OK guys, here's the deal. I've been fighting a pinging and rough Idle problem on my '00 B3000-FFV for a couple years now, with little to no success. To make a long story short, FP is good, no vacuum leaks, ignition perfect... per TSB my computer and coil assembly already have the "updated" part numbers... Cam is timed perfect (Using WDS to overlay cam/crank signals, per another TSB)... EGR working perfect... all monitors are ready and there are no current or pending codes (for some time now) basically I've gone over this thing with a fine-toothed comb.

Since I haven't worked at Ford for over a year now, I no longer have access to the NGS and WDS diagnostic tools, but the shop I work at now recently got a Genisys (OTC) tool... pretty neat setup.. anyways while "demonstrating" to the other guys how to use it, I noticed on my truck it reports the Flex Fuel sensor at 57HZ.

Now the little reference material I have access to only states that "60-90HZ is a 30% ethanol content, 90-120HZ is 60%". Now I haven't run E85 in several months now, and run the tank quite dry (but not empty) a couple times, so just about any trace of E85 should be gone by now.

Gasoline here is 10% ethanol, so I figure the sensor SHOULD be reading roughly 25-35HZ.. but according to the scan tool, I am at 57... Also while both STFT values hover around ZERO, LTFT values are roughly -10, indicating to me that the computer is slightly trying to compensate for what it thinks is a rich fuel mixture, thus leaning it out... which could cause my pinging and rough idle.

Now.. three questions here...


1> Have any of you techs out there run into a case of a "biased" flex fuel sensor that wasn't bad enough to set a code?

2> Do any of you know how to build a "flex sensor simulator".. maybe with a dial that I can install into the flex sensor connector - to output a variable frequency selected by me. It would make a fantastic diagnostic tool!

3> Are my reference values accurate? If not, does anyone have a better chart I can refer to (for Flex-sensor frequency vs. ethanol content).


I understand this may be a little 'overwhelming' to a lot of you guys out there (no offense, just can't think of a better way to put it right now), but I would greatly appreciate any input from you guys. I feel I've learned a lot and contributed a lot on here and I've had a good time doing so! So if you have any comments or ideas, please feel free to share (especially those with more Flex experience than me).. maybe we can all learn a little more about this system in the process!

Thank you

 

I'm neither a Tech nor a Guru, but here's what I have to say anyway.

The flex fuel sensor frequency of 57hz seems to be about right for a 10% ethanol blend fuel mixture, at least according to the chart (#2) referenced in this article:

http://www.babcox.com/editorial/us/us020628.htm

Regarding the "simulator", I've heard the idea kicked around before but nothing has ever become of it, as far as I know. I agree it would be a great thing to be able to both measure and dial-in a set frequency with a handy tool. Some more in-depth info regarding how a flex fuel sensor works can be found in this article:

http://www.megasquirt.info/flexfuel.htm

 

Great links, Rockledge! Yes, according to those charts my flex sensor appears to be accurate.

After re-reading the "Article" on all-data where I read that 60HZ was 30%, i noticed it's talking about METHANOL, not ethanol.. I'm wondering if it's referring to an older Methanol flex setup... <shrug> you never know with All-Data.

Guess it's back to the drawing board with my diagnostics! haha

 

The cure for pinging can be very frustrating in some cases, it sounds like you're working at it from all angles. Good luck.

Rearding the flex fuel sensor, I think you'll agree that the key to developing some sort of diagnostic tool, or even just a simple permanent work-around, lies in figuring out a way to simulate and then control the process itself.
I've been thinking that maybe one of the electronics/EEC wizards around here would be able to solve the problem, but so far it hasn't happened, at least not that I know of.

 

Actually to be honest, I'm thinking the pinging is for the most part normal. 90% of it disappears with midgrade... it's completely gone with premium or E85.

I also have a slight rough idle, but then again every FFV 3.0 ranger I've worked on idled exactly the same way... so I'm not worried about it.

I'm actually wondering if my PCV valve is trying to stick intermittantly... about 15% of the time the truck runs great.. no pinging.. full power.. nice and smooth.. <SHRUG>

I've been playing with this off and on the last few years... and I'm beginning to think the only solution may be to reprogram the ECM with the timing set to "retard"... but I'm afraid of losing a bit of power...

AND I get a consistent 24-26MPG... pretty darn good for a 3.0!

 

Go to www.crutchfield.com and spend about 300 bucks for a nice stero. Then crank it up and try and forget about the pinging.

 

You're probably topped out on power now with the way she's set up and you'll likely not even notice a drop. Getting the pcm custom tuned to massage the spark till the pinging is gone sounds good to me. The fact that the pinging reduces/eliminated by higher octane suggests that she's beyond the limit for spark advance. They may only do it for a certain range anyway, depending on where you hear it happening. Good mpg's by the way!!!

Good luck
Fred

 

I think you'd just need a simple 555 timer circuit like this: http://kitsrus.com/pdf/k111.pdf

I think that the 555 will sink 250mA at 5V. You'd also have to change the "presets" by changing the capacitors so that you had some more likely values for the application (50Hz~150Hz).

-Jim

 

Jim, let us know when you are done with the prototype.

 

Our son is making plans in the final weeks of his junior classes for his senior project next year in EE at Rose-Hulman. Maybe I can float the idea to his team.

Pat

 

Well two good clues here, but I'm not sure I yet know what to make of them.

1- The ping gets better with an octane increase & disappears with premium fuel.

That kinda suggests a timing issue, or maybe combustion chamber carbon deposits.

2- It doesn't ping all the time.

