Jump to content
SAU Community

Recommended Posts

Guys, a couple of things please
  1. TPS voltage has been at 0.36v for years (have ECU Talk readout) as could not get at it to adjust it and tuner said not a problem. Engine runs fine but now have front of engine apart and have reset to 0.44v closed and it reads 3.76v fully open. Is this about right? What is consequence of either low or high voltage when closed?
  2. Took opportunity to install adj ex cam gear. What is the go here? Currently run a TD06-25G, which is a bit laggy but once on full boost (20 psi) around 4000 RPM really gets going and holds boost through to 7800! Am led to understand retarding cam gives better turbo response as I would like it to come on a bit earlier. Is this correct? If so, approx how many degrees?
Thanks
Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/
Share on other sites

You should have left it as is! Your tuner would have already calibrated the voltage range in your ECU.

If you play around with it your ECU won't know what a WOT and idle condition is anymore. Since you've played with it, you will need to recalibrate your TPS in your ECU (I recall you're using a Haltech) - not a hard task, but you've essentially just undone his/her work.

Try ret4rd it by 3~5 degrees however you'll need to take some timing out in your peak load area - best to be done on a dyno to load hold and knock detection.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964381
Share on other sites

On 28/04/2022 at 4:57 PM, Dose Pipe Sutututu said:

You should have left it as is! Your tuner would have already calibrated the voltage range in your ECU.

If you play around with it your ECU won't know what a WOT and idle condition is anymore. Since you've played with it, you will need to recalibrate your TPS in your ECU (I recall you're using a Haltech) - not a hard task, but you've essentially just undone his/her work.

Try ret4rd it by 3~5 degrees however you'll need to take some timing out in your peak load area - best to be done on a dyno to load hold and knock detection.

OK thank you. WOT? I'll give it a try and can always reset back to original voltage. I think the voltage has changed as bit since it was tuned 8 years ago so that's why I reset it. Its a Z32 ECU with Nistune board. Yes understand re the adj cam gear and that I will need to check timing after adjusting. Mate David Zilm has a private Dyno Dynamics I can use.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964384
Share on other sites

WOT is wide open throttle, Nistune allows you to adjust the minimum voltage before the idle strategy is enabled.

Easier to leave it how it was before as the TPS calibration in Nistune isn't as straight forward as a modern ECU.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964387
Share on other sites

OK thanks for all that info, however, what you are saying is that the voltage is not that important at tuning but I constantly see posts here saying TPS voltage should be between 0.45 and 0.5 v. 

Re the ex cam gear are you saying that 3-5 degrees boofhead will improve turbo response, which I assume means boost will come on at lower RPM. Any idea by how much lower? I guess one tooth is about 8 degrees hence the need for a vernier gear.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964434
Share on other sites

On 29/04/2022 at 11:53 AM, WalkyHR31 said:

I constantly see posts here saying TPS voltage should be between 0.45 and 0.5 v. 

Yes, if you're using a PowerFC door stopper or a stock ECU :) 

If you're using a configurable one, you can set whatever voltage is the floor for the the ECU to you know you're at 0% throttle to enable the idle strategy and/or decel fuel cut.

Really hard to say, best way is to incrementally ret4rd it on the dyno and graph the differences between runs.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964435
Share on other sites

OK thanks that all makes sense and I now understand the difference. Will reset voltage back to original value.

Again makes sense so i'll try that on the dyno. Assume as cam is retarded CAS needs to be advanced the same amount to maintain correct static timing?

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964436
Share on other sites

Theoretically you shouldn't move it, because if you do your TDC will be offset.

By ret4rding the cam gear, you're just ret4rding the exhaust cam and it's unfortunate the CAS is running off the exhaust cam.

If you resync it, then your entire timing map will be off.

 

Those are my thoughts, happy to be corrected by someone at least 3x smarter than me @GTSBoy lolol

  • Confused 1
Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964437
Share on other sites

Cam timing is not ignition timing - completely different things.

Regardless of where adjustable cam gears are set you still set up the crank angle sensor as normal with a timing light to get correct engine position against the crank - It's the whole point of adjustable cam gears so the outside cam gear teeth don't move from the factory position relative to the crank to change cam lobe location.

Ignition timing is relative to where the crank and therefore pistons are (engine position), not relative to cam lobe positioning.

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964439
Share on other sites

On 4/29/2022 at 10:37 AM, WalkyHR31 said:

Assume as cam is retarded CAS needs to be advanced the same amount to maintain correct static timing?

I think this, because

(actually, not because of this)

On 4/29/2022 at 11:02 AM, Dose Pipe Sutututu said:

Theoretically you shouldn't move it, because if you do your TDC will be offset.

because that's not true. He's adjusting the cam gear, not the crank gear.

But also I disagree with Ben, because

On 4/29/2022 at 11:38 AM, BK said:

Regardless of where adjustable cam gears are set you still set up the crank angle sensor as normal with a timing light to get correct engine position against the crank - It's the whole point of adjustable cam gears so the outside cam gear teeth don't move from the factory position relative to the crank to change cam lobe location.

This is not true. The CAS is driven off the centre of the end of the camshaft. Therefore the CAS is in time with the camshaft. The gear remains in fixed relationship with the crank, but the adjustable bit of the gear moves the cam foreward/backward wrt the gear, and the CAS goes with it. So, advance or boofhead the cam by 2° and you have to boofhead or advance the CAS to compensate.

Whatever the case, you don't just twist it back..... you do use a timing light to get it set right, in which I do agree with Ben.

There. I hope I haven't ruffled too many feathers.

  • Like 1
Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964448
Share on other sites

On 29/04/2022 at 3:09 PM, GTSBoy said:

I think this, because

(actually, not because of this)

because that's not true. He's adjusting the cam gear, not the crank gear.

