Jump to content
SAU Community

Sr Injectors Max Out@6,5k Rpm!

West

By West,
in Engines & Forced Induction

 Share

Recommended Posts

West Grand Master

West

Posted
Posted

Good day all,

my mate has a Red Top SR20DET, offcourse with all the usual mods + PFC but for some reasons the injectors max out at only 9psi and hit 100% duty cycle already.

I forgot to mention its a 92model 180sx RED TOP. Meanwhile my other friend has a 95 model 200zx and making 187kw@wheels ( black top ) and runing 16psi and injectors only max out then.

i believe both engine has the same injectors rating, why one run 100% at only 9psi and other can reach up to 16psi?

can your injectors be so dirty, old to cause such consequensive or its the fuel pump?

Link to comment
https://www.sau.com.au/forums/topic/104924-sr-injectors-max-out65k-rpm/
Share on other sites
nfi Community Regular

nfi

Posted
Posted

One is tuned leaner than the other.

I am guessing that the pfc on the (redtop) car is running way to rich. Get the redtop car tuned properly and that won't happen.

Do you have a dyno sheet of the redtop car tuned? If you do, make sure the afrs are above 11.5 but under 12.0 roughly for a reliable street car.

Thunderbolt Rising Star

Thunderbolt

Posted
Posted

I had the exact same problem with my redtop. Was maxxing out not only the injectors, but also the AFM at around 150rwkw. This wasn't so noticable in day-to-day driving, but at the strip it was causing me to back the boost right off. Have since changed to Z32 afm and 740cc injectors and have not looked back since.

West Grand Master

West

Posted
  • Author
Posted
I had the exact same problem with my redtop. Was maxxing out not only the injectors, but also the AFM at around 150rwkw. This wasn't so noticable in day-to-day driving, but at the strip it was causing me to back the boost right off. Have since changed to Z32 afm and 740cc injectors and have not looked back since.

I see, i thought injectors duty is somewhat we can input signals in and make them to work either 80% or 90% at certain points.

nfi Community Regular

nfi

Posted
Posted
I see, i thought injectors duty is somewhat we can input signals in and make them to work either 80% or 90% at certain points.

You can but its not quite as simple as that. You basically have two tables and a correction map for air density vs timing. One is for ignition timing and the other is for injector timing. With too much timing the car will have to run excessively rich not to ping and that is what I am guessing is happening to you.

Putting bigger injectors with the power you have is a band aid. The car will run WAY better getting in tuned with your existing injectors rather than buying bigger ones. Not only will it make more power being tuned with the existing injectors but it will also be much nicer to drive in terms of throttle response and the linear nature of the power delivery as well as using much less petrol.

Seriously get it tuned asap... You won't regret it ;) With the stock turbo your car should make around the 160-175rwkw mark. But all dynos will show slightly different figures. They are just tuning tools.

If your in sydney PM me and I will suggest a place to go who will do a good job. A proper tune is also cheaper than injectors as well!

Thunderbolt Rising Star

Thunderbolt

Posted
Posted

Mine was tuned, but was still maxxing out (may have been the AFM reading well over 5000mv but yeah). Drivability is very nearly as good with my 740cc injectors and z32 afm, so I wouldn't worry too much if you decide to go bigger injectors.

Can't see how bigger injectors is a band-aid solution (considering you would get it tuned anyway). Band-aid solutions come when you adjust the fuel pressure to get more out the injectors.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Kapr
      RB20DE NEO smallbox clutch.

      By Kapr · Posted

      For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • Kinkstaah
      Mistakes were made, my R34 Story

      By Kinkstaah · Posted

      God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...