Go street 400 tuning tips?
I'm running a go street 400 unit on a 350 Chev with comp cams hyd thumper cam. Other than roller rockers and flat top pistons engine is basically stock. Idle afr is at 14.2. 1100rpm is 14.4 and cruise at 14.7. Engine starts and runs fine but bogs when you mash the loud peddle. On heavy acceleration afr leans out to 15.5 then goes to 13.2. I'm running th350 auto and 3:1 diff accel pump settings at +10. Any running tips greatly appreciated. Thanks
You may want to start from scratch. Looks like you have made a lot of tuning changes trying to chase this problem. First of all, I would set idle at 12.7:1. You don't want idle to lean. Can hurt the motor. Adding Accel is the right thing to do until desired results.
12.7 afr at idle sounds pretty rich, even at 14.2 it smells fuelly through exhaust, but it produces best vacuum at idle. If I hold 1st gear till around 2500-3000rpm then mash throttle it smokes tyres. The bogging issue is really only from standing start.
Sounds like accel setting to me as well. Id play in that menu adding small positive amounts at a time until bog disappears . you can set your idle target to 14.7 . motor has no power adder 14.7 is stoich .. If it pulls lean off idle when set at 14.7 add accel fuel it will take care of the dip you are experiencing .
Thanks Boosted I'll give it a try tomorrow and let you know
12.7 is the AFR you want at WOT. That would be way too rich for an idle.
Quote from MuhThugga on November 19, 2017, 2:36 pm12.7 is the AFR you want at WOT. That would be way too rich for an idle.
Agreed. My suggestion was off. My point was a stoich far at idle can be a little lean. The VE is low at idle and with a stoich idle could cause some adverse effects, such as hot spots. A little rich idle will not hurt, but it can help.
You may want to rethink your user name top tuner, initially you suggest big afr change or restart because I'd made a lot of tuning changes. Now your suggesting a tune similar to what I initially posted?
Quote from Guest on November 19, 2017, 5:21 pmYou may want to rethink your user name top tuner, initially you suggest big afr change or restart because I'd made a lot of tuning changes. Now your suggesting a tune similar to what I initially posted?
Please login.
First of all my username was picked by my web developer. Not what I would have picked, because it leads to comments like this.
Let me introduce myself. My name is Austin DeHaas, and I built this site. It is my plan to build a community Fitech Users and organize tuning processes and installations. This is for everyone to ask questions and answer questions. Not for only me to lend my advise and wisdom.
Now the matter at hand. Grunt350, I believe is way to lean at idle which will cause off idle tip in issues. If you remember from setting idle mixture screws on carbs, you set the screw to best idle or vacuum and then you fatten it a small bit. Same concept here. 12.7, yes was a little much, but I also don't want to lend advise that may cause damage. And richening at idle will not cause damage to the motor, unless so rich it won't run or it fouls the plugs.
My apologies for not being clear. I try to lend short and sweet advise. And since the negative comment came from a guest, I do not know who it was. With that said, everyone providing advise to Grunt350 has been very helpful. I respect each one of you. Let's keep things cordial and help Grunt350 enjoy his system. Thank you.