But also I disagree with Ben, because

This is not true. The CAS is driven off the centre of the end of the camshaft. Therefore the CAS is in time with the camshaft. The gear remains in fixed relationship with the crank, but the adjustable bit of the gear moves the cam foreward/backward wrt the gear, and the CAS goes with it. So, advance or boofhead the cam by 2° and you have to boofhead or advance the CAS to compensate.

Whatever the case, you don't just twist it back..... you do use a timing light to get it set right, in which I do agree with Ben.

There. I hope I haven't ruffled too many feathers.

Maybe I didn't explain it in detail enough to be clear as yes the CAS is off the camshaft, but the point of it is to reference the CRANKSHAFT, not camshaft position. CAS = CRANK (not cam) angle sensor. Yes if you adjust the the inside of a cam gear the CAS will end up in a slightly different position, but the different position is referenced relative to the crankshaft for engine position.

At the end of the day we do actually mean the same thing 👍, as the ignition timing is in reference to the crankshaft, not the cam position

Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964452
Share on other sites

On 29/04/2022 at 4:22 PM, Dose Pipe Sutututu said:

There we go, I was wrong :) 

Happy to admit it too, unlike Facebook - where most will argue they're right even if they're wrong!

As long as everyone's on the same page about what's going on, that's all that really matters 👍

  • Like 2
Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964464
Share on other sites

On 30/04/2022 at 12:43 PM, Duncan said:

I can't take it any more. Autoreplace for retard has been removed. No idea why it was ever there.

Oooh man! It took me way too long to work out what you were talking about. I had never heard of the term boofhead before reading this thread. I just went along with it and assumed it was a special way of adjusting things. Because people used it so confidently and GTSBoy is always so educated on everything.

It would have been pretty funny if I ended up asking my mechanic about boofhead timing adjustments

  • Haha 3
Link to comment
https://www.sau.com.au/forums/topic/483595-rb25det-queries/#findComment-7964674
Share on other sites

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

    • Hey y'all! I'm curious about how y'all go about widebodying your cars. I noticed that when running a square setup, my front wheels are a bit more tucked in than my rear wheels. Not by much, maybe 5-10mm. This leads me to wonder - when I widebody, should I use narrower front flares and wider rear flares? I found a set of 40mm rear flares that I really like, and was thinking of pairing them with some 18mm front flares, but I don't want the car to look strange. How have others done this? Note, I'm in a sedan. Thanks!
    • And if it was anything other than an auto tranny part, it might be a problem. But seeing as all auto trannies belong in the recycling bin, it's fine.
    • I have an R32 Fenix rad. It is good.
    • All the schemas I can see, indicate your typical setup of ATF 'cooler' (read: heat exchanger) in the bottom radiator tank..ie; https://nissan.epc-data.com/stagea/wgnc34/5413-rb25det/engine/214/ ...but I can prattle on a bit here. These trannies have a thermistor in the sump ~ the TCU reads this and 1. bumps the line pressure up when the ATF is 'cold' and 2. prevents the TC lockup clutch from operating, until the ATF comes up to minimum operating temp (keeps the ATF 'churning' through the TC so it heats up quicker) -- trigger point is around 55C. In these conditions, the engine coolant temperature rises faster than the ATF temperature, and also helps heat the ATF up, which is why it's best to think of the in radiator tank setup as a heat exchanger ; the heat can flow in both directions... ...with these trannies, the 'hot' ATF comes out the front banjo bolt, flows through the cooler/heat exchanger, and returns to the box  via the rear banjo bolt. This gets a mention, due to the wildly different opinions wrt running auto trans fluid coolers ~ do you bypass the in radiator tank altogether, or put the cooler inline with the in radiator tank system...and then, do you put the additional cooler before of after the in radiator tank system?... ....fact is the nominal engine operating temp (roughly 75C), happens to be the ideal temperature for the ATF used in these trannies as well (no surprises there), so for the in radiator tank system to actually 'cool' the ATF, the ATF temp has to be hotter than that...lets say 100C -- you've got 25C of 'excess' heat, (slowly) pumping into the 75C coolant. This part of the equation changes drastically, when you've got 100C ATF flowing through an air cooled radiator ; you can move a lot more excess heat, faster ~ it is possible to cool the ATF 'too much' as it were...(climate matters a lot)... ...in an 'ideal' setup, what you're really trying to control here, is flash heating of the ATF, primarily produced by the TC interface. In a perfect world, wrt auto trans oil cooling, you want a dedicated trans cooler with builtin thermostatic valving - they exist. These should be run inline and before the in radiator tank system ~ when 'cold' the valving bypasses the fin stack, allowing the ATF to flow direct to the in radiator tank heat exchanger, so it works 'as intended' with helping heat the ATF up. When 'hot' (iirc it was 50C threshold), the valving shuts forcing the ATF through the cooler fin stack, and onto the in radiator tank heat exchanger...and you sort of think of it as a 'thermal conditioner' of sorts...ie; if you did cool your ATF down to 65C, the coolant will add a little heat, otherwise it works as intended... ...the 'hot' ATF coming from the front bango bolt, is instantiated from the TC when in use, so all/any flash heated oil, flows to the fluid-to-air cooler first, and because of the greater heat differential, you can get rid of this heat fast. Just how big (BTU/h) this cooler needs to be to effectively dissipate this TC flash heat, is the charm...too many variables to discuss here, but I just wanted to point out the nitty-gritty of automatic trans fluid coolers ~ they're a different beastie to what most ppl think of when considering an 'oil cooler'... /3.5cents   
    • Been a busy but productive day. Axle and hubs acquired. All fitted up after a bit of modifying. Need to sort out wider mudguards and running light reflector covers but other than that the trailer is gooood to go !!
×
×
  • Create New...