hi! from a newbie in canada. rb25det neo, in 240sx

Discussions concerning the M7790 cpu

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polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Sat May 15, 2021 10:23 am

yes indeed, plug wire jumper between the coil and the spark plug.

when you say that i'm at 11 degrees advance, do you actually mean 11, and that this is too retarded? or are you saying that i'm advanced by 11 degrees too much, meaning 26?

maybe i should back up and describe the process i'm using, just to make sure we are on the same page:

the nissan field service manual says,
once fully warmed up, set base idle speed at 600rpm.
unplug throttle position sensor
make sure there are no diagnostic fault codes present
check timing marks, and adjust crank angle sensor rotation till you hit the target timing.

target timing @ 600rpm is 15, +/- 2.
first timing mark is zero, second is 5, third is 10, 4th is 15.

this is exactly what i have done, other than i set the mark at 14, rather than 15.

now, i don't want to sound like i'm shrugging off your experience with these cars, and with nistune- i am truly grateful for all of your help. but we are not standing side by side on this job. when nistune is reporting 3, it looks to me like it's just pegged there, the same way the tps pegs 5.1v when you unplug it.

if the above procedure is correct by nissan's standards, then i'm kinda leaning towards the possibility that under these circumstances, nistune isn't reporting right, and i should trust the timing light. speaking of the timing light, the digital tach on the light is bang on with the tach reading in nistune, and the tach reading in the car's gauge cluster.

however, for peace of mind, i'm willing to go back, turn up the base idle till it seems like nistune is reporting a timing number other than 3, and then compare that with the timing light. if all we are trying to do, is match the timing numbers, then the base idle shouldn't be a factor, right?

PL
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by PL » Sat May 15, 2021 1:38 pm

Yes that's right - we're just trying to match the numbers of what the ECU reports to what is on the timing marks.

Nissan's procedure is just trying to make timing sit at 15 degrees. But if you know what the ECU is commanding then it doesn't matter if it's 15 degrees, or 10 or 3 or whatever. As long as they match. The ECU is relying on you setting the reference so when it commands 15 degrees then that's what's physically happening. I hope that makes sense.

When I say you're "11 degrees advanced" I mean that the ECU is reporting 3 degrees but actual timing at the crank is 14. So when driving if your timing map is commanding 20 degrees (ie: timing reported by ECU will be 20 degrees) then timing at the engine would be 31 degrees. This would cause heavy detonation.

I often find that if I watch the timing marks and move the throttle just off idle with my hand that you can see it lock onto 15 momentarily even if it won't sit on 15 at idle. Give it a try and you'll see what I mean. You'll see the vale reported by the ECU doing the same thing.

It should sit of 15 though - if TPS is set correctly and idle speed is correct. Can be touchy though.

No matter how you set the timing just please be careful that you always monitor knock when applying boost. You'll know immediately if you have too much timing cos it'll rattle like crazy.

PL

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Sat May 15, 2021 3:29 pm

Awesome,
Ok I’m definitely on the same page now. Next chance I get, I will try a few different rpm positions, and compare the results.

I’ve only done a few boosted pulls so far at this timing, and each has been awesome. No knock. One more trip back and forth to work before I can get under the hood again. I’ll stay out of the boost till then.

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Sun May 16, 2021 6:00 pm

ok, set the timing to match nistune again. more specifically, the consult page of nistune.

i did not unplug the tps, and i had to wedge a piece of paper behind the throttle stop to get the rpm to the point where the timing wasn't jumping around.

got both the consult and actual timing marks to land solidly on 3, no wandering.

out for a test drive, i'm back to overboosting, cutting out, and backfiring. not overboosting by a lot though. afr's hold steady at 11.5, then for a quick moment hit ~13 at the moment that is cuts out. this could mean a few different things i suppose, including the possibility that i'm hitting the limit of the fuel pump (up till now i've been trusting the previous owner's word on the upgraded status of the pump)

the timing value of 3 still struck me as odd, but i just explored the timing map tab in nistune, and i see 3 as a value in the row/column for 400 and 88. so it looks like a target of 3 is actually on the map, and i shouldn't be suspect of that value. sorry for doubting.

i assume 400 is an rpm value, but what does 88 represent? (the vertical columns)

in any case, although it feels like i'm running like shit now, i feel like i trust the timing, and the issues i'm having are bottlenecks in fuel delivery and boost control. thanks for steering me in the right direction. bit of a bummer, but it looks like it's back to the fabrication drawing board. oh well.

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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by Matt » Sun May 16, 2021 7:23 pm

Are you looking at the TP (load) values? See the mapping guide on the website for information on each map

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Mon May 17, 2021 2:30 pm

nistune menu.jpg
nistune menu.jpg (21.23 KiB) Viewed 204 times

mine looks slightly different than this one below (different values at different points on the scale), but essentially the same idea.

yeah, it must be a load value. thanks for the direction. mapping guide definitely looks like the place to be. lots to read tonight.


but what i guess i can sum up is, at 600-650rpm idle speed, my ecu figures it's at a load of 88, and therefore calls up 3 degrees advance from the ignition map.
timing map.jpg
timing map.jpg (115.98 KiB) Viewed 215 times

*i'm just re-reading the neo specific documents, and i'm realizing that i may have to go back and do some setup for the map sensor. although i'm having a bit of a boost control issue, i feel like i shouldn't be cutting out as hard as i am just yet (unless i truly am at the limits of the fuel pump). it's possible that i'm hitting the map controlled boost cut, and i need to raise those values a bit.
i don't think there's any hope of holding 8-10psi, but if i can get this wg setup to the point where it will control 12-14psi (which i think is the usual limitation of the neo maf and injectors) i'll be happy for this year.

