California TCU/ECU Combination - Questions

[JohnPa]

My 90 Q45t is a California model. I have checked the posts on the TCU issue, but can't really find a definitive answer to my question. So here goes.........

I want a first gear start, but I want it to be smoother like Q45tech noted in his 08-29-2003 post, '....but the 1-2 shift will be knida rough for a while. Just takes some getting used to.' "unless you also swap the 93 engine ecu.......kind of a matched set."

What I want to know first is what are the 93 TCU/ECU numbers for a California model, or do I have to worry about that? If not, I still need the numbers for a matched set.

What I want to know second is who has a set for sale?

Thanks guys...........John

[DrewQ45]

My 90 Q45t is a California model. I have checked the posts on the TCU issue, but can't really find a definitive answer to my question. So here goes.........

I want a first gear start, but I want it to be smoother like Q45tech noted in his 08-29-2003 post, '....but the 1-2 shift will be knida rough for a while. Just takes some getting used to.' "unless you also swap the 93 engine ecu.......kind of a matched set."

What I want to know first is what are the 93 TCU/ECU numbers for a California model, or do I have to worry about that? If not, I still need the numbers for a matched set.

What I want to know second is who has a set for sale?

Thanks guys...........John

The TCU shouldn't be any different. I have a spreadsheet at with ECU listings...others here might get it to you faster since I'm at work. If you're going to swop ECUs, I wouldn't recommend going beyond a 93' if you happen to get the inclination.

Copied from another post....

"The TCU you want is from a 1993 model year with part number 31036-64U20 or 64U75. Later 94-96 TCUs will work too, but the transmission in those cars are geared differently than the one in the 90-93. For best results having the matching ECU is a good plan... you tend to get better redline shifts..."

[Jeff Williams]

I have a 1994 California model, and put a 1993 std ECU in it. I got no problems. I think the Cali model had an extra sensor or two, but the ECU will work fine.

I have not changed the TCU, so I can't help you there.

[maxnix]

The 1993 TCU will accommodate the earlier numerically higher ratio 1st & 2nd gears better.

[elwesso]

John, for 95% of driving, you wont notice any difference AT ALL with using a 94 TCU.. 93 TCUs are hard to find and can often be spendy if someone knows what they have... its not worth the extra money, trust me!

[96Qowner]

car-part has a bunch of 93 TCUs, as little as $75.

http://car-part.com/

Transmission Computer (left kick panel)

Also Calif ECUs, with or without TCS from $125
Modified by 96Qowner at 10:00 AM 3/31/2006

[RobertsnewQ]

Like everything else in 93, the early and late cars are where the difference comes from, as far as I can tell. My car (late 93) has the 94-up gearing. That's probably where the differences in TCU come from.

Also, the ECU doesn't care about the TCU. It just gets a signal that says "shift in progress" and retards the timing. There may be minor differences in the way it is implemented, but they all work the same.

As for the CA/Federal differences, they are only in the smog control part of the code. It has to do with the way the ECU pays attention to the O2 sensors, the way the EGR valve is controlled at certain times (at cruise, for one) and whether or not the ECU ignores the EGR temp sensor.

If you REALLY want a 93 CA ECU programming (not sure why you would), just send me any ECU and I can put it on there for you.

[96Qowner]

Hmmm, would that be the difference between the 64U20 and 64U75?

[RobertsnewQ]

low first gear transmission vs. high first gear transmission.

OR simple code differences.

For example, the ECUs have about 10-15 total part numbers, but the differences are really, really minor.

[Q45tech]

Robert: An interesting mod would be to raise the WOT speed lock out on 1st gear down shift from 22 mph max to something like 30-31 mph [4,000 rpm] in 90-93 and 33 mph on 94+.

Would surely solve some problems at the expense of transmission life?

[RobertsnewQ]

Yes, but there are a couple of obstacles between me and TCU reprogramming.

The original TCUs use a kind of surface-mount ROM chip that is obsolete. I'm having trouble coming up with a replacement.

[DrewQ45]

car-part has a bunch of 93 TCUs, as little as $75.

http://car-part.com/

Transmission Computer (left kick panel)

Also Calif ECUs, with or without TCS from $125

Modified by 96Qowner at 10:00 AM 3/31/2006

"I have TCUs for much cheaper"

**edit** Scratch that, they are pre-1993
Modified by DrewQ45 at 8:12 PM 3/31/2006

[Q45CALIBER]

Yes, but there are a couple of obstacles between me and TCU reprogramming.

The original TCUs use a kind of surface-mount ROM chip that is obsolete. I'm having trouble coming up with a replacement.

Robert-

This maybe simple sounding but have you thought about duplicating the process using similar hardware Jim Wolf uses to program TCU's?

[Q45tech]

In Japan the Presidents/300zxtt/others had the equivalent of a Power/Normal/Snow switch.........JWT doesn't necessarily reprogram anything.

[Q451990]

Hmmm, would that be the difference between the 64U20 and 64U75?

