I just finished my turbo build and now im on to tuning. I'm having some issues at first. Here is some background... PO had an engine built and it "tuned". I know enough to see that not alot was changed, and what was didn't look awesome. The car has an aeromotive manifold ref. regulator which I believe is possibly giving me some issues. I set the fuel pressure to 58 pounds with the car off. With it running and the ref. line off it measured 55 so I made my fueling adjustments for 55 from 43.5 on 61lbs off the siemens site(deka4 60#). Now I changed the engine size in hptunes to reflect the 383 which the tuner had not done. I also noticed the injectors were not scaled for the 58 pounds nor were they scaled for 43 pounds so again not sure what was going on there. So basic changes were correct engine displacement, injector scaled to reflect 58 pound fuel pressure flatlined because of ref regulator. Start the car runs wayyyy lean. Now I just went thru emissions so I have the stock maf infront of the turbo. I just quickly did some changes and I needed to run the ve up almost to 80% in that cell to get it to idle happy. Granted it's a big cam and idles 850rpm 50kpa, but I thought that was odd. Honest truth is I would imagine I should be able to take a stock 02 camaro tune, drop the injector size in change the engine size and have the car run... not saying awesome but run atleast in the stadium. Can anyone add some thoughts here. I'll attach the current tune im running. Mind you the car runs ok. I can drive it and for the most part its decent. Have yet to get into boost. LTFT's were all right around -10%. Thanks ahead of time.

 

Take your boost reference vacuum line off the manifold and put it before the throttle body in the charge pipe. Vacuum will lower your fuel pressure, boost will raise it. If you have any kind of cam or unsteady idle having your regulator referenced off the manifold the pressure will be all over the place and make it a bitch to tune. Then Doing that I didnt scale my injectors... just put 60 all the way across the chart (60# injectors). Worked fine.

 

Hmm... the purpose of the scaling is to account for the increase and decrease in differential pressure across the injector. Having the ref. regulator voids this because it makes this adjustment. Moving the ref line to an area where it won't sense vacuum is fine, and is almost similar to the stock setup... i.e. vacuum adjustments are done by the computer, and the boost adjustments are compensated by the regulator, but if you don't have it offset accordingly the actual fuel delivery will be off. The real issue I'm having is that the injector flow, fuel pressure and resulting afr don't seem to line up. Perhaps I'm missing something and if so I apologize, but the fuel pressure is very steady at idle, and the manifold pressure is stable as well.

PS the previous tuner has values close to 60 but not flatlined. The car does run pretty well and idles just fine, but I know it's not "correct".