Cp2295

Hey I got a 98 and when I goto manually select a lower gear to engine brake it will not go into that gear. No matter what speed or gear is selected, the car does not engine brake at all. Which i guess is fine for now because i have brakes lol but I highly dislike not being able to engine brake when i need to. Any ideas? Transmission works farely well otherwise. Fluids okay. Been meaning to do a filter and flush on it for a while.

i wish they woulda stuck with the A340. I liked the drivetrain in my 96 alot better. Just seemed to work better.

Stroock639

very much disagree, the A650 is a big part of why the 98 feels way faster than a 97, unfortunately just sounds like yours isn't working properly... if you're ever in the area please take mine for a spin lol i hate knowing that someone has an unnecessarily negative impression of the pinnacle model of LS

have you scanned for any codes?

Cp2295

no i still gotta hook it up to the scanner at work. This transmission just feels wonky but thats good to know its not working right i guess lol. Theres some hope

400fanboy

Agree on 4 vs. 5 speed transmission. That's actually explicitly the reason why I looked for (and bought) a 98+ car.

So for example, you're doing 65mph on the highway and start to go down a big multi-mile hill, you slide the transmission out of "D" and into "4" and it doesn't downshift?

When in just normal Drive, does the transmission downshift as expected when you put your foot down?

Does the snow\PWR switch change the programming of the throttle and transmission shift profile?

Yamae

Something must be wrong. Gears are all selected by the ECU using sensors and solenoids with the switch NSS even when you select gears manually. I worry that the solenoid control system in the ECU is not fully functional. A 98-00 ECU seldom fails but I have seen some of them have failed. The initial symptom was all caused by the excess ripple voltage in the ECU logic, as far as I have experienced.

Cp2295

would I be able to see potentially failed capacitors in the ecu? The solenoids are probably okay since it does shift normally otherwise. I noticed it doesn't downshift very well when i punch it. Its unresponsive. Even in pwr mode. Pwr mode does help it but not much.

Cp2295

thats exactly what happens. I don't try snow, but pwr mode seems to affect the shift points. It does not downshift as i would expect. It is lazy

400fanboy

PWR mode should downshift into the lowest possible gear with 1\3 to 1\2 throttle input almost instantly, it's quite aggressive in it's tuning. The moment you go near the throttle, bam bam bam it's downshifted to 4000+ rpm. Not only that, but it also affects the throttle programming in relation to pedal posistion. Where the normal profile is very linear, the PWR profile has a very aggressive throttle position relative to pedal posistion. aka it sharpens the throttle response quite a lot.

If you floor it and it's still a gear higher than it could be, and it's still lazy and not that much different than the normal mode... there is clearly something wrong.

Whether that's within the transmission itself or the ECU control unit of the car... I don't know. As Yamae said, it's less likely in 98+ cars but... it has happened. ECU rebuilds are a hell of a lot cheaper and easier than pulling the transmission to rebuild it imo. So I agree with Yamae, I would start with the ECU.

Cp2295

Okay I just thought this year was just weird like that. Glad to know that it's actually got something wrong because i hate how it doesn't bang down hard. I wonder if I ought to pull the pan and see if there's some excessive metal/material in the trans. With 270,000 on it, tranny could be going out. Also probably gonna take the ecu out and see if its got any noticeable capacitor damage. I had a supra i swapped a jdm 1jz into and it had a failed ecu. Ran like absolute garbage though. This thing runs fairly good though.

Is the ECU behind the glovebox on these?

Yamae

Capacitors can be checked observing the ripple level. But this needs to use an oscilloscope. A good multimeter can be used to measure the ripple voltage level roughly with a capacitor in series as is explained in the FAQ page. Other idea is to use an ESR meter. Some people try to judge just only seeing capacitors but I don't recommend that. Electrolytic capacitors are not that simple.

The ECU select gears getting variety of inputs. With your information so far, I can't point out the exact root cause yet. At least you'd better start to confirm that the ECU is working right without any harmful ripples or some others. Does the up shift always very good? Don't you have any rather rough shifting up when cold?

Cp2295

1-2 can be kind of rough sometimes but other than that it is pretty smooth. If I'm driving normal it upshifts totally fine.

Yamae

The rough upshifting when cold is often caused by the too much ripple voltage at the VCC line in the ECU. silos5 fixed it replacing ECU capacitors.
https://www.clublexus.com/forums/ls-...ml#post8173285

Cp2295

might explain the combination of issues huh...? i hope at least. When i get in there I'll get back on here. I appreciate the help so far!

400fanboy

Does that have anything to do with the hard 1-2 shift after just starting the car? Because it seems like every LS shifts hard exactly once, but then never again. Or is this a separate thing.

400fanboy

The transmission doesn't shift "hard". You aren't driving a sports car that shifts like it's pretending it can't drive. Generally speaking, the speed\hardness of a shift is pretty universal regardless of the mode you're in. That being said - generally speaking - shifts are "harder" the higher in the rev range the engine is when the shift happen, but I think mostly this is due to the increased inertia the engine has at those higher RPM's that the transmission has to deal with.

All of my comments were specifically related to the RPM the transmission would seek out, in addition to how quickly the transmission would react to the inputs you give it through the pedal. Not how much of a "jerk" you feel from it selecting a new gear.

The trans itself shifts pretty lazily, though that being said, it is pretty accurate and gets it done quickly. Better than many modern cars I've been in. It's a damn fine trans from it's era, think of your typical automatic transmissions from the 90's and you don't have fond memories. Not to mention the CVT **** that's going around these days...