When removing the duty/boost solenoid should I depin it from the ECU? And should I remove it at all?

My build is in my signature. S5 JDM engine, N370 Rtek 1.7, RB REV TII exhaust, Hallman MBC. I've removed all the solenoids accept the PRC. I've got the rats nest on but with vacuum caps on everything no longer used.

I'm planning to depin 2M which is the VDI on N/A and knock on turbos. Should I depin 3R (Duty/Boost Solenoid)? Or with the Rtek should I be keeping the boost solenoid intact?

 

The duty solenoid air out of the wastegate actuator and is attached to a metal T on the s5 turbo. When you install an MBC you would be eliminating it from the plumbing anyway. De-pinning shouldn't be necessary.

 

Thanks

Right now I have all solenoids accept the PRC removed. I was under the assumption that removing them would keep from tripping CELs. I've shared posts with one person who has an Rtek and has the plumbing capped but has at least his boost solenoid still plugged into the harness. Isn't the ECU getting the important pressure/vacuum information from the MAP on the passenger shock tower?

 

the ECU knows pressure from the boost sensor yes, the JDM fuel cut defensor is just to unplug the vacuum line.

so for the check engine light, the ecu detects and OPEN or SHORT circuit. so if you unplug something electrically, the ECU will set a code.

there are also a few other things that set a code for things besides being open or short. the TPS, or metering pump for example, these have a range the ecu expects them to be in, and if its out of range it'll set the code.

there are also a few codes that cause a FAILSAFE or LIMP home, these are always linked to fueling/or the metering pump. i'd have to look in the FSM, but on the FD, the fuel pump resistor and speed relay are limp home, if the ECU has these codes, it will fuel cut when it sees more than 1psi of boost. also the secondary injectors, and maybe the boost sensor too.

the FSM has all this info, although its not explicit. there is a chart where it lists the codes that turn ON a CEL, the codes that DON'T and then ones that cause a limp home/failsafe. there are a couple that do NOT turn the light on, but will cause a limp home.

i'm not sure what the boost solenoid does, but if you just keep it plugged in the ECU will never know, and a happy ecu = a better running car

 

I've had to look over those pages for CEL codes in the past. I never saw in there about which codes will trigger limp mode and which don't. I knew the MOP/OMP will, but that taps out my knowledge of which ones trigger limp mode.

I assumed that by unplugging the boost solenoid that the ECU wouldn't know. It seems I need an education.

One question, are all the solenoids the same internally? Can I plug any solenoid into any solenoid harness? Or do they have to match solenoid to it's intended harness? The only one seeing vacuum is the PRC.

 

I just finished my emissions removal and have an S5 TII with an Rtek 1.7 as well. My car isn't going to be running until next week though.
I'd see if it throws a CEL and puts it in limp mode. My guess is it won't.
I'd try measuring resistance on the solenoid and putting a resistor in if it does throw a code.

 

I had a thought while working on the car tonight. If the only purpose for keeping them plugged in is to keep a closed circuit. Why can't I simply take some male spade connectors and create jumpers?

My engine is just about ready to be fired up. Hopefully I'm not among the many "I just rebuilt my engine and it won't turn over" threads. It's rebuilt and just about all buttoned up. I just have small things to take care of

1. I need to read through N/A to turbo engine harness and work out a couple misconceptions I had since I last read that stuff a few years ago.
2. I need to mount my boost gauge to the A-pillar. But it's a vert so I can't get to the screw that holds that in place until I lower the top.
3. I had to order spark plugs because no where in town had 4. There was one store I could have driven to, but they only had 2.
4. I need to buy some fuses for my electric fan. I accidentally got a mini-fuse inline holder and have no mini-fuses for it.
5. Bleed the brakes... I swapped rear subframes and differentials

 

lol, education almost done, like skywalker. um unplugging the solenoid is basically the only way that the ecu DOES know. try page F2-21 in the FSM, its WEIRD it lists what causes the code, but only for some of them.... boost control is @42

the easy way is to just keep the thing plugged in, the L33T way would be to measure the resistance of the solenoid and make a resistor block next to the ECU so all the solenoids are "plugged in" but none of them are actually there.

the boost control solenoid is the only different one, however i'd bet its still around 15 Ohms like all the others. the FSM will have the spec.

the other interesting thing to try is to use a different solenoid, bigger will raise the boost. on my friends FD we ended up using a OBDII vapor solenoid, which has 10-12mm ports instead of 3, just to try and keep boost up

 

there are all sorts of solenoids you could plug in there, but since there is no way to reprogram the boost controller in a stock ECU or Rtek you are greatly limited.

 

I'll spend some time tonight with my FSM as well as some saved threads on N/A to turbo swaps. I was going to do it last night but I got mesmerized by MNF...and then promptly fell asleep on the couch.

IIRC I've always pulled CEL information NOT in the FSM from Banzai's website. I'm trying to remember codes I've had in the past. A couple were always there..what with having a JDM engine with an N/A harness. AWS, O2 sensor, I've gone through a couple TPS, I always had a code for CAS, I had a MOP/OMP go out. The MOP/OMP was the only one that put me in limp mode.

Sounds like my idea of creating jumpers won't work. If the ECU is looking for varying amounts of reistance from different solenoids then having jumpers sounds like an equally bad idea as removing and depinning.

 

easiest thing to do is keep the boost control solenoid plugged in electrically but remove it from the plumbing

 

yeah, given the advice that's the new plan.

 

Did some reading. What I couldn't remember was this. VDI harness on the N/A needs to change to knock sensor for turbo swap. Also 6PI harness needs to change to duty solenoid for turbo swap.

Got the wiring temp fixed. I didn't want to hack up a very good N/A harness. What I did do was take the duty solenoid harness off my old n/a to turbo harness. I soldered a patch with spades on the ends onto the duty harness. I have the harness plugged into the solenoid and the spades plugged into the 6 port injection harness on the N/A harness. Bolted the solenoid to the TMIC support on the driver side.

I haven't done anything with the VDI/knock harness. I don't have a knock box so it won't be functional anyway. The shop that did my previous swap for me cut the VDI harness off and crimped the knock harness to the Y/B wire. They left the ground wire simply cut. I'll probably wait and see if I get a CEL by doing nothing. If I do I'll look into duplicating what they did on my new harness.

I tested resistance on all the solenoids. I was hoping to one of the N/A solenoids that matched the resistance of the duty solenoid. My hope was to find one that matched and simply plug it in. That didn't work out.

Duty Solenoid is 31-35 ohms.

Odd though...I didn't find any resistance values in the N/A FSM chapter. Simply by testing them I found that they are all in the 36-37 ohm range.

That being said. I like your leet idea alot. After the engine is running I may look into fooling the ECU into thinking the solenoids are there.

 

That's what FD owners do for vacuum reduction when running a stock ECU.

 

Is it as simple as it sounds. Simply get resistors from Radio Shack that match the resistance the ECU is looking for and solder them inline? Or do I also need to keep the loop with the ground wire?

 

yep, you take the 2 wires that go to the solenoid and put a resistor in there. value doesn't have to be exact either.

loop with the ground wire? the power comes from the main relay, to the solenoid (or everything actually) and then to the ECU which provides a switched ground.

 

I had some success. The engine turned right over tonight and it holds idle. I'll start a separate thread about it.