motor leaning out bad!!!

[Kenny_Kline]

Ok so last year when I had this car running, the chip jeff made me was close where I only had to correct under 5% on the SAFC for the lo throttle settings at idle-3000rpm. This was on a 1g head/block bone stock with 272 cams

Now, I had the motor rebuilt from bottom up but this time, I used a 2G head/intake manifold on the 1g block. The 2G head got =1mm over sized valves and the lip in the valve bowls was removed to help flow more air. I go to do my initial tune as I did before idle - 3000rpm and the thing is running really lean off my old tune I had saved. I think something is wrong. I check everything that could effect this and everything is perfect. So I start adding fuel at 1000rpm. I bring it up to 22% before my wideband comes down to 14-13. Same thing with 2000, 2500, and 3000 rpm. Had to set it all at +22% WTF??? As you know, leaner condition means better air flow.

I mean, either something is lacking in my fuel setup (which I checked and its all perfect) or the oversized valves, port work, and 2g head design is just that much better than my old 1g setup.

What do you think? ALot of people over on adrenalin called me stupid for running this head and saying I wouldnt gain any more but eh... the lean conditions speak for themselves. I didnt expect it to be that much.

I have my 14psi tune saved from the old setup so I will compare that to the new setup and find out exactly how much more fuel I am adding.

Fuel press set at 39psi and only other thing changed on my fuel setup was the fuel rail (stock to AEM) and I got a stainless steel braided line from filter to rail so if anything, this would help give more fuel. Everything else stayed the same.

 

[Dialcaliper]

Do you have airflow logs to confirm that it's actually running lean? How are the closed loop fuel trims? Are you getting any knock? If you have logs of your previous setup, compare the airflow frequency. If it also agrees, it's possible what you're seeing isn't false.

Step one sanity check, recalibrate your wideband and see if it still reads the same. If you're still running the stock O2 sensor, see if the voltage/lambda agrees with the lean condition (it is only accurate in the range right around 14.7, but it should be able to tell you if you're up in that range or past it) If it's showing rich when your wideband shows lean, you might have an issue with the wideband

 

IMO, nothing you have done *should* have changed your tune. Since you have a MAS-based system, any improvements in the airflow would be compensated for by the ECU, so I think you need to look elsewhere. My bet would be that you either have a huge boost leak or a fuel issue.