Tag: ecu

3S: A massive quality of life improvement…

Air Conditioning! Someone may say that it is an absolute requirement in Texas. That someone is me. So going 8 years in Texas without working AC has basically limited the Stealth’s usage to just the winter… if it was hotter than mid 80’s I didn’t want to be in the stealth. It’s as simple as that.

The back story was the AC on this car has always been a shit show. I bought the car in fall of 2002. The AC gave out within the first summer. It was replaced with another by a local shop. That one failed within a few months. The shop wouldn’t cover the labor (which was half the cost) so I had them evacuate the system and I decided to do it myself. It worked ok for a while. It clearly had a leak and I had to use a bottle to fill it up from time to time.

I would argue sometime in the 2010-2012 time range, I had a new error come up on the AC. It would show the “snowflake” icon on the digital dash for about 3-5 seconds, and then I would get a “red dot” error. Someone on 3Si mentioned they shorted the “green-orange and green-yellow” wires on the harness going to the “Compressor Lock Controller”. I didn’t know what any of that was doing, but I trusted in 3Si and did it. Nothing happened. The red-dot went away, but the AC never worked again.

Skip ahead to spring of 2025. I just got the LinkECU installed, let’s see if I can get the AC going now too? The digital climate control died in the fall of 2024, so I sent it out to get replaced by a shop I found on eBay that happened to be in Houston. I replaced the Dryer & Expansion Valve, vacuumed out the system, it held vacuum for multiple days and I go to fill it and no luck. I can’t get the AC Clutch to engage. I look in the LinkECU and it is not receiving any signal to “enable” the AC. I gave up. Defeated.

Round 2!

Alright this year I was 100% going to get this working. Hell or high water it would work! I’d either fix it or throw money at it and replace everything in it!

First thing first is to remove the “short” green-orange and green-yellow wires from before. I needed to start with a clean slate. Upon doing that the red-dot came back! However I could tell the AC was actually working now for the 3-5 seconds that the snow flake was showing. So I posted on 3Si asking for help.

With the help of two great people paul93VR4 & AlmosN8kd we were able to diagnose the problem was the compressor has an RPM signal sent to the “Compressor Lock Controller” along with the Engine RPM. It does a “comparison” of the two RPM’s and if it’s within a specific percentage it will turn the clutch on. Well with the use of a oscilloscope I was able to determine that the compressor wasn’t sending any RPM signal.

I checked the actual AC the best I could without tearing everything out and as far as I could tell the sensor was plugged in and the wires weren’t destroyed. So I needed to find a way to “hotwire” this thing into working… I was able to short two of the wires (pins 13 & 15) on the lock controller, and then short pin 15 to ground with a resistor so that it would drain and disengage when the AC wasn’t requested. This worked, but it was a janky solution.

Then I pondered it and questioned “what if it didn’t have the engine’s RPM either?”… after a major struggle depinning this I was eventually rewarded with a working AC without a weird “short” or resistor hanging around. I labeled the removed pin with a heatshrink and closed everything back up.

Now this isn’t perfect. If the AC seizes, I won’t know. The belt will snap and it can damage the timing belt. So I consider this a “solved … until” and that until is when I have to remove more of parts in the way of the AC so that I can really pull out the wires and test it out to determine if it’s the sensor or just a wire that got messed up.

3S: Drive by wire installation

Watching / learning a lot about how to tune the car on an aftermarket ECU (LinkECU G4X) has been a process and one of the things often mentioned is how DBW is the best way to control idle (compared to stepper motors, etc) and it also reduces potential air leaks. I also realized if I converted to DBW, that would free up several new AUX channels on the ECU for my Coil on Plug install that is coming later this winter…. so I went down the path…

Throttle Body Installation

The Bosch 68mm throttle body is said to be a “direct” fit and just needs to be drilled out… and generally this is the case. The throttle body is already set up for M6 bolts, while the 3S Plenum is M8. So you need to drill this out to about 9mm. I had two drill bits that were close in size, I tried the smaller one 11/32″ (8.73mm) and couldn’t install it still, and ended up using 3/8″ (about 9.5mm) and it worked fine. Once you do that, the next problem I ran into was the stock bolt fitment… they technically fit but I couldn’t fit a socket over them. So I swapped them out for M8x1.25 55mm socket head caps and used some purple thread locker (retainer). The next problem I ran into was the bracket that holds the plenum up ran into the throttle body motor so I had to remove that (which was a pain if you don’t want to remove anything else).

