Problems with surging and driveability - datalog attached

Hello all,

I have a bone stock 2015 GT, which I purchased used. Long story short, I have been to the dealership with this issue, and they are of the opinion that nothing is wrong (go figure). In order to find the issue, i have purchased a tuner in order to datalog and look at the files.

I have the following issues (which are intermittent):
-surging/hesitation under WOT
-surging/hesitation under part throttle
-weak power under WOT

Attached is a log file. I'm trying to determine if anything can be seen by this file, or if the previous owner may have tuned the car and did not return it to stock.

I assume bank1 is driver's side and bank2 is passenger side?

It appears in the logs that bank2 is doing nothing in comparison with bank 1. It also appears that there are discontinuities in the maf frequency. Shown below is the bank2 curve compared with the bank1 curve.


Any help is extremely appreciated!

Make sure you are viewing them on the same scale. using datazap.me it looks like your banks 1 and 2 are doing nearly the same thing. I see no problem there.

If I had to guess I would say your throttle body is the cause of your surging. your MAF is following your throttle and the throttle is opening and closing not very smoothly. Pedal position, which is usually smooth is following throttle angle like its in open loop. Usually it's only in open loop at WOT. A tune can change this or a physical problem could cause the throttle body to use open loop through the closed loop intervention prevention safety feature. I assume a dealer would flash a stock tune on the car to undo any previous modification. That kinda leaves a physical problem with the throttle body or wiring. That's my best guess.

Markmurfie -a massive thank you for taking the time to go through my log.

I looked over the wiring and did not find any physical damage, or loose connections. I went ahead and purchased a throttle body (as they are low cost) so I will post up as soon as I get it installed.

Update: I installed another throttle body, and the symptoms have persisted. I checked over the wiring as best i could (apart from removing cables/unraveling loom), wiggled all connections and haven't found anything yet. Check out the below snapshot.



it seems like the throttle angle is changing a lot with minimal throttle movement...

If anyone could have a look at the attached log and give any input, it would be really appreciated!

Edit - i also checked the strategy with the SCT tuner, and it is a factory strategy.

Take it to another dealer if still under warranty. If not have it dyno tuned, that will have the car driving it's best.

Nightride- I have taken it to 3 separate dealers....including one that has an SVT tech.

Note- compression test has been performed (all check out ok), and smoke test was performed (no leaks found).

Here's a little bit better section of the log:


it appears that the throttle angle is moving a lot, while the pedal is not moving at all. this section of the log is attached

Best thing is a dyno tune then, they check for things to make the car run its best. A dealer is opposite where they don't want to find problems especially while the car is under warranty. An email tune will only show so much and you'll have to trouble shoot the rest yourself. Dyno tune in person will get the car running how you want for about 500.

Also does the car have any power mods? Only issue I've had like that was from a jlt intake. Maf didn't really seal that well and didn't like how it drove.

The issue I have with a dyno tune, is that the car should run reasonably smoothly from the factory. It may not have the absolute best power, but driveability shouldn't be an issue with a completely bone stock car....especially intermittent driveability issues. The other S550s I have driven do not seem to have these issues. Even at idle, you can feel the intermittent misfire/stumble of the motor.

Here is another thread of someone with the same concerns about their car:
https://themustangsource.com/forums/f806/5-0-sputter-hesitation-538243/

I also have the same issues as this gentleman:
http://www.mustangevolution.com/forum/f393/t369851/

The only time I have seen a tune help fix driveability issues on a stock car, is with the turbo Subaru cars (wrx/sti). Subaru was notorious for leaning out their turbo cars to meet emissions standards....a tune seemed to fix these driveability issues.

I think a dyno-tune would be most likely to mask the issue, not solve it. It seems like this is an issue with poor wiring connections, or a failing sensor/part.

Maybe you just got a lemon but a dyno tune is your only chance. Those guys want to work on your car and earn business. If they can't get it running maybe trade it in at these dealers who say it runs "good". I've gone through driveability issues as well before. Dealer and data logs through email tunes are a shot in the dark. Again, dyno has best chance of seeing the car run optimally. If your totally against maybe time to cut your losses.

If the car is stock suggesting he get a dyno tune is a stupid idea. Why would he do that? Also dyno tuning is not the way to go anymore but rather an email tune and logging the car on the street in real world conditions.

