Rock Auto Fuel injectors - a cautionary tale!

[SBFJ60FIG]

FYI all, I'd avoid buying 'rebuilt' fuel injectors from Rock-why you ask?

Let's just say when someone I know (maybe me??) put a set into my LX, one failed, first intermittently, then totally.

And when I say failed, I mean the solenoid just plum stopped working, so yes, dead cylinder...#5 in my case.

When did I find out? Oh, around dusk in mid-December while towing my 29' enclosed trailer in the middle of Nebraska...super fun to diagnose a misfire in a truck-stop parking lot and then by total luck, and or good planning on my part, have all the tools AND a spare injector with me! ! !

That was a pretty bad day for me...

 

[Tools R Us]

Have seen a few recently cleaned/refurbished injectors die, from a variety of sources. This combined with the before/after reports showing it wasn't needed, has resulted us no longer doing them for fun. The cleaning process looks to be pretty noninvasive, don't see how it would cause them to die, but enough have died to be highly suspicious.

 

[george_tlc]

Fuel injectors should not be run 100% duty cycle. I wonder if the 'testers' keep the injectors on for too long causing damage to the windings of the solenoid - leading to internal shorts that later lead to injectors going open circuit.

I had one factory OEM injector go open circuit (well, 20k - 30k ohms versus good at ~13 ohms) a few yrs back (#6), replaced with a new OEM. I did a core swap to get a replacement as a spare. Would have been interesting to have cut it open to determine the cause of the open circuit.

cheers,
george.

 

[Jgunner]

Fuel injectors should not be run 100% duty cycle. I wonder if the 'testers' keep the injectors on for too long causing damage to the windings of the solenoid - leading to internal shorts that later lead to injectors going open circuit.

I had one factory OEM injector go open circuit (well, 20k - 30k ohms versus good at ~13 ohms) a few yrs back (#6), replaced with a new OEM. I did a core swap to get a replacement as a spare. Would have been interesting to have cut it open to determine the cause of the open circuit.

cheers,
george.

Ive known guys running 125-135% duty cycle on gmc syclones. Don’t ask me how OR if it was a good idea, but he does own the world record fastest stock syclone. I dont even know how it can go above 100%, but he wasn’t the only one to do it.

 

[george_tlc]

^ well, in electronics we define 100% duty cycle be on continuously. 0% being off continuously.

Maybe 'their' idea of 125 - 135% is relative to the OEM maximum 'on' time...

cheers,
george.

 

[White Stripe]

Reman fuel injectors are a joke in my opinion. The take a fuel injector used I'm guessing that has many thousands of miles on it, then they clean it and install new orings but the solenoid-the most vital part in my opinion is untouched. Then they resell them. So it seems like your just installing some very used but clean with new orings injectors.

 

[SBFJ60FIG]

Fuel injectors should not be run 100% duty cycle. I wonder if the 'testers' keep the injectors on for too long causing damage to the windings of the solenoid - leading to internal shorts that later lead to injectors going open circuit.

I had one factory OEM injector go open circuit (well, 20k - 30k ohms versus good at ~13 ohms) a few yrs back (#6), replaced with a new OEM. I did a core swap to get a replacement as a spare. Would have been interesting to have cut it open to determine the cause of the open circuit.

cheers,
george.

I still have the faulty injector somewhere - I too am curious as to what happened there - I'd be curious to cut it open and see what happened????

 

[Jgunner]

^ well, in electronics we define 100% duty cycle be on continuously. 0% being off continuously.

Maybe 'their' idea of 125 - 135% is relative to the OEM maximum 'on' time...

cheers,
george.

They are batch fire systems. Im not sure what he meant or maybe I misunderstood, but several people were doing it. Wish I understood it, to explain, but I don’t. Ill try to look it up.

 

[scottryana]

Well an injector is measured a little differently than most electronics. 100% duty cycle does not mean that the injector is open 100% of the time. It is a calculation based on how much time the injector has to spray based on how long the intake stroke is. So the higher the RPMs the less time the injector has to actually spray fuel. Lets say at 6000rpms that is about 20 milliseconds, so 100% IDC is if the injector pulse width was the full 20ms. If the injector pulse width is 21ms it is 21/20 = 105% duty cycle. The guys running higher than 100% IDC start opening the injectors spraying fuel into the intake runner before the intake port has started to open.

 

[george_tlc]

^ I understand what you are describing.

I suppose calling it IDC (which I assume you mean Injection Duty Cycle) is ok since it makes it clear that it is different from just duty cycle.

Anyhow, semantics

And, energizing an injector continuously is not a good idea.

cheers,
george.