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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by Matt » Tue May 18, 2021 9:05 am

If you are at idle, it is either accessing the idle/decel tables or in idle closed loop (varying timing/AAC to maintain target RPM)

More reading:
https://www.nistune.com/index.php/suppo ... umentation

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Tue May 18, 2021 4:45 pm

today i had a look at the ignition map while online. i wish i could say that i understand it better, but it seems to get more confusing. up till now, i have only been looking at the timing value reported in consult view.

first of all, i should mention that i noticed my neutral switch was not on. gave the shifter a wiggle, and it activated. so it works, but it's a bit lazy. makes me wonder if it was activated when i was setting the timing....

so when i compare the timing value from the consult view, to the value lit up in the timing map, they are totally different. so, are the table values just index numbers that are injected into a formula for calculating timing, or are they supposed to be actual timing values? i haven't found the answer to this in any of the reading yet, but i believe that this is indeed the case for fuel, or load, or both.
timing map 3.jpg
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timing map 4.jpg
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polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Thu May 20, 2021 9:45 am

Nistune_2021-05-19_1448_47.csv
(446.22 KiB) Downloaded 4 times

made this log file just now.

looks to me like i'm creeping up to 10-11psi, then i run out of maf.

injectors aren't far behind, at 90% duty cycle.


looks like the boost spike at the end happens the moment i lift the throttle. maybe a bit of lag time on the bov... maybe that's normal? i could adjust it to be a bit softer.
nistune log stock maf.jpg
nistune log stock maf.jpg (281.53 KiB) Viewed 176 times

Matt
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by Matt » Fri May 21, 2021 1:03 am

Yeah you reached MAF limit at 9.52psi in that log (5.115 Volts). Time for an upgrade (HPX, R35 or Z32 MAF)

Calculated Injection duty 91% is not far behind either for those 380CC injectors.

Had the same problem with my R34 as soon as I upgraded the turbo

Boost shows 18 psi after (max it can read with that sensor)

Is factory BOV fitted?

Your previous post doesn't show the TPS idle indicator, but if its red (idle) then it uses idle timing maps

Your log shows with TPS idle (500-1000rpm) wiht about 11-13 deg BDTC

Use the TRACE button + ignition timing to map your timing (this is covered in the software manual)

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Fri May 21, 2021 4:06 am

Bov is a gfb respons, so it’s possible that I have it adjusted a bit too tight.
I should also admit that I have it venting 10-20% to atmosphere, cuz i love the sound. Hope I can keep it that way.


I do have the parts for the r35 maf and injector upgrades. Just have to weld up the maf housing and install the air straightener.

I’m thinking that upgrading the air/fuel is going to be easier and smarter than downgrading the wastegate.


If the timing value in consult view is the correct number to use when setting base timing, then it’s done. I’m not ready to start messing with timing values, so at this point my only concern is to be sure I’ve set the base timing correctly.

I’ll read the part about logging the timing again though.

Thanks again Matt.

Back to the shop... maf housing isn’t going to build itself. Lol.

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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by Matt » Fri May 21, 2021 10:28 am

Use "Active Tests" menu option to force a stable base timing for setting the distributor (covered in software manual)

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Sat May 22, 2021 3:27 am

dude! i can't believe i missed that. not sure it was an option the first time i was doing active tests. i updated nistune along the way.

thanks. that will make things much easier.

polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Tue Jun 22, 2021 7:26 am

Hi guys. I’m just doing my fuel injectors, and figured I should get some answers before proceeding.

There’s a slight difference at the intake runner end. Shank length, and shape at the tip.
Also, the old ones have these brown plastic seats that fit on the end. One broke and another fell off somewhere.

Do these r35 injectors drop in as-is, or do I need these plastic seats, or anything else to adapt them to the neo rail?
06A4EFE1-13F6-4CB0-9427-B6A5E25640E4.jpeg
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polemite
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Re: hi! from a newbie in canada. rb25det neo, in 240sx

Post by polemite » Wed Jun 23, 2021 10:27 am

ok, never mind the question about the injectors. i test fit one gently, and it fit, so i installed them all. no leaks.

so i've got the maf built, installed, and tested working.
injectors on and running.

ran quickly through the maf and injector resize. engine starts up, after a bit more cranking than normal.

idle is lean.

ran out of time for the day, but i took a quick log.
new maf and injectors.csv
(38.21 KiB) Not downloaded yet
gotta read up a bit, but something i found a bit confusing was that there were 2 options for the maf upgrade. r35 3.5 tube, 444hp, and r35 3.5 ~600+hp
the bigger one wouldn't load at all. the smaller one warned me that it didn't have any info or numbers or something, and i'd have to set it up manually.

*update- i was messing around a bit, and now i've completely messed it up. burnt a file, and now it's not starting. tried reverting to an older file, and i get message after message about it being incomplete or something. wanting to merge with some other bin file. gotta start from scratch i'm afraid.

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