Help: Idle hunting/surging with video

[Hofahome]

I've been having this damn intermittant issue for several months now. Seemed to start when I was stuck in stop and go traffic during 100 degree heat (I think.) typically happens during warm weather or if I have just run the car a little hard. I wonder if it has to do with the k&n getting a little too dirty and screwing up one of the maf sensors. I cleaned the maf sensors and took off the throttle body today. Cleaned the crap out of them with maf cleaner. No difference. I do not have vag-com but used dashcommand to log. The commanded throttle position would go up to about 4.5% and the relative throttle position would follow it nicely. Thoughts?


https://youtu.be/xl022i6Pk34

[KnewJack]

Does it only happen during coast down. The video shows you slowing from 15mph to 0. What happens when you just sit at idle not rolling? Was the car in neutral?

[Hofahome]

Car in neutral, foot off clutch. It has happened completely at full stop.

[Hofahome]

From some research I think it might be related to the pcv/crankcase breather. I did have to put a quart of oil in since my last oil change, which has not happened before. At this point I am not sure if the plastic cracked or pcv valve is sticking intermittantly. Has anyone else experienced a pvc, breather or oil separator issue? Happens all the time on A4's but I have not seen issues on the 3.0t.

Oh and here is a video of my same symptoms on a b7 a4.

https://www.youtube.com/watch?v=XRsDd3XWXu0

[CELison]

Check for Vac leaks.

[Hofahome]

Check for Vac leaks.

Ya I was gonna do that tonight. Can I just use throttle body cleaner and check for rpm changes?

[CELison]

Ya I was gonna do that tonight. Can I just use throttle body cleaner and check for rpm changes?

What do you mean? I highly doubt cleaning your tb is going to do anything.

[jlaudio]

i have the same issue, video included

http://www.audizine.com/forum/showth...t=jlaudio+idle

i've replaced the PCV, breather hoses, a module under the super charger. changes spark plugs, had the warranty work done for carbon done.
I've been meaning to log it with my vag com to check air flow, throttle position, etc. eventually it will throw a high idle code.

it seems to happen more frequently in hot temps with the a/c off.

[Hofahome]

i have the same issue, video included

http://www.audizine.com/forum/showth...t=jlaudio+idle

i've replaced the PCV, breather hoses, a module under the super charger. changes spark plugs, had the warranty work done for carbon done.
I've been meaning to log it with my vag com to check air flow, throttle position, etc. eventually it will throw a high idle code.

it seems to happen more frequently in hot temps with the a/c off.

Well crap. How is your oil consumption? You dsg or 6mt?

[jlaudio]

Well crap. How is your oil consumption? You dsg or 6mt?

zero oil consumption, i'm 6MT. audi dealer believes its the clutch but i'm not sold on that. i still think there is an air leak or the MAF is faulty.

[Hofahome]

Well I have a new clutch. It might be the anti-stall feature/hall switch on the POS master cyl.

[jlaudio]

Well I have a new clutch. It might be the anti-stall feature/hall switch on the POS master cyl.

you may be right. sometimes when i am sitting in neutral and i release the clutch pedal it thinks i am in 2nd or 3rd gear, the efficiency program wants me to upshift on the dash.
I don't have a new clutch but its on my items that i would like to do. Is the switch a cheap repair? any idea? this issue has been driving me crazy for 2 years, my thread was posted in 2014...

[Hofahome]

I bought a new map sensor (the one by the throttle body) for like $20 on amazon. Figured why not. I read through your thread and have had the same p0507 high idle code before. Oddly enough even though this happens the cel has not come back after clearing. BUT, your additional p0491 code may clue us into what the cause is, especially given that it popped up just before the high idle code. I have to research it more but I bet there is something wrong (cracked hose, bad pressure sensor or EGR valve.) oddly enough I have been running the secondary air system without a filter for about 6 months because I forgot to put the filter back on after installing a cold air intake. It may have gotten crap/dust in the system. Still, not sure how high temps affect it so much. It was 70 out today and of course no issue.