Others have had the same symptoms as you and it turned out to be a cracked manifold. Something I would look into.

Actually i had a surging issue with a jlt intake unable to diagnose. Then later a minor exhaust leak causing car to pull timing. Both issues were through the "best" tuners I'll leave names out. They could see it on the logs but had no ideas other than bad gas. On a dyno where they can check connections in person both problems were solved in 10 minutes. So no its not anymore stupid than continued trips to the dealer where they say everything is fine. Data log will show issues but what good does it do from a guy 1000 miles away who can't look at the car? He doesn't necessarily need the car tuned. Just hooked up to the rollers and have his logs checked in person.

I think we were both a bit confused by "dyno tune". You are referring to having someone use a dyno as a troubleshooting tool, which makes sense to me....as opposed to actually tuning the car.

I'm all for that, but I've been to the two local (St. Louis area) guys, and one suggested I go to the dealer, the other told me he had applicable software...but when I arrived, his story changed to "I don't have the software to look at 2015+".

I'm all for it, if someone can recommend a reputable tuner within 4-5hrs of St.Louis.

As you can see your angle actual and voltage are inverse from each other and move with each other. You want to compare throttle to accel pedal. I think its doing what it should be doing.



Looking at your fuel, I don't see anything wrong. LTFT are +/- 1%. STFT are +/- 4-6%. This is totally normal. Your measured lambda is exactly where it should be with no deviations.



Your cam movement is normal as well. When the load goes up (from A/C, alternator load, ETC.) the exhaust cams retard to boost engine torque to handle extra load.



Looking at the air flow from your MAF it looks fine as well. thottle body moves with load to increase airflow. It does it with out the driver knowing or needing to move their pedal. You do get torque source 13 intermittently when load increases. This could be what you are feeling.



Torque source 13 is OSCMOD / Anti-Shuffle. This mode is to reduce the chance of bucking and surging from starting that can occur from the engine or drivetrain changes during steady state accelerator pedal conditions.
When TQ source happens you can see spark is reduced and fuel is kept stoich. When it doesnt happen your fuel goes rich for a couple seconds.


I would say try to note where you are feeling the surging/hesitation and if it correlates with the TQ source 13 or when it misses the TQ source 13 and load increases. This can be disabled in a aftermarket tune if it does correlate. If it correlates with a missed torque source 13 your dealer may need to update the ECU's tune.

Can you get a log with output shaft RPM? you can compare it to engine RPM and vehicle speed to isolate where the surging/hesitation may be coming from.

I pulled some logs tonight, while the car was running smoothly, pulled cleanly to redline, and the driveability issues were essentially gone.

The below is a snapshot of a log taken at cruising, where hesitation is normally most prevalent


This is a snapshot of a clean WOT pull. Not sure if it helps, but it looks like the cams are consistently together

What kind of fuel are you running?

Always 93 octane and various stations..i haven't noticed any correlation between the issues and gas type

I went back to one of my logs where i could feel the hesitation...check out the below snapshot. You can see the STFT% are as much as 10%. From the very little i know so far, it seems like this is too much? It looks like the torque source is correlated to the STFT, and it looks like it is really active. I did not have output RPM selected during this log.

I haven't had the opportunity to log this issue again. It has been running pretty solidly the past few days.

How many miles on the car? I would try some CRC GDI cleaner if over 10k. Direct injection is great but intake valves stay dry and don't get fuel washed with detergents can build up some carbon. When I had my 13 mustang I was using methanol so never had to worry about this. In my DD now 2.0t 15 sonata at 15k my car had a very noticeable cold start, part throttle hesitation, and drop off in mpg's. One can of the GDI cleaner followed instruction all was good. Now at 30k coming back will have wash and repeat.

mhyjek said:

How many miles on the car? I would try some CRC GDI cleaner if over 10k. Direct injection is great but intake valves stay dry and don't get fuel washed with detergents can build up some carbon. When I had my 13 mustang I was using methanol so never had to worry about this. In my DD now 2.0t 15 sonata at 15k my car had a very noticeable cold start, part throttle hesitation, and drop off in mpg's. One can of the GDI cleaner followed instruction all was good. Now at 30k coming back will have wash and repeat.

Click to expand...

These cars use port injection.

The 2018s have direct and port.