Well let me start this thread with my mods so far:
Vortech supercharger
motordyne 5/16th plenum spacer
titek test pipes
hks hi power
RC 650cc injectors
Snow Methanol injection system 50/50 meth
on my 2004 roadster 5AT

the problem we have been having is this, so i towed my car up to the tuners last week, and weve been trying our best to get it to run. originally found out one of the injectors was leaking, so i bought a new injector. Problem now is when we fire up the engine everything is ok except we are getting random misfires from cylinder 4. Now we have the ss box connected, and are currently waiting to get a map from osiris for the complete tune.
so this is what we've tried so far. we thought it was a coil so i swapped the coil from 4 to 2 seeing if the misfire would move... nope, still cylinder 4.
we then changed the spark plug from cylinder 4 to another cylinder ... again, nope still cylinder 4.
but in the process, when we took out the spark plug , the spark plug did not looked fouled but it was drenched in fuel ( im assuming thats what it was) so from the time we brought it above 3k the spark either goes out , or some random miracle against me is occuring.
So we sent the fuel injectors today to RC, RC replied back that the fuel injectors were cleaned out and done.
so im going back tomorrow to my tuners shop and putting the "new" injectors back into place. but if it doesnt stop the random misfiring, im out of ideas on where to go from there... does any one in the community ever have this problem before?
ive searched the forums and only came up with partial solutions... never a complete run through. im all out of ideas and im pulling my hair out, im just hoping tomorrows injector placement sheds some light on the situation.

please help

 

FI and random misfire are best friend.

 

the problem is im a little scared to get it tuned while i have a random misfire just happening i.e i really dont wanna grenade my motor if you know what i mean :/

 

Is that one cylinder running too rich and not firing?

 

you cant run 650cc injectors without a tune and expect it to not misfire... thats like 3 times the size of stock.

 

my tuner has the 650cc injectors scaled down 50% right now because they are running too rich , when he revs the engine cylinder 4 is fine ... its when he takes it a little above 3k or lets it idle after hes revved it a bit the cylinder itself does run too rich and then starts to misfire , thats when we cut the engine , removed the plenum to take a look at the plug when we discovered it was just drenched. Do you think we should scale the injectors further 60 %+ ? and try it see if cylinder 4 is still misfiring ?

 

If it's been tuned to anywhere near stoich (14.7), then it should be perfect and should not misfire. Did RC mention that that injector was stuck open or improperly sized? That's what it sounds like... I wonder if they would even tell you if something was wrong. There have been several reported poor experiences with RC injectors. I was never happy with them and switched out to HKS.

That said, I've never had a misfire, ever. (knock on wood )

Your tuner did a good job testing, but the final test would have been to swap injectors around. I bet the problem would have followed the injector.

EDIT: By the way, I'm not necessarily recommending HKS injectors. They've worked fine, but you have to machine them to get them to fit, they are expensive, they are low impedence (not compatible with stock EMS), and they have a relatively high latency. Better options are out there...

 

Who is your tuner?

 

+1. And what EMS? I didn't see you were from SD. uh oh...

 

He said SS in the OP.

 

Haha...no worries guys, it isn't MrS...

He's over at Shawn Church, who did my tuning...I believe his EMS is a combo of Uprev and SS Box...

Good luck OP!

 

Osiris and SS box, sounds good combo

 

Yeah shawn is frekkin awesome helping me out! The best tuner bar none.. Well I'm going back to try my injectors which just returned from rc. Wish me luck...

 

Did you modify your injector harness to work with the RC's, or do you have clip adaptors? Either way, make sure the wiring has good continuity...

And don't forget make sure your spark plug harness is in the right order too...

And of course...good luck...

 

Yeah I'm going to have to check the wiring to injector 4. We used the clip adaptors from rc.

 

Update:
well the injectors came back , and they checked out fine... but low and behold we are still misfiring from cylinder 4. we moved the coil pack again, when i took the coil pack out i noticed you can seperate the actual pack in half , which i thought was strange, so i moved the pack itself to cylinder infront of 4 and the same damn cylinder 4 is misfiring.

I pulled out cylinder 4 coil pack to make sure we are even getting a spark , and its sparking but it doesnt look consistent almost like its not getting enough volts. we think its a grounding issue, but when we installed the vortech we didnt splice anything but the clips at the fuel injectors. the only wires so far spliced into i can think was the methanol injection system or the ss box itself man ... this is such a head ache

 

Wow...grounding huh? I may have had a similar issue; when I first put my vortech together I did the wiring very sloppy the first time and kinda just hooked up all the grounds that I disconnected during the install haphazardly...

About a week after getting it tuned the car suddenly died on the freeway and wouldn't start, and I had it towed to Shawn's garage for diagnosis...well while I was waiting I was playing around with the engine harness and I noticed on of the grounds was not bolted on tightly...I tightened it up and the car started...it turned out the bad ground was for the injectors...

Anyway, I hope you find and fix that issue with the spark soon...it may be worth it to send it to a Nissan dealership so they can isolate your issue more quickly...Performance Nissan is very friendly to aftermarket stuff like Vortechs, I regularly take my car there for maintenance and even talk about my FI issues to the tech...ask for John Kuo, he's their resident aftermarket tech specialist...

 

Harris where was that ground you tightened! This actually might be the answer! Pm me when you get this!

 

Getting a 650cc injector to play nicely with the SS box is extremely challenging. I bet if you switched to the flash or the UTEC, the problem would be solved.

For what it's worth, you should have used the DW 600 injectors. They tend to idle, and run cruise a lot better, without as many RCM codes.

 

good god thanks for your reply sharif! actually you were the next person i was going to hit up for some help!

update:
so.... im thinking it might be the injectors playing nicely with the SS box, the options i have is
1) get 440 cc injectors because i heard the ss box has a very hard time playing nice with 650cc. so let me paint the picture real quick.... today, i checked all the wires, and grounds! everything checked nice , shawn and i even checked the ohm resistances and power of every injector and coil and they all show nominal figures with a difference of .05 ( not enough to really cause a dramatic loss from what i could make out.) cylinder 4 is still misfiring ... the only cylinder . in fact raw fuel is still spitting from the driver side exhaust. Shawn says with the cypher reading data and the ss box , bank 1 ( im assuming is driver side... is running rich while bank 2 is running lean when we lean out the injectors almost 50%. when we cut out cylinder 4 everything plays nice with the injector test.

im all out of answers.

or 2) i can wait for the osiris map that i hope they've been working on , shawn called osiris today ,and they said the programmers were supposed to be in tonight, but they had some other work they might be working on. ( which sucks since ive been waiting for 2 weeks now woe is me) .

if anyone has any kind of answers or even something out of the ordinary im willing to try, please let me know . one of the mechanics from a different tuner shop that was there said i might wanna do a compression check again , but my mechanic said if its raw fuel i would look at the spark , fuel pump, or the injectors.
which puts me back to square 1. since the injectors were looked at RC and were cleared ok, the fuel pump is priming the lines and not leaking ( we checked when i had the plenum off and notice that the valves in cylinder 4 were soaked by observation.) and the fuel pump is a walbro 255 btw.

im getting desperate , not to mention my rental car bills are starting to stack .
maybe what would help is if anyone does have 650cc injectors how did you get it to play nice? and maybe someone from osiris can chime in if there going to be making support for my 2004 5at roadster anytime soon
im beginning to ramble, please anyone....