[jlaudio]

I bought a new map sensor (the one by the throttle body) for like $20 on amazon. Figured why not. I read through your thread and have had the same p0507 high idle code before. Oddly enough even though this happens the cel has not come back after clearing. BUT, your additional p0491 code may clue us into what the cause is, especially given that it popped up just before the high idle code. I have to research it more but I bet there is something wrong (cracked hose, bad pressure sensor or EGR valve.) oddly enough I have been running the secondary air system without a filter for about 6 months because I forgot to put the filter back on after installing a cold air intake. It may have gotten crap/dust in the system. Still, not sure how high temps affect it so much. It was 70 out today and of course no issue.

Keep updating this thread please. If a $20 dollar sensor is the fix I'd be very happy. Is the car idling normally?

[Hofahome]

Well the map sensor did not fix anything. fuck.

[Hofahome]

Hey man, I may have made some headway on this. Hope this helps anyone with similar issues and I will update soon. It can get quite complicated but let me explain. From what I understand, the ECM compares data (in this case at idle, but in other times too) from its sensors (MAP, throttle %, fuel pressure, O2, etc) to the data from the ABS module (which has wheel speed sensors, throttle input for ESC, calculated torque etc.) and the transmission. The ECM has a specified idle value (I think 700rpm) that it wants to meet. The ECM uses a computed idle stabilization program, not an IAC valve like older cars, to basically adapt what it can to meet the idle target based on the values that are reported to it. Our cars are showing too wide a range of values and the idle stabilizer/ECM throws a code (P0507) because it cannot compensate enough beyond a certain point. It basically just gives the fuck up the idle speed becomes inconsistent. The problem is, this code is non-specific. Overall this problem (assuming it is not from a vacuum leak - which is possible but not probable given that it is not constant) comes down to either a faulty sensor, damaged/shorted wiring (which I think is my case) or faulty ECM/ABS module (fairly unlikely). There are several sensors that could be the culprit, such as MAP, throttle position sensor, etc, but luckily the car will probably throw a specific code for them.

OVERALL LOOK AT THE OTHER CODES FOR CLUES, THEN COMPARE DATA/VALUES (RPM SPEED, TORQUE, THROTTLE %, LOAD) FROM THE MODULES AFFECTED. This will likely have to be done in real time via VagCom while you let the car idle, blip throttle, etc.

I will update this soon with more specifics and info.

[BlownOne]

Have either of you two tried changing the throttle body to see if that's the issue? Like possibly swap in one of your buddies who owns a 3.0L just to troubleshoot? The electronics that control the tb could have taken a shit...

[Hofahome]

Have either of you two tried changing the throttle body to see if that's the issue? Like possibly swap in one of your buddies who owns a 3.0L just to troubleshoot? The electronics that control the tb could have taken a shit...

That is a good idea and one I had last night. The interesting thing is that when logging the throttle valve angle at idle in the ECM it shows about 2% but the throttle angle in the ABS module shows 0%. However the % does change with throttle input, although it seems unstable. I think there is a short in the wire.

[MikeB8.5]

Hey all,

Just thought I'd share my experience with this issue as well since I've been searching endlessly for a solution to it before I have to take the car in to either Audi or a reputable indy shop.

So I have a 2013 S4 Premium 6MT with 154xxx KM on the clock. I am the second owner and purchased it with around 144xxx KM a little over a year ago. It's all stock from what I can tell, other than the intake and I threw a set of H&R super sport springs in (which wouldn't affect anything).

Last fall, shortly after I purchased the vehicle it threw codes for SAI flow bank 1 and 2. Around the same time it started to develop a strange idle hunt, I assumed it was related to the SAI system. After some reading on here I decided to tackle cleaning the carbon on the Intake side myself, as well as changing the PCV since someone mentioned the idle might be related to the PCV being worn out. After cleaning and reassembly the idle hunt was still present. So onto the next step, getting the SAI system cleaned. Just last week I took it in to Audi to have the SAI cleaned on both banks, hoping that this would remedy the idle hunting issue. Took them less than a full day to clean it and have my car back to me error free on the SAI side of things. Unfortunately the idle issue is still present, if not worse now.

