Forums/Z31P/z31-performance-upgrade-forums engine-management/86T NA-T Nistune ~2500RPM lean spike issue
Imported from Z31Performance.com Forums{{#if:Axel kain| — original post by Axel kain}}{{#if:2014-11-30 01:53:18|, posted 2014-11-30 01:53:18}}{{#if:23| · 23 post{{#ifeq:23|1||s}}}}{{#if:/Z31performance_archive/forum/z31-performance-upgrade-forums/engine-management/24554-86t-na-t-nistune-2500rpm-lean-spike-issue.html|
Local archive: view archived thread on dev.z31library.com}}
Axel kain: (2014-11-30 01:53:18)
I have been dealing with this for a few months now, talking to Matt off and on, wondering if anyone else has seen this. idle, fine, accelerating, AFR's fine, hit 2200-2600 RPM or so and it just pegs lean AFR's, stumbles, adn I hear the turbo spooling, but not accelerating, until past the RPM point (with some momentum already) and it will kick right back to proper AFR's and accelerate excellently!
I have had the ROM chip reflashed at AutoVaughn performance… to no change.
setup -
Nistune Type 1 in an 87 NA ECU.
NA-T VG30E stock internals, except for Jim Wolfe springs, and Isky cams (not too radical).
Palnet fuel rails, Evo 8 I think 560cc Low imp. running about stock psi. Walbro 255 pump.
Intercooled, running blow through MAF (tested with a PMAS (HPX Z32 spec) and with an actual Z32 MAF)
I can easily get it up and running with quick resize, and MAF correction in nistune, then set the latency and have it idle proper etc. but I can take and set all 3 rows from 2200-2800 or so from 0-10 values up to 20, 30, 40 values, and not really have an effect on the issue, still have it dump lean every time. I have logged in the past, no real information of value, as there's no real hiccup or jump, other than the AFR dumping full lean.
anyone else seen anything like this? I have my brothers and my car BOTH running great, with the same cams, bigger than stock injectors, Nistune, AND blow though setups. I dont understand why my friend's here is doing this!
les_joey_paul: (2014-11-30 15:42:02)
Read about a similar issue where the maf was the culprit. Try swapping maf?.
les_joey_paul: (2014-11-30 15:58:08)
Also I experienced similar symptoms on my own at about 3100 rpm. Maf tested way out of spec. Swapped it with one that was in spec and it's good.
Axel kain: (2014-12-01 13:19:23)
I have tried it with the Z32 Spec PMAS (which is currently working GREAT in MY car. his now has a working Z32/J30 MAF in it now, with same issue - that's why I swapped them out.
No relation to my issue.
Axel kain: (2014-12-01 21:31:43)
seriously considering jumping to MS2 to get away from this issue…
jaqattack02: (2014-12-03 04:06:59)
seriously considering jumping to MS2 to get away from this issue…
But didn't the issue still exist between different Nistune boards? Didn't you try it on a stock-ish tune and it didn't do it?
Axel kain: (2014-12-03 13:56:23)
Im going to take my 89 nistuned ecu to it and see what IT does next....
Axel kain: (2014-12-22 21:39:59)
swapped ECU's, tried a different coil just in case, swapped with new stock plugs and wires (plugs at .035 or so) so at this point im only thinking it's a sensor/ devise issue, as the ECU and basic ignition system has been ruled out. I tested spark at idle/free rev and compared to my non-issue car, noticing both are same. plus considering how well it runs WHEN IN boost. (above 2500)
Im almost tempted to try to find new harness connectors and just make my own harness from the ECU pigtail… driving me nuts!
floridaZ: (2014-12-22 22:09:33)
My NA2T is having the same issue. Stock.
Augustus Maximus: (2014-12-23 00:34:02)
Are you running 02 sensor.
Rick88ss: (2014-12-23 04:34:22)
So you ruled out the MAF?
How about the CAS?
Did you datalog the problem in Nistune?
Axel kain: (2014-12-23 16:48:24)
running wideband, open loop. with the feedback deselected, and voltage out of range. regardless it would be ignored.
I have swapped from the PMAS Z32 spec, to an actual Z32 maf now. same issue. PMAS is working perfectly in my car. CAS has a "07" unit. pretty sure I swapped it from a replaced "06" unit as problem solving. I have done a few datalogs. all show nothing other than the O2 dumping lean. TP, MAF, Ignition etc etc all are consistent.
Rick88ss: (2014-12-23 21:23:47)
Yup that is a weird problem. I'm stumped. Is it just a reading on the O2 sensor that shows lean or can you feel it too?
z car go: (2014-12-24 04:22:25)
Yeah, you definitely feel it. The tuner put it nicely: It runs like shit.
Axel kain: (2014-12-24 14:04:16)
Yeah, it jumps lean and is like someone just threw timing in the ditch, as it just bogs and falls on it's face. if you have momentum enough to get past it, can run awesomely!
ozzyrulez: (2014-12-24 15:12:37)
Here is a question. Does it do it only while Consult is connected or does it do it all the time? I had many many issues with Nistune, one of them being it stumbling and carrying on while Consult was connected but it ran absolutely fine disconnected.
Axel kain: (2014-12-29 15:03:05)
all the time, and as far as I can tell it is NOT Nistune related, as it did it with my perfectly fine working nistune'd ecu from my car, I just plugged in and adjusted for the larger injectors, fired it up. it did the stupid lean spike issue as soon as I took off in first and 2nd. so pretty much all I can think to do is just start trading parts between my good running car, and this one, as well as maybe make a new simplified engine harness for posterity sake.
NissanEgg: (2014-12-30 03:38:34)
Start with CAS -> MAF -> TPS -> harness
Axel kain: (2014-12-30 14:10:29)
so with that logic, I need to deal with the harness. CAS has been swapped a couple times, MAF has been changed with no avail, and TPS is working fine, even with it disconnected (non idle signal) makes no difference.
ozzyrulez: (2014-12-30 21:17:14)
Ain't no problem like a wiring problem. Good luck with that sir!
NissanEgg: (2014-12-30 21:17:24)
When you say CAS, are you swapping just the CAS alone or the entire distributor?
If not the entire distributor I would try that to rule out a bad bearing in the bottom of the distributor that can allow a wobble in the shaft and screw up the CAS signal.
Axel kain: (2014-12-31 13:29:03)
I'll change out the whole thing just to see then! it's been just the CAS I was replacing… thing is, it did great when we had it on the dyno first, until it burned up the fuel pump ground circuit trace in the ECU. I have since rewired the pump, and am running the other ECU.
Axel kain: (2015-01-18 05:26:57)
So, I have swapped distributor assemblies, with a known good running one, to no avail. Im thinking about pulling the valve covers and measuring the cam specs, and comparing to the card. they're the only other thing that have changed since the first dyno session where this issue was not present.