RB25DE+T Question

r32pat · Post by **r32pat** » Thu Aug 21, 2008 1:20 am

Hey guys,
Matt go my nistune a couple weeks back and man am i impressed

Awesome product. I wire up quite a few EMS systems in my area and im happy i went with the nistune instead of ems for my own car.

Anyways on the question.

Engine is RB25DE
Turbo: T04e
Injectors: - RB25det standard
afm: rb25det

Now last night we spent quite a bit of time on the dyno and i keep running into a problem.
Around 5500rpm to 6000rpm the engine just cuts. boost drops off all the way and revs pretty much come to a halt. Eg(get to 5500rpm and just stay there making no boost and revs not climbing anymore. and its not a revlimiter)

Is this me maxing out the standard rb25det afm and will a z32 afm fix this ?

i messed around with fuel and ignition load scales but still didnt seem to have much effect.

Let me know if you need to see logs or the map we were working with.
I would upload them now but they are sitting on my laptop and i havent had the time to put them onto my main pc.

Any info would be great guys.

Cheers

Matt · Post by **Matt** » Thu Aug 21, 2008 11:43 am

Have you changed the TP limiter table? This is a measure of the maximum TP allowed for a particular RPM point

TP is theoretical pulsewdith which is basically a load measure. This might be causing the cut issue

r32pat · Post by **r32pat** » Thu Aug 21, 2008 2:16 pm

hey matt, if you mean the tp load limit table. I set it to 255 accross the board before we started tuning.

r32pat · Post by **r32pat** » Thu Aug 21, 2008 5:51 pm

Hey matt i copied the rough fuel map and log from my laptop this arvo and ive put them online for you to look at.

If you check out the log file.
At full Throttle when the cut kicks in i noticed the TP go from 21760 to 8192.

kenbam · Post by **kenbam** » Thu Aug 21, 2008 6:45 pm

How is it that in your ignition maps, your raw and filtered values are exactly the same, has you running 0 degrees advance at the area it drops out at.

r32pat · Post by **r32pat** » Thu Aug 21, 2008 8:09 pm

Hey mate i just looked at the maps again.
The map i posted was based on the standard rb25det map that matt loaded onto my type 2 board when i ordered it. All we did was drop it by 5 degrees across all load points to prevent any sort of detonation as it is a high comp motor. I have opened the copy i made of the base map that matt included and it to has identical values for raw and filtered. Is it possible that there is a issue with the base map that was loaded onto my board when i ordered it ?

r32pat · Post by **r32pat** » Fri Aug 22, 2008 1:57 am

Update:
I copied the ignition map from another r33 rb25det map included in the rom pack. made absolutly no difference car still cuts at the same time.

Just before the engine cuts it is running in the last two bars of the load map. Is it maybe getting to this part of the map to early ? If so how would i fix this ?

Just throwing some ideas out there anyone have any suggestions ??

Matt · Post by **Matt** » Fri Aug 22, 2008 2:13 am

The base ROM you have in the board is an R32 RB20 ROM image

Then I copied over the maps from the RB25DET and adjusted the injection multiplier as a start to get you running

Something I have noticed is that the RB25DE timing is about 5 degrees more than a RB25DET. But I'm sure it shouldnt idle at 20 BDTC... so perhaps there is an timing offset in the DE ECUs?

I dont know why it is cutting. I've had a look at the logs, and it appears as Ken already mentioned that timing is getting dragged down to zero right when the cut happens and that TP gets cut. Would need to try and repeat this one on the bench to see what is causing the cut and play around with it. I'm off to melbourne this weekend so wont be able to look at it properly until I return next week

Only other thing is TTPMax that I can think of right now but that cuts the injector pulsewidth and doesnt touch TP from memory

Attached a pic of the RB25DE timing maps to show the difference in the timing maps here. Keep in mind it looks like RB25DE is 5 degrees higher than RB25DET ...

r32pat · Post by **r32pat** » Fri Aug 22, 2008 2:33 am

i dont know if this helps but with a standard rb25det ecu in the car i get a similar cut but it will keep reving. I believe this is the nissan rich and retard function on the rb25 ecu. correct me if im wrong.

Ill try another CAS and ignitor this weekend just to make sure its nothing to do with them. I have already tried another rb25 afm and im about to order a z32. but occording to the afm voltages im still within tolarences.

Only thing is with the ecu being in the last 2 load columns of the map just before the cut is it possible that it wants to jump into a load column that does not exist and so the ecu just jumps back to a lower load point ?

Im not up with how the ecu program itself handles the fuel maps so i prolly have no idea what im talking about.

Matt · Post by **Matt** » Fri Aug 22, 2008 6:13 pm

I dont think changing ignitor, CAS, AFM etc is gonig to help at all. It looks like the ECU is doing the cut

When I get back from interstate I can run it up on the bench and see what is causing it and what needs to be changed to work around it

r32pat · Post by **r32pat** » Fri Aug 22, 2008 8:08 pm

Cheers Mate

TSL · Post by **TSL** » Sat Aug 23, 2008 3:11 am

Make sure the base timing is set correctly

Ignore the last column in the standard rb25det timing map. It is there for safety only and under normal conditions the engine should not enter that part of the map.

So taking that into consideration you can see the real timing that the standard rb25det has under full load is around 20-24deg btdc. This is the sort of timing you need to have as a starting point for normal rb25det operation under moderate boost.

You could then take off 5deg to allow for your higher compression rb25de engine. You could also take off another 5 degrees for the extra boost you will be making with your larger turbo.

This still puts you around 10-15 degrees btdc at full load which is obviously a long way off from where you have your timing maps set.

Matt · Post by **Matt** » Sat Aug 23, 2008 10:55 am

Looking back at the logs the TP is hitting 85 which is when the ECU jumps to the last column

If it is hitting the last column sooner than it should then to make it use the second last column (80) you could also slightly increase the top end TP scales so it doesnt go over so quickly

It depends how much boost you have and when you need to use appropriate timing values to kick in to pull it timing out

r32pat · Post by **r32pat** » Sat Aug 23, 2008 4:39 pm

Hey Matt cheers heaps for all your help.
Totally awesome customer service even when your interstate

Now by your previous post do you mean i should adjust the fuel and ignition load limits ? after ive double checked the timing. If so do you have any suggestions for the values.

Sorry if these are silly questions im just new to nistune.

r32pat · Post by **r32pat** » Mon Aug 25, 2008 3:04 am

ok seems i have the tp load mapping side of things all sorted
turns out it was a combination of that and i believe the rb25det afm maxing out. after the few cough highway cough runs i did tonight.

Im going to order a new z32 afm tomorrow and ill keep you guys posted with how i go

cheers again for all your help.

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