Well, the MAF has not yet been replaced...going to do that this evening. We'll see. I'll post a screen image of new MAF and let you guys know the FT's. Hoping we are at end of the road, because I really am at my wits end!
'04 Ford 3.9 MAF Sensor
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Okay.....MAF didn't work. Short Term Bk 1 is around 0 all time...short term bk 2 is +3 to -5... long term bk 1 is +20, and long term bk 2 is -6... get on throttle no load and both long terms go to 0%..but then short term bk 1 goes to +20%..WTF. NO Vacuum leaks... All 6 injectors look good on scope... that doesn't mean i don't have a dirty one or two on bk 1. 02's look ok for 140K engine. Won't bug you guys anymore after this...just gotta vent"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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So we haven't spent much time on this thing lately, but buddy complained of misfire the other night. Seen 1 and 6 dipping out on Cylinder Contribution Test. Also, scoped the fuel pump. I am aware this has a Fuel Pump Driver Module, but one thing I've always had a question about these modules is: Do you still get a normal waveform from the Current Ramp test, or does the module cause the waveform to be all jacked up? One trainer I had mentioned something about the Ford's and the FPDM's or GEM modules. Here's a screenshot. I'm only seeing about 2.5-3.0 Amps KOER at idle.
And for some reason, I can't get a good upload from SSC of this saved frame off my Modis. Should have saved a JPEG of this, but still trying to upload from SSC to this forum. Any hints?Attached Files"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Here is a previous post I made on testing variable speed fuel pumps.. http://productforum.autorepairdata.c...ead.php?t=5652 Typically you should be able to view actual and desired fuel pressure and a code should set if the pressure is not where it should be.Comment
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Modis500, sorry I am a little late getting back to this thread.
In your MAF captures, notice how that spike in one capture goes BELOW 0V. That's a pretty good indicator that you are picking up some noise in the signal. Having the scope leads a little too close to the ignition coils, wires, etc, may cause this, especially when you are using unshielded leads. It could also be a problem with the scope ground. Also, i noticed that the sweep in your capture was set to 5 seconds. Next time you scope a MAF, set the sweep a little lower, I generally like mine around 100 mS for MAF captures. This will give you greater detail and clarity, and you can always zoom out to see the bigger picture after you get the capture
As far as the noise in the signal, after a lit of practice you will eventually learn to pick out noise from signal problems. If you had taken the capture with your sweep set lower, you could have seen how long that glitch had occurred. If it exists over the course of several miliseconds, it might be a signal glitch. On the other hand, if you are zoomed in close and it is still a skinny line that is basically unmeasurable as far as time goes, it's probably just noise.Comment
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Thanks for the heads up. Since I originally opened this thread, and all the help of you gentlemen, I've learned quite a bit about MAF testing. I've even gone so far to take snapshots of known-good MAF's on some Fords and Toyotas. Keep them for reference. As far as the Freestar goes, we've narrowed it down to a fuel delivery problem. Still have the 171 code. But noticed fuel trims go way up when engine needs it most. Customer out of $$, so we'll have to wait"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Okay, so we finally got this thing out on the highway tonight and got some steady cruising speeds snapshots and heavy load acceleration snapshots following all 4 lines of Fuel Trims. Here's what we're seeing after doing some 65 MPH steady cruising and then accelerating hard. ShortTerm 1 and ShortTerm2 are both around +3 to -4 or close to that at cruise, however LongTerm 1 is at +25, and LongTerm2 is around +2 or so. We then accelerate up to 75 and notice our ShortTerms both go to +17, but LongTerm1 drops to only +1, which was steady +25 at Cruise. Long Term2 stays around +2 to +4, so no increase there. I'm seeing the PCM is doing the fuel adjusting thru ShortTerm (Duh), but why in the world is LongTerm1 going in the basement under hard acceleration, when LongTerm2 is nice and steady all the time?? (Just for the guys that haven't been following this thread, we have 150K on this, recent lower and upper intake repairs and a new MAF, and still getting the 171) I've thought long and hard on this, and I'm not completely clueless, but sometimes I feel better suited to stick with carburetors!!"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Fixed!
Alright, well we finally have an answer guys, and its a couple bad flowing injectors on Bank 1. We had an inkling, and since I can't do Injector Balance with the Modis (Is this going to be available in Functional Tests soon?) We had Ford look at it, and they found 1 and 5 flowing very little fuel. So toss some injectors at it, and be on her way. Thanks for all the help guys, I know this isn't Ask-A-Tech, or Identifix. We now have one happy neighbor who brought over cigars to say thanks"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Alright, well we finally have an answer guys, and its a couple bad flowing injectors on Bank 1. We had an inkling, and since I can't do Injector Balance with the Modis (Is this going to be available in Functional Tests soon?) We had Ford look at it, and they found 1 and 5 flowing very little fuel. So toss some injectors at it, and be on her way. Thanks for all the help guys, I know this isn't Ask-A-Tech, or Identifix. We now have one happy neighbor who brought over cigars to say thanks
If you want to get really technical you can also hook up a DVOM and or your scope low amps probe and check the injector electrically for an added insight into how the injector is performing but nothing beats pulling the rail out, hooking up the injector pulse machine and visually seeing the QUALITY of the injector spray pattern where it ATOMIZES the fuel. Gaps, blobs and straight streams indicate a poor atomization pattern that can create all kind of problems. Quite often you can see 3 or 4 or 5 that are fine and the others are blatantly obvious that they are failing visually.
