Diesel Cayenne and VW emission issue
09-17-2019, 03:41 AM
#6362
Rennlist Member
The digging started based on a theory that I, and some former co-workers (diesel engineers) had over how they "fixed" it - as well as a preventative check. In a lot of diesels, I've been told that EGR is used when at WOT to reduce cylinder pressures. When considering a Malone tune, and a full EGR disable, we were wondering - if the strategy uses EGR to keep cylinder pressures down, this mighe be an issue. But testing confirmed - at WOT, EGR is 0. The other thing we wanted to look at was the tip-in performance. I/we expected to see a lot more EGR during throttle tip-in to explain the horrible lag. It was the only easy thing we could come up with that might make sense. EGR the bejeebers out of it for emissions and since you're nowhere near the "peak" performance numbers they won't get penalized.
But the instant you tip in heavy - the EGR valve is (commanded to, anyways) slam shut. So the remaining theory is that, since it's damn near (or actually IS) 100% EGR while you're slowing down... the entire intake path has backfilled with exhaust gas enough that when you tip in... you're basically gagging the engine for a bit.
I suppose there's also the chance the EGR is still hanging open - tho the system DOES monitor actual EGR position so if there's a chance for it to hang open, being an emissions component, I'd expect a CEL immediately.
But the instant you tip in heavy - the EGR valve is (commanded to, anyways) slam shut. So the remaining theory is that, since it's damn near (or actually IS) 100% EGR while you're slowing down... the entire intake path has backfilled with exhaust gas enough that when you tip in... you're basically gagging the engine for a bit.
I suppose there's also the chance the EGR is still hanging open - tho the system DOES monitor actual EGR position so if there's a chance for it to hang open, being an emissions component, I'd expect a CEL immediately.
Cooling the cylinder burn reduces the NOx produced, right? If I'm not out in left field here, why would there be no call for EGR at WOT and full EGR at idle?
09-17-2019, 12:51 PM
#6363
Alright, so I had a few free moments this afternoon and did some quick data logs with the PIWIS. It was a humid day and the throttle lag was apparent.
I feel pretty confident it’s mostly the trans. I was able to record a full 1.5s between me flooring it, and the engine calling for boost... it was waiting for the trans to react. Requested boost level remained flat until it selected gear, THEN requested boost went up and THEN actual boost ramped up.
Putting the car in manual mode and flooring it, requested boost jumps up immediately.
Contributing to the lag... my theory... has to do with the manifold being full of nothing but EGR gas. When you drop the throttle the car gets almost 100% EGR. For seconds, it will sit at 100% EGR until you tip back in and the EGR ramps down.
So decelerate from speed, you get full EGR, and tip into the throttle rolling a corner... the engine is choking and full of its own exhaust, the trans doesn’t know what to do so it sits doing nothing... THEN it decides to add boost.
I wish I had a unfixed one I could look at data on.
It also makes me think to wait until Malone offers a TCU tune to go along with their ECM tunes...
I feel pretty confident it’s mostly the trans. I was able to record a full 1.5s between me flooring it, and the engine calling for boost... it was waiting for the trans to react. Requested boost level remained flat until it selected gear, THEN requested boost went up and THEN actual boost ramped up.
Putting the car in manual mode and flooring it, requested boost jumps up immediately.
Contributing to the lag... my theory... has to do with the manifold being full of nothing but EGR gas. When you drop the throttle the car gets almost 100% EGR. For seconds, it will sit at 100% EGR until you tip back in and the EGR ramps down.
So decelerate from speed, you get full EGR, and tip into the throttle rolling a corner... the engine is choking and full of its own exhaust, the trans doesn’t know what to do so it sits doing nothing... THEN it decides to add boost.
I wish I had a unfixed one I could look at data on.
It also makes me think to wait until Malone offers a TCU tune to go along with their ECM tunes...
The digging started based on a theory that I, and some former co-workers (diesel engineers) had over how they "fixed" it - as well as a preventative check. In a lot of diesels, I've been told that EGR is used when at WOT to reduce cylinder pressures. When considering a Malone tune, and a full EGR disable, we were wondering - if the strategy uses EGR to keep cylinder pressures down, this mighe be an issue. But testing confirmed - at WOT, EGR is 0. The other thing we wanted to look at was the tip-in performance. I/we expected to see a lot more EGR during throttle tip-in to explain the horrible lag. It was the only easy thing we could come up with that might make sense. EGR the bejeebers out of it for emissions and since you're nowhere near the "peak" performance numbers they won't get penalized.
