Hello I'm still new to the forums, I purchased an 05 8 and had for some time now. Only mods I did was just put an Exhaust, Boost Gauge, EBC to get it tuned and come to find out the car is running extremely lean? AFR was at like 15 or so. I was wondering if anybody could guide me to the right way to find out why I'm running so lean. And for some reason my gauge reads the vacuum at like 10.. normal is 20 I believe? Also wondering what could be cause of that, I checked all the vacuum lines they are on there tight. Any help would be appreciated thanks.

 

Have you gotten the car tuned yet? Do you have an intake? Retarding the timing can help a little bit. I wanna know a full list of mods. I wanna see your logs if possible.

 

No I do not have an intake on it yet, will be putting one along with upgraded ic pipings as well. I don't have a datalogger to get the logs. Those are the only mods I've done to the car so far.. as for the previous owner.. I don't know if it had any motor work done or not. Hmm retarding th timing you say? Why do you suggest that? Any other suggestions before I start messing with the timing?

 

Where is it running 15, at WOT or cruise?

Vacuum is very low, i would do a boost leak test. Boost leaks will cause the car to be rich instead of leak though unless your intake tube is sucking in air after the MAF.

 

Could call never though of looking for a boost leak.

 

Well I'm pretty sure the AFR was at 15 at WOT. As for the boost leak test. Where can I find this tool to check it? The intake tube I am not sure if it's sucking air after the MAF or not but it still has the stock air box and intake tube. As I recall from reading.. there's only a few places where the boost would leak. Since I plan to upgrade my IC piping that should be eliminated and the TB seals I am unsure about that and how to actually change that.

 

Where did you get the 15:1 number from?
There are A LOT of places that could leak - especially the stock plumpings.

 

15:1 at WOT you would have melted a bunch of things.
And the leak test is just a search away.

 

Check to see if one of your intercooler pipes ain't expanding.

 

Well that was the AFR I got from when I went to get a tune just to see how it is at the time. Could've been 14-15 not exact to be sure. I will contact my tuner and see if he remembers what it was. As for the boost leak part, like I said I'm still new to the forums and this is my first turbo car so I didn't know much.. Still a newbie lol. But I'll check it when I get home, using my phone right now to post.. Not soo fast to find the info I want.

 

So is the tune completed now? How is it AFTER the tune? Got any plot of your AFR against the RPM on certain gear?

 

Vacuum is about right, my 8 with HKS 264 cams idles at 12lbs of Vac. Could have some cams in from previous owner then someone put a stock tune back into the ECU. This would explain the Lean AFR. Your tuner should have known if it had a boost leak, doesn't seem like a boost leak or anything wrong . The stock cars run leaner than modified, Better exhaust, better intake and the cars get richer Did you buy it from a dealership?

 

hmm you might be right about this, a lot of ppl say it does sound like it has cams but I have yet to actually check. From the looks of it, it did look like it was pretty modded and then changed back to stock. But the lean AFR part was found after the tune was done. I'm still in the process of getting my IC pipes/intake, is there a good brand that's compatable with the 9 bov? And I bought it at a used dealership.

 

Am I right that saying a stoichiometric air/fuel mixture is 14.7:1. Is that not what you want? How are you O2's, short fuel trims, and long fuel trims looking? Somehow if it is running lean then you are having unmeasured air entering the engine, or a vacuum leak. Check every hose after the MAF sensor to make sure its tight.

 

Check the line on the Fuel Pressure Regulator for proper connection and cracking. Car will go lean at WOT if compromised. Your boost gauge may be T'd to that line top left behind the valve cover