The U75 was a counter-measure TCU that was installed to reduce torque convertor shock in vehicles built before 2/1993 (VINS ending in 250083 or before). The TSB is ITB94-023

The countermeasure part numbers for 1991 and 1992 models (2nd gear start) ended in 64U70 replacing 64U11 and 64U12 factory TCUs. Apparently this wasn't an issue on the 1990 transmissions.

I have never seen or heard of anyone finding or buying a 64U75.

Heath

[Q451990]

What I want to know second is who has a set for sale?

JohnPa

I have a matched ECU/TCU Pair that I bought from a 1993 Federal Q. Bought them back before everyone (Wes) started experimenting with the '94 and '95 units. I'll sell them for what I paid... $235 + shipping if you're interested. I tested them for about 1000 Miles in Q2 (which is a CA Q) and they work great! I've been running the same combination in her since 2003.

To my knowledge the only difference between a 1990 Federal Q and a 1990 CA Q is the EGR temp. sensor (which a federal ECU will ignore) and the part number for the catalytic convertors...

If you want to keep with a CA ECU from a 1993 model, the Nissan P/N is 23710-71U10, but the number stamped on the actual unit will probably be either A18-A50P69...

I think I would convert to the Federal ECU if it was me though... I would think the performance would only be dimished with the CA model... otherwise I think Nissan would have used the CA programming for all 50 states.

Heath

[Q451990]

Here's a page from the TSB on ECU Identification...

[JohnPa]

JohnPa

I have a matched ECU/TCU Pair that I bought from a 1993 Federal Q. Bought them back before everyone (Wes) started experimenting with the '94 and '95 units. I'll sell them for what I paid... $235 + shipping if you're interested. I tested them for about 1000 Miles in Q2 (which is a CA Q) and they work great! I've been running the same combination in her since 2003.

To my knowledge the only difference between a 1990 Federal Q and a 1990 CA Q is the EGR temp. sensor (which a federal ECU will ignore) and the part number for the catalytic convertors...

If you want to keep with a CA ECU from a 1993 model, the Nissan P/N is 23710-71U10, but the number stamped on the actual unit will probably be either A18-A50P69...

I think I would convert to the Federal ECU if it was me though... I would think the performance would only be dimished with the CA model... otherwise I think Nissan would have used the CA programming for all 50 states.

Heath

Heath, this sounds like a winner to me, as long as the TCU is the 31036-64U20. I can send you a check and you can wait and send the goods after it clears, or I can pay via PayPal or credit card . Let's do it! I can't wait to see what the difference is...........John

ps Thanks to all of you who gave advice. This is what I was referring to in my earlier post, "Thanks and Kudos to NICO>"

[Q451990]

You've got mail!

Heath

[RobertsnewQ]

JTo my knowledge the only difference between a 1990 Federal Q and a 1990 CA Q is the EGR temp. sensor (which a federal ECU will ignore) and the part number for the catalytic convertors...

...

I think I would convert to the Federal ECU if it was me though... I would think the performance would only be dimished with the CA model... otherwise I think Nissan would have used the CA programming for all 50 states.

Heath

THere are NO performance differences between CA & Fed.

The differences are (I think I posted this above, but anyway):- EGR temp sensor data is brought out to Consult port register table- EGR temp sensor data is used to set a DTC (diagnostic trouble code) for the EGR, as well as the EGR temp sensor itself.

-O2 sensor/closed loop software differs. 1. In Federal/JDM ECU, the software uses current O2 senso reading as a switch. X number of engine cycles lean have one value, X number of engine cycles rich have another. Current moving averege of "Hits" of rich/lean voltage is used to calculate a correction factor for the fuel map in the areas that have a lambda correction factor (RPM and load point differ between JDM/Fed/CA). 2. In CA ECU, the rich/lean hits are used also, but there is a "goal seek" routine that biases the count toward the leanest reading seen without a misfire. To compensate for this, the area of the fuel map that is eligible for ratio correction is smaller than the area on the other ECUs.

At full throttle both act the same. JDM Is leaner at high load levels because no precats means no need to thermally protect them with rich mixtures.

As for the TCU programming, again, there is no connection between ECU/TCU part numbers, etc. ECU gets "shifting" signal from TCU, then counts the number of engine cycles to retard the ignition depending on the length of the pulse. TCU pulses until shift is complete. The TCU controls the transaction.

I know what has to be done for TCU programming but the chips are hard to find. And as for the mode switch, I don't believe that the Q TCU is enabled to listen to it, but I could be wrong.

If anyone is interested in this stuff email me - I've got 300 pages of disassembled 6303 assembly language so you can do your own learning

[elwesso]

Hmm, $325 for an ECU/TCU? Not bad (i think $200 would be a fairer price IMO), then you can send us the ECU nad we'll reprogram it.

[Q45tech]

ECU gets "shifting" signal from TCU, then counts the number of engine cycles to retard the ignition depending on the length of the pulse. TCU pulses until shift is complete. The TCU controls the transaction.

Then in theory you could change the advance ramp up [restore] rate for advance once the shift has completed.

