Im in the process of tuning my new setup and having issues. Here is the setup: GT headed 5.4, stock 01 Cobra cams, 160lb injectors, 90mm tb, FAST XFI, 88mm turbo, th400.
The motor has a crank trigger and distributor on it. MSD 7531 box. The motor runs and I can get it to idle pretty good while it is cool. When it warms up the idle goes crazy. It starts surging real bad, jumping all over the place. I have the iac unhooked, it is even worse when trying to use it. I have had it lean and rich and it does the same thing. I have played with every setting on the xfi. Does anyone have any idea what setting could be causing me issues? Im not great with xfi but I have I can usually get a car to atlease idle. This car is on e85 and this is my first time trying to tune one on E85. Please any suggestions would be great.

 

Are you running an injector driver?

 

No, why would I need an injector driver with FAST???

 

What kind of air fuel are you trying to target with the A/F table?

 

Trying to target at 14.5 for idle. It will not stabilize there. I finally got it to somewhat stabilize around 13.0 but it still is surging a little bit and dies fairly ofton when coming to a stop or if it just sits there idling for a wile. Its also very wierd that there are a couple spots in my ve table that while driving the car will be near or at what Im targeting the a/f but then later it will not be at what Im targeting while its at the same spot on the table. Basically its just acting real wierd. I assume my sensors are all working properly, everything is reading like it normally would. Just the a/f are jumping around. I wander if it is this e85 affecting the tune. I know it will need more fuel, but besides having larger numbers in the ve table does anything else need to be changed? Im just stumped with this. I tried driving it today and it just jumps around from real lean to real fat with just making small throttle increases or decreases while driving.

 

I also noticed right when I was getting done messing with the car that is looks like the crank trigger wheel is just slightly wobbling, like it is not centered 100%. I dont think this would affect the a/f since the car is obviously running and has spark. I will get it the crank trigger lined out tomorrow. Do you think that would of been causing any issue?

 

Subscribed, I'd like to see what fixes this also!

 

To start with you are way too lean. Stoich for E85 is close to 9.7 and you will be that or richer. You should be using Lambda instead of A/F and the equiv number there.

 

So what do I need to change in the tune to get it where it needs to be? Do I change something to put it in lambda? I have always used a/f. Everyone else I know that is on e85 is carbed and they tune by the wideband to run wot at around 10.0 on a gas scale. So I guess Im a little off as to how I should be tuning this. Any insight as to the parameters I should change and what kind of cruising a/f I should be shooting for? Also what do you reccomend for wot at 20lbs of boost on the safe side? Thanks for the help.

 

Also I have been reading about flex sensors. I wouldn't mind having the option to run the car on pump gas also. And I can make a ve table that works good on gas. So would putting a flex sensor on here be a good way to make it run good or are they not that great? I need it to be safe, this will be over 1000rwhp when turned up. Thanks

 

The flex fuel sensor works great I have setup several cars with it. What do you have your fuel energy constant set to? Do some reading on Lambda and especially Lambda to E85 ratios and Gas. If it were me I would be using Lambda for E85 that is the right way to do it. You are going to find that the A/F ratio,(if you stay that way) is way richer than you think.

 

https://www.theturboforums.com/smf/index.php?action=printpage;topic=119117.0

there is a chart here.

 

I still had the fuel energy constant set to regular gas setting. I'm going to play with it more tonight. Im supposed to take it to my normal guy that helps tune my gas setups this week but he hasn't done any e85 stuff yet and I'm worried he may not be able to figure it out and ill just be wasting money... is there any reason this setup would have problems getting lined out as long as a competent tuner is working with it? I just don't want to have anything wrong on the setup to make it not tunable. It is in bank to bank, if I got a cam sensor in there and got it in sequential would that help a lot? Basically would it be worth doing?

 

bank to bank on gas or E85 is hard to make idle with 160s especially. You have to turn off the closed loop at an idle and just listen to the engine and not even look at the A/F with that small of an engine and large injectors. Just keep moving the VE numbers until you get the best idle. Sequential will help for sure if you want to go that route. E85 will require more fuel and will like more timing compared to gas.

 

OK, I got my tfi dizzy modified to work as a cam sensor. Im trying to read up on how to wire it to the xfi, I have the 3 wires coming out of the pickup on the dizzy. Green, Red, and Black. I have been trying to read up on where to hook these and I beleive Im supposed to hook black to ground, red to keyed and cranking power, and the green goes to the FAST harness. But where in the FAST harness? I currently have the proper pins grounded in the hall effect plug to only allow the ecu to recognize the crank trigger. Where should I hook this green cam sensor wire and will I need to re-ground or change what is grounded in the hall effect plug? Thanks again.

 

Green will go to Cam discrete in the cam/hall connector and black will go to A13 ground.

Green to C yellow black
Black to D black/white
A and B get looped together.

If you already have a wire in D then this black wire splices into that one.

 

Ok got it, and in xfi instructions it says I need to put keyed power to the pink 12v he wire. I can't find that wire in my brand new harness anywhere. I just have a pink wire coming out to the engine bay side of harness that says 12v switch. What is that for or should I not use it? Should my red wire on cam sensor just go to a supply outside of fast harness or is tgere a way to do it off fast?

 

The pink switch wire is fine as long as you hooked it to 12v on the ecu end but any good 12v key power is fine.