Need help ASAP with A/F problem

[twack]

I upgraded to a 50trim and MAFT. Got it all setup and now it runs like crap. My wideband shows that at idle it leans out till --, and the logger fuel trims wont change from %100. So i got a new eprom ecu and o2 sensor. Still runs like crap, now the wideband may be bad but you can fell the car runs terrible and dies on deaccel and half the time at idle.

 

[islandigital]

If your adding a bunch more air to your engine (i.e. bigger turbo) you need to also add a bunch more gas.

Your saying that the logger is showing that your running 100% duty cycle? Thats telling you your not getting enugh fuel to that motor, once you upgrade you injectors to support that turbo, your going to need a fuel pump and a FPR to suport that. You cant slap a huge turbo on a car and expect to go fast without the other supporting mods. Hope that helps.

 

[Talesin]

island, he's saying that at-idle it does that. Even stock 450s should be able to handle idling and light non-boost driving with pretty much any size of turbo. Just when it spools is there a problem. And yes, our cars do lean out when they're idling, to conserve fuel.

My suspicion would be the MAF-T... make sure it's set for your injector size, and wired up correctly. Since you have a logger, watch the airflow values... stock should be about 5 at idle, or 4 with a hacked 1G MAS. Watch your injector duty cycle and narrowband O2 readout as well... the fuel trims take a good little while to change.

What does the wideband read under normal driving? Did you pop to larger injectors? Too big and you'll have low-end drivability problems due to the difference in global deadtime, without DSMLink or a standalone EMS. Any other tuning solution aside from the MAF-T? Have you done a boost leak test yet? Shouldn't matter too much if the GM MAS is in a blowthrough configuration, but there's always the potential... remember one 2G that came into the shop with horrible problems, with a MAF-T setup. Idiot hadn't clamped down the reducer on the TB side of the MAS, and it had predictably blown free.. not enough to be visible at a glance, but more than enough to let air in and out past it.

 

[twack]

I already had a SAFCII and 550s in the car. If i try and run it with just the safc and stock maf it acts the same as with the translator and gm in.

 

[Talesin]

Well, just remember to only set up one or the other to compensate for the 550s. I'd stick with the MAF-T on that side of things. Zero out the SAFC. Aside from that, check any/all the splices you had to do for the MAF-T. And have you hooked up the logger to check the at-idle values? Would probably cast some light on things.