RB25DET- ECU Will Not Stay Connected When Cranking

[Juicy]

Hey all,

So i've got a GTRLINK plug in for my R33 GTST.

Currently on base map, TPS, MAP and IAT all setup. Running 3 port solenoid stock wiring, basic stuff.

Now, i've got the car set @ 15° BTDC from the previous ECU, however the Link base map is saying 10°. So today I disabled Master Fuel and cranked it- car cranks about 3-5 times, ECU lights go fully off, car alarm/immobiliser starts going off.

So i've done the basic stuff as follows:

Battery is reading around 11.5-11.9V (gauge/ecu)

Pin 49- Has 12V

Pin 16- Has 0V on key on, 12V key off

Bridged Pin 16 to ground, relay clicks, car still disconnects from ECU

Pin 45 (seemed like the issue, was not) - had 12V, which drops to around 6-8ish volts when cranking so,

Bridged Pin 49 to Pin 45 to eliminate this, made no difference?

So now i'm at a bit of a loss. I'm suspecting my alarm (https://www.manualslib.com/manual/2057099/Laserline-989e.html?page=5#manual) might be the culprit, however it worked just fine with the old ECU.

I'm struggling to find out why it's doing this. ECCS relay works, and bridging a direct 12V source to Pin 45 did nothing, which from what i've read, should solve this issue (albeit not properly). Or potentially something else- as I have a few inputs showing voltage that i'm not sure what they are. Also, with key on AC Request is constantly on- could this be something?

 

Any help appreciated! Cheers all.

 

[Adamw]

As a test can you bridge pin 49 direct to the battery positive or some other good 12V supply that isn't related to the eccs relay or pin 45.  

[Juicy]

5 hours ago, Adamw said:

As a test can you bridge pin 49 direct to the battery positive or some other good 12V supply that isn't related to the eccs relay or pin 45.  

Thanks Adam, i'll do that tonight.

Assuming that does work, what's the fix?

edit- Pin 59 would be ok?

[Adamw]

8 hours ago, Juicy said:

edit- Pin 59 would be ok?

Yep 49 or 59 are connected together.  

 

8 hours ago, Juicy said:

Assuming that does work, what's the fix?

The most common problem is low voltage on pin 45 which causes the FET that controls the ECCS relay (pin 16) to drop out during cranking.  But manually grounding pin 16 has ruled that one out.  So if ecu is still dropping when we know the ECCS relay is engaged the whole time then it can only be either low voltage coming from the ECCS relay or a bad ground.  

Oh, I forgot to mention earlier, also make 100% sure the connector is pushed all the way home at the outside ends, it is easy to assume it is all the way in when the bolt is tight but it is very common for the plug to bend so the center is fully in but the ends arent.

[Juicy]

Problem solved: Battery was only ~300 CCA.

Threw in a brand new 550CCA and it stays connected. Turns out my brake lights are stuck on (no clue if this is ECU related, or a short?) but regardless that's probably why 300CCA wasn't enough.

 

Side note; does anyone know what the RB25DET injector firing mode is? I wrote it down and can't find it, since i've turned fuel off to set base timing.... woops.

 

 

Also @Adamw, if my base timing was set @ 15°BTDC on my old ECU, do I have to rotate CAS until it's 10° with the Link, or can I just change the field to 15- or will this advance the timing across the whole base map by 5°? New to all this ECU stuff lol.

[Vaughan]

47 minutes ago, Juicy said:

Turns out my brake lights are stuck on (no clue if this is ECU related, or a short?)

Brake light switch on the pedal will be dead or the thing it pushes against missing

[RyanG]

52 minutes ago, Juicy said:

If my base timing was set @ 15°BTDC on my old ECU, do I have to rotate CAS until it's 10° with the Link, or can I just change the field to 15- or will this advance the timing across the whole base map by 5°?

With the engine running (or cranking if you're not up to that yet):

Ecu settings > Triggers > Calibrate > Set Base Timing

> Lock ignition timing to a value that the engine has a reference mark for (not familiar with RB markings), say 15 degrees
> Adjust trigger offset (or CAS) until a timing light matches the exact degrees that the ecu has locked it to
> Rev engine and check drift, adjust delay to suit

Once this is done, what is requested in your ignition table is what is delivered. If you press F1 on 'Calibrate' this is outlined in the help manual.

