2015 SHO Stumbling/Bogging Down

[SpencerH]

Hey y'all,

About 6 months ago, I bought my first SHO and absolutely love the car, but in the last few months I have started having some weird issues with it. When I first got it, there were no weird power drops at any RPM. Recently, I have noticed that when I give the car any throttle over about half, I can feel the turbos spool up and the car starts to take off, but once it hits around 3000 RPM I can feel it start to bog down. What is weird is that it will stumble for a second or two and I notice the RPMs climb much slower, then around 4000 RPM it starts pulling again and it runs fine up until it shifts. As long as it stays above ~4000 RPM between shifts, it seems to run as it should.

When I first noticed the issue, I pulled off the intake tube that goes into the throttle body along with the the MAF and noticed the sensor was dirty. I cleaned off the MAF and I also noticed about 1/2" of oil in the intercooler which I drained out. This seemed to help but didn't fix the issue. Since I bought it from a dealer, I took it into them but they were not able to find anything wrong with it. I have now taken it in a total 3 times and they still have not been able to come up with anything it could be. I asked them about the oil in the intercooler and they said that was normal for these cars?? If y'all have any idea what could be causing this weird stumble any input would be greatly appreciated. Thank you!

 

[ridered74]

I'd start with verifying you have motorcraft spark plugs and that they are gapped correctly. Stock should be around .034 if I remember correctly.

 

[CastorTroyN7]

Have you tried checking to see if there are any stored fault codes in the computer?
Not all codes will trigger a check engine light, but it may help you narrow down where the problem is.
A cheap Bluetooth ELM327 OBDII scanner with a program like Dash Commander, TorquePro, Car Scanner or similar application may help shed some light as well.
You can see all sorts of data in real time.

 

[SeanDev]

Check the boots on the coils, You might be throwing spark on hard throttle. By your description I think you cleaned the MAP pre throttle body, clean the MAF at the airbox, and clean both MAPs, and throttle body. I personally don't spray cleaner in the throttle body, best to spray paper towel and wipe it out. Disconnect it first, if left connected that butterfly can be a finger chopper. And if your going to pull the plugs might as well change them and the the boots on the coils.

 

[SpencerH]

Thank you for the replies! @CastorTroyN7 I forgot to mention that when this issue first started, I replaced the spark plugs and boots, and verified the gap on them. @SeanDev I believe that you are right that I only cleaned the pre-throttle body MAP sensor, I will pull the MAF at the airbox tomorrow morning. Other than the one right before the throttle body, where is the other MAP sensor located? @CastorTroyN7 I just ordered an OBDII scanner and will check for any stored fault codes. Thank you all for the help, I'll update if anything changes.

 

[ridered74]

Thank you for the replies! @CastorTroyN7 I forgot to mention that when this issue first started, I replaced the spark plugs and boots, and verified the gap on them. @SeanDev I believe that you are right that I only cleaned the pre-throttle body MAP sensor, I will pull the MAF at the airbox tomorrow morning. Other than the one right before the throttle body, where is the other MAP sensor located? @CastorTroyN7 I just ordered an OBDII scanner and will check for any stored fault codes. Thank you all for the help, I'll update if anything changes.

Other one is on top of intake manifold. Remove the engine cover if you still have it, the sensor will be right on top.

 

[Calgary]

what codes did you get?

 

[SpencerH]

Sorry for not updating for a while, went out of town for the week. I pulled the MAF and both MAP sensors and cleaned them. The MAP sensor on the intake manifold was a bit oily but unfortunately cleaning that did not fix the issue I've been having. I also ordered the code reader you mentioned (great little tool btw) and checked the codes on it. Nothing came up for the current or stored fault codes so I'm not really sure where to go from here. Any other ideas?

 

[Usmcpi]

There is no MAF on the SHO. The sensor by the intake filter is the IAT (intake air temperature).

Does this problem only happen between 3-4K RPM? Stock?

 

[SeanDev]

There is no MAF on the SHO. The sensor by the intake filter is the IAT (intake air temperature).

Does this problem only happen between 3-4K RPM? Stock?

That is my mistake, I'm still old school on sensors. You are correct it's a MAP at the airbox not a MAF.

 

[SpencerH]

All good! The car is stock. This issue only occurs between 3 and 4000 RPM, anything above or below that feels like normal acceleration.