Stumbling under light acceleration, found PCM pulling timing

[wjcollier07]

So, the '07 has a somewhat minor issue. Under light acceleration, it stumbles, especially right around 1500 RPM. During this period of time, all timing advance is pulled, frequently going into KR by as much as 5 degrees.

 

Looking at the fuel trims, bank 2 typically sits at about twice the percentage as bank 1. These numbers aren't major, only between 2-6% on bank 2, and 1-2.5% on bank 1, but they're almost always positive, nonetheless.

 

I've monitored linear consistency on throttle position readings, MAF readings, IAT readings and MAP readings, and everything seems normal and consistent. The only thing I saw it do a couple times out of the ordinary was pop out of closed loop, and then back into closed loop in under 3 seconds (only did it a couple times in 30 minutes of driving)

 

Interestingly, I've found that Lucas fuel treatment abates the severity of the stumbling by quite a large degree. This is the first time I've ever actually thought about pulling data on it, but it is currently running Lucas. I went without Lucas for about the past year (under 10k miles) and the stumbling started to get really bad. This is the first time where running the Lucas didn't completely solve the issues.

 

Right when I got the car in late 2013, at 104k, I did plugs and PCV, so I have no reference on whether this was a preexisting condition before I took the intake plenum off. (Yes, of course I used new gaskets) I should also note that I used the exact OEM plugs and PCV.

 

Here's a 12 minute video of some extra-urban driving to show the major timing pull it does under certain conditions, as well as the fact that it shows ZERO signs of issues during relatively heavy acceleration and not a single hiccup at highway speeds. IAT was a relatively consistent 90-100 degrees F, high humidity, sea level.

 

 

142k miles, all maintenance is current. Has run nothing but top tier fuel since 104k miles, and has had a bottle of Techron concentrate in the tank about every 10k miles.

 

So, what am I missing?

[WWWPerfA_ZN0W]

Wow, 100% engine load! Haven't seen that yet, even at WOT, mostly 70% or less. Interesting. Pulled codes?

 

The throttle body is a common culprit with the Fusion (non 3.5L engine), so that's the first thing that comes to mind. Maybe you can find and switch out the potentiometer/TPS if the TB looks clean & functional otherwise.

 

LTFTs running +ve is normal. Engines running in lean conditions is what they want for fuel economy. Not great for engine life if anything goes wrong. Bank 1 always seems to run 2% or so richer than Bank 2 on the Ford V6's that I have seen.

 

Have the O2 sensors ever been changed? What readings are you getting from them? Must be worn out at nearly 150K miles.

[El Caballo]

What scanner did you use?

[wjcollier07]

I'm very sorry about the delay in response! I've been trying to tackle this problem when I have time.

 

I narrowed down several aspects of the issue to being possibly transmission related, to which I found just seemed to be the fluid being worn in some way (even though it was only 12k mile old fluid). Before I found that out however, I replaced all 6 coils and all 6 spark plugs, again, even though I had just done those about 40k miles before. The change of the plugs and coils caused no significant change once the PCM had a chance to relearn. The replacement of the trans fluid significantly improved the acceleration smoothness, with only a few blips here and there. I've been driving it like this now for about 3000 miles since I finished that whole session of ATF change and tune up, it continues to be better, but not "good".

 

I realized that I had an issue with acceleration, and because it was worst under light acceleration, I wasn't focusing on the other times when it blipped (misfired). Today, I was cruising on the highway at right about 75 mph, cruise set, perfectly flat road, and I'm noticing it blipping every 5-10 seconds. Nothing major, just sort of a imperfect sort of annoyance. I don't get on the highway much, I'm usually driving in an extra-urban setting. I got out my scantool, set it up next to the gauges as I'm cruising, and just watched it. I noticed something I wasn't even putting together before that when I'm cruising and everything is smooth as ice, I'm sitting at about 40-41 degrees of ignition advance, and every time it blips with a single misfire, that drops to about 35-37 degrees, sometimes as low as 32, and then recovers back to 40-41 in a brief period. So it actually IS something engine related, and I'm really at a loss since I've replaced everything I can within reason!

 

Stats:

145k miles

replaced oxygen sensors (both upstream) with factory NTK sensors earlier this year

replaced spark plugs at 104k with factory FoMoCo plugs

replaced spark plugs again with NGK Iridium plugs at 142k (actually much better fuel economy since this change)

replaced all 6 ignition coils at 142k, Delphi branded coils (they were the OEM manufacturer of the FoMoCo coils, in case anyone is wondering why)

replaced transmission fluid at 142k (Mobil 3309)

thoroughly cleaned throttle body while replacing ignition components at 142k

 

every other maintenance item seems to be up to date, including small things like the engine air filter

 

acceleration under 3/4 to full throttle is VERY strong for this engine series. With the exceptions of the Aisin trans having its odd idiosyncrasies every now and again, during acceleration and whatnot, it feels and sounds like a much newer car than it is.

 

as the maintenance record indicates, I'm very willing to comprehensively care for this car, I just want to figure out this strange issue!

 

Also, reference these threads, since these similarly describe the issue as well. I actually posted about this issue when I owned my 2011, and even though that issue was different in some ways, it's still very similar, which leads me to believe that it's something inherent to the duratec engine series?

http://www.fordfusionforum.com/topic/13638-2008-fusion-v6-se-stuttering-while-driving/

http://www.fordfusionforum.com/topic/9207-bucking-at-constant-highway-speeds-2012-sel/

 

Sorta worries me about reports that technicians have replaced whole bunches of parts on people's cars trying to figure these kinds of issues out!

[wjcollier07]

SO, the feeling I was noting was due to the A/C compressor cycling.