Wrecking yards for injector pigtails makes this old tool new again. Might not be the fastest method but it IS definitive. Some of the new injectors have pins that are the size of sewing needles and are almost impossible to jumper into.Comment
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Here's the OLD FASHIONED tool. It even works on lots of 2009 M/Y vehicles.
It won't work on the 65-volt pull up direct injection injectors but they seem to be only in some fairly new vehicles and for those most of the scan tools can energize them through the ECM/PCMAttached Files- Pics JUN-14-13 Fuel Injector Pulse Tester MT290 001.jpg (110.6 KB, 95 views)
- Pics JUN-14-13 Fuel Injector Pulse Tester MT290 002.jpg (103.8 KB, 95 views)
- Pics JUN-14-13 Fuel Injector Pulse Tester MT290 003.jpg (113.6 KB, 94 views)
- Pics JUN-14-13 Fuel Injector Pulse Tester MT290 007.jpg (111.6 KB, 94 views)
- Pics JUN-14-13 Fuel Injector Pulse Tester MT290 008.jpg (86.9 KB, 94 views)
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Crusty,
So this little tool will actually pulse the injector? you gotta hook this up to battery - and + and then the injector i'm guessing. used a similar tool by OTC way back in tech school, was very easy to test injectors. Was always wondering if these things were still around, and now since you've showed me this one, I've got a bid on ebay right now. Hope to use one soon, will email you for more advice when I get it shipped home."If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Crusty,
So this little tool will actually pulse the injector? you gotta hook this up to battery - and + and then the injector i'm guessing. used a similar tool by OTC way back in tech school, was very easy to test injectors. Was always wondering if these things were still around, and now since you've showed me this one, I've got a bid on ebay right now. Hope to use one soon, will email you for more advice when I get it shipped home.
Look up a 2004 GMC K1500 with a 5.3-T engine in your service information.
Find the Injector Balance Test and you'll find TWO. One where the TechII performs the command to turn on the injector for a measured length of time (which proves out the driver circuits in the ECM) and the manual test using a similar tool to the MT290. These kind of tools BTW have been around since the early 1980's.
With a decent fuel pressure guage you can check for fuel delivery volumes being equal to each injector. The variable allowed was only 1.5-PSI. They now are specing injector tolerances of up to 3-PSI which I think is too much and they also average the injector drops now which throws another curve at balancing each cylinder's power output. It is important that they all be very very close to each other.
Nothing beats doing the test manually with the rail held up in the air (safely spraying into a container) and visually looking at the QUALITY of the fuel spray and the ATOMIZATION of the fuel. Injectors can become clogged at the inlet screen which is the usual cause for a flow (balance) variation, which will affect the quality of the spray, and also internally which will also cause a poor quality of spray yet still have a balanced fuel volume (pressure drop)
There are quite literally weeks of reading regarding just injectors if you go back to the early days of electronic injectors circa the late 1970's.
Apparently Botch bought the patent rights for electronic fuel injectors from Delco back around 1955 when the 'Vettes had their mechanical fuel injection.
On a historical note, the WWII Spits & Hurricanes were carbureted and the MEsserschmitt BF-109 was fuel injected. The BF-109 could nose down and dive where the Spits and Hurri's had to ROLL and dive because the fuel would not stay down in the float bowl of the Carbs and cause a fuel starvation problem.
I'm sure there were lots of race cars in the 20's and 30's that used fuel injection of some kind too. The principles of operation ATOMIZING the fuel havn't changed much, just the tolerances & methods of control have evolved.
Air & Fuel.....basics.Comment
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Crusty,
Finally got to use the MT290 today. Wondering why I didn't have one of these 10 years ago. Used it on a VW 1.8T today, found all 4 good, pinpointed it to a coil harness that was burnt. Just wanted to pass this along, that simply because a tool is years old, they can still be quite useful. Yes, these scan tools do so much more than they used to, but it's still on us to interpret the data and info properly, and when we're confused about that, go back to the hands-on approach that "shows" you what the component is doing. Any other old tools you want to recommend that are still quite relevant in todays world?"If you aim for nothing, you'll hit it every time!"
Zig ZiglarComment
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Crusty,
Finally got to use the MT290 today. Wondering why I didn't have one of these 10 years ago. Used it on a VW 1.8T today, found all 4 good, pinpointed it to a coil harness that was burnt. Just wanted to pass this along, that simply because a tool is years old, they can still be quite useful. Yes, these scan tools do so much more than they used to, but it's still on us to interpret the data and info properly, and when we're confused about that, go back to the hands-on approach that "shows" you what the component is doing. Any other old tools you want to recommend that are still quite relevant in todays world?
Silver bullets simply do not exist. The automated equipment won't wave a magic wand for us either. Check, Test, confirm, deny, check again in logical sequences so something simple doesn't get overlooked. Other than an accurate complete schematic and a sound understanding of the system(s) being tested, a good DVOM and sometimes the old fashioned test light, I can't think of any other "old tools" right now. It all depends on what vehicle and what system we're approaching.Comment
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