I just got finished with my mini-me (y8 head, A6 block, Si OBD0 dizzy) last night. The car ran fine last night, no problems. This morning after it warmed up, it would studder between 1k and 3k rpms. Idle is very smooth, going down the interstate is no problem.

I have an adjustable FPR, and the gauge is reading 60 psi at the fuel rail!! I had it set at 42 psi, and I've never had any problems. Going down the interstate I got a CEL - code 1 o2 sensor.... I looked at the plugs and they look fine, maybe a little on the lean side. I just don't understand why it just started doing this after the swap, my fuel pressure is WAY up, and I'm still running lean... On the way home from work I unplugged the o2 sensor and it didn't help. Anyone every have a problem like this from an o2 sensor?? All of my vacuum lines are fine, I run injector cleaner every time I change my oil.... Any ideas?

 

60 psi of fuel pressure is too much. that might fix all ur problems. for d series it should be 38 stock and i think b series is 42

 

Uhh. Yeah I know that. I haven't touched my FPR settings, and it jumped up from 43 psi to 60 at about the same time that the studder came around. Since then I've tried to adjust it, but its like the injectors aren't taking any of the fuel... The fact that the fuel pressure is up that high isn't the problem, its more of a biproduct I think. I'm kind of leaning towards injector resistor box or something.... If the FPR was the problem, and I was getting 60 psi through working injectors, I would be running very rich. I'm running lean...

 

I tried to lower the fuel pressure, got it down to about 55 psi and the motor started spark knocking. I turned the fuel pressure up to about 74 psi () and it got rid of the studder, but jeez. Either my gauge is wrong, or there is something up with the injectors. I have a spare set of injectors, so I'll put those in tomorrow.

BTW, I changed spark plugs, and injector resistor box and no change. Just spare parts laying around . I love spare parts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I8ayellowcrayon &raquo;</TD></TR><TR><TD CLASS="quote">I tried to lower the fuel pressure, got it down to about 55 psi and the motor started spark knocking. I turned the fuel pressure up to about 74 psi () and it got rid of the studder, but jeez. Either my gauge is wrong, or there is something up with the injectors. I have a spare set of injectors, so I'll put those in tomorrow.

BTW, I changed spark plugs, and injector resistor box and no change. Just spare parts laying around . I love spare parts.</TD></TR></TABLE>

well gauges do go bad so that could be your problem. is your timing dead on? how are you activating vtec? its probably not your injectors but if you have some laying around it shouldnt hurt right? what did you do with the cam timing did you retard or advance it 5 deg?

 

Changed injectors, no change. When the fuel rail was off, the gauge said 32 psi.... So I guess the gauge is just wrong.... Kinda sucks because I've had it for about 4 months...

No VTEC. Timing is about 13* at the crank, and I'm running 91 octane.

 

so now you know its not a problem with fuel delivery. must be with ignition. the timing should be 16 btdc but im not sure that much change would cause a low rpm stutter. you did use a adjustable cam gear right? i had my timing at 8 degrees when i was supercharged and it didnt affect the low rpms. im suspecting cam timing.

EDIT: i just read your topic one more time. the studder doesnt happen when its cold?

 

The studder is gone. Yeah, it only did it when the engine was cold, I guess the ECU dumped a little more fuel in until the motor gets warmed up or something... Thanks for the help though man!