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Discussion Starter #1
So I have a few issues, mostly just annoyance/nuisance issues but they all add up.

I had my TRD LSD put in my car last year. I moved about a month ago. I know that a clutch type diff behaves differently but I will say that it seems more sensitive lately. I have a three-car garage and the supra is parked all the way on the left "3rd car" spot". When I back up the car out of garage I have to turn in towards the center then once I actually start to back into the street I either continue turning that way or go the opposite way. Either way when going forward and the next few right or left turns I make as I go out of the neighborhood, you can tell the diff isn't happy. You feel like you are sliding the tire/rubbing instead of freely spinning the tire. After a few of those turns and the gears moving inside it seems happier. But park the car anywhere for some bit of time and it's back to dragging again. I had Redline 75w/90 oil and Redline clutch type additive put in the diff. Anything you guys recommend?

On occasion over the years I get either a P1512 or P0420 code. The P1512 codes I get on some random frequency at least a few times a year on average. The P1512 always happens on a part throttle, barely boosting at all. I never feel anything, I just notice the light goes on and that's all there is to it. I have a Greddy BCC in my car. The P1512 error has been happening for more than 5 years on random occasion.

I got a P0420 about 5 years ago and just got one last week. Other than the car seems it might be running a little richer (maybe) and I notice a little more water in the exhaust. Otherwise it has been mostly normal in performance. It has been more humid lately, so maybe that explains the water bit. Now I have noticed one thing, I am on stock twins and a few times lately I got on the go pedal and seemed to have zero boost. But then I let off the gas and got back on it and there was boost. Not long after that the P0420 code happened. The no boost has happened about 3 times. When I have boost it's otherwise normal most of the time. (99%+) Do I need a new O2 sensor? It is the original 23 year old one. I suppose that the cat could be going bad. It's a Random tech downpipe and cat converter I installed in 2004 and have put over 62,000 miles on it in the 16+ years it has been on the car but I don't think it's actually the cat yet. I was thinking it might need the downstream 02 to be replaced. What is the toyota part # and where woud you guys recommend getting it? With Elmhurst Toyota not having the good guys there right now it's a crap shoot on who you get. Or if you guys can think of a Denso alternative I can get from Amazon or somewhere, that would be great also.
 

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You don't need the LSD additive. I'd drain that fluid and fill it with normal Mobil 1 75w/90 available from most parts stores and see how it reacts. That could be your issue while the fluid is cold. As far as the codes go-I am sorry I can't help you there.


Steve
 

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The downstream cat typically (I haven’t worked on the supras emissions equipment) just measures the catalyzer health. The upstream one is for fuel trim. The downstream one can definitely set the 0420 code. If both sensors are factory originals or you haven’t changed them ever, I would toss two new ones in regardless if its the root problem and see what happens. Otherwise it needs to be diagnosed by a tech with a scan tool.
 

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Steve (1A1) nailed it on the diff oil recommendation. The Redline stuff is fantastic, but the TRD LSD seems to prefer less fancy gear oils for reasons I haven't ever been able to divine. The Mobil 1 should do wonderfully.

But before you change the oil, I would find a nice big empty parking lot and do some tight radius figure-8's at a low speed. Doing that for 10-15mins does wonders to break in an aggressive clutch type LSD. Change the gear oil afterward and see what happens.

As for the O2 sensor, the P0420 code from the original sensor is almost certain to be a failing O2 sensor. According to the EPC I'm seeing Toyota PN 89465-19595 as the correct O2 sensor for a 97 TT 6-spd rear O2 sensor. The downside is that it is discontinued from Toyota, as is the front O2 sensor for the same.

Starting with the 89465-19595 PN, I pulled a Denso PN 234-4215 as the Denso made replacement that matches. But I would be wary of that PN as I haven't found the cross reference from Denso themselves, only sellers of that kind of stuff all over the internet. I'd also be careful about buying Denso stuff from eBay, etc as there's a lot of chinese made counterfeit trash shipping in fake Denso boxes.
So far, buying stuff like that from RockAuto has done right by me, and they show both Denso and NTK made sensors in stock under that Denso PN.

