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Coolant really...
No, not really. It doesnt miss on startup, to me it just seems to be leaning out. But a coworker saw me pull out of my drive way one day, and told me my car was smoking at the exact time It was hesitating
 

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I've been running "lean cruise" with my tunes and this post-cold start stuttering/hesitation was exacerbated. I'm pretty sure I know what the culprit is though: it's the strategy that most tunes carryover and maintain from the stock programming to run lean for a minute or two to heat up the catalyst.
If y'all watch your AFRs right when the hesitation occurs, you may see that the computer makes a sudden but significant change in AFR before it normalizes. The change in the mixture is what you feel as hesitation.
 

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I'm currently tuning with Randy and obviously I'm sending this his way, but I'm wondering if anyone else has noticed something like this. In part throttle situations the car will pull, hesitate, then continue pulling. I felt this happen occasionally when stock, but I figured the car was acting funny because it wasn't up to temperature or something.

The line on top is pedal position which I'm keeping around 2/3rds throttle. The first graph also has timing of each cylinder plotted.

View attachment 202090
I recent installed a Cobb 91 stage 1 tune. When driving between 4500rpm and 6000rpm, and changing gears, (usually between 2nd and 3rd) I have what feels like power cut, or throttle hesitation. It happens after I press the clutch in, change gear then immediately when I press the throttle, usually at WOT, I have major hesitation or power cut, similar to old style traction control. I normally have to lift off and power on again lightly to avoid this power cut feeling.

My initial thoughts was traction control, but I turn it off, and the issue was still there.

I don't have any misfires, knocks, some slight negative ign adjustments, fuel is good but the Air fuel ratio seems a bit lean, sometimes as low as 9.88, other than this, nothing major to note.

I have restored to the stock configuration and the issue is gone, engine running smooth and linear all the way to red line. Given this strange feeling, I am a bit worried to install the 91 or 93 tune.

Is this similar to your circumstances
 

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There's definitely hesitation in 2nd...it's weird. ECU doesn't seem to know what you want unless you go WOT. I'm not too bothered by it. The car makes strange noises here and there out of nowhere once in awhile...possibly possessed? I had a stick from a 2X4 stuck under my skid plate the other day. I thought I blew a tire...pulled over, looked underneath the car and there it was.
 

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It happens to me on the odd occasion too, but nothing to really be concerned about because of its randomness and quick fix........
 

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Take a look at the ETC (throttle plate) and I'm sure you will see it closing during your "hesitation".
 

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Last night when I was driving home from a car meet I was noticing in fourth and 5th when hitting the throttle 2/3 the boost would "breathe" (for lack of a better term) it would drop a few psi then go up then down a little and then back up through the acceleration. The car was warm and I was boosting btwn 15 and 29. It did it is sport mode and normal mode. it would do this as well when hitting full throttle as well through 4th and 5th. it is very noticeable to feel the changes in how the car pulls as the boost does this.
Im not sure if we are talking about the same thing. If not I will start a different thread.

Thanks.
 

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While watching my boost I noticed on hard accelleration my AFR on Cobb readout would drop to 10.00 at the lowest. Is this considered lean? If not, what is considered lean in the air/fuel ratio?

Thanks all
 

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this happens to me all the time, doesnt matter if im up to operating temps or not. 3000-3500 rpm in 2nd gear, part throttle (maybe 75%). feels just like my clutch started slipping like a mother, but unlike a slipping clutch the speed still seems to go up... its the hardest thing to explain but it feels so obvious when it happens.
 