A few things to note : During the time frame I had a few high idle codes as well, which have not returned since. The car also has some chain rattle on start ups and I'm unsure if the chains and timing system are related to the idle surge/hunt. I have noticed poor fuel mileage, possible mystery coolant loss and the idle surge only seems to occur after the car is fairly hot. highway driving seems to calm it down and stop and go city traffic makes it notably worse. I've also noticed the throttle will bog a bit if you step try to give it some revs in neutral or in first with the clutch depressed. It makes acceleration from first difficult at times since it bogs a bit. Otherwise the car drives fine and pulls hard when you want it to.

Also wanted to point out, from my experience that the OP's issue isn't related to his tune and mods. Maybe it was just a matter of timing that it happened.

This is pretty frustrating after throwing money and time into cleaning the carbon and replacing parts and still not resolving the issue. I've searched a few threads on here and no one seems to have a conclusion to what it may be.

[SteveYem]

I’m in the same boat and am scheduled take my car in later this week for carbon cleaning and PCV replacement. Idle surge, bad gas mileage, coolant loss, sluggish performance and laggy throttle response. Now I’m wondering if that’ll be $1500 pissed away...

[MikeB8.5]

I’m in the same boat and am scheduled take my car in later this week for carbon cleaning and PCV replacement. Idle surge, bad gas mileage, coolant loss, sluggish performance and laggy throttle response. Now I’m wondering if that’ll be $1500 pissed away...

It won't be a total loss if your carbon build up is bad and your PCV is actually worn out. I do however think it's not going to solve the issue.



Just realized this wasn't the thread I was originally looking for. Sorry for digging up a really old thread.

[SteveYem]

It won't be a total loss if your carbon build up is bad and your PCV is actually worn out. I do however think it's not going to solve the issue.



Just realized this wasn't the thread I was originally looking for. Sorry for digging up a really old thread.

For what it’s worth, my car seems to have the same symptoms as yours yet has never thrown any engine or emissions related codes. I’m proceeding with taking it in tomorrow for carbon cleaning and PCV replacement and will report back with results.

[MikeB8.5]

For what it’s worth, my car seems to have the same symptoms as yours yet has never thrown any engine or emissions related codes. I’m proceeding with taking it in tomorrow for carbon cleaning and PCV replacement and will report back with results.

Please update when you get the car back. I'm curious if it's related to the IC cores leaking coolant into the intake system. Contemplating buying new cores and replacing them but I don't want to have to remove the blower for the 3rd time and rebleed the coolant system until I know they are the issue.

[SteveYem]

Please update when you get the car back. I'm curious if it's related to the IC cores leaking coolant into the intake system. Contemplating buying new cores and replacing them but I don't want to have to remove the blower for the 3rd time and rebleed the coolant system until I know they are the issue.

I got the car back this weekend. The technician noted that there was no evidence of leaking from the supercharger intercoolers. He also found no issues with the existing PCV but replaced it with the updated version, as well as performed a carbon cleaning of the intake valves. I have not driven the car much since getting it back and the driving I did was in the rain, so difficult to judge any performance improvements, but I will report back later this week after putting some more miles on it.

[SteveYem]

I got the car back this weekend. The technician noted that there was no evidence of leaking from the supercharger intercoolers. He also found no issues with the existing PCV but replaced it with the updated version, as well as performed a carbon cleaning of the intake valves. I have not driven the car much since getting it back and the driving I did was in the rain, so difficult to judge any performance improvements, but I will report back later this week after putting some more miles on it.

A few days in after having the intake valves carbon cleaned, the PCV replaced (with the current/updated version) and thermostat replaced, and as I feared and half expected there is no appreciable change in the bad behavior of the car. It does feel like it pulls a bit harder, I suppose due to the carbon cleaning, but the rough/stumbling/hunting idle, laggy throttle response and excessive fuel consumption persist.

