sidneyam

Argh it's problem after problem with this car. Anyways my ecu is throwing code 51 this time( Fuel Injector Circuit Open). I checked my connections, cleaned the connectors and nothing. Before, the check engine light would come on for about a minute and then the engine would sputter and it would go away for about a day or two. So now it seems to want to stay on along with the sputtering. Do I have a bad fuel injector?

ZLover4Life

You could've searched for info on how to test a fuel injector and known for sure without ever posting.

Test the resistance across the leads of the injector. Should be 10-14 ohms. Any injector that is not 10-14 ohms is dead.

sidneyam

Thanks for the patience Zlover, I actually did do all that research before and knew I had to use a multimeter. From what I've read i could also pull the coil pack connections and see which spark plus isnt getting any fuel or affects idle. I posted on here to see if there was any other method or if an ecu code 51 could mean something else. I've checked my connections etc. I just don't know why this problem is intermittent. You have any idea?

ZLover4Life

Bad injectors can be intermittent, depending on which way they went bad. If the resistance is slightly high, it can run fine under most conditions, but struggle to provide fuel during higher demand and other times; if the resistance is low, it'll run fun under most conditions and too rich, leading to fouling out the plugs, other times.

I don't know why we're discussing this, though... test the resistance of your injectors and we won't have to speculate. Either they'll be the problem, or they won't.

sidneyam

Alright so I tested my injectors and they all fall within spec of 10~14 ohms except for 2 of them. My fifth injector, read out at 27 ohms so thats dead obviously and another read out at 9.6~9.8 ohms still under spec but very close to the minimum. And I noticed my connectors have the little orange bottoms so im assuming theyre the new style harness for the new injectors since they don't have that clip on the side. Is it safe for me to buy the new pintle-less injectors without worrying if theyll fit since they seem to fit in their right now anyway?

ZLover4Life

Close to spec is not within spec, just for the record.

Pintle-less injectors don't tend to have problems with failure... post picture of your injectors and their connectors and we'll let you know if they're the new style or not. Can you see where someone would've spliced in the new connectors? Because your 90 would've had to have the connectors spliced on...

sidneyam

I'll post up the picture during daylight tomorrow but from what I can explain in detail, like i said before the bottoms are orange and they have a push tab to lock the connector in place and there isnt those little squares on the left and right that the old connector uses to hold themselves in place. so that 9.8 is a dead injector also? or it's running real lean?

ZLover4Life

Lower than spec will run rich. Higher than spec will run lean. My guess is the one that's 27 ohms is the cause of your misfire, while the 9.8 ohm one is still firing, but not at an optimal fuel mixture (and it will cause a misfire eventually when its resistance falls low enough to be dumping far too much fuel at normal RPMs).

And from what you're describing, it is the newer style injectors, but I have to wonder if the previous owner put some crappy aftermarket injectors in to save money... like I said, the pintle-less injectors don't tend to have failure issues (as long as we're talking Nissan/Jecs injectors).

sidneyam

yeah that read out of 27 ohm was really daunting, I'll take a look into the injector when i do the plenum pull next weekend and see if i can clean anything off the 9.8 ohm injector to see if i can bring it back to spec. But it still seems like im running on 6 cylinders and when that code 51 pops up it starts sputtering, unless both cylinders are misfiring at the same time but a 4 cylinder with misfire is sure to sound very very obvious versus 5 cylinders.

ZLover4Life

I didn't realize I spoke so unclearly when I said:

I guess I should've said "the 9.8 ohm one is still firing, but not at an optimal fuel mixture (and it will cause a misfire eventually when its resistance falls low enough to be dumping far too much fuel at normal RPMs)."

And cleaning it off won't bring the resistance back up... if the resistance were slightly high, it could be caused by corrosion on the leads. Such corrosion can't cause better conduction of electricity (which is what a low resistance means). lol In fact (and I mean "what I'm about to say is fact"), the cause of low resistance is the coils inside the injector causing an arc... basically, imagine a spring, then snap it in half and connect one broken end further down the other half of the spring - any electricity flowing through the spring now has less of a distance to travel, thus reducing the resistance. Your injector is dead... it's just not causing symptoms yet.

P.S. 27 ohms is not nearly the worst I've seen. I've encountered some injectors that were in the mega-ohms (millions), as well as some that can't get a reading (the injector coil was completely rusted through), and others that read 0 (continually dump fuel). You can thank your politicians for requiring ethanol fuel blends for your issues. Their misguided (by farmer lobbyist) attempt to reduce our dependence on oil by adding a less-energy-producing form of alcohol is the reason most fuel injectors fail nowadays.

sidneyam

Ah alright, I understand. Thanks for all your help Zlover, I'll get to fixin my two injectors. Hopefully all the others aren't aftermarket so i wont have to replace em another time.

ZLover4Life

Well I doubt anybody would do an upgrade with only some OEM injectors. Post pics and I'll try to let you know if they're OEM or not.

sidneyam

alright I'm just following up with my plenum pull. Here's a picture of the injector connector and when I pulled out the injector it had the JECS engraving on it. This injector read out to 27 ohms but I don't know when it was replaced so I'm not gonna bother with the warranty. I was wondering if anyone had a detailed DIY water line delete how to. I've seen other water delete instructions but I don't quite know which lines to connect with the hoses. What worries me is connecting the wrong lines. Pictures are worth a thousand words to me. It would make future plenum pulls much much easier if i knew how to do these water line deletes.

ZLover4Life

Looks like a newer style connector, but you're totally showing me the wrong angle to be sure. lol Of all the angles you could show me, that's the only one that makes it hard to tell.

You should not need a writeup for a simple water hose bypass... you're just eliminating the lines that go to the plenum. Follow the path that it'd take and simply stop it from going to the plenum at all.

But familiarize yourself with TwinTurbo.NET autoFAQ and tech sections... there's an autoFAQ detailing the information and all autoFAQ images are archived. Here's your final fish (i.e. I'm no longer giving you answers that are easy to find, as many of yours are):
Writeup:
http://www.twinturbo.net/nissan/300z...lease-VTF.html
Pics:
http://twinturbo.net/ttnetfaq/auto_F.../880107_files/

sidneyam

Thanks Zlover, I guess I'm gonna be learning how to fish now instead of em being given to me =P. One last question though, am I just leaving the metal piping underneath the plenum not connected to anything? Engineers have such a crude sense of humor...

ZLover4Life

I'm pretty sure you can yank the metal plumbing out... it should be just (strongly) glued in. Or you can just leave the plumbing there... it's not like they'll leak... they're not connected to anything.

sidneyam

Thanks for all the help Zlover! I'll take care of her well. I already had her named

ZLover4Life

... it's a car... it doesn't need a name, nor will it respond to one.