500 rpm for approx. 90 seconds.
(b) Check the idle speed.
Idle speed: 650 ± 50 rpm


Throttle position sensor is often suspected but rarely bad.

most common causes of idle problem on 90-97 LS400

● Idle Air Control Valve
● failing ECU capacitors
● dirty intake and or butterfly

 

I've had numerous TPS's go bad on several different Toyotas over the years, and when the do go south it usually causes the idle to be very rough and unstable.

The ones I replaced started to gum up inside and failed to snap back to the "shut" position, which tells the ECU that you are pressing the gas when the throttle is totally shut.

 

yeah, but how often have you replaced a TPS on your 95 LS400? - never!