Ecu and Engine Timing Sync?

[CLEM0]

Hello all.

Probably a silly question, but need some help from some of the tuner guys- my RB won't make power unless timing is very advanced (high 20*) on my Power FC. Made another thread about this earlier. This is just a question i'm struggling to find an answer to.

The car has little knock and runs good at this extreme level of timing under full boost of 15psi on a GT3582, making ~425rwhp. Seems to peek around 26- 28* under full load, tuner said car runs good but believes the ecu is faulty. I'm going to check cam timing tomorrow and take to a shop to check base timing (don't have timing light!)

I'm trying to diagnose why this issue is present- So, am I correct in the following assumption? I'm very new to the tuning/timing side of cars, so this might be stupid:

Example only- If my base timing is out say 5* (10* BTDC on idle instead of proper 15* on RB25DET) and the Power FC is reading it as normal 15* as is has no way to directly communicate, would this mean my entire tune would be out 5* (eg when the PFC is at 25*, the engine is actually at 20*) hence the low knock and high timing, as well as when timing is around safe level of advance it makes hardly any power...

Please take it easy on me if this is a dumb question, just trying to sort this issue out- car runs good but timing numbers are very worrying!

[blind_elk]

I'm no expert, but I know enough about the basics.

The figure being displayed by the PFC is the number PROGRAMMED into it. It is not telling you what it is reading but rather what it is trying to achieve. So, the PFC gets a trigger at some point, say 60BTDC, and then calculates when the engine will be at the programmed point, say 23BTDC, when it should fire the spark. So if the PFC gets the trigger at the wrong time, the actual firing point will not match the programmed firing point.

I run a Wolf unit on my RB25DET, and it has a function to adjust the trigger point so that what is programmed is what you see with a timing light. Check if the PFC has a similar function. (And be aware, some timing lights seem to show double the actual timing)

Now more experienced people can take over diagnosing your problem.

[Murray_Calavera]

It's worth mentioning, you don't know that the car has 'little knock'. If your tuner didn't have knock ears on and was relying on the stock knock sensor values, that is barely a rough estimate of whats going on. 

Even if you have a Plex Knock Monitor (which is probably the best knock detection system you can buy at the moment), you still can't rely on the values without verifying them by listening to what's actually going on. 

I would not be surprised at all if you found that you engine was knocking in the top end with it's current state of tune. 

[GTSBoy]

1 hour ago, Murray_Calavera said:

I would not be surprised at all if you found that you engine was knocking in the top end with it's current state of tune. 

I would agree, and is the meaning of my first post in your other thread.

But, further to what Murray said, I would append to his sentence "assuming that the timing values being discussed are correct, and there's no mechanical problem causing the ECU's angle to not be the same as the engine's angle".

[joshuaho96]

Base timing on an RB26 is 20 degrees BTDC. If you actually have your base timing at 10 deg BTDC then commanding 26-28 degrees means you're actually commanding 16-18 degrees of timing.

As others have said, it's also possible that you're knocking and not hearing it.

Is the OEM knock sensor particularly insensitive or something? I was under the impression that a properly set up knock sensing setup (bandpass set up with correct bandwidth + peak, crank window appropriately set) is on par with what human ears can do.

[CLEM0]

7 hours ago, Murray_Calavera said:

It's worth mentioning, you don't know that the car has 'little knock'. If your tuner didn't have knock ears on and was relying on the stock knock sensor values, that is barely a rough estimate of whats going on. 

Even if you have a Plex Knock Monitor (which is probably the best knock detection system you can buy at the moment), you still can't rely on the values without verifying them by listening to what's actually going on. 

I would not be surprised at all if you found that you engine was knocking in the top end with it's current state of tune. 

It has ran at similar timing advance for almost a decade and hasn't gone to shit yet, so I presume whoever set the timing first didn't do it right- and as a result the value have been incorrect since day 1! I'm honestly not sure. It has had high values for so long. The stock knock sensor isn't great, but if it was knocking badly, surely it'd pick up at least something worrying, especially big knock. It picks up at most under full boost 25-30 or so.

It had from memory 28* on the top end on previous tune, which is why I immediately went to go for a retune without doing a single thing else to the car (besides a full service), because, although i'm not familiar with tuning, I knew this was absurdly high for the RB25, yet it's now retuned and doing the same thing.... Whole lotta money!

I am going to verify timing shortly with the cams only as that's very simple- and will have it checked by a shop with a timing light to verify and set correct base timing. I'd say i'll buy a timing light but this timing stuff is beyond me. I am pretty decent with cars, but i'm terrified to mess with engine timing myself haha.

[CLEM0]

14 minutes ago, joshuaho96 said:

Base timing on an RB26 is 20 degrees BTDC. If you actually have your base timing at 10 deg BTDC then commanding 26-28 degrees means you're actually commanding 16-18 degrees of timing.

As others have said, it's also possible that you're knocking and not hearing it.

Is the OEM knock sensor particularly insensitive or something? I was under the impression that a properly set up knock sensing setup (bandpass set up with correct bandwidth + peak, crank window appropriately set) is on par with what human ears can do.

That is the answer I was looking for- I thought so. I honestly think the timing is out ~10* retarded. I'm going to verify as soon as I physically can- but this would make sense, as 17-18* instead of 27-28* makes a shit tonne more sense to me on the RB25 top end.

