Ok we all know that in 2002 the infiniti Q45 came with the 2.76 rear gears and had crappy shifting, bad performance calibrations in the ecm, and was being crucified for its rather slow 0-60 with the best a mag could get being a 6.3 sec not the 5.8 infiniti claimed. Now they come out with a remap of the ecm and tcm as well as a pedal upgrade to fix this. Anyone that has had this done has been very pleasantly surprised by the results.

I just noticed that to get the improved 0-60 times down to the numbers that infiniti claimed they had to reduce shift timing, improve the shift points, and in the ecm they provided upgraded spark tables and fuel tables which would increase the horsepower and torque beyond the claimed 340 hp and 333 tq. How do I come to this conclusion ...... simple, in 03 and 04 they do not offer the ecm upgrade but they do come with the better TCM programming and pedal already done. They also were given the 3.13 rear end gear ratio, but were still rated at the 340hp and 333tq. But their 0-60 times were what infiniti claimed of 5.8 secs no faster than the 02s which never got the very much needed 3.13.

Now heres my theory I happened to need an ECM update on my computer the TCM an pedal were already done and wow oh man what a difference just having the ECM done made. Shift point increased to 6800 rpms and it pulled ALOT harder from 4000 to redline. I have yet to confirm this but I am willing to bet that the 02 update gave as much as 20 more hp to the engine as we all know its quite easy for the company to do that, as they tune them with warranty in mind. An before the update id shift at 6400 every time and mind u the TCM was already been updated, he did no changes to it as i was watching him work. I have also changed my rear diff to the 05 3.13 rear gear an my car literally jumps off the time and i have done many back to back 0-60 runs with my lil gps tracker app (and yes I know not totally perfect but hey it works, i use the exact same stretch of road, I put it in manual and let it shift itself, and I try and go when the temp is close to the same) now before the ECM update, which I had done when I got the trans flushed becus I asked him to check them for any updates and gave him the ITB number for the update. He told me the TCM was already updated but the ECM had one took them an hour and half to reprogram and he didnt even charge me, the car did consistent 5.8 to 6.0 0-60 times more 5.8s than anything but it was very consistent an this was with the TCM and pedal updated. The old tires spun more than the new ones the new stick and go, but now with the ECM done I have yet to get worse than a 5.6 0-60 and even got one 5.5. Now I am thinking of dynoing with the new ECM and then having my buddy who has an 03 dyno as well. But I would be willing to bet that the updated ECM 02 will make more horsepower than an 03 with the same rear gear in it.

But as of yet this is all in theory but a good one none the less. I still hve a good ways to go on the new motor but im having fun with the motor thats currently in it.

If nothing else, it's a fun theory to test!

well the reasoning is that the 02s were getting 5.8 0-60 after the updates to the ecm, tcm, and pedal. They didnt change the rear diff in the 02s so to reduce the 0-60 ud have to increase horsepower and change the trans shifting points. Now if this is all they would need they had no reason to change to the 3.12 rear gear but in with keeping the engine in a safer tune they put it back to how it was and added the tcm update to improve the shifting. Yet if the ecm and tcm were updated as in the 02 on an 03 with a much better rear gear then it should beat the 5.8 0-60 but it hits it in 5.7- 5.9 according to the mags. Just thinking may have to dig into this further.

After reading this last post, I finally get what you were saying before... yes it sure sounds very possible. With the oil consumption issues they were having, I'm sure the "lesser of two evils" in their mind from a warranty standpoint, was a different rear end - vs. a more aggressive tune on the ECU/TCU.

As a side note, we have an '02 Q in the pull-a-part here in town. Is there anything of value on these besides the headlights? They were trashed, but I still bought them and then cut them open with a saws-all and scavenged the lenses) and the tail lights? You'd cry if you knew how they opened the trunk for me. Let's just say that the trunk latch put up one hell of a fight against a fork lift, but lost in the end. I was amazed that it took 3 or 4 hard bounces lifting the back of the car well in to the air, before it finally popped open.

Is there anything you want me to snag for you if I make it there again before it heads to the crusher?

well all depends what color is it???

