MedicalDoc

Approximately 6 months and 3000 miles ago, when the car had 95,000 miles, I did a spark plug change (Denso), cleaned the throttle body, and cleaned the MAF sensor (using appropriate products) on my 2002 GS 430, which I have had since it had 19 miles. No MILs and no codes as per my Bosch 1200 scanner. I checked that all hoses were properly reconnected. When I started the car it wasn't as quiet, making a pleasant-sounding 'growl', but nonetheless abnormal. As I started to drive around town I noticed that the rpms did not come down as quickly as before. In fact, they hung around 2500-3000 for several seconds after which they slowly returned to 750. Sometimes they would start to come down and they would jump up 500-1000 rpm and slowly return to normal. This is intermittent and unpredictable; sometimes they returned to baseline if I pressed the accelerator . As of last week, the car is doing this 'rpm shuffle' mostly when I am going up a small incline and the 'growl' is still present. As of today, still no codes. Any ideas/suggestions would be appreciated since I can not afford to lose any more neurons than what I have already trying to find an answer. To note, the car is otherwise fine with no hesitation, loss of power, vibrations, etc.Thank you all !

badblackgs

iTrader: (1)

hook your fancy little scan tool up and pull up the data stream which is the live data the vehicle has to offer. find the one that says absolute tps or anything relating to throttle position or idle control motor. than while you watch the data, have someone tap on the throttle body and wiggle the wire harness going to it and see if the data glitches out or jumps around, than with the engine off but key on, very slowly push the gas pedal down and see if the. tp percent changes accordingly or glitches out. start there

MedicalDoc

Badblackgs, thank you for your suggestions. I did as you indicated. Tapping on the maf and throttle body sensors did nothing. With the scan tool, as I stepped on the gas all values went up accordingly, to return to baseline once I stopped. I rechecked the hoses and they seem fine. Since I was there I re-cleaned the maf sensor.

MedicalDoc

UPDATE!!
All symptoms gone. Pretty easy fix.
Step 1: replace cat gasket and remove y pipe and weld in fabricated piece of pipe. This fixed the exhaust leak.
Step 2: replace MAF sensor. This fixed rpm issue.
All the power is back. Engine is super quiet. Gas mileage improved to 27 mpg on highway at 75 mph. RPMs rock steady.
Total cost: $ 235.00