Don't know where the hell this would go.

Anyway, my 95 Nissan Hardbody is having hiccups. Every once in a while it will idle rough and it has died once, and then it will run fine for a while.

I got the engine codes and it gave me a 51 (Injector Circuit).

My question is... does this HAVE to be a bad injector somewhere, or could a dirty/clogged injector cause this?

So, could I start with some good injector cleaner and a new fuel filter (recommendations here on good injector cleaner a plus) or should I go ahead and buy an injector now, so I have it when I figure out which injector it is?

I did get some help on how to check for a bad injector, but I don't really want to start going through all of that if cleaning the injectors might solve it. If it is a sure sign of a bad injector, than I will just start troubleshooting them one by one.

Thanks all.

i think posting it in the nissan forum.. then taking the ridicule from there and it getting it moved to newbie, would have been ALOT less of an assraping than putting it in here.

Originally posted by sceep
i think posting it in the nissan forum.. then taking the ridicule from there and it getting it moved to newbie, would have been ALOT less of an assraping than putting it in here.

I don't think it is Nissan specific and it isn't 4x4 specific.

It is a general how to question...


Like, how can you make the go by faster?






















BY KISSING MY ASS! :flipoff2:

Take it to the nissan fourm!!!!!!!:flipoff2: no stinking tech in here!!!


you've got nothing to lose by trying the injector cleaner. dunno how much the injectors are, but if one is dirty, they probably all are. or if you only change one, there could be two that are problmatic. I'd look into changing them all if I was gonna change one.

Originally posted by sceep
i think posting it in the nissan forum.. then taking the ridicule from there

are they allowed to ridicule people in there? :confused:

either delete and post in nissan tech, or delete and pm bignissan

either way, GET THIS DAMNED TECH OUTTA HERE!!! :mad:




















:flipoff2:

Originally posted by Entropy


I don't think it is Nissan specific and it isn't 4x4 specific.

It is a general how to question...


Like, how can you make the go by faster?


By Bus.



Actually, I would start by tracing the injector wiring to see if there is something loose or corroded.

Originally posted by surveyboy
Take it to the nissan fourm!!!!!!!:flipoff2: no stinking tech in here!!!


you've got nothing to lose by trying the injector cleaner. dunno how much the injectors are, but if one is dirty, they probably all are. or if you only change one, there could be two that are problmatic. I'd look into changing them all if I was gonna change one.

I checked a little while ago... from Nissan they are 135 bucks a piece. I hope I don't have to change all of them, I just bought a house, I don't have 800 bucks laying around.

I already posted this on a Nissan Website and one guy gave me advice on troubleshooting the injectors.

I want general advice on whether anyone knows if a clogged or dirty injector can look like a bad one to the ecu, or if a bad one to the ecu is an internal electrical problem that no amount of cleaning is going to solve. That seems like a general car knowledge question.

Looking for a good injector cleaner too... I always figured they were scams so I don't know if any of them actually work.

Originally posted by Schly


By Bus.



Actually, I would start by tracing the injector wiring to see if there is something loose or corroded.

To California.

I'll do that... it was too dark last night to do much with it. I wasn't really concerned with corrosion, since it is a Florida truck and it is pristine compared to what we get up here. It has been through half a winter up here though, so I guess it could have gotten some salt in the connections.

I would start this philosophically.
Yes, I'm being dead serious here.

How would the computer KNOW it was an injector problem?

By measuring the voltages/currents in the injector circuit.

It comes and goes, so it's not an electrical "open" or "short".

My guess, is that you have some corrosion on one of the connectors to the injectors - disconnect each one, clean it (with an eraser, or some 400 grit wet & dry, or some steel wool), and see if it clears up your problem.

Have you recently had a large amount of moisture get to your injectors?

If it IS a single injector, and not the connectors, figuring out which one it is could be a PITA.

Originally posted by Bobzooki
I would start this philosophically.
Yes, I'm being dead serious here.

How would the computer KNOW it was an injector problem?

By measuring the voltages/currents in the injector circuit.

It comes and goes, so it's not an electrical "open" or "short".

My guess, is that you have some corrosion on one of the connectors to the injectors - disconnect each one, clean it (with an eraser, or some 400 grit wet & dry, or some steel wool), and see if it clears up your problem.

Have you recently had a large amount of moisture get to your injectors?

If it IS a single injector, and not the connectors, figuring out which one it is could be a PITA.

Good advice, thanks Bob.

