Backflushing CIS injectors

[PcarPhil]

JFairman,

Thank you for posting this procedure. While I went ahead and ordered new injectors for my current round of maintenance I do plan to clean my clean my existing injectors and keep as spares or offer them to those that may need spares/replacements for their own cars.

Keep up the good work. You're a great asset to the 930 community!

[DSPTurtle]

Quote de JFairman

I posted a picture of me doing it... you need glasses or open your mind

No, I'm referring to trying to open new injectors with a can of carb cleaner.

I have tried to backflush old injectors but the risk/reward wasn't there for me. When I'm at WOT I don't want any nagging thoughts of a burned piston creeping into my consciousnesses but to each his own.......The biggest advances in engine emissions and performance have occured due to improvements in fuel delivery and atomization. From carburetors to EFI to direct inject, fuel atomization is the thing that delivers power and economy. Since most of us are running at enhanced boost levels the margin for error in proper fuelling is smaller than a stock configuration. I see new injectors as cheap insurance vs any engine damage that could occur.

Tippy, since you think I'm a checkbook mechanic, your welcome to come to Detroit this weekend and assist me with the installation of my engine/transmission.

Pretty sure no one here would offer too much assistance to you right now. A guy tries to post some helpful info and you dog him for it. That's not what this forum is about.

[Ronnie's.930]

Originally Posted by DSPTurtle

Pretty sure no one here would offer too much assistance to you right now. A guy tries to post some helpful info and you dog him for it. That's not what this forum is about.

I didn't see any dogging going on - one guy has an idea on cleaning injectors and another thinks it doesn't work - a simple differing of opinions based on the personal experiences of both members. I would call a discussion like that very useful to any tech forum.

And no offence to Jim, but even an experienced injector shop like Witch Hunter Performance, says that CIS injectors are non-serviceable and should be replaced if not flowing properly. http://www.witchhunter.com/injectotype1.php

[RarlyL8]

"Serviceable" is a reative term with varying degrees of difficulty and completeness associated. For the average enthusiasts these fuel injectors are not serviceable. For someone with Jim's skills, they are. If serviceable implies rebuildable, they are not.
The most important aspect is to properly test them when complete and to test periodically going forward. They may function within specs for a time, but typically not as new and not for as long. It is a tool that should give improvement and buy some time before plunking down several hundred bucks for a new set.

[Ronnie's.930]

"Serviceable" was my term, not one used on the WH write-up on CIS injectors. Specifically they say that the CIS injectors do not clean well since they have non-removable filters, can not be back flushed, and should be replaced if not performing well. I know they used to clean CIS injectors, but stopped some time back, presumably due to poor results. It would be interesting to find out if they did the "hold the pintels open" bit that Jim demonstrated and/or what they mean by "can't be back flushed" since obviously, Jim and others have indeed back flushed them.

[911nut]

Brian, if the injectors are serviceable, can you direct me to a factory procedure for backflushing injectors?

[mark houghton]

This has been an interesting read, and I would concur with Ronnie's comment:
"I didn't see any dogging going on - one guy has an idea on cleaning injectors and another thinks it doesn't work - a simple differing of opinions based on the personal experiences of both members. I would call a discussion like that very useful to any tech forum."
I did the backflush thing as Jim described several years ago with pretty good success but for one injector that just wouldn't spray quite right. Pretty simple, pretty effective overall even if it doesn't bring the spray pattern completely back to new.

Just thinking out loud now; I wonder if a person could hook up a vacuum pump to the pintle end and in so doing pull sufficient vacuum to open up the pintle....then suck the cleaner of your choice through the injector? And I wonder if it wouldn't be worth the effort to disassemble the injectors (IF that can be done) and remove that damn screen all together (the thought being that modern fuel filters should remove any contaminants before the fuel ever gets to the injectors)?

[jsveb]

Originally Posted by JFairman

Another thing I just thought of... I'm basically at sea level a mile west of the Atlantic Ocean in South Florida so the differential pressure between whats in an aerosol can of brake clean or carb cleaner and atmospheric pressure is as high as possible...

Good write up!

Just to mess with you...

