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2020 XT5, AWD Platinum, Garnet Metallic, 20" Ultra-Bright
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How is exhaust gas recirculation implemented on the XT5? The engine has integrated the manifold in the cylinder head.
The exhaust gas recirculation is a nitrogen oxide (NOx) emissions reduction technique. Emission reduction engineering in the past used EGR valves to reduce the oxygen in the combustion chamber and as a result the temperature of the combustion chamber.

A detailed description of the engine design targeted at nitrogen oxide emissions reduction is hard to find, but the following features contribute to that end:
  • Oil-spray piston cooling
  • Improved Variable Valve Timing (VVT) with an ‘intermediate park’ feature
  • Reshaped piston tops to promote a better mix of the air and fuel during the direct injection process
  • New four-cam phasing system with intermediate park technology that enhances efficiency by enabling late inlet valve closing in certain conditions
  • All-new, patented “targeted” cooling system that provides strategic cooling of the engine’s hottest areas while simultaneously fostering faster warm-up to enhance efficiency
  • The new head design also has improved combustion chamber cooling enabled by the patented targeted cooling system, which reduces the chance for knock and enhance high-load efficiency.
Many of these design details are patented and closely held design secrets and therefore not readily published.
 

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2018 Cadillac XT5 Platinum AWD
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79 Posts
So no exhaust gas is returned in the LGX engine of the XT5 to coke the intake track and intake valves?
 

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2017 XT5
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984 Posts
A detailed description of the engine design targeted at nitrogen oxide emissions reduction is hard to find, but the following features contribute to that end:
  • Oil-spray piston cooling
  • Improved Variable Valve Timing (VVT) with an ‘intermediate park’ feature
  • Reshaped piston tops to promote a better mix of the air and fuel during the direct injection process
  • New four-cam phasing system with intermediate park technology that enhances efficiency by enabling late inlet valve closing in certain conditions
  • All-new, patented “targeted” cooling system that provides strategic cooling of the engine’s hottest areas while simultaneously fostering faster warm-up to enhance efficiency
  • The new head design also has improved combustion chamber cooling enabled by the patented targeted cooling system, which reduces the chance for knock and enhance high-load efficiency.
Many of these design details are patented and closely held design secrets and therefore not readily published.
It's a very unique and interesting design, and since this cools the combustion chamber significantly, it's why the engine can have a high compression ration but still operate efficiently on 87-octate rated fuel. If we could find the patents, then we could see the designs. That's the purpose of a patent - to be able to publish a design so (for example) a supplier can make parts, but the owner's rights to the design are protected.
 

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2020 XT5, AWD Platinum, Garnet Metallic, 20" Ultra-Bright
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So no exhaust gas is returned in the LGX engine of the XT5 to coke the intake track and intake valves?
I cannot find specific information regarding how much exhaust gas is returned during the intake stroke to achieve the NOX targets for the LGX, if any. If needed, it can be achieved by VVT creating valve overlap. All of these operational requirements are monitored by the ECM and adjusted constantly during all drive cycle events.
 

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did you buy certified pre owned from a caddy dealer? if so then you should have some warramty?

if you bought from a buy here pay there dealer then its probably something that a repair shop missed. almost sounds like motor mounts to me but im not an expert.
 

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2000 Deville DTS
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Hey guys, I was trying to figure out if the shakiness/vibration I’m feeling while I’m in the driver seat is normal? It feels to me as if changing the spark plugs is needed but my Xt5 only has 46,000 miles on it.
The main thing I’m wondering is since it is pre-owned and was sitting for a while, would that make the spark plugs wear out sooner than normal?
Engine mounts. Just saying.
 

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2010 CTS V
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72 Posts
Run 4 consecutive tanks of Techron throught it per instructions. Put it on the highway. It needs to be hot. Road trip it. If you have problems that will clear it up. If it does not, keep looking. There are other problems Techron is the best detergent additive in the business.
 

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Hey guys, I was trying to figure out if the shakiness/vibration I’m feeling while I’m in the driver seat is normal? It feels to me as if changing the spark plugs is needed but my Xt5 only has 46,000 miles on it.
The main thing I’m wondering is since it is pre-owned and was sitting for a while, would that make the spark plugs wear out sooner than normal?
Well, my 2006 SRX did the same after the previous owner let it sit for two years not using it. I got it for a one dollar, literally, not kidding, but I found out that the ECM went south. Had to have a new one ordered. The SRX shuddered and gave codes saying CYL-6 was misfiring and multiple misfires. By the way the ECM are very specific VIN# oriented. Cost, well $359 at Flagship one to $1103 at dealer. Hopefully that is not your problem. Scan it!
 

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2017 XT5 FWD
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18 Posts
Discussion Starter · #31 ·
did you buy certified pre owned from a caddy dealer? if so then you should have some warramty?

if you bought from a buy here pay there dealer then its probably something that a repair shop missed. almost sounds like motor mounts to me but im not an expert.
Yes it’s CPO and my dealer appointment is this Saturday. It feels like engine mounts as well so hopefully they can find the problem! Thanks!
 

