Jeffersonc

I am looking into fine tuning the boost control. I am reading the help files to get a better understanding on how closed loop control and PDI works. Have a look at my log and give me an idea what area I could look into for adjustments. I can see that my boost integral (%DC) goes into (-). Whats happening exactly?

Rb25. I have selected the correct sensor calibration but it reads roughly roughly 15 degrees different from my aftermarket Defi gauge. I have my Defi sensor located in the block between cylinder 5&6. My factory sensor is located in the intake manifold right at the water neck outlet. What would be the best sensor location for this type of engine? (RBs are known to run warmer at the rear). If the block sensor reading is best, how would I go about setting up a table to suit?

Funny, I am having the same issue. Would like to hear what others have to say. Good read here in regards to same problem.

How important is it to get the fuel table cell numbers close to 50 in the middle of the table as stated in the help files? I have not gotten that far into the table yet without a proper dyno and knock gear, but with the rate I am going my numbers seem to be around the 30's, low 40's in the middle. What would be my next approach to get these values a little higher? Perhaps start by changing my Master fuel from 8ms down to 6ms and do the correct calculation on the fuel table to bring my AFR's back into target? I also need a little better explanation on what the master fuel trim % does? Mine is currently set to 0%. I can't quite grasp the understanding that the help file information is giving me.

How do you guys like to set up the VCT trigger on an RB25? I was recommended this way as shown. The car runs great so far, I have some good street miles on it with very minimal issues. I find the way its currently setup its switching on and off lots with light cruising because of the (AND 3) switch condition. Perhaps just try a few other switch conditions and see what the car likes best?

On some forum someone mentioned that the fuel equation was about something like this, for what it's worth : Base pulse width= Master Fuel x MAP/100 x %VE/100 This means for example that if we substract 25% from, or multiply by 3/4, the Master fuel we therefore need to add 33% to, or multiply by 4/3, the values in the Main Fuel table (%VE) to get the same Lambda correction. I did just that and was able to confirm from checking in the Real Time values table that the % of Lambda correction was exactly the same as before. Since 100 is the maximum value that can be entered in the Main Fuel table the maths simply say that reducing the Master Fuel "will allow" or "require", depending which way you look at it, a higher resolution/finesse of tune from the Fuel Table and logically result in a "smoother" Fuel Table without peaks and valleys that some folks occasionally comment about

Yup, that was my plan on tomorrows drive, I will log it and get you that. How does the master fuel work? Reading the help browser it makes it sound like it's the set amount of time (ms) the injector sprays fuel for every injection event. This would require you to make adjustments to fuel table 1 to achieve the same targeted afr numbers lets say. If I make correct sense of this, then perhaps my situation with having the ITBs is, once they shut it becomes such a sudden "stop" in airflow through the intake ports and engine vs a single TB that would give a smoother off throttle movement due to the greater plenum volume. I can work off that trying both directions and seeing its effects , if I'm making sense of this? Found a solid forum post explaining it. Other then his stalling issue, its a ton of good information I can use. https://www.hpacademy.com/forum/general-tuning-discussion/show/link-g4vi-pec-vxx-master-fuel-setting

Hope that works. After reading some more... what if I adjust the master fuel that's currently at 8ms?

So I'm in the process of street tuning my RB25 and would like some advice on what I could adjust to eliminate this rich spot in my tune. It's only after I rev the engine, (the throttle plates are now closed) It stays good for a quick moment then goes really rich then finally clears up. It also happens when driving and I decelerate. For a split moment it will go rich before the decel fuel cut comes active. I have changed the accel from 60% down to 30% but with no change. It revs up nice and clean without issues. This is an RB25 with RB26 ITBs if that makes a difference. I am street tuning and breaking it in (first time tuning) before going to the dyno and getting my tuner to start adding boost and making any required changes. I tried attaching a small video but it was too large.

Now it's time to adjust my timing delay, I wanted to know if I should leave my locked ignition timing to the 10 deg, or should I lock it at something higher, say 30? I don't think the engine would like 10 deg at higher revs. When revving up the engine to find any timing drift, what's a good way going about it? Should I slowly bring the rpm up and pause at say every 1k? Or be a little quicker and maintain a smooth rev increase?

Roughly what direction does the injector timing move once VCT activated?

Some thoughts on what I should set my base injector timing at? Engine is an RB25 but with adaptor plates (1'' in thickness total) mating RB26 ITBs and intake setup. This lengthens the intake runners and moves the injector location further back. In base maps the GTR RB26 is set at 390 deg BTDC, where as the GTT RB25 is set at 400 deg BTDC.

So my tuner stopped by yesterday and helped me adjust a few things before we started up the car for the first time. I must say, the help section in the ecu program extremely helpful and so far made my first ever wire in ECU and program setup an excellent experience. The only problem I'm having is trying to setup my wideband values for accurate readings between both my gauge and ecu. My tuner made some adjustments so we could heat cycle it correctly. No problems and warmed up great. In this instance would I want to take my ecu lambda readings as ths most accurate and try to adjust the values to get the gauge to read the same afr numbers, correct? This autometer gauge is an oddball 0-4v setup. 10.0 - 16.0 afr sweep. My tuner said he got it close but because this gauge does not come with a values table like most others it may require some work. Please see how it's setup and advise on what I could do to make it more accurate. It's currently setup in Cal 4. My tuner entered the output value A and B. After looking at it, I can understand Value B 1.090 Lambda (16.0) but not sure why Value A 0.410 Lambda? Would something closer to 10.0 like 0.680 roughly.. be better to use? Lastly I found these 2 small bits on some other forms about getting an autometer to work accurately.

I am setting up the base map for my first ever ECU installation and inital setup to assist my tuner to help save him time (and my money) I have built a solid RB25 engine setup, using splitfire coils and a Microtech X6 Igniter box. What is a sufficient dwell time for these coils? I read online guys going 2.0 overall. Is my graph correct?

Fixed! the power circuit for the VCT, CAS and INJ was actually on a constant power supply. Well, a power supply that is hot when the vehicle safety switch is turned on. (it was considered the "dome light" circuit according to the fuse block manual I found) For a test I used an IGN switched power source and it's fixed. Now question. Should the +14 power supply for the ECU have a fuse? It's currently a direct feed right off the IGN switch on the dash.

Wiring my first ECU into a racecar I recently bought. Custom chassis and engine harness. I am getting electricity back feeding out from the +14 pin on the ECU. It starts once I turn on the main power safety switch to the vehicle. The engine is an RB25 in a 240sx chassis. The only way I can get it to stop back feeding is by unplugging the VCT plug at the solenoid. I have tried another solenoid for testing purposes but it continues to back feed. If I unplug the solenoid and install a light bulb, the back feeding stops. The VCT, CAS and Injector harness +12 power wires are grouped together and supplied from a fuse circuit from the custom fuse box. The coil harness +12 power is on a separate circuit as I was told to wire it this way. Any ideas where to start? The VCT is wired into AUX Output 2.