[Juicy]

2 hours ago, Vaughan said:

Brake light switch on the pedal will be dead or the thing it pushes against missing

Ah. Sweet. Thanks brother.

 

2 hours ago, RyanG said:

With the engine running (or cranking if you're not up to that yet):

Ecu settings > Triggers > Calibrate > Set Base Timing

> Lock ignition timing to a value that the engine has a reference mark for (not familiar with RB markings), say 15 degrees
> Adjust trigger offset (or CAS) until a timing light matches the exact degrees that the ecu has locked it to
> Rev engine and check drift, adjust delay to suit

Once this is done, what is requested in your ignition table is what is delivered. If you press F1 on 'Calibrate' this is outlined in the help manual.

Cheers for the reply mate.

I've got all that down (up to cranking) but I have already set my CAS @15° BTDC on my old ECU, so I know the timing is 100% 15°.

More so curious if I can just set the base timing to 15° in the calibration box, or do I rotate the crank angle sensor and get it to line up with the ECU @10° or, if I just keep the CAS where it is and adjust the delay in the calibration box.

Then, i'm assuming if the base timing is 15°, it'll compensate in the map and won't throw the timing off (as it's just base timing to gauge position) Again, sorry if this doesn't make sense/is stupid. I can do engine work but this stuff is too much Ahaha

[RyanG]

3 minutes ago, Juicy said:

I've got all that down (up to cranking) but I have already set my CAS @15° BTDC on my old ECU, so I know the timing is 100% 15°.

More so curious if I can just set the base timing to 15° in the calibration box, or do I rotate the crank angle sensor and get it to line up with the ECU @10° or, if I just keep the CAS where it is and adjust the delay in the calibration box.

Then, i'm assuming if the base timing is 15°, it'll compensate in the map and won't throw the timing off (as it's just base timing to gauge position)

You can line up the calibration with either the CAS or the trigger offset. The calibration just matches timing between what is happening at the engine and is requested by the ECU. The actual number it's calibrated to is somewhat irrelevant.

You can calibrate and check/lock timing at TDC, but after exiting the calibration, if the cell in the ignition table which the ecu idles at is requesting 20 degrees, then its 20 degrees.

If you're confident that your last timing map was calibrated and accurate, then you can calibrate timing and then copy-paste/reference your old ignition map into the Link to get you started.

[Juicy]

39 minutes ago, RyanG said:

You can line up the calibration with either the CAS or the trigger offset. The calibration just matches timing between what is happening at the engine and is requested by the ECU. The actual number it's calibrated to is somewhat irrelevant.

You can calibrate and check/lock timing at TDC, but after exiting the calibration, if the cell in the ignition table which the ecu idles at is requesting 20 degrees, then its 20 degrees.

If you're confident that your last timing map was calibrated and accurate, then you can calibrate timing and then copy-paste/reference your old ignition map into the Link to get you started.

Thankyou once again mate.

I'll set the link calibration 15° and double check with a timing light to make sure it's accurate, but from memory it was recently set @15°, so should be no issues.

I'd love to copy/paste my old ignition timing table but unfortunately my old ECU decided to burn out (when I accidentally touched the two battery terminals together using a ratchet.... woops)

Also, would you know what firing mode the RB uses? I'm guessing it was Sequential iirc.

[RyanG]

13 minutes ago, Juicy said:

Thankyou once again mate.

I'll set the link calibration 15° and double check with a timing light to make sure it's accurate, but from memory it was recently set @15°, so should be no issues.

I'd love to copy/paste my old ignition timing table but unfortunately my old ECU decided to burn out (when I accidentally touched the two battery terminals together using a ratchet.... woops)

Also, would you know what firing mode the RB uses? I'm guessing it was Sequential iirc.

Not a problem at all. The trigger offset in the Link will more than likely need to be adjusted. I'd lock the timing at 15 then adjust the trigger offset to make the crank mark line up. I'd say it's sequential given it had a cam sensor, yeah.