Does anyone elses (95-96) SC400 Surge a bit around 40mph?

My car surges pretty bad around that speed, generally when it cold, or after driving for a real long time.

 

TealLexus,

I'v got the same problem on my 92 SC400. I thought it was the plugs so I changed them out to Bosch Platinum+4. No luck, still have the problem. Was thinking maybe its the wires, or ignition system.

I remember my moms old Maxima (86') had the same exact problem at about 45mph, it turned out to be a bad/miss firing fuel injector. I doubt thats the case with Lexus engines. Anyhow let me know if you find out anything.

Thanks
Biz

 

These cars have a lock-up type,electronically controlled torque convertor that switches over to lock-up mode at around 40mph.
Pretty sure there's a torque reduction feature in the ECU to save the convertor from abuse at lower speeds,that's why these cars are a bit quicker from 40 up.
The features tend to flutter at that speed,probably wouldn't be noticeable if the tranny was brand new.

 

I've read elsewhere on this forum that you can reduce the surging with a tranny fluid & filter change. Try higher quality fluid. I believe that the tranny takes Dextron 2. Anyone have any reccomendations for premium fluids?? Changing tranny fluid will not stop the surging entirely. It is just a fact of life with an SC400.

 

I had shaking problem around exact 40mph, and after I replaced my o2 sensor, it's fine now. it might be just my issue.

 

No dexron!

Toyota Type-IV only. It's the smoothest and safest bet.

 

I guess I should have posted the things I have already done to combat this problem...

1st- Replaced the Entire Tranny and T/C with a Rebuilt Factory Ordered Lexus Unit ($1800)

Still had the problem

2nd- Replaced the Drive Shaft with a new one from lexus (Included new Center Support Bearing) ($800.00)

Still had the problem

3rd- Replaced Spark Plugs (Though it was misfiring)

Still had the problem

4th- Replaced O2 Sensor

Still had the problem

5th- Replaced Idle Air Controller

Still have the problem..


Yeah.. I'm broke from this little venture..

 

um.. i notice i had that problem too. i though it was an O2 sensor.

 

1. Check proper operation of cam sensors (located by distributor caps) and engine speed sensor (located close to oil filter).

2. Verify proper operation of ECU.

3. Verify proper operation of MAF.

Good Luck,

DJL