The P1512 code is a common one from the old school BPU days. Thanks to Stu Hagen's keeping of much of the old knowledge, here's a description: http://www.97supraturbo.com/Trouble Codes/P1512 Boost High.pdf

Basically it means the ECU is seeing higher boost pressure than it expects under a low RPM and often part throttle condition. This is typically from using a boost controller or other method of boost pressure being elevated beyond stock. Hopefully someone better with BPU wizardry can chime in, but I believe there's a way to put a restrictor into the MAP sensor line as to bring the MAP sensor reading down just enough to avoid triggering these issues. Since the 2JZ-GTE ECU adjusts timing and fuel off of the MAFS signal and not the MAP, adjusting what the MAP sensor sees doesn't endanger tuning or engine function at all.
 

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Discussion Starter #5

DENSO 234-4215 {#8946519595, 8946519695, 8946549075}
Downstream

DENSO 234-4514 {#8946519605}
Upstream

I found them like you mentioned on Rock Auto. Amazon can get them to me for essentially the same price and a little quicker.


So get this Mobil 1 75W-90?

Image looks different, but this is the same thing?
 

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I strongly suggest not buying sensors, especially the front O2, from Amazon. The counterfeits are rampant on there and you won’t be able to tell the difference visually very easily. I personally don’t trust Rock Auto either. I’d bite the bullet and get an oem replacement from your local Toyota or online dealer.

Edit: What Wreckless said.
 

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Discussion Starter #7
For what it is worth, both 02 Sensors are listed as being sold by Amazon, not some third party vendor.

Local Toyota dealer is useless, never has anything in stock, charges way too much for parts. I'd have to get it from someone out of state if that is even possible. Elmhurst Toyota is useless, doesn't show anything on their webpage.

Any thought about the Mobil 1 75W-90?
 

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The 75w/90 Mobil is what I've been using with my TRD diff for 15 years.

Steve
 

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Discussion Starter #9
251314
251315


I've seen the bottle look two different styles on the web. Other than that is this what I am looking for? I understand the LS is for limited slip.
 

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I use the Amsoil Severe Gear 75W-90 along with 2 oz of their LSD additive. If the car sits for an extended period, the clutches chatter a little on the first few turns. The clutches get dry from sitting and the fluid has to get worked into them. I'm talking about 6+ months or more, but a shorter period could do it to a lesser degree.

Al
 

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Gary,

That's it.

2 of them and you'll have some left for next time.

STeve
 
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For what it is worth, both 02 Sensors are listed as being sold by Amazon, not some third party vendor.

Local Toyota dealer is useless, never has anything in stock, charges way too much for parts. I'd have to get it from someone out of state if that is even possible. Elmhurst Toyota is useless, doesn't show anything on their webpage.

Any thought about the Mobil 1 75W-90?
I recommended RockAuto for a reason.

On at least two occasions I've seen counterfeit items sold as genuine by Amazon, including one that was over $450. No luck, Amazon refused to even consider that it was a counterfeit item even though it was clearly demonstrable when compared to a genuine part.
After a few other issues I experienced with car and non-car related Amazon purchases, I'm avoiding Amazon if at all possible.

For Toyota genuine parts, I've had good luck with Olathe Toyota's parts department for MR2 and Celica stuff, and sometimes Supra stuff too when Elmhurst was unavailable.
 

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Cool Springs Toyota for me and Rock Auto for Denso parts if needed.

Steve
 

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Discussion Starter #14
Well I have the Denso O2 Sensors in hand and the Mobil 1 Gear oil, so I'm ready. Last thing unrelated is some Motul RBF 600 brake fluid for a brake fluid flush is on the way later this week.
251342
The bottle at the Auto Zone store and ordered from Amazon looked like this.
 
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