Ford Injector Relative Flow Test

Just got my Modis updated from 15.4 to 16.4 recently, and I noticed a new option in the Functional Tests menu for an '08 Escape:



Sweet! :woohoo: I'm excited because the injector balance test has been an exclusive Ford IDS test for a long time. Does it work? Let's try it.

After some instructions about not flooding the engine, you end up at the first series of tests:



A built-in leak down test? Not why we're here, but handy. Next screen.



I can hear the fuel pump cycling through all six injectors during this time. Different from the GM injector test, where you manually run each injector step-by-step. Finally, we arrive here:



Soooooo, the results are in milliseconds? :huh: Wasn't expecting that. :lol:

No known running issues on this engine, so I'm figuring a 2ms spread from low to high is a good range, but what are we actually measuring here? Looked through the Ford service manual and Mitchell, no answers. I'm guessing that the 70-ish milliseconds is the amount of injector firing time it takes to get from rest pressure to some specified lower value. It's tough to know what exactly the strategy is here without having a fuel pressure gauge on the rail OR another scanner looking at the fuel rail pressure sensor during the test. I'm welcome to any information or theories you might have!

Anyway, keep your eyes open for this test on Ford Electronic Returnless systems! I'm all about doing all the testing I can from the drivers seat.

I saw this the other day as well, I ran the test and wasn't expecting the ms results, I wanted to use the fuel rail pressure sensor voltage reading to try to compare the reading but didn't have the time. Next time I get some one of these in I will try to do some experimenting

Ro-longo wrote: I saw this the other day as well, I ran the test and wasn't expecting the ms results, I wanted to use the fuel rail pressure sensor voltage reading to try to compare the reading but didn't have the time. Next time I get some one of these in I will try to do some experimenting

Let us know if you get the chance! I know the results of this test look different on the IDS. More like this:



It looks like there's a 'range' there, but it doesn't specify the minimum or maximum.

Also, have you tried using the Relative Compression Test? I attempted it with two different Modis scanners, both popped up 'No Communication' when attempted on my Escape.

I have not tried the relative compression test either. Seems like I never have enough time when I see something I want to experiment with. As far as the Injector flow test, I would have to calculate the voltage to pressure values in order to know what I am looking at.

I have tried the relative compression test and it didn't work, tried it on the ford transit with the bad valve spring if I remember right. I could tell there was a misfire the difference between the the cylinder was only 5%. and the relative injector flow test I have not used it. its very spotty coverage its only available on a few model years though. why does snap on advertise they have new tests then there spotty as heck, like when ford pats came out in 15.4 barely any coverage then another update there were additions

cheryl hartkorn wrote: its very spotty coverage its only available on a few model years though. why does snap on advertise they have new tests then there spotty as heck, like when ford pats came out in 15.4 barely any coverage then another update there were additions

Just got upgraded to 17.2 today, and it looks like this Relative Compression is now working on my Ford. :silly: Cheryl called it.

First, you're given a crash course in how the test works:



Of course, it also wants you to be in Park (duh), with a sufficiently charged battery (makes sense), and have the parking brake on (who cares?). This screen checks to make sure you're playing by the rules:



You're then asked to crank the engine for 10 seconds straight. After it tells you to stop, you get some results:



And just to see how repeatable this is, I ran it again:



Not exact science, but good enough!

Played with these tests some more today. Mostly wanted to see if the Relative Compression was accurate or not, and how it'd behave with a actual compression problem. Pulled the #4 plug first, and ran the test:



ID'd the cylinder correctly, but 40%? :huh: Kinda surprised at that. Just for giggles, I put #4 back and pull the #6 plug instead.



Now it's 20%? That's pretty optimistic! :lol: I was initially excited about this test, but now I'm not so sure it'll be able to pick up smaller compression losses.

Sure doesn't seem to a accurate... I assume this is done from the crank sensor and or cam sensor speed up rather than cranking voltage

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Ben wrote: Sure doesn't seem to a accurate... I assume this is done from the crank sensor and or cam sensor speed up rather than cranking voltage

Correct! All based on the crank and cam sensors.

I guess this test needs some scale adjustment? 20-40% = zero compression. 10% might be a leaking valve?

It doesn't seem sensitive enough I would guess a 20 psi difference would only show up as 2-5 %

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