THROWING IN THE TOWEL

[red coupe89]

looking for a good shop/guy to take my problem child too. im located in RI. short story is i have replaced injectors and cams, car was running fine when i disassembled, have put it back together and now it runs like crap. i use NIStune and have made the proper adjustments for the injectors but still cant get the car to idle/ run correctly.

please see my thread
bad-iacv-t614836.html

and also my posts
1990-jdm-z32-new-nistune-550-615-swap-i ... 15174.html

if anyone can point me in the right direction it would be much obliged

[NolimitZ32]

What injectors and what cams did you install?

[DCaff300ZX]

Yes, let's start there...what injectors first, and then what cams?

[red coupe89]

Yes, let's start there...what injectors first, and then what cams?

injectors are nismo 740cc
https://www.z1motorsports.com/fuel-syst ... -3088.html

cams are the jwt mild
https://conceptzperformance.com/jim-wol ... _p_163.php

hope this helps!

thanks guys!!!!!

[NolimitZ32]

What did you adjust in your maps and by how much? I couldn't tell you off the top of my head what the values would be for the cams, and those would need you to adjust the cells individually in TP and fuel/timing maps, adjusting for the injectors usually can be done with changing the K-value and working from there.

[red coupe89]

What did you adjust in your maps and by how much? I couldn't tell you off the top of my head what the values would be for the cams, and those would need you to adjust the cells individually in TP and fuel/timing maps, adjusting for the injectors usually can be done with changing the K-value and working from there.

i changed the injector size with the resize tool provided in the software, it worked before with the 555cc i had in there. I have tried adjusting the K-constant and the injection latency, and when i do it will idle with an almost perfect a/f ratio and then as time (and heat) increases it beings to go dead lean 21.0 a/f. i have ruled out a vacuum leak as i have psi checked and used the good ol fashon either to no avail.

[red coupe89]

also, once i get the idle correct by adjusting the K and the latency and accelerate the car will stall and then refuse to start.

[DCaff300ZX]

With no real tuning experience, my thoughts come more from the side of what you report and what must be happening with the engine.
I sense that there is a fuel flow or pressure issue perhaps that is causing the fuel flow to not be changing with the temp changes, perhaps the dampner is partially failed? Maybe even fuel pump begins to flow less as it heats/runs? Have you run tests of peripherals to ensure that everything is getting it's correct dosages?

[red coupe89]

Attached is a video with my a/f the upper gauge and fuel psi the lower. Please take a look
And let me know if it's like anything anyone has seen and what may be the cause

https://youtu.be/0f4N6HNjTA8

https://youtu.be/0f4N6HNjTA8

[DCaff300ZX]

You know, that looked a little like when pulling the intake/turbo hose loose and losing MAF the way the engine starts laboring and the way it hunts.
Which fits A/F issues...maybe a MAF swap/check/clean? Possible it got oil on it from the filters?

[red coupe89]

You know, that looked a little like when pulling the intake/turbo hose loose and losing MAF the way the engine starts laboring and the way it hunts.
Which fits A/F issues...maybe a MAF swap/check/clean? Possible it got oil on it from the filters?

ill have to ohm them out but i have the dual maf set up and cleaned both thinking it may have been that. ill have to go over the intake piping under the bumper and see if something is a miss. whats odd is when i fired it up yesterday it was perfect for about 5 min, then it became what you see in the videos.

[NolimitZ32]

That definitely looks like a vacuum leak to me, or some other hardware issue, the car is in open loop when cold using preset values from the maps, once warm it switches to closed loop reading TPS and O2s, I would be willing to bet that's where your issue is. Now it could also be that your resolution isn't high enough in the maps, also your latency may be off because its not a direct 1 to 1 ratio when you upsize the injectors, play with the latency a bit (very small increments) and see if that helps your idle, but first go over all your sensors with a fine-toothed comb because 90% of the time issues like this happen its because of a bad connection or bad sensor. Also how is your twin MAF connected? I had a similar issue when I first ran my twin MAF because the connection from my SAFC to the ECu harness was intermittent (bad solder-job).

[red coupe89]

@NolimitZ32 to be honest the dual maf set up pre dates my ownership. im not 100% how it was installed, i do know that it was in working condition before the end of last season, not sure if i pulled on something or disconnected something that may have changed it. my tps is set at .045. im not sure about my oxygen sensors as i believe they were deleted from my board via nistune which runs off of my wideband. ill have to do some digging tonight......ill report back with findings/more video.

thanks!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[NolimitZ32]

If you are running your O2 signal off the AFR this could also be the issue, I never messed with doing so and always ran my factory narrowbands so I can't be of much help there. As for the MAF, you could be running it one of 3 ways:
1. Selin translator, which you should be able to find somewhere by the MAFs by tracing the wire loom from the MAF back.
2. SAFC, this requires a second shielded signal cable to be run back to the SAFC, all other wires would be spliced to the factory MAF connector. The factory MAF wire is cut at the ECU, ran into the SAFC along with the second shielded wire (both inputs to SAFC) then the SAFC output is run to the ECU MAF input. Both of these use the respective device to add up the total flow thorugh each sensor to let the ECU know what the total air volume intake is.
3. is to run a dummy MAF and adjust your MAF values to basically be doubled by your ECU. Not knowing what your maps look like and what you have installed I can't tell you much more. have a look at everything and let us know your findings.

[DCaff300ZX]

Good call with the dual MAF translator, the car in the video also did act a lot like when I first ran my TT after installing the dual MAF and Selin translator, and I had it on the "add" instead of normal setting. The car ran almost exactly the same way and would die unless I held a tad of throttle...anything more and it would puke out. If I got it to higher RPM's it would seem OK-ish, but any let-off on the throttle and it would puke out and die. I thought I'd also made a mistake somewhere but tried changing the setting first and it went to perfect.
So, hopefully you have a Selin setup and the selector just got moved...would be a super-easy fix!

[red coupe89]

I will have to double check on the install for the dual mad set up. Below is what I got yesterday the first being a cold start. I'm beginning to think it may bale an o2 problem

https://www.youtube.com/watch?v=oNO9pGbCKN0

https://youtu.be/NAIHVxBHHeI

[red coupe89]

edit!!!! the 2nd video the upper RH corner is the LH o2 sensor
the 2nd row first gauge is the RH o2 sensor.

the LH sensor never changes while the RH starts at .32 and ends up going down to .26

thanks!!! sorry about not adding context

[DCaff300ZX]

That's definitely a good place to start looking. Definitely weird with the multiple symptoms that seem contradictory...hope that it's an O2 as that wouldn't be so bad.

[NolimitZ32]

Thats actually wierd, again not sure what your resolution is but you should see a sinusoidal change in the outputs on the O2s

[red coupe89]

Thats actually wierd, again not sure what your resolution is but you should see a sinusoidal change in the outputs on the O2s

yea....tell me about it. im going to dig them up today and try to test them and see what comes up. dont really have any other place to look

[NolimitZ32]

Only other suggestion I have would be to test the inputs and outputs of the sensors and the AFR controller itself, fault might be somewhere there.

[red coupe89]

so i ran some tests last night. i ran the car with the fuel temp sensor unplugged and it warmed up fine with no stumbles or idle hunt. it did not begin to act funny until i snapped the throttle. then all the old symptoms returned. my RH o2 sensor started at .32v and once warm got down to .16v the lh held at .32v and did not change at all on idle. only when i snapped the throttle did it get down to .24v-.26v. im getting the feeling the the o2 is a problem but not the whole issue.