I got my zeitronix zt-2 unit installed. I have been datalogging rpm, afr, and tps on 3rd gear runs and tuning via SAFC-II. I am having a few problems. I have tuned before on the dyno, and never had any problems. Here is what is happening. I have all the rpm range tuned to 13.2:1, except for right around 5900rpm and up until redline. I can't get the values where I want them. 5900-7000rpm is around 14:1. I tweaked and tweaked on the SAFC until I went from +10% adjustment to around +30%, and it only affected the afr down to about 13.8:1. It has never taken that much before to move it. I tried going the other way just to see, I went to 0%, which made the afr 14.5:1. It seems I can lean it easily, but I can barely richen it after 5900rpm. The rest of the curve adjusted very easily.

Is there something I am missing or certain things I need to check? Last time I dynoed, I had no problems adjusting the curve anywhere. The only things I have changed are a ported MAF sensor and the adding of the zeitronix. I tapped power, ground, TPS, and RPM for the WB off the SAFC harness, would this affect anything possibly?

 

the injectors could be at 100% duty cycle. What is your base fuel pressure?

 

Yeah you could have max'd out the MAF/Injectors.

 

i doubt it is the maf. The A32 maf is good up till a little over 300whp as far as i know

 

The MAF can't be maxed out, since I ported it, it reads lower values now than it did before. Maybe it is a turbulent air problem inside the MAF?

Surely these A33 injectors aren't maxed out? I am running around 48psi of fuel pressure. It does seem like it would be fuel related now though, I might try upping the fuel pressure some and see what I can do.

edit: I had a mental lapse. The injectors are at 100% duty cycle at the current fuel pressure. If I raise the pressure, I should be fine.

 

Well, I raised the fuel pressure from 48psi to 56psi, it doesn't seem to help. It did richen up the curve almost everywhere, but around 5900rpm it goes to 14:1 afr and adding fuel via SAFC does not seem to bring it down any.

How does the 2k2 regulate fuel pressure? I used a tee and made my fuel system returnless like the 2k2. I have the Adjustable fpr on one leg of the tee going to the tank return. the other leg of the tee goes to the standard 2k2 fuel system with damper.

It is weird I never had these problems before tuning on the dyno...

on the log graph, the afr curve has small up and down variations until it gets to 5900rpm, where it goes perfectly flat 14:1 with no variation until redline, this makes me think something is up with my wideband?

 

by using the method in the stickies you are converting the returnless style fuel rail of the 3.5 and converting it to a return style.

My thinking is that even though you have up'd the fuel pressure that might not be enough. Think about it, your car is potentially making +270 whp. A 4 th gen w/ a SC has to use it's stock 240cc injectors along w/ the 8:1 fmu w/ a auxilary fuel pump to supply enough fuel for 270 whp. The 3.5 injectors IIRC flow less than the 270cc 5th gen injectors at the same fuel pressure so it might be time to up your injector size.

BTW I assume you have a walboro?

To rule out your WB 02 being f'd up i guess you should use the wb 02 at the dyno and compare

 

Can you calibrate your wideband?

 

I think the wideband is ok, It shows 14.7:1 at idle which is correct. I am thinking more about the fuel. I have a stock 4th gen fuel pump. Even though I am upping the pressure, maybe it is not enough.

 

The 5.5 gen injectors should be 270cc at stock 4th gen fuel pressure and 315cc at stock 5.5 gen fuel pressure. Even if he is making 270whp the 315cc should flow more than enough for that.

I'm thinking it might be a problem with the FPR or its installation?

 

Can you take a picture of how your AFPR is setup?

 

96sleeper, you can switch to the 2000-01 DEK injectors FBJC100 they are rated at 315cc at 3.5 bar fuel pressure (same injectors as 350z, only running at 3.0bar on the DEK). should help with supplying enough fuel, and walbro 255lph IMHO is a must for a setup like yours. (3.5L cammed, headers, etc) top end is tricky with that 2k2 IM if you have that valve in.

 

is a walbro fuel pump required on a boosted 4th gen with bigger injectors making 270whp? Even if I up the fuel pressure, maybe the pump is what is having a hard time supplying fuel?

 

I don't have a picture, but it is exactly like stephenmax posted in the 3.5 swap thread. fuel line comes in to a tee, one leg of the tee goes to the returnless fuel rail setup, the other leg goes to the afpr, and then from there to the tank return line.

 

That is exactly what i am thinking. I would deff suggest getting a walboro.

A boosted 4th gen would require either the auxilary fuel pump or a walboro to help in supplying the fuel

 

Do you know what your fuel pressure is when this happens? Maybe rig up a flexible line from it if its mechanical and put it on the outside of the windshield so you can monitor it.