Jump to content
SAU Community

Recommended Posts

  • Replies 63
  • Created
  • Last Reply

Top Posters In This Topic

Pred, without being an expert on the subject, it appears to me the most economical means of producing higher flowing injectors is low impedance, while Nissan use an ECU that favours high impedence or lower current handling transistors.

Waldo, just use a multimeter to measure impedance (ohm symbol or the horse shoe shape) then calculate the correct resistor to bring to the correct value of between 12-14ohms.

Given the cost of the resistors is about $6 I'd say even $130 is a scam.

ok just went and measured the resistance using a top of the line mega, the GTR injectors measured out to be 1.88ohms and the standard RB20det injectors measured to be 14ohms exactly, so i will use 12 ohm resistors to correct the resistance. Hope this helps anyone

I've just measured the resistors in the resistor pack in my R32 GTR....each has a resistance of 5.5 ohms. I also measured the L-jet resistor pack that I have, which is either from an r30 or a 280ZX (I can't remember, but it doesn't matter as they use the sam injector system, more or less)...each resistor also has a resistance of 5.5 ohms. So using an R30/280ZX resistor pack is an option, although as I said the connector is different.

i dont understand how this works, if each resistor is reading 5.5ohms in your resistor pack then the total resistance of the gtr circuit would be 7.5 ohms....does the rb20 have a resistor pack at all for the injectors? so its means if u stick gtr injectors with the injector pack you will still only get a reading of 7.5ohms whereas the rb20 injector resistance is 14ohms...i must be missing sumthing

i think i understand it now....with injectors the computer sends a signal to them for example at 2000rpm it will send 3 volts, and at 7000rpm (full throttle) it sends 12v. by having more resistance (14ohms) the volts that are going to the injector will be significantly less, say 5 volts at full throttle instead of the required 12v, this is because more resistance you have it will lower the volts, but not having enough resistance it will fry the ecu. So therefor you would have to find a medium, say instead of making the total resistance 7.5ohms make it 10ohms, so that the injectors can still receive an adequate amount of volts and then its just a matter of the tuner to change the volt range at differant throttle points...

SteveL do you have any rb20det injectors if so what resistance do you get with those

Umm, this is a bit confusing from those figures for the impedences. Time for some research.

Sorry Waldo, the voltage will always be the same, just the switching frequency and timing for open/closed will differ with rpm.

Just having a think about this. With the GTSt's I'd suggest keeping the same impedences to suit those computers if making a pack, but enough success is had using the GTR resistor pack to warrant anywhere from 8-14ohms impedence.

Anyway, it could be an expensive error. Worth further investigation.

i think i understand it now....with injectors the computer sends a signal to them for example at 2000rpm it will send 3 volts, and at 7000rpm (full throttle) it sends 12v. by having more resistance (14ohms) the volts that are going to the injector will be significantly less, say 5 volts at full throttle instead of the required 12v, this is because more resistance you have it will lower the volts, but not having enough resistance it will fry the ecu. So therefor you would have to find a medium, say instead of making the total resistance 7.5ohms make it 10ohms, so that the injectors can still receive an adequate amount of volts and then its just a matter of the tuner to change the volt range at differant throttle points...

SteveL do you have any rb20det injectors if so what resistance do you get with those

I don't have any RB20DET injectors...sorry. The injectors always see the same voltage...it is the current drawn by the injectors that will be different - but I'm no electronics tech. The way I understand it is this....injectors with low resistance (2-3 ohms) are used where fine control is required because they have opening/closing times which can be tightly controlled. OTOH high resistance injectors do not have the fine control capability, but are by far the most commonly used (so might be cost issues, etc).

The crucial thing is that the injector drivers in the ECU will be 'matched' to the injectors, so if you are going to use GTR injectors (low resistance) with an RB20DET ECU designed to be used with high-resistance injectors I would have a tendency to add a sufficient resistor value in parrallel with each injector to more-or-less match what the ECU would normally expect to 'see'. I doubt that you need to get things 'exact', butmy understanding is injector current has a crucial effect on injector life as it effects injector heating.

Aftermarket ECU's (eg Motec) have more complex injector drivers which can vary injector current via software settings, so they can cope with a range of injector resistances.

With regards to splicing it in to the loom.

Do the GTS-T owners simply cut the plug off and begin soldering directly to the loom or??? :P

Nah, i kept the plug and spliced the wires into the loom.

One day when that girl next door finally confesses her deep seeded love for me, my lotto numbers get up and my RB20 makes enough power to strain GTR injectors, well with the plug then all i need do is unplug the resistor and plug in a leed that simply loops the wires back together so that the ECU will once again see low impedence...allowing me to run RB20 550cc injectrs etc etc

As Roy says there are 7 wires in the resistior pack plug. In the case of the R32 GTR resistor pack, one wire is white, the other 6 are black. The white wire is connected to the battery +ve terminal, so carries +12V. Inside the resistor pack the white is connected to one end of each of the 6 resistors, the opposite end of the resistors is connected to one each of the black wires. Each of the black wires connects to one terminal of each of the injectors. The other injector terminals are connected to the ECU. The ECU fires the injectors by intermittently earthing the injector terminal connected to it.....current flows, etc, etc.

