2011 Shelby studdering on the way home tonight.

[forsho]

Car started to studder under full throttle on the way home from dinner tonight. Seems to be fine and idle perfectly when driving normally. I have been able to repeat it only under load/boost. If I put it under a heavy load in 3rd and 4th it will break up a bit. Popped the hood when I just got home and nothing looks amiss. Figured that I would let it cool off and check the plugs tomorrow (probably 15K miles on NJK's, since pulley/tune/intake upgrade). Nothing has changed with the car otherwise and everything else is working normally as its a daily driver and gets miles on the regular, no codes, no lights, but I can feel it. Had to do a few short lower 3-5K RPM pulls before the wife could feel the studder as well. I've got Lund tuner in the car and logged a few of the times that I duplicated the studder, once I get a few things done at home I'll pull/post the logs.

Anything that I should check first, am I wasting time checking the plugs?

What should the plugs be gapped at, might as well check that also.

 

[heatsoaked12]

I'd check the fuel filter before any more pulls.

 

[1st usa car]

I am assuming you have a step colder plug.. I am going to guess around .30 -.32 for your boost/power levels.... but verify with your tuner.

 

[forsho]

thanks all... I'm going to pick up a ford fuel filter in the AM (car is turning 50k) and I know that the existing one has been on it since 20K. I plan to pull the plugs and check them also. Any more suggestions once I get it up in the air?

 

[leafmaple]

have you changed he clutch yet? when it's starting to let go it feels like a light shudder under high load.

Sent from my SM-G950W using Tapatalk

 

[forsho]

here are 3 logs from my nguage, they are quick pulls in 3rd and 4th. Any input as to why it's missing or whatever is MUCHO appreciated.

 

[forsho]

have you changed he clutch yet? when it's starting to let go it feels like a light shudder under high load.

Sent from my SM-G950W using Tapatalk

no.... but I'm confident it's not the clutch - look at the logs, something is up.

From what I'm reading - looks like I'm overdue on a fuel filter change, and these NGK TR6's that came in my Lethal Performance combo are not long life plugs. After 30k miles daily driving sounds like they might be done.

 

[MastaAce03]

no.... but I'm confident it's not the clutch - look at the logs, something is up.

From what I'm reading - looks like I'm overdue on a fuel filter change, and these NGK TR6's that came in my Lethal Performance combo are not long life plugs. After 30k miles daily driving sounds like they might be done.

30k on TR6s is definitely a lot of miles. You're getting up to a degree of knock sensor activity in some of the logs, which is not much. I'd venture to say what you're feeling is definitely not detonation or preignition. New plugs should solve your issue.


Sent from my iPhone using Tapatalk

 

[moncho]

30k on TR6s is definitely a lot of miles. You're getting up to a degree of knock sensor activity in some of the logs, which is not much. I'd venture to say what you're feeling is definitely not detonation or preignition. New plugs should solve your issue.


Sent from my iPhone using Tapatalk

1st off I'm not or don't pretend to be someone that is versed on reading datalogs. Just trying to help by using some logic interpreting the logs. The log0027 seems to show the studder at about 2100-2200 RPM. At this same time spark takes a huge hit and engine load spikes. I would start with the plug replacement as mentioned above. I'm sure I'll be corrected by more knowledgeable folks if I'm way off.

Good Luck!

 

[HillbillyHotRod]

Question? How does one read those. They are in csv format. What is needed to read those. Never have read the logs so do not know what they are saying.

 

[MastaAce03]

Question? How does one read those. They are in csv format. What is needed to read those. Never have read the logs so do not know what they are saying.

I'm using an IPhone. When I download the attachment, I open it with Excel and it puts it on a spread sheet.


Sent from my iPhone using Tapatalk

 

[HillbillyHotRod]

When I download it on the pc it opens with open office. It appears to be a spreadsheet but I have no way knowing what all these number are as the all seem to be about the same. Not a tuner or anything, just trying to learn something.

 

[CobraBob]

Question? How does one read those. They are in csv format. What is needed to read those. Never have read the logs so do not know what they are saying.

FYI, a CSV extension means it is a 'comma separated values' file. It can be read with any spreadsheet program (Excel, Open Office Calc, Google Spreadsheet, etc.

 

[jenkins_1120]

Belt slip?


Sent from my iPhone using Tapatalk

 

[moncho]

Launch LiveLink & open file "log027" after you DL it. Now click on top left corner, open, Datalog (*.csv), now find where you DL'ed the file. Once you do this the file will populate LiveLink. Now you click on each PID, note the color on the right as that's the color that highlights on the gragh. This makes it a bit easier to correlate what's going on.

Cheer,
Ray

 

[moncho]

Belt slip?


Sent from my iPhone using Tapatalk

Was studder a symptom when you had belt slip?

 

[HillbillyHotRod]

Launch LiveLink & open file "log027" after you DL it. Now click on top left corner, open, Datalog (*.csv), now find where you DL'ed the file. Once you do this the file will populate LiveLink. Now you click on each PID, note the color on the right as that's the color that highlights on the gragh. This makes it a bit easier to correlate what's going on.

Cheer,
Ray

Thanks that is what I was looking for. Now if had the faintest idea what that all meant.

 

[moncho]

Thanks that is what I was looking for. Now if had the faintest idea what that all meant.

Since the OP was having studder or sudden drop in RPM, that's what I keyed on. The file I referenced, the 1st PID (RPM) shows a sharp drop @ about 2100-2200 RPM. You then click on the next PID's one at a time and look for any other sudden change @ that same time. 2 things popped up - spark TDC (sharp drop) & load (sharp rise). So since spark dropped as the load increased the RPM or power dropped. For plugs that have 30k miles & are recommended to be replace @ about 12k that would be the 1st thing I would suspect. I'm probably missing other things on this log as this is something new to me as well.

Cheers,
Ray

 

[forsho]

thanks all.... so I've had to order the NGK TR7IX and they will be in Tuesday, I've got a Motorcraft fuel filter coming as well. I actually have a replacement belt I had already purchased assuming that I would need it shortly. Is the consensus that the belt is slipping? I'm not picking up any dust in the engine bay and the belt looks to be in great condition. ( I guess not a bad idea anyways)

 

[forsho]

I am assuming you have a step colder plug.. I am going to guess around .30 -.32 for your boost/power levels.... but verify with your tuner.

yeah the TR6's are in it, I've order the TR7IX set that everyone recommends, I'm running a Lund tune for my mods (see sig) 93oct. I was planning to gap these new ones at .30. Any input?