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Newbie questions! RB26 wont start after swap to Link

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Hi all, I may have something very obvious wrong but I can't see what! I'm coming from the car working with a PFC to the swap with a G4X where it won't.

I made the change to a 24-tooth AEM disc at the same time and believe I have the settings correct and the timing correct. All lines up when I use the timing light in the calibration mode now I have moved the offset to +10 there.

I have 600cc (vs 440cc stock) injectors so I changed the master trim to -20% but tried both ways and no difference.

I also have R35 GTR coils so I adjusted that as well but again, it makes no difference whether I leave them standard or adjusted to the no-start situation.

Any help much appreciated.

P.S Don't even know if the log I attached is correct, just shout if not.

Cheers

Attached Files

Your injector duty at cranking is 0.7%, you'll need a lot more fuel to get the engine to fire.

Change the master fuel trim to 0% and the master fuel to 8ms and see if it's any better. Post a log with these settings

Thanks, Chris. Missed your reply earlier. Tried it at 8ms and 10ms (attached) What % should it be and what could be the reason that increasing the ms is not changing it much?

Also got a couple of very loud backfires.

Attached Files

Backfires indicate you might be firing at the end of the exhaust stroke instead of compression. Add 360 deg to your timing offset in the Calibrate Base timing menu.

Thanks, will try that soon. I did wonder about my offset only being 10. I've seen quite a few posts saying that -85 was common for the RB26. But not seen 370 or those kinds of high numbers mentioned anywhere. How normal is it to have it that far offset and what would be the reason for it?

2 Reasons for this, you replaced the CAS wheel with something else than OEM, then it depends also how the CAS itself is physically rotated when it is installed. It's a very quick test and that will just eliminate that possibility.

An important thing to mention as well is how you check your timing with the timing light. I always put an old distributor spark plug ignition lead between the coilpack and spark plug, and clamp my timing light to this lead. Some people use the "wire loop" in the coilpack wiring but I never had success using this one.

I also agree with Chris that 8ms master fuel should be a good starting point to get you going.

Thanks, I will report back soon.

I've always had to use my timing light with the gate held open and I've put it through the cable running to spark plug no1. Just before it goes to the plug for that coil pack. I'll see if I can find an old HT lead though.

Frank, that sorted it :)

The issue I have with that is that I can't put in 370 (360 got it to start) as it will only accept the -360 / 360 range.

What's the best / most logical way to sort this? Software or swapping the CAS plug wires or ECU wires around?

Don't think there is any other way of installing the CAS as it has a half-moon key on it.

Actually, come to think of it there is a DIP switch on the ECU it's self. Not sure if that's trigger related but will take a look now.

You can enter -350 and it will be the same as 370 would be!

As for the DIP Switch, I don't use plug in ECU so I can't help with that.

Maybe you put the trigger wheel upside down? I don't know if it matters on the AEM CAS wheel, it depends of the indexation of the wheel itself.

Haha, of course! Can't do any more tonight as the neighbours are going to get cross but will do that first thing tomorrow.

I couldn't see a difference when I put the disc in but maybe there was. I'm definitely not opening it again though. That thing was a PITA to swap over.

Yeah installing that disc in the RB CAS (Except NEO) is definitely a PITA. Depending on your setup, I would suggest a crank trigger kit... those 30+ years old CAS aren't getting more reliable with time hahahaha!

Glad you found your issue and that the car is now running!

Yeah got that on the to-do list at some point.

Do I need to adjust the dead time vs battery voltage table for my injectors? They are Denso 195500-1370 550cc (Not 600cc like I thought). I'm also running a Nismo FPR and an upgraded fuel pump. This is currently running at 3.5 bar at idle. I believe the standard RB setup is 2.5 bar at idle.

Also, what's the deal with the 12v value going up and not following the curve down?

[img="blob:https://www.hpacademy.com/6291610e-b40a-4e18-a285-9000360fe316" alt="" alt="" ]

Attached Files

OEM Base fuel pressure (Idling with the vacuum removed from the fuel pressure regulator) if the R32 GTR is 3bar. If you check the pressure with the engine idling and the vacuum still connected, it will be 2.5bar.

You should adjust the injectors deadtime as much as possible. I use Injector Dynamics so that makes it pretty straightforward. One way to adjust the deadtime is with the engine running idle at Lambda 1.0, you enter a richer target (let's say .85) in the lambda table and the actual lambda should reach it. If not, you change the deadtime value at this particular voltage (probably 14v if the alternator is charging) and try again. You can do the same with the alternator disconnected and do the same for the 12V cell in the deadtime table.

Thanks Frank. Mine has a Nismo adjustable FPR so I'm not sure how much difference that will make to my injector settings?

I have some decent info for the injector dead times so I have set that now.

Mine is 3 Bar on idle or 3.6 Bar on idle with the vacuum pipe removed from the FPR. So looks like the FPR has been adjusted for around 0.5 bar more pressure.

It's common when people are running out of injector to nip the base fuel pressure up a little. This does impact the dead times so if you've good information for the injectors at 3 bar I'd adjust the base pressure down a little.

I've not used the AEM discs in the OE CAS as the sensors are all old, if I'm sticking with a simple RB build, one without cams and valve springs upgraded I'll use a NZ wiring trigger kit, it's still bolted to the cam so can suffer belt deflection but on mild builds it's not an issue, any big builds get a crank/cam set up

Ok, thanks for the info. Well, I don't know how good this info is or whether these are the values at 3 Bar but they did match roughly what was previously in the PFC.

https://injector-rehab.com/knowledge-base/fuel-injector-lag-times/

In all honesty I probably need to get some modern injectors with decent datasheets!

I'm slowly getting to grips with the PC Link software along with some help from an experienced tuner and the car is running a lot smoother already compared to the PFC.

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