Let us say there is 3bar of pressure in the aerosol can. At sea level there is close to 1bar of atmospheric pressure. The guy doing the same thing with the same 3bar pressure can in Leadville in the Rockies sitting at about 11,000 feet above sea level. Considering the atmospheric pressure is half of sea level pressure at 18,000 feet (0.5bar) we can make a SWAG and say the pressure at 11,000 feet is close to 6.33bar. The conclusion of this would be that the guy at Leadville has got a delta pressure of about 2.4 whereas you have a pressure delta of only 2.0 bar.
In other words. he is better off regarding pressure delta than you in Florida.

[RarlyL8]

The factory has no interest in servicing injectors for many reasons. This is strictly an enthusiasts endeavor.

[jeos]

I bought 6 new and have never regretted the engine runs like a dream

[jjeffries]

Would an ultrasonic cleaner do anything for these injectors? I admit to having no real knowledge of how such cleaners work. John

[DSPTurtle]

I tried the ultrasonic deal and didn't notice any difference. Could have been the fact that it was a cheapie ultrasonic cleaner my wife bought to clean her jewelry. Shh... Don't tell her.

[Tippy]

Hit the wrong frequency and there will be no injectors in the ultrasonic cleaner.

That's a good question though!

[gsxrken]

I also did the same thing a few years ago, to a tee. I also used my air compressor and blasted techron through the way they normally operate to see the circle pattern.
I can get Brian's point about not bothering to do it anymore due to mixed results. If you're selling something, the end user doesn't want mixed results. If you're doing it in your garage, and you get a bunch of crap out of them like I did, you feel better about it. But the results may or may not be worth paying for. I wouldn't want to go through it all, making what's probably a pretty small margin, and then have to back them up with my reputation. With 100k on what I'm sure are the originals, I'm glad I did it.

[911nut]

Originally Posted by RarlyL8

The factory has no interest in servicing injectors for many reasons. This is strictly an enthusiasts endeavor.

Could one of those reasons be that they consider injectors to be subject to wear, especially since many of the cars that use them are getting rather elderly?

[Robbbyg]

I think Back flushing shouldn't be done due to the design of the filters inside
i believe you should flush in the same direction until they're clean
If they don't come good that way then replace

[Tippy]

It's standard procedure to backflush filters. Going in the direction of flow only lodges the debris in.

[Robbbyg]

Originally Posted by Tippy

It's standard procedure to backflush filters. Going in the direction of flow only lodges the debris in.

Darn now for the FIFTH time this month ive got to take mine out again

[spuggy]

Originally Posted by jjeffries

Would an ultrasonic cleaner do anything for these injectors? I admit to having no real knowledge of how such cleaners work. John

I cleaned two sets of euro 930 injectors, wired the pintles open, soaked them in concentrated Techron for a week or two.

Then I ran them for two weeks in a relatively high-power hobby ultrasonic cleaner with a heated tank ($70 from Amazon), and a teaspoon of dish soap as surfectant. (Without surfectant, the cavitation doesn't work, heat makes a big difference to effectiveness too)

I'd remove them every day or so, change the solution (usually when it got so dark I couldn't see what was going on anymore, or when cavitation bubbles stopped forming in the solution), backflush with brake cleaner and put them back in.

Took them to my wrench, told them to discard any they wouldn't put in their own motor.

They have a Bosch CIS tester on the bench. They said the crack pressures were all fine - but they discarded two for bad spray pattern.

The injectors were amazingly clean. Eventually. It's not that fast a process - an industrial cleaner would probably work much better.

But even so, stains that looked like rust turned out to be decades-old baked-on fuel varnish or something - and lifted off. Slowly. You could sometimes see little black particles drifting out of the pintle or the thread. The solution ended up filthy quite quickly at first, then slowed down after the first week, then it seemed to be diminishing returns - I gave up after I didn't really see much different for 3-4 days, which was about two weeks of just running it all the time.

I'd say it can't hurt.

[Tippy]

There's scientific data that needs to be applied in ultrasonic. More transducers equals more power. Too much, and it'll blow the injectors into bits if you reach the right frequency and amplitude.

Worked with this a little in aviation and it was a serious topic due to the ability to destroy or weaken parts.

I suspect the household ultrasonic units you guys used were simply too weak to work effective.