Still thinking about the usefulness of a dual PROM [for a mild shot of Nitrous] unlike the JWT 75HP something like 25 HP that comes in earlier [2500 rpm in 2nd gear only]............since there is tcu to ecu communications about which gear the Q is in.

Every JWT Nitrous system I've seen burns the rear tire off in 1st wasteful

We would need to calculate the Nitrous time delay [in revs] from air box to injectors vs rpm to avoid the telltale black cloud of richness before the Nitrous got there.

Since most Q have some miles looking for a less stressful yet cost effective mod.........In 1st for 5.2 seconds, then in 2nd for 10.2>9.5 in quarter mile.

[RobertsnewQ]

Then in theory you could change the advance ramp up [restore] rate for advance once the shift has completed.

YEs, I think there is a table for this. It depends on engine temp.

Quote »Still thinking about the usefulness of a dual PROM [for a mild shot of Nitrous] unlike the JWT 75HP something like 25 HP that comes in earlier [2500 rpm in 2nd gear only]............since there is tcu to ecu communications about which gear the Q is in.[/quote]Unfortunately the ECU does not know for sure what gear the transmission is in. Nissan got around adding a communications protocol by having the ECU calculate which gear it is PROBABLY in. It divides the RPM by the road speed and multiplies it by an X factor to determine when the car is in 4th gear. It also calculates 1st gear, but that calculation is not used by USDM ECUs. No other gear is calculated or assumed.

Quote »We would need to calculate the Nitrous time delay [in revs] from air box to injectors vs rpm to avoid the telltale black cloud of richness before the Nitrous got there.

Since most Q have some miles looking for a less stressful yet cost effective mod.........In 1st for 5.2 seconds, then in 2nd for 10.2>9.5 in quarter mile.[/quote]I have an EXPERIMENTAL code that uses the EGR (could also use EVAP) solenoid as a Nitrous control line. The JWT system has no mixture control at all - it just tells the ECU to hold the injectors open. That's why the black cloud. What mine does is switch maps (using the OEM 5th gear maps suitably modified) and then fire the solenoid.

Why have I not released it? I don't want to be responsible for any exploded engines. I don't think I ever will, because the risk is just too great. (sorry guys!)

[JohnPa]

You've got mail!

Heath

OK, let's do this thing. Please email me at [email protected] with the details.

Thank.............John

[JohnPa]

Hmm, $325 for an ECU/TCU? Not bad (i think $200 would be a fairer price IMO), then you can send us the ECU nad we'll reprogram it.

Hey, Wes, he said $235, not #325!

Soon as I get the ECU, I'll be in touch about the mods..........Thanks...........John

[Q45tech]

Robert:Send a 25 HP jet with ecu and wash your hands of any liability.

Require a 40 psi [minimum FP] via a pressure sensor after fuel filter.

Actually never heard of the JWT kit blowing up any Q engines;seen a few with weaker compression [rings] but what would you expect after your explantion of the simple trigger mechanism. The massive jolts of fuel too early wash the rings clean before the nitrous arrives Black smoke]. Then some Nitrous is still in pipeline after the TB closure -.shutdown.

I would have though a more elegant solution would be required to maximize reliability.

Back

YEs, I think there is a table for this. It depends on engine temp.Could you post a 174F ignition ramp up after shift table I have made some rough ones with Consult in 0.03 sec increments.

As to which gear determination maybe just take the voltage from speedometer driver [0>5volts......available at Consult port] to determinine minimum speed for Nitrous activation [analog solution] and use AT solenoid combinations signals to assume 2nd gear] is engaged....[1 st gear and or 3rd/4th lockout].........some analog and/nand gates to trigger Nitrous assuming armed switch is on to tell ecu what you want [5th gear table] use 6500 shift command to shut down Nitrous.

Is there any ecu output signal relay driver that is not used in stock system [not wanting to use ecu or evap relays]?

I am a big fan of analog fail safes as you can see.

[elwesso]

Hey, Wes, he said $235, not #325!

Soon as I get the ECU, I'll be in touch about the mods..........Thanks...........John

i am retarded

[RobertsnewQ]

Robert:

Is there any ecu output signal relay driver that is not used in stock system [not wanting to use ecu or evap relays]?.

I think there is at least one, but it would require some minor hardware mods to the ECU. There's a second (green) LED driver that isn't used by any ECU that I've seen. You could add a simple power transistor driver circuit to it, and then fire a relay with that.

There may be at least three others but I'm not 100% sure how to activate them from within the software. One is the AIV aux. intake valve that's used by the 300zx, and the other is the boost control solenoid. I think that solenoid driver hardware for both is on the Q ECU board, but there's a jumper or two that may have to be moved.

If I ever get around to doing a manual transmission swap, I will configure the green LED output as a shift light and install an ultra-bright LED in one of the dash vents.

I may install a nitrous kit on my car and play with it. If I do that I have no problem releasing the code "at your own risk" to other people.

At this point I have a good enough understanding of the early 90-93 software that I can program the ECU to do just about anything I want.

I'll find that table for you today if I have time.

[maxnix]

I'll find that table for you today if I have time.

So did anyone ever obtain the nitrous table?