As I was sitting here lamenting and thinking about it some more, I recalled that these symptoms seemed to intensify (or maybe appeared altogether) around the time that I had my OEM clutch line replaced with a stainless steel line (delay valve delete). Following on the discussion above (post #16), I know that there is a sensor on the master cylinder assembly that allows the engine to blip the throttle based on clutch engagement position to avoid stalling the car. I'm wondering if something was disturbed during the clutch line swap-out that led to my current issues. With that said, I have not found any fault codes such as those mentioned in post #16.

I do however have occasional timing chain rattle when starting the car from cold engine condition, most prevalent on warm days. I had the timing chain guides replaced under warranty by Audi and noticed that I had quicker throttle response and smoother 1st gear clutch engagements right after I got the car back. The car felt more solid and stronger in general. After ~6 months or so (when the weather heated up) I started hearing the intermittent timing chain rattle at startup and the car went back to this crappy behavior. Unfortunately when I took the car back to Audi and complained about the chain rattle again, they were "unable to replicate the issue" and the car was "operating within normal parameters". I am starting to think all of this weirdness is related to a timing issue.

With that said, if there was a timing issue how can I detect it? What would I need to look at in VCDS? And is it possible for ignition timing to be so far off that it causes rough idle, poor throttle response and decreased gas mileage yet does not throw any fault codes?

[MikeB8.5]

A few days in after having the intake valves carbon cleaned, the PCV replaced (with the current/updated version) and thermostat replaced, and as I feared and half expected there is no appreciable change in the bad behavior of the car. It does feel like it pulls a bit harder, I suppose due to the carbon cleaning, but the rough/stumbling/hunting idle, laggy throttle response and excessive fuel consumption persist.

As I was sitting here lamenting and thinking about it some more, I recalled that these symptoms seemed to intensify (or maybe appeared altogether) around the time that I had my OEM clutch line replaced with a stainless steel line (delay valve delete). Following on the discussion above (post #16), I know that there is a sensor on the master cylinder assembly that allows the engine to blip the throttle based on clutch engagement position to avoid stalling the car. I'm wondering if something was disturbed during the clutch line swap-out that led to my current issues. With that said, I have not found any fault codes such as those mentioned in post #16.

I do however have occasional timing chain rattle when starting the car from cold engine condition, most prevalent on warm days. I had the timing chain guides replaced under warranty by Audi and noticed that I had quicker throttle response and smoother 1st gear clutch engagements right after I got the car back. The car felt more solid and stronger in general. After ~6 months or so (when the weather heated up) I started hearing the intermittent timing chain rattle at startup and the car went back to this crappy behavior. Unfortunately when I took the car back to Audi and complained about the chain rattle again, they were "unable to replicate the issue" and the car was "operating within normal parameters". I am starting to think all of this weirdness is related to a timing issue.

With that said, if there was a timing issue how can I detect it? What would I need to look at in VCDS? And is it possible for ignition timing to be so far off that it causes rough idle, poor throttle response and decreased gas mileage yet does not throw any fault codes?

Thanks for the update.

It’s good to know that now I’m not the only one who’s done all of the same maintenance and still have the idle issue. Makes me believe more that it’s related to a worn sensor or issues with the chains/timing system on these cars. The only thing that keeps me leaning towards a sensor is the fact that (in my case) the idle hunt and laggy throttle only happens when the engine is fairly hot.

My clutch line and slave are all oem from what I can tell and leads me to believe that this isn’t the cause of the problem.

I noticed that if I park the car in my garage during my lunch break and after it’s been sitting for an hour or so with the garage door closed in it’s own heat, the idle issues and throttle response seem to be much worse.

I’ve gone ahead and ordered all three new MAP sensors. Originally I planned to just clean them but I cracked one during removal and decided I’ll replace them all.

I have zero experience with VCDS, hopefully someone else can chime in on that for you.

[SteveYem]

Thanks for the update.

It’s good to know that now I’m not the only one who’s done all of the same maintenance and still have the idle issue. Makes me believe more that it’s related to a worn sensor or issues with the chains/timing system on these cars. The only thing that keeps me leaning towards a sensor is the fact that (in my case) the idle hunt and laggy throttle only happens when the engine is fairly hot.

