2011 XFR: Strange engine performance issues, no codes
#1
2011 XFR: Strange engine performance issues, no codes
Approximately 3 weeks ago something odd started happening with my XFR. I would start the car in the morning, letting it go through it's warmup routine as always, put it in reverse, then slowly back out of the driveway. During this time, the car would hesitate, with an rpm drop like it wanted to stall, but it never did.
After backing out of the driveway and putting the car in drive, it never hesitated like this. I've noticed is that the idle is a little "off" in that it doesn't feel rough, but isn't buttery smooth either. What's doubly odd is that the engine is pulling stronger than usual, as if it's in dynamic mode, though that isn't the case. It stays in gears longer than usual for some reason, though shifts are still smooth.
I've noticed is that occasionally I will see the average mpg display drop noticably -- one time I watched it go from a rather solid 15.6 mpg down to 14.1 over the course of a 9 mile drive. And this was to a rolling average based on over 2000 miles of driving. I have since reset the counter and it has held pretty steady.
And today I noticed that sometimes if I rev the engine and let my foot off the gas suddenly, the revs don't start to change until 1-1.5 seconds AFTER my foot was off the gas.
Dealership cleaned the throttle body but it made no difference. In fact, I'd say the problem has gotten worse since then. They suggested we try replacing the MAF sensors, but I wasn't going to give them $1100 for parts and labor based on a guess.
All this and not a single code! Any ideas what might be going on here?
After backing out of the driveway and putting the car in drive, it never hesitated like this. I've noticed is that the idle is a little "off" in that it doesn't feel rough, but isn't buttery smooth either. What's doubly odd is that the engine is pulling stronger than usual, as if it's in dynamic mode, though that isn't the case. It stays in gears longer than usual for some reason, though shifts are still smooth.
I've noticed is that occasionally I will see the average mpg display drop noticably -- one time I watched it go from a rather solid 15.6 mpg down to 14.1 over the course of a 9 mile drive. And this was to a rolling average based on over 2000 miles of driving. I have since reset the counter and it has held pretty steady.
And today I noticed that sometimes if I rev the engine and let my foot off the gas suddenly, the revs don't start to change until 1-1.5 seconds AFTER my foot was off the gas.
Dealership cleaned the throttle body but it made no difference. In fact, I'd say the problem has gotten worse since then. They suggested we try replacing the MAF sensors, but I wasn't going to give them $1100 for parts and labor based on a guess.
All this and not a single code! Any ideas what might be going on here?
#2
Join Date: Feb 2014
Location: Adelaide, South Australia
Posts: 8,303
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#3
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#6
Similar thing happened to me. Started my XF in the morning and felt like it was struggling to reverse out of my drive way. It felt like the brakes were sticking slightly. I didn't look at the rpms.
On my driveway slope I put car in park and did walk around didn't notice anything. Then I decided to shut engine off and restart. On the the start loud noise came from engine compartment closer to passenger side. Eventually the sound went away like in 6 seconds.Driving it around I had transmission issues with gears slipping from 2-3 and the lurch on slow stop. Booked an appointment with JLR service. Over course of a week the symptoms dampened out and car healed itself. when I finally got it in the dealership it was pretty much No fault found - no codes or symptoms.It's strange
#7
Any chance it could be carbon build up from the DI system?
Have you had a Motorvac service done?
https://www.motorvac.com/index.cfm?id=66616
Just a thought?
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Have you had a Motorvac service done?
https://www.motorvac.com/index.cfm?id=66616
Just a thought?
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#9
Similar thing happened to me. Started my XF in the morning and felt like it was struggling to reverse out of my drive way. It felt like the brakes were sticking slightly. I didn't look at the rpms.
On my driveway slope I put car in park and did walk around didn't notice anything. Then I decided to shut engine off and restart. On the the start loud noise came from engine compartment closer to passenger side. Eventually the sound went away like in 6 seconds.Driving it around I had transmission issues with gears slipping from 2-3 and the lurch on slow stop. Booked an appointment with JLR service. Over course of a week the symptoms dampened out and car healed itself. when I finally got it in the dealership it was pretty much No fault found - no codes or symptoms.It's strange
If you make any discoveries, let me know. I will be sure to do the same!
Last edited by BigMikeATL; 01-06-2018 at 05:36 PM.
#10
#11
Any chance it could be carbon build up from the DI system?
Have you had a Motorvac service done?
https://www.motorvac.com/index.cfm?id=66616
Just a thought?
.
.
.
Have you had a Motorvac service done?
https://www.motorvac.com/index.cfm?id=66616
Just a thought?
.
.
.
#12
#13
$1100 to replace the MAF sensors!!!
They are taking you for a ride, they take 10 minutes tops to replace and shouldn't cost more than $100 for a new pair, heaps on Fleabay at around $50 each.
Worth a try to clean them yourself, a 10 minute job, just get a spray can of MAF sensor cleaner.
They are taking you for a ride, they take 10 minutes tops to replace and shouldn't cost more than $100 for a new pair, heaps on Fleabay at around $50 each.
Worth a try to clean them yourself, a 10 minute job, just get a spray can of MAF sensor cleaner.
#14
$1100 to replace the MAF sensors!!!
They are taking you for a ride, they take 10 minutes tops to replace and shouldn't cost more than $100 for a new pair, heaps on Fleabay at around $50 each.
Worth a try to clean them yourself, a 10 minute job, just get a spray can of MAF sensor cleaner.
They are taking you for a ride, they take 10 minutes tops to replace and shouldn't cost more than $100 for a new pair, heaps on Fleabay at around $50 each.
Worth a try to clean them yourself, a 10 minute job, just get a spray can of MAF sensor cleaner.
#15
Join Date: Feb 2014
Location: Adelaide, South Australia
Posts: 8,303
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It seems all the cheap ones on Fleabay (eg here: https://www.ebay.com.au/itm/Mass-Air...QAAOSwtGlZBFE9) are used, not new, which means there is no guarantee they are any better than your existing ones.
The new ones (eg here: https://www.ebay.com/itm/Mass-Air-Fl...pZfx4-&vxp=mtr) cost a lot more, US $176 and higher.
#16
#18
Did you look at the link I posted?
It has the products listed by name and part number and I would at least try one bottle. I can't see that it would hurt anything?
Just remember that you can't dump it in the gas tank. You need to have the engine running and use the engine vacuum to suck it in thru the intake tract. The bottle will have some basic instructions on it.
If you do try it please post back as all of us with DI engines will run into this at some point. I don't know if regular cleaning will help or not? Some engines require dismantling to get at the carbon.
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It has the products listed by name and part number and I would at least try one bottle. I can't see that it would hurt anything?
Just remember that you can't dump it in the gas tank. You need to have the engine running and use the engine vacuum to suck it in thru the intake tract. The bottle will have some basic instructions on it.
If you do try it please post back as all of us with DI engines will run into this at some point. I don't know if regular cleaning will help or not? Some engines require dismantling to get at the carbon.
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#19
Maybe that's what the dealership did. I don't think they specified what sort of cleaner they used.
#20
So, got a code reader. Not one. Damn. Code.
I also looked at the data from the engine and nothing is out of the ordinary. Fuel trims are good, data from the MAFs, O2 sensors, etc are all nominal.
I speculated that there could be a vacuum leak and whipped out a can of carb cleaner, but it did not reveal anything.
I'm at a loss here...
I also looked at the data from the engine and nothing is out of the ordinary. Fuel trims are good, data from the MAFs, O2 sensors, etc are all nominal.
I speculated that there could be a vacuum leak and whipped out a can of carb cleaner, but it did not reveal anything.
I'm at a loss here...