ehabmarco

Tps checked it was ok finally ransmission changed and problem is resolved

Update: Cleaned the solenoids valve, no improvements In the repair manual is says if there is a harsh engagement between N to D first thing to check is the TPS then the solenoid valve # 4, I started wrong by the solenoid I will try now to adjust TPS and see what is gives

I returned to the mechanic today to schedule changing the transmission, when I asked him again about the particles he found he told me it was aluminum parts catched by the filter I still doubt the problem might be electrical When I am in N position and raise the rpm and wait for rpm to return to idle, and then shift to D, I can feel this jump, if I repeat this operation without also moving the car, this silly jump disappears So playing with rpm few times and returning to idle while the car is stopped make this jump come or disappear This is driving me crazy....

Bad news While changing the transmission oil my mechanic noticed many metallic parts and said that transmission is in a very bad condition and needs to be changed

Thanks Steve I was doubting this problem might be caused by a stuck solenoid valve or transmission fluid as you said I think I shoud start by changing the transmission fluid this week and I will post the result, I hope this will clear the problem Last time I changed the transmission fluid was 2 years back and I am not sure about its type I am quite sure this "jump" is not resulting from a bad mount or joints as I would have felt it each time which is not the case Is there any filter I should change in the transmission while changing the fluid?

i need help for an intermittent problem which could badly damage the drivetrain I feel a sudden severe shock (jump) when I shift from N to D When I start the engine in the morning and before engaging the transmission, I hear a very loud sound of oil flow like Whistling as if the oil is stuck somewhere This sound goes away after about 1 or 2 minutes If I hear this sound when starting the engine, I know that certainly the shock (jump) from N to D will happen, if this sound don't come still the jump might happen but not all the time The shock is felt only when the car is stopped and I shift from N to D However sometimes the shifting from N to D is smooth (providing that this sound when starting the engine did not occur) The transmission is shifting very smoothly between all gears at all times No codes for transmission when checking in normal or test modes Thanks for your help

Very old post but I see it worth posting as the problem was not fixed here I Had this same problem for months till reaching the cause It was the oxygen sensor that was causing this hesitation when cruising

Hi My car is a 1990 lexus LS 400 I am hearing a continuous alarm (beep) for about 5 seconds everytime I insert the key then it stops, anybody knows what it could be and how to stop it It can only be heard when inserting the key, when removing it no sound Thanks

Thanks fsuguy Yes my question was about testing the oxygen sensor, it is a 4 wires type (2 black, 1 blue, 1 white), it would be great if you can post it About the other trac code error 47, it was a little adjustment that needed to be done to the traction control sensor position and the code now is cleared Thanks a lot

Sorry, I find it a bit hard to accept that a defective MAIN O2 sensor in an engine with TWO sensors, would result in a lean misfire. Over the years I have been reponsable for the care and maintenance of a '90 LS (a Bill Gate's trade-in), a '91 LS, 3 '92's and a '95. The '90 and one of the '92's are now off the list. Amongst that group, all now pushing close too or over 200K, I have encountered numerous instances of O2 failures. ALL have result in a CEL but NONE exhibited any physical indication of fault. I assumed that once the ECU detected that one of the sensors was faulty it simply relied on the opposite for fuel trim corrections/adjustment. Why, if you think it through, should it be otherwise. I suspect you cleaned, as anyone would, the MAF/IAT sensors at the same time, more likely the actual "misfire" cause, as installing the O2 sensor. Yes before changing the O2 sensor, The MAF/IAT sensors had been cleaned AND even changed without any improvement One more thing I want to mention is that the O2 sensor was completely dead (no reading for any resistance) I knew that this sensor was faulty (I had a CEL) but I could not imagine that this is the reason of misfire, that's why I left it to be the last option The 2 wires leading to the sensor element will always read open. The only way I know to test those is to heat the element in our oxygen rich atmosphere and test for the output voltage to be in the proper range. It appears that if you had "read" the actual code it would indicated an open O2 sensor HEATER, not the sensor itsself. the heater is only used during initial engine start up. Once the exhaust is supplying HEAT the sensor will provide good outputs. Yes you are right but it seems that by chance the sensor itself was also out of order But could you elaborate more how to test it I did not understand how to test the voltage? which of the 4 wires to connect? Thanks

Thanks fsuguy Now I need help and I am not sure if I should start a new topic or not This is related to error code 47 in traction control (When idle switch is ON, sub-throttle position sensor signal is 1.45V or higher) Any ideas if that means that I should replace the sensor or it can just be adjusted Thanks

Sorry, I find it a bit hard to accept that a defective MAIN O2 sensor in an engine with TWO sensors, would result in a lean misfire. Over the years I have been reponsable for the care and maintenance of a '90 LS (a Bill Gate's trade-in), a '91 LS, 3 '92's and a '95. The '90 and one of the '92's are now off the list. Amongst that group, all now pushing close too or over 200K, I have encountered numerous instances of O2 failures. ALL have result in a CEL but NONE exhibited any physical indication of fault. I assumed that once the ECU detected that one of the sensors was faulty it simply relied on the opposite for fuel trim corrections/adjustment. Why, if you think it through, should it be otherwise. I suspect you cleaned, as anyone would, the MAF/IAT sensors at the same time, more likely the actual "misfire" cause, as installing the O2 sensor. Yes before changing the O2 sensor, The MAF/IAT sensors had been cleaned AND even changed without any improvement One more thing I want to mention is that the O2 sensor was completely dead (no reading for any resistance) I knew that this sensor was faulty (I had a CEL) but I could not imagine that this is the reason of misfire, that's why I left it to be the last option

Actually I called it misfire based on the link below which explains that misfire can be caused by one 3 things: 1- loss of spark 2- the air/fuel mixture is too far out of balance to ignite 3- loss of compression http://www.autotap.com/techlibrary/diagnosing_misfires.asp In my case a random misfire (hesitation) was happening every 4 to 5 seconds and was caused by a bad air/fuel mixture (lean misfire) due to the bad oxygen sensor This sensor was causing a rough idle too, after changing it, no more hesitation when cruising and idle became much smoother the link below helped me to test the sensor http://www.lexls.com/tutorials/EFI/mainoxygensensor.html

I am sharing my experience with this chronic problem of misfire at a certain speed when cruising that I see repeatedly in this forum First I admit that this forum helped me a lot to find the cause of my problem but unfortunately after spending lot of money in changing many parts First thing I want to say is that many issues can lead to the same symptoms of hesitation or misfire between 40 to 60 mph Hesitation at this speed does not mean that the engine is only hesitating at this speed and THIS IS THE TRICK The misfire is clearly felt at this speed because the torque converter clutch is engaged that means the engine and transmission are considered as 1 unit so any slight misfire in the engine will be felt in the transmission and this is happening only when cruising My advise is to go with the following sequence: 1- check spark plugs and wires (must be original) 2- Oxygen sensors (and this was my case one of the 2 main oxygen sensors was dead and caused the random misfire) 3- throttle positioning sensor 4- throttle body These are the most common causes of misfire Hope this helps