Newb needs help getting a base tune

[DSMNerd6889]

Hey guys, I'm pretty close to having my car all put back together and I'm totally new to any kind of a/f tuning. I'm hoping that someone can find it in their heart to walk me through figuring out a safe tune before I try and start up my car for the first time. I'm running a PTE SC-6152E turbo, 660 injectors, a GM-MAFt, and tuning with a SAFCII. I consider myself relatively intelligent, but really have no idea where to even start. If you guys could point me in the right direction, I'd really appreciate it. Thanks.

[david-b]

I don't think the SAFC is going to do much for you. Those injectors may be too big for it.

Do you have any datalogger and/or WBO2? You're going to need at least the datalogger. You'll probably want to tune to 10.9-11.2afr but you HAVE to watch what's going on with the car.

[DSMNerd6889]

Yeah, I also had an lm wideband 02 and I'm going to get a pocketlogger. I intended on getting dsmlink asap, but I just need to get this running at this point. So there is really no way to compensate for those 660 injectors between the Maft and SafcII?

[steviek]

no there is. When tuning with safc2 there are two things you gotta keep in mind. The first is that safc bridges the airflow wire to your ecu and then "subtracts" airflow from the signal and reduces the amount of airflow the ecu sees. This tricks the computer into spraying less fuel and the a/f ratios are accomodated proportionally. However, the ecu is blind to the fact that you are actually running more airflow. This makes it continue to have advanced timing according to the airflow it is seeing not the actual airflow which is in the motor. That is the recipe for knock. Now that being said the safc can compensate the injectors down. the formula is simple 450/660-1. That will give you a percentage in your case -32%. That would be your start for tune. Provided everything else is running properly fuel pressure is good fuel pump can sustain the extra fuel flow etc that number would be the proper correction. There are many more things to consider like knock, timing, airflow in hz etc before you can really have your car properly tuned. Safc is very limited in this regard. Gm Maf translator can help but requires at leaswt a logger very recommended dsmlink to switchover etc.
Check my write up for some more info
http://www.automotiveforums.com/vbul...d.php?t=647000

[DSMNerd6889]

Thanks for the response. I'll definitely read that write up asap. Just to make sure I understand correctly. I'm going to need to do a global adjustment of 32% to get to a starting point? I'll post back once I have everything installed and have had time to read your write up. Once again, thanks for the responses.

[steviek]

yeap that is correct
but i might start it at -25% and see how she runs to be on the safe side.
Remember your ecu will be using a more advanced timing curve for every percent you subtrac type of thing

[DSMNerd6889]

Okay guys, I've decided to man up and get DSMlink... I just need a little help from you guys before hand. I got some injectors second hand and I was told they were 660's, but etched on side it says 650's. Can anyone tell me if they recognize them? Also, what should I have my idle and launch rpm set at? Thanks for the help.

[steviek]

what you have there is some fic 650's
http://www.extremepsi.com/store/cust...cat=429&page=1

you can set your launch to whatever you please. Idle I like 950 or 1050rpm. Those options are no big deal you can change them whenver you want.

[DSMNerd6889]

Cool, I think that's all I need to know to order it up.... hopefully I'll have it ordered by the end of the week. Expect more questions to follow, lol.

[DSMNerd6889]

I got a nice package in the mail from dsmlink today... hopefully this will be the kick in the ass I need to get wrenching.

[vanilla gorilla]

Sweet deal. Hopefully I will be running Link, shortly.