My clutch line and slave are all oem from what I can tell and leads me to believe that this isn’t the cause of the problem.

I noticed that if I park the car in my garage during my lunch break and after it’s been sitting for an hour or so with the garage door closed in it’s own heat, the idle issues and throttle response seem to be much worse.

I’ve gone ahead and ordered all three new MAP sensors. Originally I planned to just clean them but I cracked one during removal and decided I’ll replace them all.

I have zero experience with VCDS, hopefully someone else can chime in on that for you.

I’m curious to hear your results. Do you have any reason to suspect the MAP sensors?
I should also add that my issues seem to be at their worst when the engine is warmed up as well. It really sounds like we are both chasing the same issue.

[MikeB8.5]

I’m curious to hear your results. Do you have any reason to suspect the MAP sensors?
I should also add that my issues seem to be at their worst when the engine is warmed up as well. It really sounds like we are both chasing the same issue.

Does the car have the same symptoms when it’s cold or only when it’s been driven for a while and it’s hot?

Symptoms of bad MAP sensors are bad fuel mileage, poor throttle response and rough idle. Truthfully I’m just throwing money at it now to narrow down the possibilities of what might be causing the issues. Probably the worst idea haha. Saves me the trouble of dealing withthe stealership giving me the same answer they give everyone else “ could not duplicate problem” and then handing them more of my hard earned money.

My new sensors come in this week, I’ll follow up once I have a chance to install them and drive it again. It’s currentlh out of commission since I was a dumbass and broke the passenger side MAP on the SC trying to remove it.

Also trying out some fuel injector cleaner as another troubleshooting method. I think someone noted it helped but only for a few days and the symptoms came right back.

[SteveYem]

Does the car have the same symptoms when it’s cold or only when it’s been driven for a while and it’s hot?

Symptoms of bad MAP sensors are bad fuel mileage, poor throttle response and rough idle. Truthfully I’m just throwing money at it now to narrow down the possibilities of what might be causing the issues. Probably the worst idea haha. Saves me the trouble of dealing withthe stealership giving me the same answer they give everyone else “ could not duplicate problem” and then handing them more of my hard earned money.

My new sensors come in this week, I’ll follow up once I have a chance to install them and drive it again. It’s currentlh out of commission since I was a dumbass and broke the passenger side MAP on the SC trying to remove it.

Also trying out some fuel injector cleaner as another troubleshooting method. I think someone noted it helped but only for a few days and the symptoms came right back.

I don’t notice the issue nearly as much, if at all, when the engine is cold. As soon as the temperature gauge gets near or at temperature, the symptoms are apparent.

Here’s another observation- when I let off the gas and coast down in gear, I can hear pops and burbles from the exhaust, and the instantaneous gas mileage readout shows values bouncing around - 20mpg, 45 mpg, back to 32 mpg etc- whereas what it SHOULD show is - - (no value). What I am seeing and hearing leads me to believe the car is errantly adding fuel when it shouldn’t be. This is perplexing.

I just got done flashing my car back to stock from EPL Stage 1 to at least take the software aspect out of it and see if it makes any difference. Maybe the ECU needs to be reset so it can readapt after having the carbon cleaning and PCV replacement done...?

[SteveYem]

Update:
Over the weekend I performed two 'services'
1) Removed, cleaned and reinstalled the three(3) MAP sensors from the supercharger. I sprayed each sensor bulb and all of the electrical connectors with CRC MAF sensor cleaner, let them dry and reinstalled them.
2) I changed the engine oil. I have been using Mobil 1 04-40 for years and finally decided to switch to Castrol Edge 5w-40 as recommended by the Audi dealership.

I am still noticing the surging/hunting idle although it may be more intermittent than it was before. I am also still noticing the laggy throttle response and bad gas mileage (presenting itself real-time as the mpg readout going to 5.0 mpg and staying there thru 3rd gear, even when I am barely giving the car enough gas to accelerate it), but again it seems just a bit less consistent.