In the case of engine control systems that don't use a resistor pack (GTSt's, etc), there would still be 6 wires connected to one terminal of each injector for +12V feed, but at some stage in the loom they would all become connected in common down to a single wire to the battery. It would probably be a case of some wire tracing to track that join, although I have seen an RB20DET (red top from memory) that had a small 'sub' loom for the injectors (sort of like the sub loom for the coil packs). Don't know about RB25's.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • So, I started this repair and got as far as "fixing" the holes with some fibreglass. God all those years working on boats came back quickly. I decided I'd reach out to some rust guys just to see what they would say about it. I came across a guy about 40 mins away and went to see him. He said the windscreen needs to come out, that there might be some more bits around the windscreen and he'd quote them at the time. But his quote was $300 to remove and replace windscreen and $3k for the damage he can see. He said he could respray the roof for $1200 and the bonnet for another $800 (somebody has previously rattle canned it, its horrendous). This is $5300 + any small additional bits. It's a lot, I get that and the name of one of my fave youtube channels 'Not Economically Viable' comes to mind.  I'm not being financially rational, but I've taken him up on the quote. He's opening a new shop in November with more room, so we're waiting for that. I'll leave the currently missing headliner out until then. I'm looking forward to it being fixed and having the paint looking nice again (lots of clear coat issues on the roof too). / flame suit on.
    • Oh and some up-and-comings; New rear drivers wheel bearing. I'll do that this weekend while the diff is out. The car is already up and the d/c axles and missing exhaust will help with space. This is the last bearing for me to do and I've been dragging my feet on it. I also have some new EBC blue stuff pads for the car and some new brake fluid. I haven't ever flushed the fluid in this car and looking forward to it. I have 600 degree fluid to put in. Not exactly "race fluid" but better than the typical stuff I have been using.
    • A proper clutch/plate type mechanical diff with quite a lot of pre-load and high locking % is better for drifting. Much more consistent in its behaviour. A helical can be annoyingly vague and inconsistent in how it responds under the sorts of abuse found in drifting.
    • Some updates here. I pulled the entire interior out, minus some trim to respray the seats with Colourlock dye. It turned out really nice though I accidentally let the dog in the car after and she scratched up the front seat.  This is what it looked like before, the colour was just washing out everywhere but thankfully the leather was in good nic. Then after the respray   And after the bloody dog jumped in The headliner is out waiting to be retrimmed, but it will stay out now until Nov - see why below. I replaced the stereo/headunit with a period-styled Android headunit. I have no after pics, but I'll get some. This is because of the missing pixels. I tried to fix this twice with replacement ribbon cables but couldn't. Also the bluetooth interface I'd bought for this was crap. Then there's the rusty roof. Pics and info in this other thread. I have decided to get this repaired professionally, but I'll update that thread. This is why the headliner will stay out for now. I'll be getting the roof and bonnet resprayed at the same time the rust is fixed. I also had an interesting issue with my drivers door lock.  For a small period I was having issues getting any 12v power to the car - I mean *any*. It would have no dash lights, nothing. It happened while I was at the shops and I couldn't get in the car. So, we had 2 problems. The most pressing here is that I was locked out. I have only a single physical key hole on the car, the drivers door and no amount of turning would unlock the car. Surely it doesn't need power for this? The second issue is why am I losing all power periodically, The battery isn't dead, its almost like the battery isn't even there. Two issues that were surprisingly easy to fix. You fellow BMW over-engineering lovers will appreciate this. The lock in the door has 5 states; mechanical lock, electric lock, neutral, electric unlock, mechanical unlock achieved at -90 degrees, -45 degrees, 0 degrees, 45 degrees and 90 degrees. Although, the unlock is towards the front of the car, so opposite for LHD countries. Sticking the key in and turning 45 left or right is what is used 99% of the time. It activates the central locking etc. 90 degrees is for dead battery access and, obvs, only un/locks the one door. But because the mechanical lock is never used and is 27 years old, it seizes up. I was totally unable to turn the key far enough to get to the mechanical unlock (At the time of locking myself out, I didn't even know this was a thing). I eventually did it with some vicegrips and teflon spray.  I made a quick vid for other E39 peeps.   The battery issue is totally new to me also - It wasn't making sufficient contact between the post and the terminal. The terminal was bolted on tight, but the car wouldn't have power. After checking the battery with my multimeter I accidentally contacted the terminal and the battery post and the car got power. The battery was only a few years old and in good condition. I cleaned the post and the terminal with a wire brush, bolted it back on tight and never had the issue again. I'm still surprised that despite having solid contact it didn't work. Also, the car was getting Warragamba sized pools of water in the back when it rained. My initial concern was another rust problem. But when I went out on Weds while it was raining and while I had no headliner in I could see a steady stream of water coming through the roof mounted aerial. As this aerial is for the (now removed) car phone I pulled it out and whacked a blanking grommet in the hole. It seems fine now. I'm thinking I might get the hole permanently filled when the rust is fixed. Moving forward and things in progress; The tailgate needs some attention. I have taken all the trim off to clean it all and address some small rust spots. I have partially done all of this but I'll finish it up hopefully this weekend. As all the trim are now entirely devoid of trim clips I have bought a heap of strong velcro and I'm hoping it does a good enough job as any of this trim in good condition is super expensive and usually in Europe as we dont have many of the wagons here. Suspension and brakes!!! This is exciting. In the front; New control arms New sway bar links New lower Eibach springs (the only modification I'm planning on this car) M Sport shocks (these came with the car and will replace the longer shocks in the car) New top mounts Used 540i calipers (stock brakes suck!) New 540i disks and pads (22x296 mm for 528 and 30x334 mm for 540i) New front wheel bearings (thank all that is holy for bolt on bearings!) Annnnd in the back; New control arms New sway bar links Adjustable air suspension arms (fool the car into what the current height is so the self levelling suspension can match the new front ride height) New ball joints I'll also be doing a brake fluid flush while I'm in there. I'm planning on switching the car over to the 16's that came with it so I can clean up and respray the M Sport 17's. They've lost a lot of colour over the years and have some gutter rash. None of this will start until the E90 is back.
    • You mean you will regret it for drifting duties? I don't quite follow.
×
×
  • Create New...