Silver or kind of a medium metallic gray? I vaguely remember the interior being a light color... it was trashed pretty well... the center console had already been ripped open around the raido. I was mostly trying to avoid the steak knife laying on the passenger seat.

hows the passanger side front fender look?? If it looks ok will u take a pic and post it?? Does it still hve the motor in it?

are the rims salvageable?

I definitely like your theroy n I'm thinking of implementing my self.. I have n 02 Q already I seen the rear end off a 05 m45 for 300 on ebay not too bad but will it fit my car? Is it an exact fit do all the connections fit. I tooK a good look at it but I'm no expert jus pretty handy lol.. will I have to change any thing? I also seen the pedal off n 04 m45 for a few bucks on ebay as well seems to be the 1 i been hearing about looks like n easy fit, does it really make a difference? And wat about the update? Do I need to hav need to get my software updated? I hav n 02 not sure of my software how would I check?.. n where would I go about getting that update? Hope not dealer that pricey lol. But I like wat u doin we definitely need to talk asap I wanna get started.. lol.. [email protected]

2.76? Ouch. I can only imagine how much you could wake that thing up with a 3.55 posi from an earlier q45...
I'm assuming the 5-sp auto has significantly shorter gearing as well.

Q45-02 wrote:well the reasoning is that the 02s were getting 5.8 0-60 after the updates to the ecm, tcm, and pedal. They didnt change the rear diff in the 02s so to reduce the 0-60 ud have to increase horsepower and change the trans shifting points. Now if this is all they would need they had no reason to change to the 3.12 rear gear but in with keeping the engine in a safer tune they put it back to how it was and added the tcm update to improve the shifting. Yet if the ecm and tcm were updated as in the 02 on an 03 with a much better rear gear then it should beat the 5.8 0-60 but it hits it in 5.7- 5.9 according to the mags. Just thinking may have to dig into this further.

Question, I have an 05, did hose come from the factory with all the upgrades discussed, do I have any ecu upgrades necessary that the 2002s clearly needed?

I think all of the ECU/TCU upgrades were complete by the '03 or '04 model year, so you should already be benefiting from any revisions that were done.

Q451990 wrote:I think all of the ECU/TCU upgrades were complete by the '03 or '04 model year, so you should already be benefiting from any revisions that were done.

I figured just as much, on a side note, this is literally the finest car I've ever driven, and i really can't imagine a car that is better than it in any way, price being a factor or not....

Great thread Q45-V8!

I am currently driving an '02 Q45 as well. I would like to find out if the ECU/TCU tuning has been done. It appears that my pedal is the old one that needs to be replaced.

Do I have to go to the dealer for the ECU and TCU tunes? The tuning that is being done to the 2013 (up) Q50's seems to be different from what is done on our ECU. I believe our ECU is flashed with new information where the newer ECU's are adjustment tuned on the fly?

I'm eager to get this done! Thanks for any info. [email protected]

All the best,
~Hollywood Jackson~

Q45-02 wrote: ↑

Mon Mar 28, 2016 3:35 pm

... I asked him to check them for any updates and gave him the ITB number for the update.

What is the correct number for the update? I have an '02 with the crappy accelerator pedal. I'm thinking I need the ECM and TCU updated. I've called a few Infiniti dealers around L.A. and they keep telling me there's no Bulletin item for my car regarding the pedal, ECM and TCU. It's so frustrating!

All the best,
~HollywoodJackson~

I just sent you links to the two TSBs to the email address you posted in October. They're on another forum, and you'll have to register to get them, but it's a good resource for TSBs.

Q451990 wrote: ↑

Thu Apr 05, 2018 9:33 am

I just sent you links to the two TSBs to the email address you posted in October. They're on another forum, and you'll have to register to get them, but it's a good resource for TSBs.

Thanks!!

Here's my question... I have a 2005 and am wondering if I put the original 02 rear end in mine would I get better gas milage? I run 2400-3000 on interstate around 70. Wouldn't the lower ratio drop my revolutions?

O5Q45 wrote: ↑

Fri Apr 06, 2018 1:40 am

Here's my question... I have a 2005 and am wondering if I put the original 02 rear end in mine would I get better gas milage? I run 2400-3000 on interstate around 70. Wouldn't the lower ratio drop my revolutions?

I would say yes.

All the best,
~HollywoodJackson~