lexus-is2

I was having some random power lag issues and my mpg was suffering, after cleaning the MAF sensor, it helped a little but the problem didnt go away. I also cleaned the throttle body. I then replaced the sensor with a brand new Denso part. MPG has improved alot, i dont get the usual power lag as before however, I do randomly get an issue where if i am driving at a steady speed and then usually you just touch the throttle pedal a bit and rpm increase slightly and so does the speed. However, the problem I have every now and then is that it doesnt seem to respond to gentle throttle taps, i have to actually hit the throttle enough to increase the rpm by 1k then it picks up speed. If i stop the engine and then restart it, it all returns back to normal. When this problem doesnt occur, increasing rpm by small amounts is easy but when this problem occurs, it doesnt seem to want to increase rpm slowly. This doesnt happen all the time.

Also, one thing i noticed since i installed the new MAF sensor is that when i start up the car and it's idling cold at about 1500rpm, after a few seconds the rpm jumps by about 500rpm to 2000rpm and then immediately drops back to the 1500rpm. This only happens the once as if i accidently pressed the throttle pedal. This always happens on start-up idle.

Can anyone advise as to what this might be?

Thanks

panda08

iTrader: (1)

maybe a throttle position sensor starting to go bad? when you step on the gas pedal it sends a signal to the electronic throttle to open it, so maybe its not receiving the signal quick enough?

knguyenk

Maybe when you were cleaning the throttle body you didn't push it back to the neutral position. I had a similar problem but when I was having the sparkplugs changed. Here's a link to my thread that goes a bit into detail: https://www.clublexus.com/forums/is-...egularity.html

chi123

iTrader: (12)

I just cleaned my throttle body and airflow sensor this week and I noticed my car was running a bit out of the ordinary and the idle was higher than usual on cold starts immediately after cleaning. I just unplugged the negative terminal on the battery for a few minutes and plugged it in again. Started up the car, drove around, and it ran like normal again. Try resetting the battery before anything else to see if that helps.

Noeh

iTrader: (3)

maybe not be the MAF sensor, but the O2 sensors

lexus-is2

I'm sure i pushed it back to the closed position that it was in originally. I got high idles initially, but this was resolved by disconnecting the negative battery terminal and resetting the ECU.



aw04lfan, that is exactly what I am thinking. But how can I test if it is the O2 sensors and if so which one? How many o2 sensors are there on the IS250 and are they easy DIY to replace?

knguyenk

That's good that your issue was resolved. I remembered resetting the ECU really didn't do nothing for me but relearn my driving habits and reseting all the automatic windows..