SAFC-2 on boosted 420a

[ILLegit420aT]

i have a 2gnt with turbo, and i just bought another safc2 off my boy. the safc comes on and the car starts and runs, but as soon as i build boost and lett off the car dies. its blowing the fusible link for engine/motor under the hood. the fuel pump stops working and the car will not start. i have a custom turbo kit, built bottom end, walboro...etc. but im not sure if maybe i just have bad grounds or maybe the input and output has something to do with it...anyone help!

 

[PieEyedPiper]

Did your son happen to mention the history of the SAFC? It sounds like your problem lies in the wiring, but the only reason I'd suspect the SAFC as the culprit is because it was the last thing done to the car by the sounds of it.

If it was the most recent mod, remove the unit and test the car. If the problem goes away then you have your answer. If nothing changes, you have your work cut out for you.

Good luck.

 

[psycho]

I wouldn't put a safc on a boosted 420a. Take it off.

 

[ILLegit420aT]

I wouldn't put a safc on a boosted 420a. Take it off.

why? what possible reason could there be to not use an safc on a boosted car?

 

[cs82685]

why? what possible reason could there be to not use an safc on a boosted car?

For starters...

SAFCs don't really do shit for 2GNTs. The ONLY time I would suggest someone with a 2GNT consider an SAFC would be if they had aggressive cams and needed something cheap to lean out their idle a bit. The MAP set up we have means using the SAFC to add fuel at any point isn't happening.

From what I've read, my understanding of it is the SAFC reads vaccuum/boost through the map sensor. Our map sensors don't like to see boost so people either use a missing link or a FCD to prevent the map from seeing boost in order to prevent fuel cut. Anything over 5v to the map (i.e. when it sees boost)and you fuel cut. Therefore if the SAFC is taking it's signal from the map which is being fooled into not seeing boost then you can't make any adjustments when in boost because the SAFC will never know you're boosting.

The only thing this makes me wonder (because I know nothing about electrical) is if you could wire the safc to the map and then wire the fcd after the safc. Soo it would be Map---->SAFC---->FCD---->ECU. I'm not sure if the problem lies directly at the map where that would not work, because of the way the FCD and or SAFC has to be wired or what?


Usually people only use it for tuning our cars out of boost. As said by Driggs above, people use it to lean out their idle. With DSM 450's like your profile states, I could definitely see wanting to use it to smooth out your idle and out of boost driving, but once you get into boost, well it doesn't do any good. Not to mention with the cost and info available on MSnS it's become the ideal way to go. I'm headed there but have yet to research it as I know it's going to take a lot of time and learning and I think that's what deters most people. There's a local Miata guy using MSnS and he said he had to carry his laptop with him everywhere for the first few months he had MS installed b/c of having to make adjustments here and there in case for some reason his car wouldn't start or would run like crap.

I'm surprised that with a low 13 sec slip you're unaware of this. BTW what psi was that run on, I'm always interested in seeing what people can do with these cars on the track?

edit: I don't see an FCD or ML in your profile. If you're one of the lucky few whos car for whatever reason runs fine without either, then I don't see there being a problem using the safc as long as it is seeing boost from your map

 

[Car_guy_09]

How are you running 16 psi (profile) with little to no fuel control??

 

[ILLegit420aT]

well for starters...if you know what your doing with air/fuel you dont need much to tune...see if you just get the car really close to running condition on mods alone, you need very primative tuning. with my 450's i have the bare minimum fuel delivery at WOT...but the car runs pig rich at idle, and without the safc will not idle at all...so why wouldn't i be running 16 psi?

 

[cs82685]

^so all you're using to control fuel is an safc?

 

[ILLegit420aT]

yeah, with the mods i have, my fuel pump and 4g63 fuel setup is enough to run on the stock ecu if i retard the fuel -50% across the board. its a rich idle but a solid one. i have a 65% tps setting for high throttle and around upper 40's across the board. now i do have lower setings for lower rpm's but i dont put it into boost below 3500-4000rpm. with that tune it runs well enough to hit the 13's and its a daily driver right now im having wiring issues where my fusible link for the engine circuit keeps blowing key on engine off. i did get it around the block, but it got progresssivley worse. im puzzled, i know that link controls the fuel pump circuit. are walboros known for any problems like this? im doing my best now to figure it out and sell the car.

 

[Car_guy_09]

Wow... Pm me if you would to explain more as I am currently trying to figure something out for fuel so i can run about 15-16 psi on my 20g