Acceleration Problems

[ISLex300]

Hey guys,

I have a 2001 IS300 with about 185,000 miles. Recently, I have started having issues with acceleration. First thing in the morning when I start the car, it drives great and normal. Then after about 25-30 mins, the engine noticably bogs down, and when I push down the accelerator, the cars does not react. I have to push the pedal all the way to the floorborad in order for the car to move. Also when this happens, the RPM"S shoot up to around 1500 when in Neutral. I changed the O2 sensor as I wire had come loose, but that did not fix the problem. The check engine and trac lights are also on; the code i get for the check engine light is P1120. I have cleaned the MAF and throttle body, and no results. Any thoughts???

Thanks for your help!!!

[bartkat]

Your MAF may be going bad or there's a leak in the intake pipe after the MAF that's drawing in hot air.

[ISLex300]

Your MAF may be going bad or there's a leak in the intake pipe after the MAF that's drawing in hot air.

Thanks! I'll check that out and see hopefully that works. The problem has been consistent over the past two weeks - the car runs fine when cold, and once it heats up, it starts with the hesitation and the accelrator pedal problems. I'll work on those items and post the results. Thanks for your response!

[TypeS-IS300]

Your MAF may be going bad or there's a leak in the intake pipe after the MAF that's drawing in hot air.

second that.... make sure you inspect all the hoses going to your intake manifold...

[ISLex300]

Your MAF may be going bad or there's a leak in the intake pipe after the MAF that's drawing in hot air.

second that.... make sure you inspect all the hoses going to your intake manifold...

Ok - i'll double check them. I looked once before and everything looked good. Would a loose hose be the cause for the check engine code I got (P1120 - Accelerator Pedal Position Sensor)? Also, if it were a loose hose, wouldn't the problem be a little more consistent? Basically, everytime I turn the car off and back on, it will drive fine for a few minutes, sometimes even the whole trip, but then just like that the engine will bog down and I have to depress the accelerator all the way down in order for the car to move...could it be a bad TPS?

Thanks again for your input!

[ricotony]

Hi there,

I am having the same issue with my 2001 Lexus IS300, I have the lagging throttle response from a standstill. I give it some throttle and it hesitates for a second, then decides to go.

Were you able to get this issue resolved or fixed at all?

When I called the dealer and described my issue, he wanted me to go in for a diagnostic. He quoted me $114 for the ECU reflash.

He stated that they have ECU reflashes for shifting issues, but he didn't know of anything for my complaint.

Looking to see if anyone here has dealt with this issue and if the reflash only will sort it out.

Please let me know,

Thanks

[FactoryIS]

mine was doing the same when i bought it. I replaced the MAF (2 screws and a plug) 1 minute job and it worked perfectly. take the negative battery cable off, replace MAF, connect battery, make sure a/c..radio is off, start car and wait for the radiator fans to kick on 3 times before driving. (car may not want to start or bog/die on first couple trys after MAF replacement) this is normal as the ECU is in learning mode. do not rev engine, just keep starting it until it idles on its own.

[ricotony]

That's a very good point and thank you bring it up.

I did as you advised me just a couple week back, first I replace the mass air flow sensor (cost me $180 just for the parts)and test drivo it again to see if all the symptoms were gone, one thing is that the Check Engine light is now off and hasn't come back since. However I am still experiencing that quirk during acceleration, specially when turning it hesitates to go and unless a step on in harder it won't react.

Im not sure what else to do, I gues I can follow the step by step process that you did, such as and I quote from you "make sure a/c..radio is off, start car and wait for the radiator fans to kick on 3 times before driving". I dont believe I followed this same steps do you think that the ECU is still in learning mode??? sorry for dumb questions but any suggestions would be greately appreciated.

thnks

[Bigdaddy631]

The same thing is happening to me. The gas pedal just sinks in and I just have to press down harder for it to go. But it happens raondomly and consistanlty. I also have the check engine light on and the code it gives me is the one where bank 1 and 2 of my car aren't working. Does the accelerator sinking have to do with the car or the same problems everyone else is having?