#2 kinda makes me want to add a sensor thats weather sensitive, to the suspect list.

Maybe something thats monitoring relative humidity, or intake air temp, or maybe an acting out or borderline MAF sensor.

Or as you've postulated, maybe an intermittent acting out & sticking open PCV valve, which can be thought of as a controlled/calculated vacuum leak, such that if it sticks open, the air/fuel ratio goes lean.

Kinda difficult to pick one, as all seem plausable, without some more clues.

BTW what brand & heat range spark plugs are you using in your 3.0L flex fuel?????

I remember Bob Ayers fighting a ping problem with his 3.0L, that turned out to be solved with a colder plug. SO, when this ping problem began, had the plugs just been changed?????

Did this ping problem come about after some "event"??????

On Edit: On the PCV thought, seeing as how the air intake, the PCV valve uss to vent the crankcase, is located after the MAF sensor, the PCV valves air flow is already measured by the MAF, so it seems to me the system should be able to compensate fo a stuck open PCV, without it causing the A/F ratio to go lean. Maybe if sticking it could mess up the idle smoothness though.

Just some more things to ponder.

 

OK.. keep in mind there are no codes.. no pending, no current...

The pinging I would assume is based on either a lean running condition or a timing issue. I've owned this truck for 3 1/2 years now and has pinged since the day I bought it. When it DOES ping it starts to do so at about 40% throttle (under load) and gets louder the more gas I give it.

Truck was 1 month out of warranty when I purchased it used with 27,000 miles on it. The dealer I bought it from gave me a rental for 2 days while they sent it to Mazda who said they could find nothing wrong. After I got it back I replaced the plugs and wires (Both Motorcraft O/E equivalents, sorry can't remember part #'s) and got reimbursed for the parts. I also did an Induction cleaning and fuel filter at this time.

At 32,000 miles I got a P0401 which was promptly corrected with a new DPFE (Motorcraft).

At 45,000 miles it started cutting out above 3,000 RPM (like a rev limiter) and the check engine light came on. I pulled a cam sensor code and upon instection found out the hold down bolt for the synchro had come loose, and the entire assembly had rotated itself as far as it could. This is when I re-timed it using overlaid cam/crank waveforms on the Ford WDS tool. I never did replace the synchro nor the sensor, and have had no problems with either since.

At about 52,000 I replaced the IAC to repair an intermittent stalling at idle condition.
I very recently performed another induction cleaning, and I've had the EGR valve off just to make sure there's no blockage, and I've wasted about 4 cans of carb cleaner trying to find a possible vacuum leak, both cold and hot.

I now have just over 60,000. During all this time, I haven't put this as a 'high priority' thing.. just checking this and checking that when convenient... actually I've been waiting for it to get worse so I could actually find it.. but it continually refuses to do so. I know I have checked fuel pressure, cleaned and tested MAF... CTS... Air Intake Temp sensor... DPFE... basically everything electronic and the only thing that even remotely sticks out is my -10 LTFT on both banks.

I know -10 is perfectly acceptable, but I also know how touchy these engines are to pinging and the like. I figure either it's running a tad rich, and it is compensating... OR it THINKS it's running a tad rich and in actually making it a tad lean in the process.

O2 sensors switch like crazy and STFT's hover close to zero. Sometimes I get a bit of a sulfur smell from the converters (same smell a rich running car emits), but it's not consistent.

Now that my flex sensor theory is out the window, I'm considering pulling the injectors and soaking them overnight in C.L.R. or something... I'm wondering if I have a bad spray pattern in one or two. Really the only thing I can think of that can cause it to run "rich and lean" at the same time. While I'm in there I'll put on a new plenum gasket and a new PCV valve. Probably pull the plugs and see if any look different.

I should add, like I said about 20% of the time it runs absolutely fantastic! There seems to be no rhyme or reason to it... doesn't matter if humid or dry.. cold or hot.. empty or full gas tank.. <shrug>

I'll keep you guys posted.. in the meantime if you have any more ideas I'll be looking forward to them!

 

OK, another good clue, with it begining at 40% throttle under load & getting worse as speed increases.

I like the "read the plugs" idea too!!!! While your there, make note of the plug type number & post it.

I can't remember if a Motorcraft plugs heat range goes up (hotter) with the number sequence, or if lower numbers are hotter plugs. Anyway seems to me I remember Bob Ayers went from the specified 22's to 12's, or maybe it was the other way around, but it was from a hotter plug, to a colder one, to solve his 3.0L ping problem.

 

Even if I built it, I wouldn't have a way to test it. I don't have an FF vehicle, and you can't find E85 in NJ.

-Jim

 

OK guys... got an update. Our scanner has an EGR test... you can manually tell the computer how far to hold the EGR open, in 10% increments.

At idle, I hit 10%.. no change... 20%.. nothing.. 30% nothing... 40%.. engine starts bucking and missing, just like I had full vacuum applied to the valve.

I removed the valve... found what I found normal carbon buildup on the pintle, etc.. but it moved freely. Just for the heck of it I sprayed it out with intake cleaner a few times then again with penetrating oil.. while manually opening and closing it... let it dry out then reinstalled... (By the way.. the tube came loose very easily.. probably because i had it off to inspect it awhile back)

INSTANTLY got a smoother idle (still not perfect but 90% better) and smoother acceleration.. drove it home.. pinging was 90% gone as well!

Now here I am a couple days later.. pinging is coming back and it's getting a little rough again. I think I'm going to remove it again and work with cleaning it for awhile (or maybe just buy a new one, but I'm trying to be cheap here)... see what happens.