Fuel injector replacement

I couldn't see anything coming out. But I will take your word for it.

 

Yeah, it was harder to see in that vid. probably camera position. If you watch it on full screen on a big monitor it’s more visible. The first couple pulses are easier to see as well.


-Spiral

 

I went full screen on my 15 inch MBPro, and slowed the video down to .5.
Then I could see it, barely. A darker background and it would have been easy to see.
Looked clear to me though.

 

The point isn't the current it draws though. These things are engineered, meaning somebody did calculations around how much V²/R heating takes place during each injection pulse, and made sure that much heat can be carried away (by conduction, convection, radiation from the injector, and by the fuel flowing through it) before the next pulse, with the peak temperature attained in that process being within what the device can stand. Keeping them compact and cheap is among the objectives, so they're not super-over-engineered for being operated in ways that weren't assumed in the calculations.

Similar cautions apply to other small solenoid valves in similar applications, like the ones in the brake actuator.

Rich's suggestion is a good way of dialing back the damage risk, because backing voltage from 12 to 9 (a 25% reduction) is a 44% reduction in heating (because of that ² in V²/R). If a task calls for getting the thing to open enough to pass some fluid through, and some voltage lower than 12 is enough to do the task, it helps with the safety margin.

Maybe a literal 9 volts can be too low. Looking back, I remember I was using an "Imedion" rechargeable 9 volt. Most rechargeable "9 volt" batteries have an even lower output voltage than a plain-Jane 9 volt, because they are just built by swapping NiMH (at 1.2 volts each) for the six 1.5 V cells in the plain-Jane one, and end up with 7.2. Imedion shoehorns two more cells in, ending up at 9.6. (I don't know if anybody out there splits the difference and sells a seven-cell, 8.4 volt "9 volt".)

 

Usually it's 8.4v. A 1.5 v battery is 1.25v
I don't remember exactly how it was explained but simply a "device" that calls for 9 volts
needs a constant 8.? volts, can't remember if it's 1,2, or 3. And a rechargeable battery holds
a constants voltage, then dies. A none rechargeable will slowly loose voltage.

I don't know all the math and science to it, and it doesn't matter to me, as long as it works!

 

The 'it' has to be specified, because different battery chemistries produce different voltages. The super-familiar alkaline cell's nominal voltage is 1.5, which a spanking-fresh one can exceed a bit when under no load. A standard alkaline "9 volt" is a little stack of six of those, so its voltage is 1.5 ✕ 6, or 9 volts, to no one's great surprise.

Both NiMH and, earlier, NiCd have slightly lower nominal cell voltages, both 1.2 volts. Early rechargeable versions of the "9 volt" still stacked only 6 cells, so the voltage was way lower than an alkaline 9 volt, down at 7.2. It would run some devices but not others, Back in the NiCd days, apparently "some manufacturers such as Varta" made seven-cell stacks, getting closer to the 9 volt target by adding up to 8.4.

That seven-cell, 8.4 volt stack may be the most common flavor of NiMH "9 volt" these days, while also some, like Imedion, cram in an eighth 1.2 V cell so they end up at 9.6.

 

I measured a fresh alkaline 9 volt: 9.29 volts.

 

It's just a battery.

 

I sure would like to know about 3rd party injectors as the own are $200 plus per. eBay has reconditioned Denso???

 

Meant oem

 

Originals are super durable and there are services that'll clean and restore yours and give 'em back with certified test results, less money than replacing perfectly good (but dirty) injectors with new OEM, and less risky than replacing perfectly good (but dirty) OEM with something an eBay seller claims to be "reconditioned Denso".

Not sure where you are in LA, but if I remember right, one of those well known injector service outfits is in Torrance.

 

Thank you. Took all the stuff necessary to get to the plugs to change them so of course pulled the injectors out. They looked very clean so I put them back.. your thoughts?

 

How did you look at the spray pattern?
You can't really go by looks with injectors. Unless you have a microscope to
see the opening. It's the spray pattern that you need to be concerned with.

 

If someone wanted to test fuel injectors, they would connect them to a "test bench" that lets them safely inspect spray pattern and measure flow rates.

Lacking that, I would put the car back together and drive it while using a scantool to monitor fuel trim data. Most any injector problem is going to affect fuel trim. If total trims are near 0 under most driving conditions, injectors are probably just fine.

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If you suspect that an injector is bad, swap it with one of the other ones and see if the symptom switches cylinders.

JeffD

 

What he said. The injectors can be trouble-free for a very long time, and fussing with them might be reserved for when you have some measurable sign of an issue. Watching the fuel trim numbers would make a good measurable sign.

If you have reason to suspect an injector problem, these are the guys I remembered in Torrance who have the exact kind of test bench mr_guy_mann referred to; they can confirm the spray pattern and volume delivery of your injectors for you, and if there's an issue they can fix them.

https://www.rcfuelinjection.com/