Problems tuning 850cc's with nistune

[sd8ted]

I bought a set of Power Enterprise/Sard 850cc injectors for my car. My mechanic/tuner was trying to tune the injectors and couldnt get the afr's above 9's. The car would just break up under boost and dump hella fuel. He ended up having a spare set of nismo 740's laying around so he slapped them in and "tuned the hell out of them" (his words). But these injectors that were just laying around are actually his son's and he needs them back within the week, which sucks. I am running a NISTUNE and I know for a fact that it should work, as there are other builds/cars that are using the same thing. Just trying to get any feedback that I can asap. So If anyone has any advice I would greatly appreciate the help. Thanks

[anton1o]

Lets just get some information out there.

So how was the tune on the 740's was it good? Was the tuner happy with it, were you happy with it? Would you walk out of the shop and drift the shit thru it without a care?

If so, then we may have an issue with the 850's but if the car also ran like balls on the 740's then youve got a different problem all together so going back to the 850's could just be a waste of time.

More info please :)

[cotbu]

I run 850cc sard injectors, i had no problem tuning them. Download the bin post it online.
He may have not put in the time and used a 740cc base map.
I've tuned from a stock redtop base.bin, mines Sr 555cc z32.bin, and s13 740cc z32.bin

I'm running the modified mines.bin, because i already tweaked it for my 555cc z32 s15turbo setup.

Did he have the knock and 02 flags turned off when tuning? if not it could have jumped to the knock map and regardless of what he/you do to the main fuel maps it will not change anything(except for the constants). And that could explain why he could not lean out the afr's

[sd8ted]

Lets just get some information out there.

So how was the tune on the 740's was it good? Was the tuner happy with it, were you happy with it? Would you walk out of the shop and drift the shit thru it without a care?

If so, then we may have an issue with the 850's but if the car also ran like balls on the 740's then youve got a different problem all together so going back to the 850's could just be a waste of time.

More info please :)

Tune on 740's was great. Made 351whp 339 tq at 18psi. We both were happy with it. Im pretty positive he had some values off in the nistune. Im not super knowledgeable when it comes to nistune speak so I won't try to sound like I know what I'm talking about haha. I was originally gonna go with 740's but the sard's were a tad bit cheaper and would give me some headroom incase i went top mount setup or E85 later. We know its not the wiring bc the 740's would be acting up too. Something surely is off in the nistune. I guess there's always the possibility that I could have a bad injector too.

I run 850cc sard injectors, i had no problem tuning them. Download the bin post it online.
He may have not put in the time and used a 740cc base map.
I've tuned from a stock redtop base.bin, mines Sr 555cc z32.bin, and s13 740cc z32.bin

I'm running the modified mines.bin, because i already tweaked it for my 555cc z32 s15turbo setup.

Did he have the knock and 02 flags turned off when tuning? if not it could have jumped to the knock map and regardless of what he/you do to the main fuel maps it will not change anything(except for the constants). And that could explain why he could not lean out the afr's

He fooled with the 850's for a day and half. He could get the car to idle good but not make pulls. I'll see if he can send me the bin file or get him to post it on here. I talked to him yesterday and told him the lag time on the 850's were .85ms and he was gonna look back at the saved tunes he was messing with and see if he can figure out anything. I'll relate the info on the knock and o2 flags and see what he says.

I bought them from phase2 and they told me that nistune can't tune injectors larger than 740's...which is BS. And that I need to either switch injectors or get a REAL ems such as AEM, Haltech, or PFC.

[sd8ted]

Both o2 and knock were disabled when tuning.

[Def]

He doesn't know what he's doing. It's a simple k-value change and ignition map adjustment.

[sd8ted]

Hes fairly new to the tuning game but is very car knowledgeable. He has tuned 1600cc injectors on nistune for his drag car. Gonna drop my car off to see if he can figure anything out tomorrow.

[japautobiz]

dont claim to be the greatest out there but have made my share of tunes. I loaded a base map , resized injectors, changed air mass and adjusted inj mult to get car to idle. I have tried this in every imaginable sequence. I can get the car to idle but once you try to accelerate, the afs go to sub 10s and will not accelerate. I have adjusted injector lat. (lag) but made very little difference other than worse idle. Both maps matched so no confusion takes place. If anyone has some input that would help then let me hear what you got...

never had this problem with any other injector yet.. 555, 740, 96lb, 1600cc bosch

[Def]

Well, the fact that you're talking about loading a "base map" makes me more than a little nervous about how much you understand about what the ECU is doing.

I'll take a wild stab that your fuel map is more than a little off, and your basemap didn't have the proper injector lag time for the k-value and fuel map values.

[z31t]

I believe by base map he means a stock sr20 bin file to build off of. If he can tune all these other injectors and is only having trouble with these 850s I would have to assume he knows his way around this ems system. A bad tuner isn't going to be able to spit out a 350hp tune in a half hour. On 740s and then have his butt kicked the next two hours from just an injector change.

[sd8ted]

I think there's something little off or possibly a bad batch of injectors. Idk

[japautobiz]

as I stated... I can get the car to idle good but will not rev without going very rich. Injector lag really doesnt make a difference on anything but idle. After 2000 rpms the time really does not matter. The K is adjusted by the calculated difference between the stock injector verses the upgraded injectors in the program with a way to fine tune using the multiplier.... any other STABS at me..... I mean it

[Yellow4g63]

I have Sard 800cc's on my RB20 with nistune. The calculated values are just a starting point. I had to adjust my K with the 02 off to get it to idle right and read right. Also I had to hit the burn to rom button once I was done muking around. I spent a good part of 2 months driving up to the shop to work on my car and battling idle problems because I didn't do that lol. it's about 50miles to the shop from my house.

[Boostin240sx]

Did you check to see if perhaps an injector was leaking. 43.5 psi through a torn/ not sealed o-ring or leaking injector can send a whole lot of fuel to combustion regardless of the fuel settings.

Sounds like the tuner knows what he was doing... he got 350hp out of it, but sometimes it is the simple stuff.

Relieve fuel pressure, take the rail off the mainfold (keep fuel lines connected), install the 850s, let fuel pump prime or try to start and see if any fuel leaks.

[s14unimog]

It's a simple k-value change and ignition map adjustment.

I'm betting this.... post your K-values.

[sd8ted]

Car is all straightened out. Dropped it off the other night and got it yesterday. Car feels good and made 354hp and 330tq. He got some help from a nistune buddy of his and got it all figured out. Very relieved now lol

[s13silvia123]

you should explain what was wrong so people who search this thread can solve their own problems.

[Def]

you should explain what was wrong so people who search this thread can solve their own problems.

Sounds like someone learned a bit on how a Nissan ECU calculates its fueling.

Like I said, the k-value and injector latency that is good for a given injector and a "messed up" fuel map might give "good" AFRs, then when you scale the k-value for another set of injectors it will not be "good" anymore.

You can monkey with those values to get things working, but it's best to know what each does, and set them correctly with the correct way the ECU is calculating fuel (hint-look up the formula).

[sd8ted]

He explained it to me and it kinda was above my head. I'll have him post what he did for future reference.