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Discussion Starter · #1 ·
Hi all,
I took order of a new 2021 Macan GTS and noticed a few issues that I cannot seem to wrap my head around. It’s been in and out the shop several times already and nothing seems to be getting better no matter what repairs are done. I am currently dealing with 2 very strange issues.

Issue 1:
When starting the car and waiting for the engine to idle to normal RPM I notice a consistent stumble that occurs as the engine RPMs drop and can see a RPM fluctuation between 610-580ish once the engine is at normal idle. It almost feels like the engine is starving for air. During this stumbling you can hear it in the exhaust note and hear it from the front of the car as the engine RPMs fluctuate. This issue happens even if I drive the car and all fluids are up to temp. I did a 2 hour highway drive and arrived at my destination. Parked my car and let it sit idle for a bit and sure enough, the stumbling started.

I took it in for service and when sitting in the drop of bay you could clearly hear the exhaust note sounded completely off as if the timing on the engine was wrong. The SA acknowledged this and confirmed that this was not normal. He even noticed the RPM fluctuation. After service I was told that I had 3 bad plugs all on one side of the engine bank with incorrect gaps from the factory causing a misfire. I found this very hard to believe but who knows. The plugs were replaced, the car was road tested and I was reassured that everything is ok now.

After picking up the car and driving for about 30 mins I noticed the issue was not fixed and still had a very noticeable stumble. It almost seems worse now. The car is going back in for service but don’t like playing wack-o-mole with a brand new car and replacing part after part and maybe... fixing the issue.

Issue 2:
When car is in “Normal” engine mode and comes to a gradual stop the engine will shift from 2nd to 1st gear. During this shift the car lunges forward once the shift takes place. It’s not engine braking but more like a slight acceleration once the down shift occurs. It’s coming to a point that when pulling into a parking spot and creeping forward in the spot I have to be extra careful and time the shift and apply more brakes otherwise the car will lunge into whatever is in front of me. It’s a very noticeable jerk forward.

I was able to find another article on the forums about this that described my issue exactly but could not find a resolution or reason for it.

I don’t know what to do at this point besides just keep bringing the car in for service. Any advice or help would be much appreciated!!
 

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I suspect that the transmission shifting issue is tied into the engine problems. It is computer controlled based on a "normal" engine operation and it's probably getting mixed signals.

There is probably a bad crank sensor, vacuum sensor or some other thing that is going to require the dealer's more experienced mechanic to actually diagnose instead of guessing and throwing parts at it. Based on the fact that you had three spark plugs not gapped/ torqued properly, someone at the factory was having a bad day.

Be polite but firm with the service manager about this, insist that he keep the car for few days to check everything on the engine and enjoy your loaner vehicle in the meantime.
 

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Consider the possibility of water contamination in the fuel tank. The gasoline will float on top of the water, which will temporarily
mix from sloshing about. When the water in the fuel reaches the combustion chamber, it will not burn and results in a misfire.

Do you live in a climate where the temperature varies? Condensation can develop in the fuel tank. The same happens at filling stations.
Sediment is another possibility with filling station tanks. Did you refuel your Macan while a tanker truck was delivering fuel at a filling
station?

While the root cause for your issue(s) may be complicated or complex, it seems always best to try the simplest things first, then
work your way to the more convoluted causes.


Good luck!
 

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Discussion Starter · #4 ·
I suspect that the transmission shifting issue is tied into the engine problems. It is computer controlled based on a "normal" engine operation and it's probably getting mixed signals.

There is probably a bad crank sensor, vacuum sensor or some other thing that is going to require the dealer's more experienced mechanic to actually diagnose instead of guessing and throwing parts at it. Based on the fact that you had three spark plugs not gapped/ torqued properly, someone at the factory was having a bad day.

Be polite but firm with the service manager about this, insist that he keep the car for few days to check everything on the engine and enjoy your loaner vehicle in the meantime.
Thank you for the reply. I spoke to the SA when I scheduled my appointment and advised that it sounds like it maybe a vacuum issue or along those lines. I will definitely be a bit firmer and insist they keep the car until the issue is fixed.
 

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Discussion Starter · #5 ·
Consider the possibility of water contamination in the fuel tank. The gasoline will float on top of the water, which will temporarily
mix from sloshing about. When the water in the fuel reaches the combustion chamber, it will not burn and results in a misfire.

Do you live in a climate where the temperature varies? Condensation can develop in the fuel tank. The same happens at filling stations.
Sediment is another possibility with filling station tanks. Did you refuel your Macan while a tanker truck was delivering fuel at a filling
station?

While the root cause for your issue(s) may be complicated or complex, it seems always best to try the simplest things first, then
work your way to the more convoluted causes.