We have had about 4 straight days of rain up here... it was getting down-right old. I never really thought of that being a contributing factor though. I guess I'll do the injector cleaning and fuel filter change for shits and giggles and check all the wiring that I can get too. At least with your explanation there is a chance it isn't a 135 dollar injector... that is what I was unsure of.

You aren't kidding about the injectors... 4 of them are easy to get too, but two of them are "down under". As in down underneath the damn intake manifold.

Drain the fuel pressure. Crank it for 5 seconds, with breaks in between, several times to get the fuel out of the chambers.

Repressurize system, pull coil wire and plugs. Crank for 10-15 seconds. Insert tube into chambers through plug holes and smell.

If you have a bad injector or bad wiring to one, you might be able to tell which chamber (no/weaker/burnt smell in that chamber).

as for testing the injectors you can pull them out, plug them in and have someone turn the car over. injector should spray not "piddle"

you can also feel them when they are working, fire the car up and start grabbing the injector plugs. you will feel them pulsing. if you have a dead one.. well. ;)

you can have injectors rebuilt for ~$100 a set.

1: check fuel and coolant temp sensors-ohmeter?

2: Idle Air control valve and base idle?

3: O2 sensors?

The computer takes input from the sensors and does its best guess as to what's causing the problem and tells you. It is most likely an air/fuel ratio problem throwing the code.

On-Board diagnostics only exist to tell you that an engine operating parameter is out of control and could cause an increase in emissions.

Originally posted by Pazuzu
Drain the fuel pressure. Crank it for 5 seconds, with breaks in between, several times to get the fuel out of the chambers.

Repressurize system, pull coil wire and plugs. Crank for 10-15 seconds. Insert tube into chambers through plug holes and smell.

If you have a bad injector or bad wiring to one, you might be able to tell which chamber (no/weaker/burnt smell in that chamber).

I'll keep that in mind, sounds like a good trick. You should be able to see the fuel as mist or something similar with a flashlight when it cranks right?

Don't know if it will work in this case though, the biggest bitch about the problem is it is intermittent so far. Although it has been getting worse. That lends more proof to the wiring and clogged theories for sure... but I don't know if a bad injector can be "good", "bad", and "going bad". I figured it either worked or it didn't.

Originally posted by Entropy


I'll keep that in mind, sounds like a good trick. You should be able to see the fuel as mist or something similar with a flashlight when it cranks right?

Don't know if it will work in this case though, the biggest bitch about the problem is it is intermittent so far. Although it has been getting worse. That lends more proof to the wiring and clogged theories for sure... but I don't know if a bad injector can be "good", "bad", and "going bad". I figured it either worked or it didn't.

Even an intermitant problem could give a burnt smell to that chamber...try the smell test both before and after evacuating the gas from the chamber.

Injectors have two basic failure modes.One is dead with a failed solenoid coil. The second is clogged, either open (piece of crud lodged in orifice) or closed (passage obstructed complately with crud-rust from water infuel most common).

They can be cleaned at any good diesel shop for around $10/ea at the most. Look at the Bosch website for a shop with a cleaning machine, but don't expect miracles.

not sure bout nissans but the jeep 4.0 will take mustang injectors....cheap, readaly available, more power/efficiency, and you'll have 2 spares.

Originally posted by Michael Klotz
not sure bout nissans but the jeep 4.0 will take mustang injectors....cheap, readaly available, more power/efficiency, and you'll have 2 spares.

The motor I have will take 300Z injectors if I am not mistaken... but that is the only one I know of. I know they are more readily available as rebuilts and whatnot, but I doubt they are cheaper.

Originally posted by Michael Klotz
not sure bout nissans but the jeep 4.0 will take mustang injectors....cheap, readaly available, more power/efficiency, and you'll have 2 spares.

Shh! That's my last secret! Mustange injectors are a very common style, they fit nearly everything (or can be made to fit) and are available in a wide variety of flow rates to suit various engines, shouldn't cost more than $40 each for good ones.

Well, that problem resolved itself... errr, at least I know what it is now.

Put a new fuel filter on it, and started it up, started feeling the injectors and inspecting wiring... poking around.

Drove it up the street and everything is fine.

Get it back in the garage and I am scratching my head and all of a sudden, the idle drops and it starts idling rough.

Look behind the truck and there is a big cloud of smoke... look at the tailpipe and there are huge plumes of white smoke coming out. Guess I have a small head gasket leak, or one that doesn't show it's face until the engine warms up anyway. The engine had just gotten up to normal operating temperature when it happened.

So, now I'll be changing the head gasket. Might as well do the timing belt while I am in there.

Fun times...