rb25 RB25DET Timing Advance issues

[CLEM0]

Hello.

Recently picked up an R33 GTST, S1.5, and I am very worried about the timing issues.

The car ran rich when I got it, which was fixed by adjusting the TPS to correct voltage, but the idle seemed a little off still. I took it and got it retuned, as the last tune was very old and outdated.

The car made 425 RWHP on a hub dyno, at 15 PSI. Tuned on Apexi Power FC and a GT3582. The car has very little knock on the hand controller, and seems to run fine. The tuner said however he had to advance the timing a massive amount, and believes the ECU is misreading timing, and it is an ECU fault.

The timing degrees is at mid to high 20's under full boost, which seems very high. Again, low knock (under 30) on Power FC sensor. It was running similar timing to this for the last 7-8 year apparently, and had a very similar ignition map on the old tune.

 

What's the go with this? How can I get the timing to a 'normal' level? Has the belt slipped? CAS failed? I am concerned the Power FC knock reading is inaccurate and I don't want this car to explode, as Covid tax meant this was not a cheap buy!

Cheers all!

[Murray_Calavera]

Did anyone even check the timing with a timing light?

Are you on E85?

[CLEM0]

2 minutes ago, Murray_Calavera said:

Did anyone even check the timing with a timing light?

Are you on E85?

Apparently the tuner did check it with a timing light- going to go get it rechecked and the CAS adjusted if it's out. Second opinion is probably cheaper than an engine rebuild

 

i'm on pump 98 also

Edited December 5, 2020 by CLEM0

[Murray_Calavera]

I'm a bit confused, so the tuner checked the base timing, found that what the timing was reading and what the timing was in the ECU didn't match - and then tuned the car anyway? 

Do you know if the tuner used any type of knock ears during the tune?

[CLEM0]

1 minute ago, Murray_Calavera said:

I'm a bit confused, so the tuner checked the base timing, found that what the timing was reading and what the timing was in the ECU didn't match - and then tuned the car anyway? 

Do you know if the tuner used any type of knock ears during the tune?

Apparently the timing matched according to the tuner, and only reads wrong when not on idle, which sounds odd. Apparently this is why the ECU might be faulty

Don't think any knock ears were used either

[Murray_Calavera]

Mate, I think it's time to find a better tuner. Where abouts do you live?

[GTSBoy]

8 hours ago, CLEM0 said:

Power FC knock reading is inaccurate

Name a time when that hasn't been true.

[Dose Pipe Sutututu]

5 hours ago, CLEM0 said:

Apparently the timing matched according to the tuner, and only reads wrong when not on idle, which sounds odd. Apparently this is why the ECU might be faulty

Don't think any knock ears were used either

Idle strategy involves timing correction, you need to disable the idle closed loop by unplugging the TPS before checking the base timing to see if it's synced to the GameboyFC.

[CLEM0]

2 hours ago, Dose Pipe Sutututu said:

Idle strategy involves timing correction, you need to disable the idle closed loop by unplugging the TPS before checking the base timing to see if it's synced to the GameboyFC.

I've been reading about all of this, setting the CAS and all. Would the CAS being out cause all the timing numbers displayed by the 'GameboyFC' (haha) be out of sync? Or is the timing is shows what the actual engine is seeing?

[CLEM0]

8 hours ago, Murray_Calavera said:

Mate, I think it's time to find a better tuner. Where abouts do you live?

Tuner was highy recommended, i'm in Perth.

[GTSBoy]

Listen, this shit is very simple.

Step 1: #1 sparkplug out.

Step 2: Engine to TDC firing on #1. You will have to convince yourself that both cam lobes are facing away from the cam followers on #1. Use a screwdriver down the sparkplug hole to find TDC. This is done by marking the screwdriver against some feature (the edge of the hole for example) while the piston is rising and close to TDC, then rotate past TDC until the mark is back in the same place. Note the engine position at the pulley timing marks for both. TDC is halfway in between. If TDC is not right bang smash on the TDC mark on the pulley - there's your first warning sign.

Step 3: Now that you know that the engine is mechanically telling the truth about TDC, the next paranoid step is to make sure that the cam timing is not 1 or more teeth out on eaach/either cam. Timing cover comes off the engine. You will have to rotate the engine several times until the timing marks all line up at the same time. If you cannot every get them to line up, there's a significant warning sign. You simply can't get the ignition timing to make sense if the cam timing is not.

Step 4: Throw the PFC in the bin.

Sorry, got ahead of myself there.

Um, Step 4: After all this, it is just a case of the usual stuff. Using a timing light (properly) to check idle timing against what the PFC says the engine angle is. "Properly" means disconnecting the TPS and triggering the timing light correctly. If the PFC says 15° but the engine says 5° on the pulley, then you have probably missed something in the earlier steps.

Step 5: Throw the PF ....ah nearly did it again.

Step 5: Find a better tuner. A good tuner is not necessarily a good mechanic. There is no such thing as a "good tuner" if they are not also a good mechanic when you are trying to solve this sort of problem. Also, trying to fix this sort of shit while the car is strapped to the dyno is a dumbness, because it costs a lot more to fix strapped on a dyno than it costs to fix it on the other side of the workshop.

[CLEM0]

3 minutes ago, GTSBoy said:

Listen, this shit is very simple.

