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Hesitation on acceleration when cold 2011 v6

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2011 v6
10K views 77 replies 12 participants last post by  tombrochard 
#1 ·
Hi guys, I'm looking for a little help figuring out an acceleration issue on my car. When it's cold it accelerates unevenly. If you mash the accelerator to the floor it moves right out, but if you give it partial throttle it stumbles a bit. Warmed up completely there's a slight stumble. The car has 62k miles and it's a manual, still using original plugs. The only mods are mufflers, BBK headers, CAI, bama tune

I've checked the map sensor and cleaned it, cleaned the throttle body, cleaned the fly by wire potentiometer under the gas pedal, removed the bama tune and reinstalled it. Clean intake filter too

Any thoughts?


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#2 ·
Does running the stock tune make a difference or are the issues still there?
 
#4 ·
Same issues with the stock tune. I'm thinking it might be an issue with a sensor somewhere, but I haven't dug into that yet. No codes from the computer either.
It seems it hesitates between 2000 and 3000 RPM


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#5 ·
Precisely! Like if you are rolling at mid-high twenties in third so around 2-2.2k and put the pedal down a good amount but not WOT it starts accelerating, does a buck, then continues through the rev range. Maybe it has to do with wiggle room in the transmission since it is shifting momentum so suddenly.
 
#6 ·
Poor cold throttle response is a symptom of intake valve deposits in an otherwise good engine. Try a bottle of Techron, BG 44K or other gas additive than claims intake valve cleaning. Sometimes you can see this problem with changes in air/fuel ratios and fuel trim with a scan tool but fuel additives are so cheap I'd just try it first.
 
#8 ·
Let us know what you find out...
 
#9 ·
Thanks for the advice on the fuel additive, I'm going to pick it up tomorrow. I wouldn't be surprised about the deposits on the intake valves, I had the intake off last summer and there was all sorts of crap on them. I'll let you guys know how the BG 44k works. That stuff has gotten pretty good reviews from what I can see


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#10 ·
Hi guys, I couldn't find the BG 44 in my local auto parts store so I'll probably order it online. I did try the seafoam spray that you spray into the throttle body. Totally a pain in the *** to use because if you don't get it right in front of the throttle plate the damn stuff leaks down the air intake and all over the air filter. Once I got it situated I sprayed about three quarters of a can into the intake and let it hot soak for about 30 minutes. As soon as I started the car it clogged the O2 sensor so I had to clear out that code later on. Took it for a ride and as the instructions say drive it aggressively. It was pretty funny, the car looked like a crop duster airplane going down the road, it's all that seafoam stuff burning off I guess. Long story short the hesitation when it's cold is almost gone so I'll order the BG 44 and that should finish the job off. That's the only stuff I'm gonna use in the tank because my local ford dealership highly recommends it.

If the car still hesitates after all that I'm going to take off the intake manifold and manually spray the intake valves and manifold. I did that last year and it certainly was an oily mess but it didn't hesitate either.

Any other thoughts on this?

Thanks too for the advice on the cleaning, that's clearly the issue here


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#17 ·
Hi guys, I couldn't find the BG 44 in my local auto parts store so I'll probably order it online. I did try the seafoam spray that you spray into the throttle body. Totally a pain in the *** to use because if you don't get it right in front of the throttle plate the damn stuff leaks down the air intake and all over the air filter. Once I got it situated I sprayed about three quarters of a can into the intake and let it hot soak for about 30 minutes. As soon as I started the car it clogged the O2 sensor so I had to clear out that code later on. Took it for a ride and as the instructions say drive it aggressively. It was pretty funny, the car looked like a crop duster airplane going down the road, it's all that seafoam stuff burning off I guess. Long story short the hesitation when it's cold is almost gone so I'll order the BG 44 and that should finish the job off. That's the only stuff I'm gonna use in the tank because my local ford dealership highly recommends it.

If the car still hesitates after all that I'm going to take off the intake manifold and manually spray the intake valves and manifold. I did that last year and it certainly was an oily mess but it didn't hesitate either.

Any other thoughts on this?

Thanks too for the advice on the cleaning, that's clearly the issue here


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Is it possible an old timer owned it before and it now has carbon build up? I'm just tossing out ideas so don't make too much fun of me. lol
 
#11 ·
Glad the Seafoam helped despite the James Bond smoke screen. I won't ever do that where I live as there are environment police :lol: You'll find the 44K more effective and should notice more improvement after 100 miles. It even continues to work after you finish the tank by attacking carbon.
 
#15 ·
I remember reading somewhere that some of the Top Tier Gasoline companies, use Chevron 65740 Techron Fuel System Cleaner.
 
