carferna

I was wondering if anyone can provide some advise on this issue. I have recently purchased a certified GX460 that runs pretty smooth however it seems to have trouble downshifting. For instance, if am doing 40mph and suddenly need to accelerate, it would take 5 to 10 secs for the car to respond unless I manually downshift. Also trying to climb hills are really challenging while using the automatic transmission. Sometimes also from a dead stop the vehicle has trouble accelerating. Has anyone else observed similar issues on the GX460?

tecman

https://www.clublexus.com/forums/gx-...ion-surge.html

dmccombs

Tecman nailed it. Posts number 3 and 7 have helped me with this issue.

JDSTL

If it really takes 5-10 seconds to downshift, you have something wrong. If it's CPO, take it in and let the service department deal with it.

These GXs do upshift quickly at part throttle which makes them feel sluggish but what you are experiencing is unusual.

carferna

I will take it in but I will have to wait for a month or so, for the CPO warranty to kick-in according to what I have been told. However, up talking to my service advisor, he thinks since I just got the car, the problem may be with the adaptive transmission. He thinks the vehicle is used to the old driver's habits. He is suggesting to drive the vehicle for a couple more weeks.

carferna

Has anyone reset the adaptive transmission ECU on the GX460? I have seen posts for resetting the ECU for the RX via the fuse box. Other's have suggested pulling out the left battery terminal and waiting 20secs. I was wondering if the same applies to the GX460.

tecman

I don't think the GX 460 has adaptive transmission.
I do see what you are asking about.

https://www.clublexus.com/forums/rx-...ion-reset.html

carferna

Just wanted to post an update to the issue I was experiencing. Initially, the Lexus tech that test drove my vehicle thought that it could be normal for the delayed shift. He also thought that flooring the accelerator to cause it to shift can be expected during an incline. However, I did read earlier of a service bulletin for reprogramming the ECU on 2010 and some 2011 models due to Hesitation. I did bring that to the tech's attention and asked him if that applied to my vehicle. Anyway, they went ahead and did the reprogramming and now my GX is flying again. Previously, when taking off from a dead stop there was a slight drag on the second gear and now that has disappeared. Now, it shifts pretty fast and smoothly.....don't feel any sluggishness. I also don't feel the lack of power the moment I approach a ramp. However, the original downshift issue has significantly improved but still somewhat exists. For example, if I am on a ramp and accelerate to 50Mph and then brake to 20 Mph. Now, attempt to suddenly accelerate rapidly by flooring the accelerator. Here is where it doesn't do too well. There will be a 2 to 3 sec lag but then it ends up gradually accelerating(acceleration is slow). Performed, the same test on an IS 250 or a RX350, there will also be a 2 to 3 sec lag, then experience a rapid jerk after which the vehicle rapidly accelerates.
Overall, I am very happy with the ECU reprogramming. Despite it having over 60K, it now runs smoother than the loaner RX350 that had only 12K miles. One other thing I noticed after the reprogramming, was the fuel consumption gauge. There was a point there where right after resetting it, I got it to read 55MPG when I had let the gas off. I had never seen a reading that high prior to the reprogramming. Overall, I am seeing a 2 to 3 mile per gallon improvement in gas mileage. So far, It has barely been a day, so am hoping the trend continues.

tecman

Please post that bulletin.

keep us posted on the performance.

Thanks for the feedback carferna