Good luck!
I live in the north east and the humidity here is not bad at the moment. At this point I don’t suspect contaminated fuel. I only notice the engine stumble during idle. Normal driving I don’t really feel any negative effects or at least I cannot tell.
 

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I live in the north east and the humidity here is not bad at the moment. At this point I don’t suspect contaminated fuel. I only notice the engine stumble during idle. Normal driving I don’t really feel any negative effects or at least I cannot tell.

You can lead a horse to water, but you can't make him drink.

You posted in the forum because you don't know what the root cause for the issue is - only the symptoms.

Whether you suspect something as a root cause or not is irrelevant at this point. You seem to have already decided what it is not.


In the end, it's your time and money.
 

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Hi all,
I took order of a new 2021 Macan GTS and noticed a few issues that I cannot seem to wrap my head around. It’s been in and out the shop several times already and nothing seems to be getting better no matter what repairs are done. I am currently dealing with 2 very strange issues.

Issue 1:
When starting the car and waiting for the engine to idle to normal RPM I notice a consistent stumble that occurs as the engine RPMs drop and can see a RPM fluctuation between 610-580ish once the engine is at normal idle. It almost feels like the engine is starving for air. During this stumbling you can hear it in the exhaust note and hear it from the front of the car as the engine RPMs fluctuate. This issue happens even if I drive the car and all fluids are up to temp. I did a 2 hour highway drive and arrived at my destination. Parked my car and let it sit idle for a bit and sure enough, the stumbling started.

I took it in for service and when sitting in the drop of bay you could clearly hear the exhaust note sounded completely off as if the timing on the engine was wrong. The SA acknowledged this and confirmed that this was not normal. He even noticed the RPM fluctuation. After service I was told that I had 3 bad plugs all on one side of the engine bank with incorrect gaps from the factory causing a misfire. I found this very hard to believe but who knows. The plugs were replaced, the car was road tested and I was reassured that everything is ok now.


Issue 2:
When car is in “Normal” engine mode and comes to a gradual stop the engine will shift from 2nd to 1st gear. During this shift the car lunges forward once the shift takes place. It’s not engine braking but more like a slight acceleration once the down shift occurs. It’s coming to a point that when pulling into a parking spot and creeping forward in the spot I have to be extra careful and time the shift and apply more brakes otherwise the car will lunge into whatever is in front of me. It’s a very noticeable jerk forward.


I don’t know what to do at this point besides just keep bringing the car in for service. Any advice or help would be much appreciated!!
How many miles on the vehicle? When brand new on a cold engine my stops were a bit harsh like you're saying but never enough where I thought I would hit something. I think it will get better with miles as I'm at 3000 now and can't remember the last time I noticed it.
Issue 1, sounds like you have some mechanical experience if you're telling the SA "it feels like a vacuum leak". I would let them go through the process for misfire which is fuel, air leaks, plugs, coils, fuel injectors.
 

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Discussion Starter · #8 ·
How many miles on the vehicle? When brand new on a cold engine my stops were a bit harsh like you're saying but never enough where I thought I would hit something. I think it will get better with miles as I'm at 3000 now and can't remember the last time I noticed it.
Issue 1, sounds like you have some mechanical experience if you're telling the SA "it feels like a vacuum leak". I would let them go through the process for misfire which is fuel, air leaks, plugs, coils, fuel injectors.
The vehicle has about 2000 miles on it. I do have a bit of mechanical knowledge. My father was a car mechanic for 30+ years and I have done my fair bit of work myself. My suggestion to the SA was more of a “take a look at this” instead of me trying to diagnose it for them. The car had work done to the front end when I first got it and a ground wire was not attached properly which caused a radiator fan failure amongst other codes. I am just not sure what other sensors in the front of the car might have been affected by this. Thanks for the advice!
 

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Discussion Starter · #10 ·
Brand new car had work to it? This is something you should have mentioned in the OP. What is the background of the car? This changes everything.
It’s a pretty lengthy story. I had originally taken delivery of a 2020 Macan GTS. After having the 2020 for 3 weeks and around 700 miles the car had a a major suspension issue. The airbag suspension got stuck at top ride height and peak stiffness. This generated a code and the car was brought straight to the dealership for diagnosing. The suspension compressor was replaced 2 times, wiring checked, road tested and they could not figure out the issue. They even worked with Porsche in Germany to help troubleshoot. After having the car for about 4 weeks in the shop, they replaced the valve system that controls the distribution of air to each airbag. After that the issue appeared to be resolved. During this whole operation the GM of the dealer offered to put me into a brand new 2021 GTS seeing that this was my first Porsche and wanted me to have a better experience. For the 2020 I did not skimp on options and went all out. I was asked to order a 2021 but the issue was the PCCBs that I had on my 2020 were not available on the 2021 models. They agreed to swap over the PCCB setup to the 2021. This involved moving the calipers, mounting brackets, brake lines, brake shields, master cylinder, and brake booster. In order to perform the swap they needed to remove several components from the front end to reach the brake booster. Once the brake swap was done everything seemed good until the radiator fan code which didn’t pop up until after several drives.
 