I mentioned in my last post that when I let off the gas and am coasting in gear I can hear pops and burbles from the exhaust and the instantaneous mpg readout shows various values, as high as 60 mpg, as low as 18 mpg, while I am coasting down. To add to that I have also observed that pushing the clutch pedal in causes the instantaneous readout to go immediately to '- -' (i.e. no value) where it will stay, until I push the clutch pedal back in, at which point it will start reading whatever random values like it was doing while coasting down in gear. Then most likely when I start out in first gear from a standstill, even feathering the throttle barely giving enough gas to avoid stalling out, the mpg readout will go down to 5.0 mpg and the car will feel down on power. Keep in mind, my car is a 6MT.
Why would clutch engaged/disengaged status affect the amount of fuel being consumed by the engine?

Someone mentioned it could be a problem with the sensor on the master cylinder which is causing all of this (the sensor which I believe effectively looks at the clutch engagement position to trigger the engine to add fuel to help avoid stalling). A couple years back I had a shop replace the OEM clutch hydraulic line with a stainless straight-through line (i.e. clutch delay valve delete). I can't remember for sure but I feel like these issues were exacerbated, maybe started altogether, when I had that work done. Meanwhile, I have scanned the car multiple times in VCDS and have never found a fault code related to the engine or transmission. Any advice here would be greatly appreciated, as I am nearing my wit's end on this.


So to summarize up to this point, I have done the following service to the engine since these symptoms cropped up a couple years ago. Also note that these symptoms exists whether I am running the stock tune or EPL Stage 1:
1) Replaced the spark plugs with the brand/model and gap recommended by EPL (I was running their Stage 1 tune at the time)
2) Sprayed a can of CRC intake valve cleaner thru the throttle body
3) Run a can of Seafoam fuel injector cleaner through the gas tank
4) Had the intake valve carbon cleaning performed
5) Had the PCV replaced
6) Had the thermostat replaced
7) Removed, cleaned and reinstalled the three(3) MAP sensors in the supercharger
8) Changed oil from Mobil 1 0w-40 to Castrol Edge 5w-40

[MikeB8.5]

I finally had a chance to replace all three MAP sensors with brand new ones from Audi, like I figured it didn't resolve the issue at all.

I've completed all of the same troubleshooting points that you have other than cleaning the throttle body. Also had Carbon cleaning done on the emission side. None of this has helped my idle problem.

Pretty much ready to just leave it running in a shady neighborhood for a few minutes and wish for the best.

[SteveYem]

I finally had a chance to replace all three MAP sensors with brand new ones from Audi, like I figured it didn't resolve the issue at all.

I've completed all of the same troubleshooting points that you have other than cleaning the throttle body. Also had Carbon cleaning done on the emission side. None of this has helped my idle problem.

Pretty much ready to just leave it running in a shady neighborhood for a few minutes and wish for the best.

Amen, brother.

[jsh139]

I'll have to check mine on the way home, but I think pushing the clutch pedal in always makes the instantaneous mpg goto --.

[SteveYem]

I'll have to check mine on the way home, but I think pushing the clutch pedal in always makes the instantaneous mpg goto --.

Thank you - it will be good to get some more data points on this. Also please let us know whether your mpg readout goes to -- when you let off the gas and coast down while still in gear.

[jsh139]

Thank you - it will be good to get some more data points on this. Also please let us know whether your mpg readout goes to -- when you let off the gas and coast down while still in gear.

It definitely does this.

[jsh139]

I took a vid this morning. Pulling out. Light throttle. Medium throttle. Shifting. Coasting. Clutch in-coasting. etc. Not in any particular order. Car is dirty. Waze is on in the background. It's portrait orientation. It's hard to drive, shift, and video all at once, haha.

But, you can see some of the characteristics of my car and compare to yours. Let me know if you want me to try anything specific.

https://www.youtube.com/watch?v=cfyMpu43yfs

[SteveYem]

I took a vid this morning. Pulling out. Light throttle. Medium throttle. Shifting. Coasting. Clutch in-coasting. etc. Not in any particular order. Car is dirty. Waze is on in the background. It's portrait orientation. It's hard to drive, shift, and video all at once, haha.

