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rb25det Neo MAF cut issues...

Posted: Wed Mar 05, 2014 12:37 pm
by timturboz
Holset HY35 Turbo
Turbonetics External Wategate
R35 570cc Inectors
JGY Fuel Rail
Venom FPR
Godspeed Intake Manifold (properly installed and looked over)
CXRacing Thick Topmount Exhaust Manifold
Nistune (obviously)
N62 MAF
LS2 Coilpacks (tuner set dwell/associated settings for these)

On the dyno I had a hole in my intercooler causing a MASSIVE boost leak but it still made 18psi and had no cut til redline. Now that I fixed the intercooler and many other leaks I have this rumored Nissan cut.


I have tried 2 MAFs and sorted out my boost leaks (will still re-boost leak test and try another MAF)
I even relocated my maf to be further away from the turbo to avoids bad readings aswell.
but I consistently have the car cut and run lean around 4500-5k

MAF voltage reads up to 4.3v and bam it cuts

Clamping the voltage with a resistor seems sketchy but I know I can tune to ensure it doesn't run lean.

any help would be appreciated thanks

Tim

Re: rb25det Neo MAF cut issues...

Posted: Wed Mar 05, 2014 3:57 pm
by timturboz
rebuilt motor with wiseco pistons
rebuilt head
Good compression
Cosworth Metal Headgasket
new bkre7e11??? copper plugs I believe I know they're good tho
new sparkplug wires
timing has been checked

Re: rb25det Neo MAF cut issues...

Posted: Wed Mar 05, 2014 4:33 pm
by Matt
Increase 'boost counter' parameters (bottom values in intermediate+ mode)
Check TTP max is suitable
Check TP limit table is suitable

Re: rb25det Neo MAF cut issues...

Posted: Thu Mar 06, 2014 8:17 pm
by timturboz
I saved a copy of the tune with the adjustments wanted to post a pic for reference

Re: rb25det Neo MAF cut issues...

Posted: Mon Mar 10, 2014 6:26 pm
by Matt
This is fine, those counters can be maxed out (255)

Re: rb25det Neo MAF cut issues...

Posted: Fri Mar 14, 2014 11:44 pm
by lolo37
Have you solved your problems?

It seem I'm expieriencing the same problem since I passed my RB30 with a GTX3582 turbo instead of my GTX3071 before.
It cut at 4.66V on my Z32 maf and it is a fuel cut.
My map sensor is unhooked because if i connect it the engine has eratic working when i press the pedal (combuqtion of for 0.5second and then it goes :/ )

I will try to test the car with the boost cut soft and hard passed from 10 to 255. That could be this... At least I hope so.

Re: rb25det Neo MAF cut issues...

Posted: Sun Mar 16, 2014 5:36 pm
by Matt
It should be the same. I adjusted your tune and no cut with these set

Re: rb25det Neo MAF cut issues...

Posted: Wed Mar 19, 2014 1:45 pm
by timturboz
I still have a cut last night I slowly increased throttle in 4th and at 6100 it cut it has issues sooner if I try to accelerate quick. I had made a cold air intake to space the Maf out no luck.

can I increase the tp limits all to 255 safely aslong as afrs stay ok, it's scary to see high 13's or a 15 afr when it cuts: / if those settings are why then that's simple. I will re boost leak test my car Wed/thur but it should be fine.

it was missing after my pull so I checked the plugs they were ok, just need to go restart it and see if it's still missing possibly need new coil packs but this missing happened only twice. it always cuts think it's still the Maf. no chance to log a run with a passenger so I can't see what's happening

Re: rb25det Neo MAF cut issues...

Posted: Thu Mar 20, 2014 10:08 am
by Matt
check end of this thread:
viewtopic.php?f=11&t=2780
same issue as you are having

Re: rb25det Neo MAF cut issues...

Posted: Thu Mar 20, 2014 2:22 pm
by timturboz
I will try that thanks. my tuner set my rev limiter to 7000 which I know is low. I plan to do drift events so riding a 7k limiter sounded fine to me but Im not worried about 7500. I didn't do the crank collar mod tho so not risking too high