[CLEM0]

6 hours ago, GTSBoy said:

I would agree, and is the meaning of my first post in your other thread.

But, further to what Murray said, I would append to his sentence "assuming that the timing values being discussed are correct, and there's no mechanical problem causing the ECU's angle to not be the same as the engine's angle".

Yep I think at such advanced timing knock would be very high. There must be a mechanical issue.

It has had similar timing for almost a decade so fingers crossed there is indeed a timing issue because if not i'm shocked this engine survived 370-400rwhp for so long!

[CLEM0]

9 hours ago, blind_elk said:

I'm no expert, but I know enough about the basics.

The figure being displayed by the PFC is the number PROGRAMMED into it. It is not telling you what it is reading but rather what it is trying to achieve. So, the PFC gets a trigger at some point, say 60BTDC, and then calculates when the engine will be at the programmed point, say 23BTDC, when it should fire the spark. So if the PFC gets the trigger at the wrong time, the actual firing point will not match the programmed firing point.

I run a Wolf unit on my RB25DET, and it has a function to adjust the trigger point so that what is programmed is what you see with a timing light. Check if the PFC has a similar function. (And be aware, some timing lights seem to show double the actual timing)

Now more experienced people can take over diagnosing your problem.

Can't find a similar PFC setting, going to have to verify timing and then retune it seems.

[GTSBoy]

There is no sync setting on a PFC. It is not a general purpose ECU. It is set up to work with only that type of engine and its original CAS. So it expects that CAS to be set to the right timing wrt the crank. The timing numbers shown in the igniton table in a PFC are supposed to be exactly the same as the engine angle, so long as the static timing was set correctly at idle, as previously discussed. If you instead crank the CAS forwards or backwards from "correct", then the ECU could be saying 28, but the engine actually be + or - from there by however much the CAS was moved.

Also, ignore the 20°BTDC static timing number that Josh gave you, as it is for RB26. Manual RB25s are 15°. if yours was originally an auto (and the PFC is for an auto - which I don't know is a "thing" anyway), then 20° would be correct. But either way, Josh's sentiment is correct. It would just be a question of whether the error was 5 or 10°. Even 5 would possibly be fine, because 22-23° is not outrageous. Not as outrageous as 28, anyway.

[CLEM0]

40 minutes ago, GTSBoy said:

There is no sync setting on a PFC. It is not a general purpose ECU. It is set up to work with only that type of engine and its original CAS. So it expects that CAS to be set to the right timing wrt the crank. The timing numbers shown in the igniton table in a PFC are supposed to be exactly the same as the engine angle, so long as the static timing was set correctly at idle, as previously discussed. If you instead crank the CAS forwards or backwards from "correct", then the ECU could be saying 28, but the engine actually be + or - from there by however much the CAS was moved.

Also, ignore the 20°BTDC static timing number that Josh gave you, as it is for RB26. Manual RB25s are 15°. if yours was originally an auto (and the PFC is for an auto - which I don't know is a "thing" anyway), then 20° would be correct. But either way, Josh's sentiment is correct. It would just be a question of whether the error was 5 or 10°. Even 5 would possibly be fine, because 22-23° is not outrageous. Not as outrageous as 28, anyway.

I think this is the issue then. Let's hope it hasn't been at 28* full load for almost a decade or this engine is on borrowed time!

[CLEM0]

So if anyone is still able to help, I really thought I figured it out but I'm stumped again.

- Thanks for all the helpful responses, I took them on board and checked it all today.

- I have checked all timing on the car. Intake and exhaust camshaft markings line up. When these line up, so does the harmonic balancer, with the marking point (more of a shaved section than a point) on the timing cover corresponds very closely to the 4th marking, AKA 15* degrees on the balancer. (0,5,10,15...) Hard to say it's 100% perfect but it's very damn close as far as I can tell.

- The engine is also at TDC at this point. Marked a thin metal rod with a permanent marker, and got it as close as possible to TDC by visually watching for the point the marking was neither going down when the crank was rotated clockwise or counter-clockwise. It all lines up.

- Literally all the timing points assessed line up (not perfectly as it's all judged by eye so leave some room for error) but it's all close enough to not be an issue.

- The timing of the ECU and the CAS is within 2*. This was tested at idle, and verified under of around 2000RPM. Used a timing light with the signal directly attached to plug #1 with a lead, not the crappy wiring harness/coil-plug loom. As far as timing goes - it's fine. (Only thing I didn't check is crankshaft marking under timing cover as this is a big job, ran out of time)

- THE ONLY ISSUE I CAN THINK OF NOW- I have a receipt from previous owner for a very recent plug change, done within the last few thousand kilometres. They are 6 x new NGK BKR6E - great, or so I thought. Pulled them today, turns out they're gapped at 0.20 to 0.25mm!!! I have no idea who would use such a stupidly low gap. Anyway; would this have any effect on the ignition timing? I know it'll affect car performance overall, but will it mean that to make power I need seriously advanced timing, as the spark is not strong enough until the mixture in the cylinder is pushed right to the top, right up to the spark plug? (advanced timing)

- It's the only major issue I can find on the whole car. I verified timing several times as I simply didn't believe it all lined up. I was sure this was this problem. From the tests I have conducted today, I can pretty happily eliminate timing from the equation, for now at least...

-If I still can't find solution this will be my last resort before either a new engine goes in or I give up for now.

Thanks again for all the help in this thread all, hopefully someone can guide me from here!