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2010 CTS
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Hey guys, I was trying to figure out if the shakiness/vibration I’m feeling while I’m in the driver seat is normal? It feels to me as if changing the spark plugs is needed but my Xt5 only has 46,000 miles on it.
The main thing I’m wondering is since it is pre-owned and was sitting for a while, would that make the spark plugs wear out sooner than normal?
Dude it could be your engine mounts. I was having horrible vibration in my car as well but my car is way older (2010 CTS premium). I did the throttle body cleaning first and that did nothing for the shaking. So then I did the the engine mounts and that completely stopped all the vibrating.
 

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XTS-4 Vsport Platinum
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8 Posts
Hey guys, I was trying to figure out if the shakiness/vibration I’m feeling while I’m in the driver seat is normal? It feels to me as if changing the spark plugs is needed but my Xt5 only has 46,000 miles on it.
The main thing I’m wondering is since it is pre-owned and was sitting for a while, would that make the spark plugs wear out sooner than normal?
I agree with another poster to check the motor mounts for looseness, cracking or separation. If the idle speed is normal (not too low rpm) and if it accelerates ok, might just be normal engine shaking going undamped. Does flooring it from a standstill cause a momentary clunk or feeling like the tranny is slipping a bit? Motor mounts. Mileage is a little early, but maybe if the car has been driven hard a lot could be.
 

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So I had a similar issue from my 2017. After a few useless attempts, I replaced my battery, which I haven't changed before. The interesting part is that after battery replacement, it runs much smoother and I barely notice vibrations during parking. I don't know the root cause. But if you've never changed the battery and your auto-stop-start works less frequently or even stops working, it's time to change the battery. I know lots of people hate auto-stop-start, but I personally hate the vibrations more. The cost is around 300-400 bucks, AGM is expensive though.
 

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2006 STS 1SG & 2007 STS 1SE
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Haha no definitely not the safety alert! But I normally run Shell 87, but I will go for the premium for the next few to see any change. Thanks!


I actually haven’t tried to go for a hard run at all in the vehicle. I have had some experience with law enforcement and over here in Gretna, LA they are always looking to cause trouble. But I will have to go ahead and do that to see if it helps. Thanks!
 

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I agree with another poster to check the motor mounts for looseness, cracking or separation. If the idle speed is normal (not too low rpm) and if it accelerates ok, might just be normal engine shaking going undamped. Does flooring it from a standstill cause a momentary clunk or feeling like the tranny is slipping a bit? Motor mounts. Mileage is a little early, but maybe if the car has been driven hard a lot could be.

A bad motor mount is often the root cause after clean code report. If so, it may only be the drivers side.
 

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2017 XT5 FWD
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18 Posts
Discussion Starter · #37 ·
I think I found the problem. After almost 2 weeks of troubleshooting, I decided to give in and schedule my appointment with the dealer. But before I did, I decided to change the oil because I had a few days left and it had already been 3k miles on the current oil. Well, after servicing my vehicle, I checked the coolant reservoir and BAM! The SOB was not closed all the way, resulting in a lower than normal pressurized cooling system. Granted, it only needed a 1/16th of a turn to click in place, but I believe this was the culprit. After realizing, I opened the cap and let it cool down for a while (about 30 minutes). Cleaned the MAF & Went out for a ride and reset my throttle idle learn (idk if that specifically did anything honestly) and after about a 30 minute ride on the highway, I went home and let the bad boy cool overnight. This morning, woke up with barely any roughness on idle and a smooth ride other than a little noise from the Evap Purge Valve Solenoid which I’ll probably just end up replacing in the next couple days. And Other than when I release brake from complete stop it makes a groan/grind/thumping sound, but that’s for another thread!

Long story short, make sure the coolant cap is not loose because although I am lucky my heads aren’t blown, it could have had such a more terrible ending.

Now it’s time to flush out this coolant!!!
 

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2020 XT5, AWD Platinum, Garnet Metallic, 20" Ultra-Bright
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I think I found the problem. After almost 2 weeks of troubleshooting, I decided to give in and schedule my appointment with the dealer. But before I did, I decided to change the oil because I had a few days left and it had already been 3k miles on the current oil. Well, after servicing my vehicle, I checked the coolant reservoir and BAM! The SOB was not closed all the way, resulting in a lower than normal pressurized cooling system. Granted, it only needed a 1/16th of a turn to click in place, but I believe this was the culprit. After realizing, I opened the cap and let it cool down for a while (about 30 minutes). Cleaned the MAF & Went out for a ride and reset my throttle idle learn (idk if that specifically did anything honestly) and after about a 30 minute ride on the highway, I went home and let the bad boy cool overnight. This morning, woke up with barely any roughness on idle and a smooth ride other than a little noise from the Evap Purge Valve Solenoid which I’ll probably just end up replacing in the next couple days. And Other than when I release brake from complete stop it makes a groan/grind/thumping sound, but that’s for another thread!

Long story short, make sure the coolant cap is not loose because although I am lucky my heads aren’t blown, it could have had such a more terrible ending.

Now it’s time to flush out this coolant!!!
Cody, you are now promoted to Cadillac Master Technician.(y)
 

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2018 Cadillac XT5 Platinum AWD
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I can't imagine the cooling system leaking. Maybe it was the oil change? (Camshaft adjustment)
 
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