#18 ·
I'm laughing when I read the old timer remark, that's exactly the case. It had 12k miles on it when I bought it and now it has 62k. I also ordered the BG 44, it'll arrive on April 4th and we'll see what happens. My car now has only a minor hesitation now after sea foaming it, I'm hoping the BG 44 cleans the last bit up. I'll let you guys know


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#20 ·
So I put in the 44k, first I put about 1/3rd of the can into my half full tank and ran that down to 1/4 tank, and then filled up and put the rest of the can so likely a little higher percentage than you're supposed to, no ill effects.

I have noticed that it has made a difference but I also replaced the air filter with a new OEM one and I think that made a bigger difference, the engine picks up revs way smoother. Especially downshifting and not well Rev matched, the engine picks up speed way more smoothly with no hesitation. Id recommend both steps to fix the issue. My car drives way better now.

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#22 ·
Sorry, I shouldnt have made a blanket statement like that. I just wondered if maybe it didnt hit the 5k+ area in the RPMs enough with the previous owner.

I dumped a entire can of sea foam in half a tank 2 days ago and no smoke whatsoever, so I dont think the sea foam alone makes the smoke. I believe the smoke is carbon or gunk burning off, but I cant say for sure. I does make a funky stench though. Lol

I read up on the SF thoroughly and wouldnt use it or any additive more than once a year.
 
#23 ·
LOL
This old guy hits the 5K+ every time I take mine out.
But I guess you could say I'm not the typical old guy.;)
 
#25 ·
Hmm, I didn't put the seafoam into the tank. I sprayed it into the intake and smoked like hell when I burned it up. I put BG 44 in the Tank yesterday, I'll let you guys know how it works out. Hopefully the hesitation goes away.


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#26 ·
And don't worry about the old guy comment, I guess I'm not the typical old guy either. My mustang hits 6000 rpm probably more often than it should ...


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#31 ·
Hi guys, just a quick update - used the BG 44 stuff, no difference to the hesitation. I'm guessing there's too much junk built up on the intake valves. I'm going to take apart the intake manifold next and spray things out manually. I'll take some pics and post them for you guys

Hey, do guys know how to turn that motor manually? I'm going to rotate it so I can expose each intake valve and spray it with intake cleaner.

Any thoughts?


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#36 ·
You may have another problem other than intake valve carbon as the 44K should have worked in 1 tank. If you see enough carbon left on all 12 valves to fill a teaspoon or more that's too much.

Easy ways to turn engine over is wrench on crank pulley or turn rear wheel over with manual in high gear. Helps if spark plugs are out but you don't need to open valves. Spraying through ports and soaking overnight will work open or closed as fuel side is soaked.
 
#32 ·
So I picked up some seafoam after running through my gas tank of 44k, I haven't run through much of it but I don't notice a difference yet between the 44k and this as far as improvement as seafoam is supposedly stronger. Also there is no cloud of smoke like I have seen some cars do when using sea foam, so it likely isnt all that dirty anymore.

I had a lot of driving time yesterday and was having a lot of fun with the better throttle response due to no hesitation, it drives like a new car. Almost 70k miles on it and likely has never had anything like that done.

Will update after I finish this tank of seafoam.
 
#33 ·
I dont think you get the white smoke when you run it through your gas tank. I get it when I spray it into the Throttle Body when the car is on. The instructions are on the can. But I dont use the Sea Foam for the gas tank.
 
#34 ·
Ok that makes sense, I remember seeing videos and having friends do it where they did the 1/3 can in oil, 1/3 of can somewhere else that I cant remember, and one third in gas tank, so I thought I might have some smoke.

I followed the directions on the can and it said 1oz per gallon of fuel, the can is 16 ounces and the tank is like 14-16 so I put almost he whole thing in as I had just filled up.
 
#40 ·
Yeah, I talked with a ford tech today that had a 2011 GT, he said it could be plugs as well. I'm just going to replace the old ones with new stock ones. That might be the issue. I'll do it this weekend and let you guys know


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#44 ·
I only have one from last year when I peeked into there. I can't remember if this was before or after I sprayed the valves manually with carb cleaner. there's a lot more crap at the base of the valve in this picture and that's like 20K miles ago.

I'll try to upload the pic later, it won't upload for some reason
 
#47 ·
Hi korak, I checked the LTFT with my tuner +1/-1, well within tolerances. What's next?


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#49 ·
IIRC, cylinder deactivation only occurs when cruising in order to conserve on gas. When accelerating, all cylinders are used.
 
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