Nistune Forums

Hey Guys I know this horse has been beaten close to death, but i m having many issues resizing my injectors i am going from stock rb20det injectors which are to my knowledge 270cc and going to 750cc drop in injectors by Deatschwerk I still have the factory MAF installed and have not changed to the Z32 MAF yet.

Now my issue lies along these lines due to the fact I have gone through the tutorials and have been able to smooth my AFR readings to around 14.1 or so but no matter what combination of K constant and injector latency i go with the car just tuns off after a minute or so, I am boggling my mind trying to understand why, as soon as I give it gas and let off it will die also. I have ticked the "flags" box off on the fuel map also but still have had no luck I have even attempted to adjust manually the

My TTPMAX: is reading way off the chart 35ms to way off the chart as rpms increase, when the injectors are re sized to 750cc

TTPMIN: is reading 0's across the board

If anyone has any info it would be greatly appreciated I dont really know where else to go with this situation.

Regards

Rob

best post a log of this one.

K' for your combo would be somewhere between 90-110.
110 would be a better start if your not using anything higher already.

Unfortunately by changing your injector size so radically and not going to a bigger AFM your K constant must change radically. This is not good as it throws everything out a long way. So you may well find that there are parameters that usually don't get touched that you'll need to adjust.

Although it may seem like a strange approach, my advice would be to go to a bigger AFM and that'll bring your K constant back a bit closer to std. This will save you hours of messing about. If you've gone to 750cc injectors then I'm assuming an AFM upgrade was on the cards anyway?

PL

yes of course i have tried numerous combonations around 70 to 110 nothing has worked I might very well just go ahead and switch to the z32 maf but i m wondering if this is common because i had it running with smooth idles around 14.1 and it would litterally just cut rite out

You may find that there's a warmup table somewhere that normally works fine but becomes more critical once you go to big injectors. EVERYTHING becomes more critical with big injectors. Sure, you can use them and the ECU will control them just fine, but going from 270cc to 750cc all the figures become 2.77 times more critical.

Going to a bigger AFM won't change that, but it WILL get your K constant headed back in the right direction, which has gotta help.

PL

so other than the warm up tables and changing the maf to the z32 one, would there be anything else i recommended that should be considered?

Ideally we would like to see a log of what happens when it does (to determine the cause and so I can repeat here if needed with your current BIN file)

Would like to see RPM, TP, speed, temp, TPS, inj time, AFRs at a minimum. Wondering whats going on when it dies off.

Initial enrichment tables are used at the start for about a minute and taper off (with a timer). If your remaining tune is too lean for example afterwards it would explain why it dies

okay here is the log from resizing to 750cc

Ecu is changing TP based on an enrichment table and not MAF voltage, hence drowning spark.

The injectors have not been modeled for one of the enrichment variables.
or wrong image file??

a working 02 sensor might hide this tuning fault by lowering its influence temperature but not a a great workaround though.

TTPmax reading way off is normal after resizing.. (nistune noob feature) later on after tune is complete, then you bring the values within the scope of requirement to assist the Ecu safety mechanisms to work correctly.

so i am assuming it would be best to switch to the z32 maf and see what happens?

I surely would!

PL

Hey guys I have an update i changed to the z32 maf and the it is still having the same issues as before starts up and then it just dies, the latency stays is positioned at 760 and the k constant is adjusted to 153. any ideas i tried playing with the latency but still have had no luck

Can this topic help You?
viewtopic.php?f=11&t=1879

i dont see the maf positing being an issue, i believe it might be because of the size of the injectors throwing everythinf out of wack

Can you post your current tune here also?

Helping a customer today and the auto calcs do not play nicely with larger injectors and the TP scaling (needs to be pulled back a bit on the scaling down)