Cobra MAF or Tune Problem?

[URG8RB8]

I am not having much luck getting Nistune to work properly with the Cobra MAF. I went down to Z-Fever and they did not fair much better. Should I just switch over to a Z-32 MAF? Please take a look at current tune and see if there are any issues that I am missing. I have not touched this car in a very long time and I am very rusty on this to say the least. The car doesnt idle well when cold. After warming up for five minutes or so it idles pretty well. However, when attempting to drive the car, it radomly goes maximum lean and starts to stubble very badly. Flooring the accellerator, has about a five second delay, and then the A/F ration slowly comes off lean and goes back down to normal and the car takes off like a bat out of hell. I will try to post a couple logs as well with simple drives around the block. I have never posted this stuff before, so wish me luck. I just noticed that I am not getting a wideband readout and it also does not appear to be configured properly. I need to look into this a little more. I might have an issue with the factory O2 sensor as well, but asked that it be not looked at by Nistune.

Some information:
1986 300ZXT Manual
1988 N/A ECU
T3/T4 Hybrid
3" Turbo back CM Exhuast
Walbro 255 Fuel Pump
440 Jim Wolf Injectors Balanced
Big Schneider Cams
Race Valve Springs
Adj. Cam Gears
Port Matched 240SX T-body
Engloid Plenom
Ported/Polished Heads
Greddy WG controller
Everything Jason sells
Jason's best clutch
HKS Lightweight Flywheel
HKS Intercooler System
PLX Wideband O2

I am sure I have forgotten some items, but you get my drift.

[Matt]

What is that MAF curve there? Nistune doesnt recognise it and doesnt look close to the Cobra one in the MAF list

I did the MAF / injector resize here and got K=227 starting point (this is only a rough start) compared to 304 in your tune

Also posted here about warmup issues with using larger MAFs on these ECUs
viewtopic.php?f=7&t=2126

Try the attached file with the proper VQ map, your fuel maps and scalings (not a very smooth fuel map here... another story)

Wrong AFM calibration will cause leaning out, bad acceleration etc

Also put in my cold/warm enrich tables which are fairly rich but should get you started

[URG8RB8]

Matt:

Thank you for your assistance. I have not touched this car in about three years. I forgot almost everything about working on this car as I have moved on to working on my other cars. I decided to take the car down to Z-Fever in Tampa as I heard good things from there. They did all the tuning on the car. It cost alot of money in my opinion and did not get the results I expected. The car only put down 350 to the rear wheels and I was expecting over 400. I will install the tune you provided in a few minutes and see if the car runs any better. I am not sure I know how to use the cold start enrichment tables but will read as much as I can to try to get it done. I will let you know what happens later today. Thanks again for the assistance.

[Matt]

Do you have the original tune before it went there for comparison?

[URG8RB8]

Hi Matt, I have lots to report after 12 hours under the hood today. I guess you are never too old to learn, even though I feel like I don't know squat about Nistune. I have cured my lean issue, but had nothing to do with tune. Early this morning feeling very stupid for spending alot of money down at the shop, I discovered that it might not be their fault. I could not get your bin to work properly, just like my original tune. I assumed I was going to upload your Bin and all my problems would be solved. That was not the case. When you select the Cobra MAF, my car will not even start. Well, it kind of starts and sprays tons of smoke and back fires tremendously. I tried a couple times with the bin you supplied me and then gave up and reverted back to Martin's tune. I will upload Martin's tune again, I might have done something incorrectly when I uploaded it last night and corrupted it. He could not get the car to run using the Cobra MAF either. I can't remember which unit he choose, but it appears to work properly, and yes I do have a Cobra MAF installed. After reverting back to his tune file, it said that it was incomplete and needed to be married with a standard ROM, I choose a 1988 ROM but should have picked a 1986-89 one. I am still confused about this, so I will skip to what worked. I put the ignition switch to ON position, uploaded the 86-89 address file, opened his bin file from last night and the car went back to where it was. I then sifted through years of collected data and found out that I had the wrong O2 sensor installed. Actually, someone else installed the incorrect one for my ECU. I have an N/A 1988 ECU so needed a Zirconium sensor. After climbing through the attic, I located one and the correct bung. Three hours and a lot of cursing later, the car ran well and no more lean issues on cruise. The bad idle when cold is still there, but at least I can drive the car back down to Tampa tomorrow and have him correct the cold start issues. I am also attaching the original Bin from 1SICKZ that would not run properly (lean issue on cruise), and thus the trip to Z-Fever. However, I think the issue was the same with this Bin, wrong O2 sensor.

[URG8RB8]

Latest update, Martin and I spent most of the day today trying to figure out the cold idle issue. We don't think it is tune related anymore. Car runs perfect when over 170 degrees. Car hesitates and lopes at idle when cold like a cold start in the morning. It oscillates from 700-900 rpm like it is hunting for something. Martin thinks it is a mechanical issue, either the AAC Valve, or the bimetal valve I think it is called idle intake air sensor. Both appear to work properly though. I swap swap out with spares I have tomorrow and see if it helps anything. We also think it could be related to the fuel pump. I have not made the relay mod to assure fp has 12-14 VDC all the time. No adjustments to tune files helped and have to wait for cool down each time so very time consuming! Still can't figure out why car will not run with cobra mac selected either. Starting to not worry about it though car pulls hard and strong to redline and doesn't miss at all. Still can't break 400 rwhp though at 15 psi. I think that should be achievable with all my mods.

[URG8RB8]

Matt:

I only have a few more days left here to work on the car. I would appreciate any advice you might have as to why I can't run with MAF set to Cobra. Any advice on how to make cold idle run properly would be appreciated as well. I can send any information you wish, just let me know what you need. Thanks!

[Matt]

Apparently there are different types of Cobra MAF curves out there. I've gone through my binaries today and found I have three different types. Updated the Vqmap directory for the next version so these are all autodetected

- JWT cobra MAF (yours is this btw so all good)
- Jason (redZ31) cobra MAF (not sure on specifics would need to ask him)
- Another sourced cobra MAF curve (this one is in Nistune)

As for all the tuned files you have posted they are the same tune. TP max warmup timing was slightly different on one (40 instead of 36 TP value)

I've taken the last merged tune and added some extra enrichment with the idle. This is probably too much but you may need to tweak it since it runs rich on mine at the moment but will help idle a bit better

[URG8RB8]

Matt

I am finally back home in Florida after a very long business trip. I will try the new tune tomorrow and see what happens. Thanks and Happy New Year!