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I can understand wanting to keep the carbons but having had them, whew a lot of aggravation to keep. Anyway, it is certainly possible you have a loose hose or connection somewhere from the minor surgery they did to replace the brake booster. As an armchair mechanic it is pretty tough to figure out. I would connect a scan tool and interrogate individual cylinders to see whether these misfires are registering.
 

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I’m not a professional mechanic, just a hobby or enthusiast.

Nobody sets the gap on plugs anymore, there factory set by machines. I’m sure your running Bosch double platinum or iridium which is pretty bullet proof. The Engine is still OBD2 andUS Federal smog compliant, CARB compliant and is a pretty robust computer system. There would of been codes that pointed to misfires on bank one or two, which is the end result of some other failure so they changed the plugs and checked the gaps. there could be other codes in the DCT before the misfire.

anyways being a new car, can’t be crud built up between the throttle body butterfly and throat bore, causing erratic air to leak into the intake port runners. I would say it’s a faulty ICT solenoid that controls air pass the closed butterfly through a secondary air passage for smooth idle at cold startup or proper operating temperature. The computer only really kicks in controlling proper fuel air ratios to reduce pollution when accelerating or diving at a constant speed. Really it’s about keeping the catalytic converter happy even if it waste unburned fuel to keep the converter cool.

Im just having fun here and testing my knowledge. But thats what I would look at first because I would try to actually fix it if the dealer had no clue. Maybe the solenoid wire is just unplugged.
 

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Sadly, while your Porsche dealer attempts further troubleshooting, You should familiarize yourself with your state's Lemon Laws.
BTW, that brand new 2021 GTS that your dealer offered you & you accepted....Was that car factory ordered by you? Or was it a lot car or one driven by dealership staff?

Having so much trouble with 2 new Macans seems very unusual. Terrible "luck.'

I hope you get it fixed to your satisfaction.

If they do fix it, maybe ask for a N/C extended warranty for your trouble?
 

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Discussion Starter · #15 ·
I’m not a professional mechanic, just a hobby or enthusiast.

Nobody sets the gap on plugs anymore, there factory set by machines. I’m sure your running Bosch double platinum or iridium which is pretty bullet proof. The Engine is still OBD2 andUS Federal smog compliant, CARB compliant and is a pretty robust computer system. There would of been codes that pointed to misfires on bank one or two, which is the end result of some other failure so they changed the plugs and checked the gaps. there could be other codes in the DCT before the misfire.

anyways being a new car, can’t be crud built up between the throttle body butterfly and throat bore, causing erratic air to leak into the intake port runners. I would say it’s a faulty ICT solenoid that controls air pass the closed butterfly through a secondary air passage for smooth idle at cold startup or proper operating temperature. The computer only really kicks in controlling proper fuel air ratios to reduce pollution when accelerating or diving at a constant speed. Really it’s about keeping the catalytic converter happy even if it waste unburned fuel to keep the converter cool.

Im just having fun here and testing my knowledge. But thats what I would look at first because I would try to actually fix it if the dealer had no clue. Maybe the solenoid wire is just unplugged.
Thanks for the useful information here. I am hoping it’s just a loose/bad connection somewhere, sensor or solenoid. Car goes back in on Monday.
 

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Discussion Starter · #16 ·
Sadly, while your Porsche dealer attempts further troubleshooting, You should familiarize yourself with your state's Lemon Laws.
BTW, that brand new 2021 GTS that your dealer offered you & you accepted....Was that car factory ordered by you? Or was it a lot car or one driven by dealership staff?

Having so much trouble with 2 new Macans seems very unusual. Terrible "luck.'

I hope you get it fixed to your satisfaction.

If they do fix it, maybe ask for a N/C extended warranty for your trouble?
It was brand new factory ordered by me. At this point my wife wonders why I bought a Porsche since we have had 2 so far and only issues to speak of. At this point I am very well versed in the lemon laws here after the first car. I am hoping this gets resolved cause I love the car a lot!
 

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I (too) get this “stumble” scenario from time to time... it probably happens, maybe once or twice a month, only on a start up. But my GTS is pushing 65K, so I figure it’s going to have its moments. Until it throws a code or becomes a daily issue, I’m not bothering with it.

Really sorry this is happening to your brand new ride, and the fact you had to trade back in your original build. Hopefully this gets solved quickly.