Step 1: #1 sparkplug out.

Step 2: Engine to TDC firing on #1. You will have to convince yourself that both cam lobes are facing away from the cam followers on #1. Use a screwdriver down the sparkplug hole to find TDC. This is done by marking the screwdriver against some feature (the edge of the hole for example) while the piston is rising and close to TDC, then rotate past TDC until the mark is back in the same place. Note the engine position at the pulley timing marks for both. TDC is halfway in between. If TDC is not right bang smash on the TDC mark on the pulley - there's your first warning sign.

Step 3: Now that you know that the engine is mechanically telling the truth about TDC, the next paranoid step is to make sure that the cam timing is not 1 or more teeth out on eaach/either cam. Timing cover comes off the engine. You will have to rotate the engine several times until the timing marks all line up at the same time. If you cannot every get them to line up, there's a significant warning sign. You simply can't get the ignition timing to make sense if the cam timing is not.

Step 4: Throw the PFC in the bin.

Sorry, got ahead of myself there.

Um, Step 4: After all this, it is just a case of the usual stuff. Using a timing light (properly) to check idle timing against what the PFC says the engine angle is. "Properly" means disconnecting the TPS and triggering the timing light correctly. If the PFC says 15° but the engine says 5° on the pulley, then you have probably missed something in the earlier steps.

Step 5: Throw the PF ....ah nearly did it again.

Step 5: Find a better tuner. A good tuner is not necessarily a good mechanic. There is no such thing as a "good tuner" if they are not also a good mechanic when you are trying to solve this sort of problem. Also, trying to fix this sort of shit while the car is strapped to the dyno is a dumbness, because it costs a lot more to fix strapped on a dyno than it costs to fix it on the other side of the workshop.

Thanks mate. I'd love to bin the PFC but I just bought the car and don't have the budget yet, but will eventually be getting a Link when I am experienced enough to go forged bottom end. Will need to buy a timing light during the week it seems

[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!

 

[Murray_Calavera]

Let's take a step back and a deep breath, keep it simple. 

What exactly is wrong with the car? Does it start, idle and drive well? 

 

[CLEM0]

8 minutes ago, Murray_Calavera said:

Let's take a step back and a deep breath, keep it simple. 

What exactly is wrong with the car? Does it start, idle and drive well? 

 

Damn... every other forum I used to get clowned for not giving enough detail, now too much- can't get shit right 😂😢

Anyway- Idle sounds choppy, did so both before and after retune, car struggles/won't start cold unless given throttle, misfires/shoots flames under light load (2-3.5k RPM). Does this randomly, which is now made worse since retune.

Drives fine, feels like about 400whp, goes hard. Only shows issues when approaching rev limit, about 500-800 RPM before redline it'll backfire hard occasionally, so I decided to stay well away from higher RPM until I can fix this.
The car actually runs and drives fine when warm besides isssues mentioned persisting. Cruises well, doesn't stall.

Idle still not amazing when warm but very hardly noticable choppy sound, retune set idle to 950RPM instead of 650 which improved it decently. Was really only bad when cold.

The main reason i'm going through all of this literally the timing numbers. The car makes shit all power under regular safe timing maps, so now they're far too high and that is what i'm struggling to figure out- why? The tuner only set them so high as he simply believed the ECU was faulty, as it runs very solid at stupidly high advance, and makes normal power for the boost and setup.

 

[Murray_Calavera]

These issues, have they been there the entire time you've owned the car? You've had it about 8 years now?

[CLEM0]

Just now, Murray_Calavera said:

These issues, have they been there the entire time you've owned the car? You've had it about 8 years now?

Sorry if I wasn't clear- had the car just over a week. Previous owner had for 7-8 years give or take.

I would never let a car run like this for more than 8 days, let alone 8 years

[Murray_Calavera]

Ok, that makes sense. 

You've got a dinosaur ecu, you could also have dinosaur injectors. Do you know what injectors you have? 

Shitty side feed injectors could be the culprit for a lot of those issues.

When you say it makes shit power on regular timing, how much timing and how much power exactly? 

Do you have a wideband? What are your fuel mixtures like in the areas you are having issues?

[CLEM0]

1 hour ago, CLEM0 said:

- 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 2am. Just realised I measured this in inches. 0.020 inches in 0.5mm, and 0.025 is roughly 0.6mm. 
 

Plug gap is fine. No idea what to do.

Nothing makes sense with this issue and not even mechanics who build RB engines for their job can figure out what is going on. It literally just doesn't make sense whatsoever.

[CLEM0]

2 minutes ago, Murray_Calavera said:

Ok, that makes sense. 

You've got a dinosaur ecu, you could also have dinosaur injectors. Do you know what injectors you have? 

Shitty side feed injectors could be the culprit for a lot of those issues.

When you say it makes shit power on regular timing, how much timing and how much power exactly? 

Do you have a wideband? What are your fuel mixtures like in the areas you are having issues?

Injectors are I believe 740cc side feeds. Will need to pull to check. Stock fuel rail, FPR 800 with no gauge for pressure.
I have a wideband from my old car but haven't got the bung I ordered from eBay yet to put it in. Car ran 11.5:1 on full boost according to tuner. No clue how he measured this....