Ok. Got the car running good but the afr is like 16-18 at idle and drops to like 13.5-15 when on the throttle up to 3500 rpms. Because of break in tune. The wideband sensor is directly behind a perrin ultra high flow cat so not sure if that should affect it that much. This is also prior to a tune just so i can break it in. Any advice?

 

wb should be before the cat..

 

This.

It'll throw off readings if it's after the cat.

 

Would it throw it off that bad even behind the ultra high flows? I saw on another forum that it wouldnt which is why I tried. What about the EGR, would that raise it this high potentially?

 

I could see it having an effect on the AFR reading. But I don't think it would throw it off that bad. Professional tuners clip a wideband in the exit of the exhaust to tune with. Sure they use a way better and more expensive WB, but I doubt it would throw you off 2 points.

Was the driving AFR at cruise? If so, that's not too bad. I'd go over everything and make sure you don't have a boost or vacuum leak.

 

I looked for a leak. How can you tell if you have a boost leak? I havent hit boost since the build. I know its definitely lean because it does chug a little like its not getting fuel until you give it a good bit of throttle.

 

You could get a boost leak tester put some air into the system. Then put soapy water on the couplers and connectors and check for bubbles.

What all modifications you have done to the car?

 

Its a full port and polish head
ti valves and springs
kelford 272s
egr deleted
wiseco 9.0:1 pistons
manley h beams
manley crank
ams fuel rail
hks IC piping
hks suction intake
Theres more but thats the only things i can think of that would affect the AFR

 

Do you have evoscan and ecuflash? It would be wise to do some logs. What are you fuel trims like? What injectors are you running? Are they scaled correctly? Definitely check for boost leaks but test it the right way (piping, gaskets, throttle body shaft seals, etc.)

 

With the modifications you have. I'd just check the best you can for boost leaks and if that's good. Contact your tuner and ask them what they recommend to do for the break in period and get it tuned professionally.

 

^^^ this!!!

 

I dont have any kind of programs for it. I plan on taking it to Atlantic motorsports for a tune but i wanted to put more miles on it before then. Just dont want to melt the fresh engine

 

if you have any kind of exhaust leak you will get lean AFR readings... so it is always better to have the WB up front, where there is less chance of a leak.
bottom line is that you are not exactly sure in the reading and there are other sources of error possible (type of WB, WB calibration, type of logging... etc)

as a first measure, I would compare the reading with the stock narrowband... around 14.7 even the narrowband is accurate..

 

Most shops will boost leak test the car before it sees the dyno for an additional fee usually. Maybe have them look over everything before you pay for a tune. You can always reshedule it and dial it in later when you have more miles on it. Don't risk hurting a new build it could be nothing or something simple but its going to be hard to diagnose over the internet.

 

boost leak will give you rich AFR not lean..

you either are measuring it wrong, or have a really lean mixture.. need to double check