Turbo 'flutter' during low rpm / high gear acceleration...

[zzfb]

I've been chasing an annoying problem on my 2011 F150.

It generally makes plenty of power. Good stock, very good with SCT canned tunes, and great with custom tunes, but there is a persistent problem.

Scenario that will allow me to most reliably reproduce it:




• Cruising at 50-70 mph
• Slight incline
• 1,800-2,000 rpm
• Top gear (or similar rpm at reduced speed in lower gear)
• Light but increasing pressure on throttle

Response...



• Transmission holds in gear, does not downshift with the light throttle
• Boost builds... but then starts to flutter. (boost, dump, boost, dump, cycling boost/dump about every half second).
• Light tunes will flutter between 10 and 15 psi, more aggressive tunes will flutter between 15-10 psi.
• Pattern will continue until I give it enough throttle to get it to kick-down to a lower gear and get the RPM's above 2,200 or so
• hardest to reproduce with stock tune, but I think mostly because it won't build much boost in that scenario.
  
• flutter noise sounds like wastegate is opening rather than BOV, but can't be sure.
  
• If I just boot it, the transmission kicks down a gear or two, boost builds without flutter, rocket ship takes off just fine, but light to medium throttle causes this extremely annoying behaviour

I can't figure out what is causing this...




• Is the wastegate being commanded to dump boost by the ECU, or a boost leak?
• I would suspect a boost leak, perhaps boost burping out of a hose clamp at higher pressures, but it seems to hold pressure fine when the RPM's aren't low...
• Should my transmission be kicking down at those light throttle pressures to keep the rpm's higher?
• Is it detecting knock and dumping wastegate pressure?
• Thoughts that this is related to my specific 'strategy code', as all aftermarket tunes just build upon the base strategy code?
• Any other thoughts as to what is causing this and possible remedies?

Other info:

• I believe the 2011's had integrated mechanical wastegates...
• The drivers side turbo was previously removed and reinstalled by Ford to install a block heater as part of a TSB, and given their track record, I don't trust they did everything perfectly. They say they've checked there work and everything is fine (though initially there were loose bolts, hose clamps, etc.)
• I believe there is a TSB for some 2011 EB's for sticking wastegate actuators, though this doesn't seem as much like sticking as being commanded to open.

Ideally, I'd just bring it to the dealer and have them diagnose and fix it, but I have no confidence in them. I've tried several of the dealers in my area and they all seem to be inept at any diagnosis or troubleshooting that doesn't involve check-engine-lights and specific 'pinpoint diagnosis' tests associated with the trouble codes.  Plus it's hard to reproduce on city streets in an urban area, so it usually means scheduling a day to leave the car, dealing with a rental, then just getting it back with a 'could not reproduce' or 'normal operation' result and zero progress.

[SHOdded]

Have you checked all the piping to make sure it is not cracked or loose?  Oil in the intake or intercooler?  Does the intercooler have the fix/TSB applied?

It can always be a sticking wastegate, but I would get those things off my checklist first.

[zzfb]

Have you checked all the piping to make sure it is not cracked or loose?  Oil in the intake or intercooler?  Does the intercooler have the fix/TSB applied?
It can always be a sticking wastegate, but I would get those things off my checklist first.

I've tried to check the piping as much as possible... No visible cracking, clamps all seem tight.  Access is pretty tight, so it's hard to really check it all out without a lift and removing the wheels and fender liners, but it seems good. Plus, if it was a boost leak, wouldn't it bleed boost when I have high boost at higher RPM's? It only seems to flutter when below 2,500 RPM. Really more like 2,200 RPM max.

No intercooler band-aid's... Original intercooler, no restriction devices.  I've never had the water ingestion/fall on it's face problem. My understanding is that the various revisions of intercooler TSB's just went from bad to worse in an attempt to limit flow and charge cooling to reduce condensation.

Don't know about oil in intercooler... No catch can or weep hole setup at this point. 

[ZSHO]

I certainly agree with SHOdded,would definetly check all the hoses and especially the wastegate hoses and the actuator itself could be bad,also check the solenoid valve may be sticking causing your issues,check for any random misfires on cylinder 1,and 4,BTW has Ford updated your PCM. Z

[zzfb]

I certainly agree with SHOdded,would definetly check all the hoses and especially the wastegate hoses and the actuator itself could be bad,also check the solenoid valve may be sticking causing your issues,check for any random misfires on cylinder 1,and 4,BTW has Ford updated your PCM. Z

Thanks...  Will try and check more, though I'm still thinking it's a strategy glitch as the pressure normally holds fine. 

BTW has Ford updated your PCM

Do you mean the hardware or just a revised strategy?  With the dealers around here it's like pulling teeth to get them to do something simple like 'Check if my PCM has any strategy updates... If it does, load the revised strategy'.  Should be simple, no? But instead it's 'we can't replicate any problem, and can't check the strategy or update it unless we have a problem'. 

I guess I'll just tell 'em to do it on my nickel and have them charge me for several hours of labor for ten minutes of an actual tech's time, and have about 50% confidence that they did it correctly.  I so wish there was a mechanic I trusted with IDS hardware and subscriptions...