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Hi all, firstly. I have to say the service from Cobb is amazing and have taken my query seriously. Cobb didn't need to do anything, so I appreciate Cobb taking the time to even review the Logs

As I suspected, it was nothing major, in fact, even in the stock form the feeling of hesitation/cut out was there, but less noticeable. I sent the Logs off, here was their response from Cobb (shortened version)

"We did a bunch of testing over the last couple days. In short, it appears that your car is making throttle closures even when TC is fully disabled. The reason is because it is slightly exceeding certain load values at times, so there are built in safety systems that automatically close the throttle at least partially. We were actually able to see it happen on a couple of our test cars as well, but it's usually subtle enough that the driver doesn't even notice. So its a normal behaviour, but your car seems to just do it a little more aggressively for some reason. One of my tuners is working on making a test map that we will send you to get some more data"
 

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I wouldn't edit this out unless you're vehicle is a full time track car and you've the bank roll to replace exploding engines and the like. Some safe guards are there for your safety not simply for the neutering of your fun.
 

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I wouldn't edit this out unless you're vehicle is a full time track car and you've the bank roll to replace exploding engines and the like. Some safe guards are there for your safety not simply for the neutering of your fun.
Thank you, new to all this stuff and the forum. I was not sure what is acceptable to post on this thread so just edited to the point.

I initially had a tune on the accessport for the ST 2013 (no issues with that tune, actually loved it) so I thought I would update the AP for the RS. After a few drives, I took the tune off as I wasn't 100% happy, hesitation being the big issue which I raised with Cobb.

Cobb were kind enough to give me feed back on my logs and a revised tune, which was an improvement.

I should note, I do not intend using any tune, I have kept the RS with the stock tune but with the Cobb AP installed for monitoring, which I thought would not void warranty. I am always learning

Thanks all
 

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Discussion Starter #38
Please keep us updated on what Randy comes up with.
Mine has the hesitation also. Randy tuned of course.
So right now I have no hesitation any more. Randy and I went through many revisions. Not trying to slight Randy, but we had a pattern of fixing one issue and creating two more.

At one point we had a boost that looked like this...
screenshot.png

Prior to the most recent tune I ran into this issue of negative timing under load which was... bad.
unnamed (1).png

Me to Randy:
Still dealing with the negative timing under load and weird power fluctuations. Newest rev didn't change the feeling of a power cut under negative timing. Feels and sounds pretty awful.
Also, I'm noticing that where I averaged ~24 MPG prior I'm getting about 20 now. Obviously more power requires more fuel, but I'm just wondering if this drop is inline with what you normally see.
Randy's Reply:
I'm going to have to abandon my usual approach to the RS calibrations and change you over to the Ford OEM approach that employs throttle closures to regulate primarily. I don't normally do that, but for the very rare problematic cars it has worked well.

I have not used this on the upgraded IWG cars, but you can try this out and see if it works for you. There's no slot switching on this file.
So now I am running this new calibration. I noticed that there is a little less torque than his previous strategy, but so far I haven't had any issue with weird fluctuations or any negative timing, etc. Feels like the stock tune, but without the hesitation from the OP. I sent Randy a new log. I think there are a couple timing changes that need to be made on the latest rev, but that's to be expected having moved to a new strategy.

I'd say right now I think we are on the right track, even if we don't pick up the gains from the old strategy I am happy enough where it is now.

screenshot.png
 

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Xicutioner - Thank you for updating this thread. I also have a Randy tune that I am overall happy with and am running stock WGA, IC, and catback. But I have a weird 2nd gear issue that might be what you are describing: With traction/stability controls all the way off, when going to full throttle in 2nd, there is a brief hesitation then BOOM it picks up over 1000 rpms in a split second like the tires or clutch are slipping but they aren't. It can make coming out of a lower speed corner very interesting for sure.

Is this similar to what you experience?
 

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Xicutioner - Thank you for updating this thread. I also have a Randy tune that I am overall happy with and am running stock WGA, IC, and catback. But I have a weird 2nd gear issue that might be what you are describing: With traction/stability controls all the way off, when going to full throttle in 2nd, there is a brief hesitation then BOOM it picks up over 1000 rpms in a split second like the tires or clutch are slipping but they aren't. It can make coming out of a lower speed corner very interesting for sure.

Is this similar to what you experience?
What revs are you at? It's not turbo lag?
 
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