Knock sensor code.

Replaced knock sensors and harness (aftermarket).

Went to fire it up and it up and I had a crank no start.

Poked around and found a bundle of ground wires on the back of the intake I missed. I reattached them and it fired right up.

had a CEL for O2 sensor. Replaced it.

Finally test drove it and it shifts very late and hard… sometimes it feels like it goes in and out of gear a couple times when shifting. Or maybe between gears.

Bought this car with a new trans installed 30k ago. Shifted fine for me for the last 6 months. Fluid is beautiful. Car was owned and maintained by a mechanic who was a really close friend who recently passed away.

No Codes. Screwed around with an Altel scanner and couldn’t find anything helpful.

Got desperate and replaced knock sensors with OEM. Still shifts badly.

It seems to get worse when hot, or it is getting worse period. I stopped driving it after a 15 min drive hoping it would relearn or re-adapt.

I’m at a loss at this point. I found another post about someone who did this exact mistake and ultimately replaced the ecm.

Anybody have any suggestions for how to confirm it’s an ECM problem, or eliminate an ECM problem? Any other ideas?

 

Try full reset. Disconnect 12v for about 1/2 hr.

Check transmission fluid level when hot and idling in Park on level surface.

Salim

 

Ive already been down both of those roads multiple times. No dice.

 

Here is another post that I mentioned where it resulted in an ECM replacement.

https://www.clublexus.com/forums/rx-...-issues-2.html

 

knock sensors are not universal for first gen RX. It is imperative that you take your vin to get the right sensor. By chance you may have the right part but there is a chance that you may not have the right part.

In theory knock sensors do not control shifting directly. It is when ECU senses engine knock [real or from a bad sensor] it locks out overdrive, forcing you to have the system repaired.

I cant say it for sure, but your issue just might be transmission related or the ECU is fried. If you go down the ECU replacement path, do think about the immobilizer [registered master keys]/cylinders for all locks etc.

Salim

 

I also tried installing the old sensors again and the shifting problem persisted. So I don't think this is related to a wrong knock sensor or faulty knock sensor. Can you explain what you mean by this:

"If you go down the ECU replacement path, do think about the immobilizer [registered master keys]/cylinders for all locks etc"

 

Please look through the sticky threads and read up on MasterKey.

Our first gen along with many other Lexus, have a theft prevention system, where the ignition key talks to the ECU and ECU will only allow spark plugs to spark [run engine] if the stored signature matches. Armed with a Master key you can program additional keys. Without a master, [but still registered key] you can run the engine. If you purchase a new ECU, the stored signature will not match the key(s) you have. Your keys will allow the physical lock and ignition to be turned but the ECU imobilizer will not allow the engine to run. The EEPROM has to be cleared or programmed to your key. Check with you local lock smiths if they can do this operation on your RX.
Other choice is to procure a replacement ECU with master keys and cylinder locks that match the grooving on the key blade.

Salim

 

Last time I removed the plenum I left a ground unconnected and had the hard late shift issue.
There are three grounds, see photo below. Left two connect to the end of the plenum. Third connects to the back.
I had left off the one that connects to the back