 

However, with a significant amount of additional research done this week, I'm narrowing the cause down to something related to the EGR. This conclusion is solely based on the frequent failures of the DPFE sensor on older duratecs, 4 cylinder and 6 cylinder alike. This sensor however, does not seem to exist on this generation of Duratec 30, and so I'm still working on narrowing down where the PCM is getting its EGR flow feedback information. Any help on that would be great.

[WWWPerfA_ZN0W]

IDK if the 2008 is the same as 2007, but if so

2008 Fusion 3L Engine Emission Control.pdf

[wjcollier07]

It would be, yes. That's perfect, it solidified my suspicion that the MAP sensor is the direct reporter for the PCM to calculate EGR flow.

 

When watching the MAP readings in the scantool video I made, I noticed that MAP was spiking to full atmospheric pressure under some conditions, then upon further analysis, I realized that the only time when the ignition advance goes to zero or negative is when the MAP sensor is reporting 14.5 PSI, causing the calculated load to shoot to 100%. I would understand MAP going to atmospheric under high throttle conditions, as would be normal, however, I was noting 14.5 PSI when TPS was reporting as low as 21.2%, which actually has a base number of ~17% when idling. Something doesn't seem right there.

 

A new map sensor sure would be an easy fix....considering that replacing it is only slightly more difficult than adding washer fluid.

[wjcollier07]

Replaced MAP sensor. New one seems more accurate. Slightly broader readings than original sensor. Did not fix stumble with A/C on. Stumble is still very much present.

 

I noticed today that it was actually a little worse than it has been, even under the same outside temperatures with A/C on. The only difference was that it was extremely humid today, due to a massive low pressure system sitting over us today. The humidity could be unrelated, but the lower atmospheric pressure, which seems sort of ridiculous, when you consider what a small change we're talking about, seems like it made it worse.

 

So. What next?

[WWWPerfA_ZN0W]

Probably a silly question, but is your Fusion AWD? Issues under light acceleration, especially going uphill, have been linked to a problematic PTU, is why I ask. Check the PTU fluid to see if it has been changed at all. If it is black/gunky/goopy, but with no noticeable debris (only fine metal shavings at worst), then a fluid change may be just the ticket.

[wjcollier07]

Nope. FWD. Good information though.

[WWWPerfA_ZN0W]

Ok, so the search continues. Do you actually have KR monitoring? Pulling timing is not the same as Knock Retard. I am thinking fuel injectors or fuel pump issue now, since the Lucas fuel treatment helps. Probably due to the additional lubricity it provides. You can see the total fuel trim shifting upward at the time the timing is pulled, may or may not be a coincidence. I would monitor it again with the Lucas product in the tank to compare. Or vice versa if you were running Lucas when you made the video above.

 

Do you have PIDs for spark duration? I know Forscan does for each cylinder on my 2010. We can kind of see how the ignition process is doing.

[wjcollier07]

I have no KR monitoring. None of the scantools I have access to seem to be advanced enough. I finally got trans temp on my ScanGauge II, but only because I tried the half dozen codes to get it to work, but haven't seen any codes on that device for KR. Something about load, specifically, is precisely what I've been thinking this whole time too.

 

I haven't done a test with the Lucas recently because it's so difficult to be definitive about the how much better or worse it really is. The funny thing is, a couple of years ago is when I discovered the Lucas thing making such a difference with this car, and I used to add it periodically because it seemed to add more power, long before this strange jerking issue came about. When I did notice the difference in the jerking, in relation to Lucas, the jerking was much less severe. I don't expect the Lucas to make anywhere near as much of a difference as it did before. Also, I used to just squirt it in from the large quart bottle, but have since developed a much more measurable way of doing it, so I'm not even sure how much I was putting in when I was noticing it "seeming more powerful".

 

I'm going to try running without the EGR plugged in first, to see if it's EGR related, and then once that changes nothing, I'll try out your recommendation of trying again on Lucas.

 

My scantool doesn't seem to tell me anything about spark duration. The only thing I could see are the Mode 6 parameters, with monitoring for misfires on each cylinder, which seemed to uncover nothing. https://goo.gl/photos/kMpCB8LXWcY8JKwN9 There are a few screenshots from when I did that a while back.

[Milan65]

Older post so you may not have this issue anymore. Just in case. My 2011 V6 Milan (70K miles) always felt as if it was stumbling under constant speed or light acceleration. It felt almost like pulling a trailer. It was at the dealer for weeks undergoing every test they could do. Long story short, after a lot of research I decided to re-look at the rear (dogbone) motor mount even though the dealer checked and determined it to be within spec. I replaced it with a solid version from Steeda (https://www.steeda.com/fusion/steeda-ford-fusion-engine-mount-06-12/). No more problem (at least not noticeable). The inner part of the OEM version gets softer and softer.

 

Might not be your issue but I really hated the symptom and was extremely pleased with the result.

 

[Darren139]

I’m having a similar problem on a 2015 that’s driving me nuts. Usually starts to shudder around 30-35mph. When in 4th gear. And when coasting around 40mph it bucks like it’s in too high a gear.

did you have these symptoms with the factory mount?

[Oracle_Ed]

39 minutes ago, Darren139 said:

I’m having a similar problem on a 2015 that’s driving me nuts. Usually starts to shudder around 30-35mph. When in 4th gear. And when coasting around 40mph it bucks like it’s in too high a gear.

did you have these symptoms with the factory mount?

 

Have you carefully checked out your CV joints?

Do you hear any kind of grinding noise when making sharp turns (even at low speeds)?

[Darren139]

No but I find even if I put parking brake on and in neutral, I Can almost recreate the feeling by reving the engine up.

 

[Darren139]

I’m not the only one to feel this.

There are several posts describing this feeling. Nobody seems to have a fix. 

If I put it in manual 4 around 35-38 miles 

if I play with the throttle there is so much play.