Hi guys,

my car is popping at idle every now and then, mostly at idle, sometimes right after I open the throttle, but mostly at idle. The car is even shaking as if it was caused by an explosion in the exhaust when I'm standing at a traffic light e.g.
Can it be unburned fuel in the exhaust or something else?
Maybe my fuel pressure is set to high? I think it's at 60 psi.
Can it make any damage to the motor? I'm trying to fix this problem and I would appreciate any help.

My setup:
VTSC @ 8.5 psi
AEM EMS
AEM FPR
RC 750cc
Walbro fuel pump

Thank you!

Igor

 

From my experience RC injectors suck at idle, you have to run really rich or it will misfire constantly. Could be other things though too.

 

Whats ur afr at idle?

 

The popping is caused by too little a duty cycle for the given fuel pressure . If you turn down the static fuel pressure it will help the problem but youre car will need retuned . I recommend getting better fuel injectors as rc injectors are not the greatest . Id 1000s are awesome !

 

Cars without enough timing on tip in will pop like that as well.

 

i get that at idle. the motor is 100% stock except for a test pipe. even stock intake and everything. but i have my walbro 255 still in the tank from being turbo. i think it may be from additional pressure at idle as well, because i never noticed it while being turbo with the ID's.

ever since i went back to stock, its had a light shudder or *piff* every now and then only at idle in any condition( hot, cold, morning, night, 4 hour trip, 5 mins of driving).
compression reads 240 across the board and i have every emissions component working and installed. not a CEL in sight.

can anyone confirm?

 

My AFR from a cold start is bad, it starts rich 13.2 and goes to very lean while standing at traffic 16-18..
whe the car is warmed up the idle AFR gets better.... 13-14.

I recently retuned my car with the new 750cc injectors, with that I was hoping to get rid of the problem because I had the same problem with the stock injectors.

Should I lower the fuel pressure and get the car retuned? What adise can you give me?
Can anyone help me?

Igor

 

PM'ing you

 

What? I have had no trouble with any of the High Impeadance RC's?

Must be the tuner?


Yes there is a good chance you are damaging the motor.

Why would you run 60PSI base pressure???? You need to keep it lower, say 43 PSI w/ no vacuum attached. The Walbro pump has a pressure cutout at 75PSI and you are going to hit this VERY easy with a little boost and the line losses to the rail.

Have you called your tuner this should not be happening and with your description without a data log with AFR there are none of that are going to be able to give you a good answer. If you Tuner set this up it is time to find another.

Save your money useless you have a bad injector buying new ones will not held. ID1000's are great b/c they have the ability to flow more fuel than was previously possible with a High Impedance injector and still exhibit good linearity.

 

I'm running 60 psi base presure because my tuner said it's ok and tuned it like that. I don't like that but he's the only tuner here in Austria who can work with AEM EMS. I wish somebody with skills could tune my car but as long as I don't have any other option I have to stick to my current tuner.