Sent from my iPhone using Tapatalk
 

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@jkerkirks
I’m not a professional mechanic, just a hobby or enthusiast.

Nobody sets the gap on plugs anymore, there factory set by machines. I’m sure your running Bosch double platinum or iridium which is pretty bullet proof. The Engine is still OBD2 andUS Federal smog compliant, CARB compliant and is a pretty robust computer system. There would of been codes that pointed to misfires on bank one or two, which is the end result of some other failure so they changed the plugs and checked the gaps. there could be other codes in the DCT before the misfire.

anyways being a new car, can’t be crud built up between the throttle body butterfly and throat bore, causing erratic air to leak into the intake port runners. I would say it’s a faulty ICT solenoid that controls air pass the closed butterfly through a secondary air passage for smooth idle at cold startup or proper operating temperature. The computer only really kicks in controlling proper fuel air ratios to reduce pollution when accelerating or diving at a constant speed. Really it’s about keeping the catalytic converter happy even if it waste unburned fuel to keep the converter cool.

Im just having fun here and testing my knowledge. But thats what I would look at first because I would try to actually fix it if the dealer had no clue. Maybe the solenoid wire is just unplugged.
This is brand new car and you should not try fixing anything yourself; this could be a lemon case. This state it takes three tries to fix same problem or 30 days in the shop the first 12 months. First you have to have documentation from dealer that there is something wrong. Make sure they give you a copy each time you take it in of what your complaint is and what they did to fix it. Make sure your complaint is worded the same every time you take it so you can protect your lemon claim.
A lot of what @jkerkirks said doesn't apply but he admitted he's just having fun. This car has DI and the computer controls the A/F mixture 100% of the time. The best self diagnosis you could do would be buying a cheap scan tool and see whether any codes or misfires are logging.
 

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ALL: Please note in the OP's post above this vehicle has previously had some significant work performed on it to swap
in a carbon ceramic braking system. It also experienced an issue with the Air Suspension system. This is a 2021 Macan
with not a lot of miles under its belt.

The best place to get its issues sorted out is most likely a Porsche dealership, since it is under warranty.

I understand people mean well trying to electronically and remotely diagnose this Macan's ills, however we don't have the complete
background for the vehicle, nor a comprehensive understanding of all of the systems touched, disassembled and reassembled and/or
modified in its service history.

The people with the most experience, not to mention factory training, are to be found at the dealership. Further, the Porsche dealership
warranties its service work. If the OP goes in and fiddles around with things, and its detected by a Porsche tech, it won't be pretty.

Hopefully, the OP will be able to report back to the forum just what the root cause(s) were, as determined by Porsche, for the anomalies he's reported.


Good luck!
 

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Hi all,
I took order of a new 2021 Macan GTS and noticed a few issues that I cannot seem to wrap my head around. It’s been in and out the shop several times already and nothing seems to be getting better no matter what repairs are done. I am currently dealing with 2 very strange issues.

Issue 1:
When starting the car and waiting for the engine to idle to normal RPM I notice a consistent stumble that occurs as the engine RPMs drop and can see a RPM fluctuation between 610-580ish once the engine is at normal idle. It almost feels like the engine is starving for air. During this stumbling you can hear it in the exhaust note and hear it from the front of the car as the engine RPMs fluctuate. This issue happens even if I drive the car and all fluids are up to temp. I did a 2 hour highway drive and arrived at my destination. Parked my car and let it sit idle for a bit and sure enough, the stumbling started.

I took it in for service and when sitting in the drop of bay you could clearly hear the exhaust note sounded completely off as if the timing on the engine was wrong. The SA acknowledged this and confirmed that this was not normal. He even noticed the RPM fluctuation. After service I was told that I had 3 bad plugs all on one side of the engine bank with incorrect gaps from the factory causing a misfire. I found this very hard to believe but who knows. The plugs were replaced, the car was road tested and I was reassured that everything is ok now.

After picking up the car and driving for about 30 mins I noticed the issue was not fixed and still had a very noticeable stumble. It almost seems worse now. The car is going back in for service but don’t like playing wack-o-mole with a brand new car and replacing part after part and maybe... fixing the issue.

Issue 2:
When car is in “Normal” engine mode and comes to a gradual stop the engine will shift from 2nd to 1st gear. During this shift the car lunges forward once the shift takes place. It’s not engine braking but more like a slight acceleration once the down shift occurs. It’s coming to a point that when pulling into a parking spot and creeping forward in the spot I have to be extra careful and time the shift and apply more brakes otherwise the car will lunge into whatever is in front of me. It’s a very noticeable jerk forward.

I was able to find another article on the forums about this that described my issue exactly but could not find a resolution or reason for it.

I don’t know what to do at this point besides just keep bringing the car in for service. Any advice or help would be much appreciated!!
 
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