View Full Version : Injectors going static at 10psi. Normal?

08-11-2002, 09:39 PM
I just installed an AVC-R on my car. Excellent piece of equipment. I have the OEM S14 SR ECU and 370cc injectors. According to the AVC-R my injectors go to 99% duty cycle at a setting of 0.65 bar (9.5 psi) is this normal and if so why does it happen at such a low boost? Is it possible that the OEM ecu is dumping excess fuel in because it sees so much boost? Did I hook up something wrong?

08-12-2002, 02:03 PM
shameless shameless bump. Any thoughts?

08-12-2002, 08:39 PM
Asad and I have discussed this in private and on this forum and we haven't been able to come to any conclusion. The same thing occured to me with my A'PEXi Multichecker. I now have 550cc injectors along with the Z32 MAFS and I only show about 43% duty cycle at full throttle/boost.

08-12-2002, 09:18 PM
This is indeed very strange. If you are getting 43% duty with injectors that are only 50% larger, it must be a function of the OEM ECU going into some safety mode due to the higher than stock boost and the MAF being in the higher end of its range of operation. Glad to know that I am not the only one with the phenomena, thanks for your reply.

08-12-2002, 11:50 PM
i have an s13 sr and at 12 psi my multichecker reads about 90% max. normally it never gets above 85%..i think once it spiked up to 95 but never been higher than that.

08-13-2002, 12:40 AM
KmanSilvia -- are you sure the AVC-R is set up to read injector duty cycle? AFAIK, the standard wiring setup for the AVC-R uses the duty cycle measurement to read the boost solenoid duty cycle...


08-13-2002, 12:47 AM
I believe I do have the AVC-R set up to read injector duty cycle. I connected the rpm sensing wire for the AVC-R to the injector wire on the ecu harness and set the number of cylinders to 1

08-13-2002, 01:26 AM
? i dont know a damn thing about the AVC, but that doesnt sound right to me...? you connected the engine RPM wire to what? the ECU has its own rpm wire...maybe you already know this and me be's an idiot http://forums.freshalloy.com/ubbthreads/images/icons/grin.gif

08-13-2002, 08:38 AM
yeah it sounds strange but the instruction manual says you can do it that way. If you think about it the rpm signal taken from the rpm wire on the ecu is just a pulse, just like the pulses going to the injectors. The AVCR can use either pulse to measure rpm. Only problem with setting it up the way I have is once you go to 100% inj. duty you can't measure rpm anymore. But that shouldn't be a problem anymore in a while when I install the 555cc injectors on the weekend.

08-13-2002, 08:48 AM
Yeah, I have a problem with mine also, it says the injector pulse is at like 90% at idle.

08-13-2002, 08:52 AM
yeah that sounds like a problem. you may have your avcr rpm wire connected to the wrong wire on the ecu. also make sure that you have the number of cylinders set to 1.

08-14-2002, 01:53 PM
just wondering something. The boost pressure sensor for the ECU is supposed to take signal before the throttle body and after the intercooler. I currently have the signal reading from before the intercoler. ie it sees about 1-2 psi more than the engine. Could this be causing the ECU to dump excess fuel?

08-14-2002, 02:41 PM
Possibly. What I would try first of all is just disconnecting the signal line to the boost pressure sensor (and of course capping the vacuum line) and see if you still get the same duty-cycle issues.