But, you can see some of the characteristics of my car and compare to yours. Let me know if you want me to try anything specific.

https://www.youtube.com/watch?v=cfyMpu43yfs

Thanks very much for posting this. It looks to me like yours is behaving very well (the way mine used to so many years ago). Would it be too much to ask you to switch the driver display to the green 'eco' setting and toggle it to show the trip average and instantaneous mpg readouts, and capture a little bit of another drive? Then it would be apples-to-apples with what I am observing. But with that said, it looks to me that your instantaneous mpg readings are more realistic and proportional to your throttle application, whereas in my case it drops down to 5.0 mpg (which is the lowest value it will display) even when starting out in 1st gear, even under super light throttle application.

Again to disclaimer that I am not hung up on the displayed mpg being an actual value, but I think it is certainly a gauge and diagnostic tool for an underlying issue. As I understand it, the mpg value is calculated based on fuel injector duty cycle, i.e. how much volume of fuel is being injected into the engine per combustion cycle. The 5.0 mpg reading I commonly see on the DIS tells me that for some reason there is a lot of fuel being dumped into the engine when it's not being called for, e.g. when lightly feathering the throttle in 1st gear accelerating from a stop. So, what would cause the car to add so much fuel, feel down on power, have laggy throttle response, all the while not showing any engine or emissions-related fault codes any of the times I have run a full auto-scan in VCDS over the past couple years? I'm not sure if I mentioned it previously in this thread, but the car also appears to be consuming coolant and occasionally I can smell coolant immediately when getting out of the car after a drive, yet I have never seen any apparent leakage in the engine bay or under the car.

[jsh139]

Thanks very much for posting this. It looks to me like yours is behaving very well (the way mine used to so many years ago). Would it be too much to ask you to switch the driver display to the green 'eco' setting and toggle it to show the trip average and instantaneous mpg readouts, and capture a little bit of another drive? Then it would be apples-to-apples with what I am observing. But with that said, it looks to me that your instantaneous mpg readings are more realistic and proportional to your throttle application, whereas in my case it drops down to 5.0 mpg (which is the lowest value it will display) even when starting out in 1st gear, even under super light throttle application.

Again to disclaimer that I am not hung up on the displayed mpg being an actual value, but I think it is certainly a gauge and diagnostic tool for an underlying issue. As I understand it, the mpg value is calculated based on fuel injector duty cycle, i.e. how much volume of fuel is being injected into the engine per combustion cycle. The 5.0 mpg reading I commonly see on the DIS tells me that for some reason there is a lot of fuel being dumped into the engine when it's not being called for, e.g. when lightly feathering the throttle in 1st gear accelerating from a stop. So, what would cause the car to add so much fuel, feel down on power, have laggy throttle response, all the while not showing any engine or emissions-related fault codes any of the times I have run a full auto-scan in VCDS over the past couple years? I'm not sure if I mentioned it previously in this thread, but the car also appears to be consuming coolant and occasionally I can smell coolant immediately when getting out of the car after a drive, yet I have never seen any apparent leakage in the engine bay or under the car.

No problem. Happy to help. I have a 2010, I don't think it has the eco screen you're referring to? But, I think I can make the instantaneous MPG show up in the center part of the DIS (instead of the speed) and have the Trip 1 avg MPG shown on the bottom part. Is that what you need?

[SteveYem]

No problem. Happy to help. I have a 2010, I don't think it has the eco screen you're referring to? But, I think I can make the instantaneous MPG show up in the center part of the DIS (instead of the speed) and have the Trip 1 avg MPG shown on the bottom part. Is that what you need?

Yep, that would work! Then I can switch my DIS to the same readout and compare my results to yours. I really appreciate your effort on this! While it doesn't make my car run any better, it does make me feel like I'm not crazy.

[jsh139]

Yep, that would work! Then I can switch my DIS to the same readout and compare my results to yours. I really appreciate your effort on this! While it doesn't make my car run any better, it does make me feel like I'm not crazy.

Cool, I'll do some filming on the way home from work.