Injector Pop Testing Question (Video) - PeachParts Mercedes-Benz Forum

300SD90 · #1 03-25-2014, 07:43 PM

Hey all,

I finally got around to building my injector pop tester. I may be using it wrong, so any input would be appreciated! The injector seems to begin "popping" around 400 PSI or so, and loses its pressure.

http://youtu.be/hq5H-C-g8Bs

Thanks!

tangofox007 · #2 03-25-2014, 07:59 PM

For one thing, a liquid-filled gauge is not the best option for pressure testing. Its response time is too slow.

300SD90 · #3 03-25-2014, 11:51 PM

Quote:

Originally Posted by tangofox007

For one thing, a liquid-filled gauge is not the best option for pressure testing. Its response time is too slow.

I was told to only use the glycerin filled gauge. My spray pattern looks good but the pressures seem off. I may give a non-liquid filled gauge a try also.

Anyone else have experience with pop testing?

mach4 · #4 03-26-2014, 01:25 AM

Quote:

Originally Posted by 300SD90

I was told to only use the glycerin filled gauge. My spray pattern looks good but the pressures seem off. I may give a non-liquid filled gauge a try also.

Anyone else have experience with pop testing?

I use a glycerine filled gauge. It just dampens the response a bit so you get a more representative reading.

From what I can see it appears to be working as expected. Your popping is more pronounced than what I get, but I think that's just higher flow with yours. Are you popping injectors with new nozzles or just checking your existing injectors as they came out of the car? What are your readings across all injectors?

tangofox007 · #5 03-26-2014, 08:32 AM

Quote:

Originally Posted by mach4

I use a glycerine filled gauge. It just dampens the response a bit so you get a more representative reading.

Not sure what, exactly, is being "represented." Except that it's not reality.

I suspect that you won't find a professional injector tester that uses a damped pressure gauge.

Quote:

Originally Posted by ah-kay

Cannot see anything wrong with liquid-filled gauges.

Can you show me a single, professional-grade injector tester that utilizes a damped gauge? Bosch? Bacharach?

ah-kay · #6 03-26-2014, 11:01 AM

Quote:

Originally Posted by tangofox007

Can you show me a single, professional-grade injector tester that utilizes a damped gauge? Bosch? Bacharach?

Here we go again. It is wasting my time to response. I thought you are far better poster after a long period of hiatus.

mach4 · #7 03-26-2014, 11:56 AM

Quote:

Originally Posted by tangofox007

Can you show me a single, professional-grade injector tester that utilizes a damped gauge? Bosch? Bacharach?

Last time I checked this was a DIY-focused forum. If we all had access to professional-grade tools and instruments, we'd probably be in the business and have access to professional-grade documentation...though I'd argue that the forums are likely even better in many respects.

Regarding pop testers, if I felt I needed accuracy to +/- 1 psi on a pop tester, I'd buy a $5000 digital unit with integral printer, 16" screen and a .5 micron filter assembly and automatic popping and digital recording of each pop in super slo-mo, rather than building one. I can live with a lot less accuracy and bells and whistles and only have $21.47 invested...and you know what? The car runs perfectly, and has for the last 30k miles since I last popped my injectors.

I kind of like my HF tools, too... and my swap meet tools and my Craigs List equipment. And I kind of like making my own tools and solving problems without investing a fortune.

If you want a dry gauge, go for it...

ah-kay · #8 03-26-2014, 01:59 AM

Quote:

Originally Posted by 300SD90

Hey all,

I finally got around to building my injector pop tester. I may be using it wrong, so any input would be appreciated! The injector seems to begin "popping" around 400 PSI or so, and loses its pressure.

W126 Injector Pop Testing - YouTube

Thanks!

I did not watch the video but 400psi is too low. Turbo injector opens at 135 bar or 1958psi. Non turbo at 115bar or 1667psi. They are way off or you read it wrong. Cannot see anything wrong with liquid-filled gauges.

yvairguy · #9 03-26-2014, 04:16 AM

I thought you might have meant it was 400 psi low until i watched the video and saw it chatter around 400.

How was the car running? and did you check your 0 to 60 before you pulled them?

vstech · #10 03-26-2014, 12:35 PM

your popping appears to be around 135 bar... I don't know where you are seeing 400psi pop... it's over 1500psi... hard to tell exactly, as the needle is very slow to respond, but it's certainly not 400 psi...

eatont9999 · #11 03-26-2014, 12:36 PM

This little unit has a liquid filled gauge:

Caterpillar Cat 1U6661 Pop Injector Tester w Cart Used | eBay

mach4 · #12 03-26-2014, 04:19 PM

Quote:

Originally Posted by eatont9999

This little unit has a liquid filled gauge:

Caterpillar Cat 1U6661 Pop Injector Tester w Cart Used | eBay

You make a great point!

For future reference, once the eBay ad expires...

vstech · #13 03-26-2014, 12:42 PM

also, the liquid level in the gauge makes it hard to read the pop pressure... but it's sitting stable around 1000 psi... it only pops as you pump it over 1500...

300SD90 · #14 03-26-2014, 05:05 PM

If you think using a liquid gauge is not beneficial, just try using a gauge without liquid and let us know what you find. From my understanding the gauge will break, but that's not what this thread is about. There's a guy who has been very helpful that has very good YouTube videos on pop testing and cleaning injectors for the OM617. He told me that my pressure seems to continue to rise even after I've stopped pumping, and he thinks it's a result of going from 1/4" fittings up to 3/8" fittings. I ordered the right fittings and will hopefully have an update tomorrow.

The gauge does seem to be delayed because from what I can see the injectors begin chattering at 400 PSI. Hopefully this is due to the fitting sizes and not a faulty gauge.

mach4 · #15 03-26-2014, 05:33 PM

Quote:

Originally Posted by 300SD90

There's a guy who has been very helpful that has very good YouTube videos on pop testing and cleaning injectors for the OM617. He told me that my pressure seems to continue to rise even after I've stopped pumping, and he thinks it's a result of going from 1/4" fittings up to 3/8" fittings. I ordered the right fittings and will hopefully have an update tomorrow.

Fitting size will have absolutely no effect on pressure. Liquids are non-compressible so the pressure will be the same regardless the line (or fitting) size. If you check the orifice size on the gauge it is going to be a lot smaller than 1/4". If it were to have an effect, you would need to order a gauge with the inlet size the same as the line size (or tank size, if you were checking the pressure of a tank).

Line size does have an effect on flow rates, but I can assure you that the orifice on the nozzle is much, much smaller than the line size going to the injector.