[zzfb]

Here's a datalog of the flutter...

Again, doesn't flutter at higher rpm's or in other situations, so I'm thinking it is not a boost leak. Plus the wastegate signal is going high, so it looks like the PCM is commanding it to open?  Why?

[BiGMaC]

First, I agree with everything Manu and Z have suggested and encourage a diligent search of those things you can check. As far as a strategy update... The last one for the SHO was about six months ago... And my dealer did it without my asking (a good reason not to be tuned at the dealer)... If your dealer is won't even look, maybe a change is in order.

I would bet your KR rises in these conditions... Basically lugging a little... And the ECU (PCM) is pulling timing and so dumping boost to prevent knock or misfire.   I would suggest that the 3.5 TT GDI like to be pushed.  I have found that developing a touch for a one gear downshift has improved my performance and kept my KR 0.  Does the fluttering happen when you acellerate hard enought downshift?

Just my $0.02.  ...good luck with the problem.

[FoMoCoSHO]

I have this same issue going up a steep hill to my house. Car wants to be in 4th 20-25 up the hill.

Force a kickdown and it stops.

Max negative KR all the way up.....(Blend torture test😈)

The 2013 behaved the exact same way....stock or tuned.

Hoping the dreaded "megaknock" doesn't pay a visit.

[r1crusher]

I have felt this same issue in my wife's '13 F150 both stock and tuned. I think it's just the nature of the ecm trying to deal with the scenario some of us put the EB into. I have also had this happen in my tuned '13 SHO on the same local highway hills.

IMO, I think it's normal behavior given the circumstances.

[zzfb]

Great feedback...

My original strategy was much better in shifting performance, a light touch on the throttle would instantly and seamlessly put it in a lower gear, much how our Audi and BMW's I've owned in the past shifted.   It was, in fact, one of the things I liked best about the truck when I bought it.

Along with an unrelated TSB, Ford flashed a PCM update and the shifting strategy has never been as good. Around town, kick-downs aren't nearly as seemless and you really have to give it plenty of throttle... What typically happens is no kickdown, boost builds, RPM's rise, THEN it kicks down anyway with a huge rush of power. Not smooth or natural.

For this particular problem, it usually occurs when i'm driving at highway speeds, 55-70, typically mountain driving conditions. I want a little more power, not gobs of it. I'd be happy to have it downshift a single gear quickly and spool up a bit, but it won't do that... I either feather the throttle and potentially get flutter or womp the throttle a good bit and I'm gone. 

I've heard some suggestions that bad or weak HPFP's can cause a bunch of bizarre symptoms, but again, I wouldn't think it would happen in only in a lower rpm (lugging?) situation.

Even the custom tuners don't want to (or can't) put the 'breath on it to downshift' characteristics back in my truck.... Moral of the story: If your truck or car is running well, do everything possible to prevent the dealer from 'upgrading' it!!!

[BiGMaC]

Doubt if fueling causes your concern. I have lost the LPFP in my car... This results in a wrench from the HPFP which is a low fuel rail pressure warning and also a communication code is set for communication to the ECU... If you don't have a wrench or codes set I suspect the programming and nature of the 3.6 GDI are what's happening.

[FoMoCoSHO]

I've got plenty of FRP even with 30% E with a splash of M, so I don't think that is the issue.

Seems like it just may be a glitch in the matrix...

[zzfb]

Max negative KR all the way up.....(Blend torture test)

The 2013 behaved the exact same way....stock or tuned.

Hoping the dreaded "megaknock" doesn't pay a visit.

Can you elaborate on this a bit?  Max negative KR? Megaknock? 

Seems like it just may be a glitch in the matrix...

Then I need the red pill.

[zzfb]

By the way... As you can see from my post count, I'm new here. But thanks for the great info, seems like a knowledgable and helpful group. Not a given in the forum world these days.

[AJP turbo]

Here's a datalog of the flutter...

Again, doesn't flutter at higher rpm's or in other situations, so I'm thinking it is not a boost leak. Plus the wastegate signal is going high, so it looks like the PCM is commanding it to open?  Why?

You have it a little backwards. When the wastegate duty cycle goes high it's keeping the wastegate CLOSED longer in an attempt to increase boost.

Your wastegate duty and map readings are peculiar and suspect. WDC should be much smoother and nowhere near as jagged as your pic, along with the map reading as long as you were steady on the pedal. Speaking of that I would've like to see actually throttle angle and pedal in that  log. I'm guessing that wasn't a canned tune. you peaked at some boost at well over 20 psi which surprises me because you said it was fairly light throttle and steadily increasing....

I had some weird issues early on when trying to make really high boost at very low rpms. I never really isolated what it was. But I switched who tuned the car and I also suspect that I may have had some corrupt tune files.

I had made some tunes where I was making about 24 psi at about 1800 rpm's and the car didn't like it and it surged and acted weird until rpms went higher

Also, ACTUAL THROTTLE ANGLE should be added to everyone's config files when they log. These cars do some weird things and controls engine output in a lot of different ways and times via the throttle. It's good info to see.

Sorry if that doesn't help much