Rough idle with new injectors?
 

So I recently had some 2000cc and walbro450 tune for a gtx3576r and what I've notice is a rough idle. It sounds like I have cams during start up and when it idle for 5mins. I've also notice some increase popping and burping sound coming from the exhaust, I have a test pipe btw. With my first tune on the turbo I didn't get any rough idle but after the new injectors/pump and another tune it's really rough. I ask the last tuner(jon@5150) and he's saying it's normal. Is it?

Alot of comfort stuff goes out the window once you get into the bigger injectores/turbo stuff, depends i guess how rough is rough to you..

I don't mind the rough idle or losing some "comfort". I just want to know if it's normal. Is it coming from the bigger pump? Larger injectors? Anyone with similar setup can chime in?

I cant really say cause I have aftermarket Cams with solid motor mounts so I have the roughest possible. :lol:

This is my theory:
Short answer: yes, this is normal with huge jumps in injector sizes.
Long answer :lol: is:
2000cc is a big step up from the stock injectors (550-ish?)
If your stock injectors were open for .1 seconds (for example) @ idle before, your new injectors will open for about 0.28 seconds now. Realize, that as injectors open and close, it isn't 2000cc immediately and transitions from 0 to 2000 to 0 (every injector manufacturer will likely have different times to fully open and close). Tuners will adjust the pulse to compensate and because it is so much faster, and the spray pattern isn't the same, so we just have to expect a rough idle. The research time to smooth out the idle is not on their priority list since idle tuning doesn't blow engines. I will be surprised and very impressed if a tuner can get 2000cc injectors to idle smooth like stockers. :mitsu::mitsu::mitsu:

My injectors are 1200cc with 320 or 340lph pump and I think my tuner cheated a little by increasing my idle to 1000rpm (1200-1400rpm when cold).:lol:

2000's are supposedly a b1tch to tune.... i have 1700'a and a 450 with GSC s2 and my idle is butter smooth at just under 1k with the occasional lope here and there... my guess would be the bigger injectors and Baka knows what hes talking about so I'd trust him

It's normal. You have a HUGE injectors on a set up that requires almost no more fuel than stock at idle. And the injectors are way oversized for the setup. Also, what brand are they? All of the knock off injectors never idle as well as Fuel Injector Clinic or Injector Dynamics.

Thanks for the inputs everyone! I kinda figure it's normal. I love the power that the gtx3576r makes with the setup!

Drill out you siphon tube when running a 450 pump, idle fuel pressure is probably to high. When tuned correctly those injectors will idle just fine on a stock motor. You need the IPW linearization mod with the stock computer.

https://www.evolutionm.net/forums/ec...ion-table.html

This mod to your stock rom really helps the idle/light throttle afr's

https://www.evolutionm.net/forums/ev...le-issues.html

This is a must do for proper idle fuel pressure with a 400/450 pump.

All that might help. But I've been around a few properly setup stock cam/stock displacement Evo's, and the 2000's just don't idle perfectly, especially on pump gas. The motor just doesn't flow enough air to need that much fuel.

You can bet your azz it will.

Oh yea make sure your fuel pressure regulator solenoid is disconnected, run your vacuum hose straight to the intake manifold.

If you do all these things it will idle much better.