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I'm baaack: C34 Stagea

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Sweet.  What's the point of the mechanical gauge? Surely they are so outdated now, and you would really want a engine protection strategy based on fuel pressure.

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On 7/22/2021 at 9:57 PM, Ben C34 said:

Sweet.  What's the point of the mechanical gauge? Surely they are so outdated now, and you would really want a engine protection strategy based on fuel pressure.

You're right, I will be adding a couple of sensors for engine protection. But for right now the gauge is enough to get my base pressure set and was only like $30 or something. The equivalent sensors to run to the ECU are $100-$250ea from what I've found so far, so will take a little more planning.

I'm leaning towards getting my tuner to do them while he's doing everything else as I am leaving him a couple of small wiring jobs to finish off, mainly cause I don't feel comfortable hacking up the $700 Haltech harness myself hahaha.

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Managed to drive sedately just one suburb over to a local car meet and got some neat pics.

Worked some more on my idle with the new injectors as well. I forgot I had slightly adjusted the main/base fueling table to get it running stoich at idle/cruising (with the new turbo but only standard injectors) and even though I looked over the table a bunch of times it didn't click. I adjusted those 9 or so cells related to idle and cruising and she sounds really good and sitting solidly on the rich side of stoich. It still swings lean on throttle tip-in (normal) but only for a second then drops down to the 12-13 range. Still not perfect and I'm keeping off boost/not pushing it hard, but I'm now more comfortable to drive it to my tuners shop now. 

Also got my base fuel pressure dialed in better by replacing the vacuum hose from inlet manifold to regular. I dunno wtf that blue hose I was using was (came with the car, looks like the kind you get in an ebay boost controller kit) but it was really flimsy thin (probably porous) "rubber" so I replaced it with some new typical black vacuum hose and also re-tightened the locking nut on top of the FPR and now it's dropping from 42-43psi down to just over 30psi which I think is about right. Sometimes it's the simple things!

Anyway... pics -




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  • 1 month later...

In order to save a few bucks I decided to wire in a couple of things myself before dyno time which turned out to be pretty easy. 

I re-purposed the stock boost solenoid wiring to run the new Haltech boost solenoid and mounted it in the same place. Of course for right now I have the duty cycle turned down to 0 at all load points (so still running only wastegate pressure to drive to my tuner) but I did verify it worked by changing the DC and listening to the solenoid clicking away.


Then... I committed sacrilege... I CUT THE MAF CONNECTOR OFF :50_open_mouth:



...So that I could re-use two of the MAF wires for my new Intake Air Temp (IAT) sensor, following the below guide for my RB25 S2 (white wire with blue trace = ground; orange wire with black trace = signal). I terminated the remaining MAF wire  (12v) and threw the connector plug in the bin where it belongs... (not really, it's sitting safely in my old MAF which is sitting in my spare parts pile)


Since I'm using a Haltech Elite it was really easy to change the wiring in the software, I didn't need to re-pin anything at the ECU. I just had to "remove" the MAF input in the software then reassign that input to IAT sensor input and it seems to work perfectly I.E. about 18-20 degrees at night then shot up to 40-50 degrees instantly when I held a lighter near it and dropped down when I removed the heat source.


Then I ran a long two core wire across the radiator support and down to my cold side intercooler piping where I drilled and tapped the corresponding hole for the sensor. 



Coilpacks and fuel pump should be in the next week...

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  • 1 month later...

It's been a few weeks and I did in fact manage to get coilpacks done.

The PRP kit is such high quality and comes with their shorter stalks so I can fit my valley cover if I ever want to again (which I likely will. The kit  comes with genuine Hitachi coils, shorter stalks, replacement loom and the billet bracket as well as all bolts for fitting.



It looks great once fitted... shame about my cam covers though haha


The only issue I ran into was the eyelet on the new loom that's used to ground the coilpacks was the wrong size to fit where my stock ground bolts to... so I cut it off and spliced into the original ground, which I also reconnected to the same bolt. 


I added a spade connector so I can remove quickly and easily in future without having to also unbolt the ground wire from the back of the head (being a S2 RB25, having no igniter box etc).


The finished product:


Once that was all hooked up it fired up right away with no weird hesitations etc. I played with the dwell settings in the Haltech but using PRP's suggested settings made it run like crap... so I reverted to the stock dwell times and she's running mint. I'll leave that up to the tuner. 


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On 09/10/2021 at 7:55 PM, mosquitocoils said:

Right! I'm glad you said that, I was wondering what I'd done wrong haha

I used to run the recommended dwell too, then Alex from Birrong had a look at my tune when I was using his dyno and recommended I dropped the dwell.

This may have also fixed the misfiring issue as well, however can't fully attribute to this because at the same time swapped out the iridium plugs to coppers at the same time.

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  • 1 month later...

Walbro 460 fuel pump install time

Firstly fuel pumps suck in these cars!

The fuel pump in the Stagea is under the floor of the rear cargo area on the driver's side. Remove the access hatch and you'll see this. Remove the clamps/lines (remember which is which!) then undo the big nut on top.


Carefully pull the tophat up taking care to not bend the fuel level float.


Then, and this is the most annoying part, disconnect the fuel pump cage (dark orange above) from the cradle which sits on the floor of the tank (yellow below). There's a big clip on the bottom you have to release while sliding the cradle. This took me far longer than I want to admit... then the cradle has to come up by unclipping it from the tank. I could have left the cradle on the floor of the tank but it was full of crud so I decided to get it out to clean it. 

Here is everything out of the tank, including a whole bunch of decomposed black rubber stuff from in the tank. 

While I had this all out and since I had run my fuel level very low in preparation for doing this fuel pump install, I siphoned what was left of the fuel (along with almost all the rest of that black crap) out of the tank and replaced with fresh fuel from jerry cans.

To fit the Walbro 460 I had to trim the pump cage slightly with some pliers, nothing too big though.

Then I ziptied the pump in as the original cage can't clip together anymore. I realise I'll  probably have to replace these and plan on doing it soon.


Then I ran the new, supplied wiring loom along the same path as the original and soldered it onto the original top hat wiring. Later on, my tuner and I decided to pull it out and re-do the wiring loom by using crimp-solder connectors, just in case the solder by itself cracks in future it will still be crimped together.


Overall this went well and the car started up immediately. I had to adjust the FPR slightly but after about 5 seconds I had a rock solid idle and AFRs were all good. 

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