bekind

I am new here but I wanted to put out some info.about what I have learned from working on my lexus , I own a 93 ls400 , I have had it for 8yrs , and last I remember it had right at 250,000 miles , I say that because the instrument cluster stopped working(lighting up) over a year ago so in order to see how fast I was going I had to have my flashlight handy and all this time no idea how much gas I had and no odometer reading , I also started having fuel issues which I am still working on ...

The car started randomly dying and it got harder and harder to start back up , rpms rise and fall or shoot real high and stay or drop and it dies , and with it being a 93 I had trouble finding a scanner with the right plug so I read where I could read my own codes with a paper clip , so I did ! I replaced the fuel pump and filter , checked sensors and so far have replaced the throttle position sensor , plugs and wires, checked the coils , ignition sensor, and now its come down to replacing the Idle air control valve , and im hoping I can find one cheap ! Ha good luck with that huh?

So, during all this I needed new tires and im thinking great, I need the odometer reading for the warranty on the tires so I pulled the instrument cluster and fixed it myself , there are 3 capacitors on the board that needs replaced , I did that and put it back in and it worked (I have the link if u want it), and I have to admit , I was so happy I did my own touch down dance, anyway, I drove it a day or two and when I went to see about the odometer reading I thought I couldn't get it to come up , it would switch from trip A to trip B but I wasn't seeing the actual miles , well , it was there the whole time reading 252miles , at first I thought it had to have rolled over but theres no way , so I looked it up in the forums and the odometer reset itself when I fixed the dash lights , and the miles are clicking along ... true story !

I got new tires , my dash is fixed , im still working on the fuel issue and its been a long haul...but I am a learner !!! bekind

LScowboyLS

have a look at this thread it may well be "the fuel issue"

there are other caps on the cluster that need replacing besides those three

bekind

Wow ...Thank you so much for that info.! I read some where in my search that the Idle Air Control Valve should click or that you should be able to hear it kick in when the motor is started , We are not hearing any thing from the IACV which makes us think it is not working properly or at all , would the ecu /cap.needing repaired cause this ? Is there a for sure way to check the IACV other than listening for it to click ? What would be your next move to locate the issue ? The ecu/cap.replacement or the IACV ?

You don't know how thankful I am for the help here , Im single with little income so Im having to figure this out on my own and then find a way to fix it the best I can ( I don't trust just anyone to work on it) !

LScowboyLS

the bouncing idle issue can be either ECU caps or the Idle air control valve, there are tests to determine which is likely the issue:

Yamae's ECU ripple test

you can also pull the ECU and carefully open it and photograph the inside and let us have a look, you want high quality pics taken in bright light, and be sure to disconnect the negative battery cable before disconnecting or reconnecting the ECU - and when opening an ECU, be gentle and careful and be bare footed and wearing all cotton clothes for static protection!


Idle Air Control Valve test