simpson227

Transmission Shuddering while shifting on my 170,000 mile 2004 LS430 has an issue with the transmission. Driving along and accelerating from a stop, it shudders at the top of second and third gear before it engages the next gear. Difficult to describe the issue in words. Smooth through first gear, smooth most of the way through second gear the top part of second gear before shifting the car shudders (pulses) then shifts to third gear. Third gear issues are a repeat of second gear. 4, 5, 6 are all smooth.

I have ready many of the threads on here about people having "rough shifting" transmissions. That can be a very subjective assessments. Is that rough shifting the same as my shudder, who knows.

Multiple people have said the ECU repair has helped their issue. I just don't know if it will help my issue.
I removed the ECU from the car and brought it to a friend who is a Avionics technician on aircraft. He examined the ecu under a 10 power lens with bright lights. There was no visible cold solder joins, cracks in solder or puffed up capacitors.
So should I buy a used ECU from ebay or an automotive recycler? Send in the ECU to get repaired at one of the couple of shops that your guys like. (SIA Electronic is a name I have seen over and over in this forum. Others include Tanin, Relentless Motorsports, Foreign Auto Computer Repair) And the repair costs are $115-$350 and more disturbingly is how unreliable the customer service is. Reading the replies on this forum, one guy gets his ecu repaired in a week and is pleased as punch, the next guy went to same vendor it took 5 weeks turnaround time and it was not fixed. So I am paralyzed into inaction for the past year. Car keeps running with the same rough shift in second and third gear and I am not sure which direction to turn. Gladly spend a reasonable amount of money to keep my Baby on the road. If everyone agreed that it needed a transmission or an ECU it would be easy to budget for repair. This is not the case. Ask any questions you want for clarification.

jharris400

It's always the ECU on 6 speed ls430s

jharris400

LS430Lexus

I had a very hard downshift issue and sent it to Relentless in suburban Dallas.

Before sending it out, I replaced a shift solenoid sensor which required dropping the pan. In that process, I also replaced about half the transmission fluid. That work helped to minimize the hard downshift but it was still there.

Sending the unit to Relentless completed the fix and eliminated all other issues. The transmission was shifted more smoothly when accelerating and decelerating in all gears. It also seemed more responsive and peppier. The reason I used and recommend Relentless is that I was able to talk to the guy that did the work. He was also able to offer a very quick turnaround. I overnighted to him on a Monday with a prepaid return overnight label and got it back on Friday. The other places, like SIA etc, may be great but couldn't promise the turnaround. It was right after New Years and they had been closed so they had a backlog. I didn't want to wait and liked the personal connection. My suggestion is to go with the place you can "connect with" while giving you the service and turnaround that you need. My two cents, good luck.

cyclehead

I got my shop to use their "autologic" scanner subscription to install software upgrades for the transmission (old Technical Service Bulletins that had never been incorporated on my car). Basically they plugged into the car, and relinquished control of the handheld unit to a guy at the factory via an ethernet connection. He installed all the Service Bulletin upgrades, and rewrote the ECU to correct my VIN for no charge. (apparently my car had a junkyard ECU installed) The process took about 2 hours and $250. Didn't have to remove the ECU from the car. I was having jerky shifts after slowing and reapplying throttle - the upgrades corrected all the goofy transmission behaviors.