1st Gear Start-90 Q45t California Model

[John Nordling]

I know from reading the posts that the ECU for a California model is different than the Federal models. What I want to find out is what TCU I need to look for to get a first gear start for a California model. Any help always appreciated.

[maxnix]

You need a 1993 matching (Fed/CA, Active/Not, Traction/Not) TCU.

Or see if JWT will build you one.

[elwesso]

Or you could manually shift it from 1-2!!

[Q451990]

The TCU is the same for CA vs. non CA models. P/N is 31036-64U20 or 31036-64U75.

Heath

[maxnix]

The TCU is the same for CA vs. non CA models. P/N is 31036-64U20 or 31036-64U75.

Heath

Yep, I was flashing to ECU.

I just noticed my Seattle car (1995 Q45t sold in NY) is a CA specification car on its Infiniti window sticker sheet.

What difference does that make? Seem to recall they had an extra O2 sensor.

[SFBayQ45]

You need a 1993 matching (Fed/CA, Active/Not, Traction/Not) TCU.

Or see if JWT will build you one.

So does this mean I can't replace my '91 with a '94-'96 G50 TCU? What are the potential damage if I leave the '91 TCU in place? Would it cause the transmission to break down faster? From what I know, theoretically Infiniti used the 2nd gear start for the smoothness affect, right?

[Q451990]

2nd gear start was for smoothness, but creates more heat and faster transmission failure. Shift points were different on the 94+, so I wouldn't use anything but the 93 TCU for 1st gear start. Seems like someone here tried it with pretty decent results, but I wouldn't risk it.

Heath

[elwesso]

Brian, the only difference is an extra temp sensor...... In the older ones they had a EGR temp sensor, but that didnt come until 94 on every one....

[rsiwicki]

I am running a 95 TCU against my 92 transmission and no problems so far. Also sijko and our Austrailian member are doing the same and have not had any adverse results. Running a 94-96 TCU on a 90-93 transmission will move the redline shift point from 6,900 to 7,300 or so, but your ECU cuts off the fuel at 6,900 so as soon as the engine starts to loose power the shift starts anyway right around 6,900 rpm. I now have the JWT ECU and now shift at 7,200 rpm with the 95 TCU on a 92 transmission in my 95 model year car....if that makes any sense.

Search down the posts in this forum thread and you will see my experiences. I also ran a 93 TCU against my 95 transmission before I had it replaced with the 92 transmission and had no problems as the only thing it did was move the shift point down to 6,500 rpms or so.

This just might be be only seeing this, but as our Q's get older and we experiment more on how interchangeable the parts are from one year to the next we are learning a lot more about the Q and also that the parts are much more interchangeable than we originally thought. As until a couple of months ago...nobody had and many thought that it was not possible to run a 92 transmission in a 95 car. Now we have 3 members with one of them having 50K on the transmission. Another member is running a 94 ECU in his 95 car. I am not saying that there is no harm to doing these things as only time will tell, but I think the Q's parts are much more interchangeable than originally thought. Even Q45tech at T3 never put in a different year transmission into a car due to the unknown complications or lack of complications that might occur....but now he/T3 or others might consider the option if the exact year was not available.

[maxnix]

Brian, the only difference is an extra temp sensor...... In the older ones they had a EGR temp sensor, but that didnt come until 94 on every one....

Thanks. I need to read the manual better. I guess I was thinking about the two downstream sensors behind the cats in the OBD II 1996 Q45.

[elwesso]

Just for your information, on the fed models there is the temp sensor on the Tstat housing area, and on the Cal models there was one in the Y shaped thing that goes to the heads....

[fxjackso]

I run JWT 49 state Active TCU and ECU's (bought for a 91 A) in my Standard 49 state 90. Everything works perfectly.

I suspect there is downward compatabilty, but not upward. Maybe anything works in a standard car, but a T or A would need the right unit. Strictly anecdotal evidence there.

[maxnix]

Just for your information, on the fed models there is the temp sensor on the Tstat housing area, and on the Cal models there was one in the Y shaped thing that goes to the heads....

Without looking, is the "Y-shaped thing" the coolant supply return? Wonder why it was relocated?

[Q45tech]

Multiple ecu coolant temp sensors one [at standard location] for engine ecu another for traction/active ecu on the coolant cross over pipe. Just like California cars have an extra temp sensor to determine if EGR is clogged/restricted.

Remember the TCU looks at driveshaft SPEED not engine rpm for shifts you are just reflecting the gearing effects on speed ......5% just happens to be the ~~300 - 350 rpms you need in 1st and 2nd gearat 6500-7300.

A happy coincidence.

[maxnix]

Thanks, Dennis. I assume it throws a CEL if the EGR is clogged and the temperature goes too high on the CA models?

[elwesso]

It is after the EGR valve, so it would throw a CEL if its too LOW...

I have hte opportunity to have a cal model!!

[SFBayQ45]

You need a 1993 matching (Fed/CA, Active/Not, Traction/Not) TCU.

Or see if JWT will build you one.

MAXNIX - If I can't find one that matches my '91 completely in terms of CA/Not Active/Not Traction, does it have the potential to do more damage than good. There's one on ebay right now that I'm interested, however I don't know if this is advisable. Not sure if I will bid at all, but just want to check in and see what is the general recommendation from NICO.

http://cgi.ebay.com/ebaymotors...=WDVW

[elwesso]

11/93 would be a 94 model..... I think that running a 94 TCU would be just fine as Rsiwicki has done it and the car seems to run perfect...

[SFBayQ45]

I'm confused now...so should I be looking for a 11/92 production date TCU instead?

I know that Rsiwicki tried it with a '94 TCU, but he's volunteered himself to be a guinipig - and only time will tell if it's a correct match. I, on the other hand, want to put something that's proven.

What are your thoughts?

[maxnix]

I have been corrected in that it does not have to be CA/Federal compliant.

The part number is also posted somewhere here. I think it was Heath, but I am sure he knows.

Joe for sure would know!

[rsiwicki]

Quote »I know that Rsiwicki tried it with a '94 TCU, but he's volunteered himself to be a guinipig[/quote]

OINK !!!! OINK !!!! OINK !!!!! I am a mad man on a mission for more speed doing what was once thought was impossible with my Q45.

[Q451990]

I know that Rsiwicki tried it with a '94 TCU, but he's volunteered himself to be a guinipig - and only time will tell if it's a correct match. I, on the other hand, want to put something that's proven.

The only proven ones are the 60U20 and 60U75.

Heath

[SFBayQ45]

Thanks for the info Q451990 (Heath). It looks like I'll have to pass this one (Nissan Partnumber 31036-68U10) on ebay, since it doesn't match either of the aformentiond ones you've listed.

Rsiwicki - More power to you (in every sense of the word)!