Hi,
I have an RB25 with a Nistune in an ZX300 ECU, with a MAP supplied from Nistune.
When I resize the injectors from 370cc to 480cc the K constant goes from 286 to 177.
The car wont run on this untill I bump up the K constant to 420, then I have to pull it down to 385 to get it to idle at 14.7 AFR.
Any ideas on what is happening here?
Carl
Re-size injector problem
Moderator: Matt
Re: Re-size injector problem
Default injection multiplier in RB25 image is 172 (or with Z32 MAF 296)
This gets lowered with larger injectors so should be:
K=228 with Z32 MAF, or K=132 with R33 MAF
To have K set upto 420 for the vehicle to run okay, something else is quite wrong, but not sure what
Please email current tune and log file of problem through to have a look
This gets lowered with larger injectors so should be:
K=228 with Z32 MAF, or K=132 with R33 MAF
To have K set upto 420 for the vehicle to run okay, something else is quite wrong, but not sure what
Please email current tune and log file of problem through to have a look
-
Carltonmaurice
- Posts: 2
- Joined: Wed Feb 18, 2015 4:28 pm
Re: Re-size injector problem
I have come to the conclusion that the problem is fuel pressure.
Having brought a cheap and nasty fuel pressure regulator from Ebay, I think it is not working properly.
When I block the vacuum line I get no change in pressure.
What pressure should the fuel be at for 480cc (448cc) S15 injectors?
I looked up the net and people are saying that at 3bar (44.1psi) they are only 448cc injectors,
and to get them up to 480cc you need to run 3.5bar (51psi), also a comment that at 4 bar they become 510cc injectors.
I have ordered a new fuel pressure regulator.
And booked in a Dyno tune.
So, set fuel pressure to 44psi ? or higher
With 480cc and Z32 MAF K should be 228?
Your advice will be appreciated.
Carl
Having brought a cheap and nasty fuel pressure regulator from Ebay, I think it is not working properly.
When I block the vacuum line I get no change in pressure.
What pressure should the fuel be at for 480cc (448cc) S15 injectors?
I looked up the net and people are saying that at 3bar (44.1psi) they are only 448cc injectors,
and to get them up to 480cc you need to run 3.5bar (51psi), also a comment that at 4 bar they become 510cc injectors.
I have ordered a new fuel pressure regulator.
And booked in a Dyno tune.
So, set fuel pressure to 44psi ? or higher
With 480cc and Z32 MAF K should be 228?
Your advice will be appreciated.
Carl
Re: Re-size injector problem
That would be about the starting point K=228
Best to check fuel pressure whilst the engine is running (compared to idle fuel pressure)
Fuel pressure regulators are driven by vacuum/boost. So if you put pressure into the regulator it will increase the fueling further (about 40psi sounds right on idle and something like 60psi on boost)
Best to check fuel pressure whilst the engine is running (compared to idle fuel pressure)
Fuel pressure regulators are driven by vacuum/boost. So if you put pressure into the regulator it will increase the fueling further (about 40psi sounds right on idle and something like 60psi on boost)