I covered up the connector and the whole housing to prevent any metal shavings from getting into it while drilling it out…
Very tight fitment with the stock bolts and the socket on the bench. When trying to install it on the car, it wouldn’t fit…
Custom 3D Printed TPU Gasket installed (linked below).
Brackets which I removed. The one on the back of the valve cover had three bolts, 2 12mm sockets and 1 10mm socket iirc. The steel braided oil lines to the turbos are pretty rigid which made the removal more annoying. If you pulled the plenum off it would have been easier….
Finally installed with the brackets removed.
All buttoned up. The previous silicon coupler fit, but it was tight. I had to increase the size of the t-bolt clamp. The previous one was 67-75mm (iirc) and this is just a tad too big. I have a 73-81mm ordered. I do not plan on replacing the silicon coupler though.

350Z Pedal Installation

I bought the pedal adapter from Outsider Garage over the EvoSpec one as the pedals were much more commonly available and significantly cheaper I think I paid $55 shipped for mine (used) versus most evo ones were close to $200. The pedal adapter was only $45 which was cheaper than I could make / design this myself (as I was going down this path originally).

There is a piece of folded medal on the back of the 350z pedal that needs to be removed, otherwise you only have about 1/2″ – 3/4″ travel on the pedal (probably about 30% it’s total capacity). I removed a good amount, and now the pedal hits the floor. I would argue I have about 80-90% the total throw now, and once you get it into the ECU you calibrate it and so it’s not a big deal. I do wish the angle on the adapter was a little steeper so that pedal stuck out further, but it is what it is. I know outsider garage sells a replacement pedal for this, and maybe that fixes some of my complaints.

The adapter shifts the pedal to the left a bit as it’s more inline with where the stock one was.
You can see it sits a bit lower than the brake pedal, but it’s in a good position (horizontally)
Back of the pedal trimmed down.

Wiring

Wiring was my least favorite task of this whole effort. I really didn’t know where I wanted everything pinned to in the ECU, but I eventually came out with a solution that cleaned it up a little, but didn’t require me to re-wire everything. I had a lot of wires on my expansion “ports” for the ECU previously but I moved them to the main harness and used the expansion port for the DBW as it was designed for that. The throttle body and the pedal both need 2 sensors each ( redundancy ), and the TB needs two (three) AUX ports.

Throttle Body Connector is a Tyco Electronics Micro Quadlok System (TE MQS 6 Way). I originally purchased this from Haltech as it was convenient, but they are expensive and don’t give you any extra pins and I messed up the first one which was annoying. You’d think for $16 they could include an extra pin that only costs them pennies. Anyways it used a lot smaller pitch crimp, I don’t recall which exactly it was, but it was around 1.6 in size based on the “Engineer” crimper I have.

The pedal I bought came with a pigtail that was long enough for me to swap it over to a TE Deutsch DT connector which I use for all the connectors I can. While it’s a bit larger in size, it’s a good strong water proof connector. I am 99% positive the Nissan 350z is a Sumitomo MT branded connector. I have linked it below in the event you need it.

I’m not going into the tuning process at all. That’d be a whole discussion by itself. I will admit I messed up one setting when I first turned it on. I changed everything to the throttle position…. except my “startup offset” which was set to 10, which meant it added 10% throttle to the idle base position… so the car idled at 3k RPM on a cold engine… thankfully that was an easy fix, but I rather not idle at 3k on a cold engine…

This is my overall pinout. At the point of this post, I have completed everything in Part 1. The left column is where it was prior to the install, the yellow highlight is things that are pins that have moved from their stock location. The orange ones are the proposed changes for each “part” of the upgrades this winter. Hopefully Part 2 will be all that I ever have to do for this car [we know it won’t be].
This is my expansion ports on the Link G4X Plug-in ecu. I never really thought I was going down the DBW path and didn’t realize that connector 2 was really made exactly for the DBW setup… so that’s why i had to move most of my sensors to the main harness.

It Runs!

Testing out the pedal and throttle.
Actually running!

Parts List:

Bosch 68mm Electronic Throttle Body – 0 280 750 156
Throttle Body Gasket (Makerworld)
Outsider Garage 350z Pedal Adapter
Nissan 350z Pedal (with pigtail or Sumitomo MT-6S-3)
TE 6 way MQC (OEM P/N: 1-967616-1)
M8x1.25 55mm Socket Head Cap Bolts (4x)
Mishimoto 73-81mm Constant Tension T-Bolt Clamp

Disclaimer: This is just where I bought stuff from based on prices and shipping times. You can probably find cheaper / better parts if you look around more for some of these items.