But the instant you tip in heavy - the EGR valve is (commanded to, anyways) slam shut. So the remaining theory is that, since it's damn near (or actually IS) 100% EGR while you're slowing down... the entire intake path has backfilled with exhaust gas enough that when you tip in... you're basically gagging the engine for a bit.
I suppose there's also the chance the EGR is still hanging open - tho the system DOES monitor actual EGR position so if there's a chance for it to hang open, being an emissions component, I'd expect a CEL immediately.
But the instant you tip in heavy - the EGR valve is (commanded to, anyways) slam shut. So the remaining theory is that, since it's damn near (or actually IS) 100% EGR while you're slowing down... the entire intake path has backfilled with exhaust gas enough that when you tip in... you're basically gagging the engine for a bit.
I suppose there's also the chance the EGR is still hanging open - tho the system DOES monitor actual EGR position so if there's a chance for it to hang open, being an emissions component, I'd expect a CEL immediately.
That just seems weird, based on what I know about what/why EGR exists. If the goal is to reduce NOx by reducing cylinder combustion temps, wouldn't it be more likely that at WOT you get more EGR in there so you're not combusting as much as a pure fuel/air mixture?
Cooling the cylinder burn reduces the NOx produced, right? If I'm not out in left field here, why would there be no call for EGR at WOT and full EGR at idle?
Cooling the cylinder burn reduces the NOx produced, right? If I'm not out in left field here, why would there be no call for EGR at WOT and full EGR at idle?
09-17-2019, 01:12 PM
#6364
RL Community Team
Rennlist Member
Rennlist Member
09-18-2019, 12:49 AM
#6365
The purpose of EGR is to limit fuel/air ratio in the first place as too much oxygen in the mixture leads to excessive NOx amounts. There is no need to limit oxygen concentration at WOT as it is all used up to burn the fuel.
09-18-2019, 09:56 PM
#6366
Rennlist Member
Well, that's an interesting twist.
Of course I coudn't get the car to do its shuck and jive routine more than once on the test ride this morning. So they checked for codes, found none (surprise). They called PCNA to see if there was anything else to check or do.
PCNA basically said that's the way it is now, you have to live with it.
Oh, and because they couldn't find anything, they charged me $100 for the diagnostics. Apparently Porsche won't reimburse now if they don't find anything, so basically, it has to be broken or throw a code or you'll be paying to get something looked at should they not be able to duplicate the problem.
Normally I blow off the surveys because it's a waste of time to just rate all 5 stars. Doesn't help Porsche, doesn't help the dealer and takes my time to submit a worthless evaluation. This time, I'll be brutally honest, though they are focused mostly on the dealer who seems to be doing what they can.
Of course I coudn't get the car to do its shuck and jive routine more than once on the test ride this morning. So they checked for codes, found none (surprise). They called PCNA to see if there was anything else to check or do.
PCNA basically said that's the way it is now, you have to live with it.
Oh, and because they couldn't find anything, they charged me $100 for the diagnostics. Apparently Porsche won't reimburse now if they don't find anything, so basically, it has to be broken or throw a code or you'll be paying to get something looked at should they not be able to duplicate the problem.
Normally I blow off the surveys because it's a waste of time to just rate all 5 stars. Doesn't help Porsche, doesn't help the dealer and takes my time to submit a worthless evaluation. This time, I'll be brutally honest, though they are focused mostly on the dealer who seems to be doing what they can.
09-18-2019, 11:06 PM
#6367
Rennlist Member
Well, that's an interesting twist.
Of course I coudn't get the car to do its shuck and jive routine more than once on the test ride this morning. So they checked for codes, found none (surprise). They called PCNA to see if there was anything else to check or do.
PCNA basically said that's the way it is now, you have to live with it.
Oh, and because they couldn't find anything, they charged me $100 for the diagnostics. Apparently Porsche won't reimburse now if they don't find anything, so basically, it has to be broken or throw a code or you'll be paying to get something looked at should they not be able to duplicate the problem.
Normally I blow off the surveys because it's a waste of time to just rate all 5 stars. Doesn't help Porsche, doesn't help the dealer and takes my time to submit a worthless evaluation. This time, I'll be brutally honest, though they are focused mostly on the dealer who seems to be doing what they can.
Of course I coudn't get the car to do its shuck and jive routine more than once on the test ride this morning. So they checked for codes, found none (surprise). They called PCNA to see if there was anything else to check or do.
PCNA basically said that's the way it is now, you have to live with it.
Oh, and because they couldn't find anything, they charged me $100 for the diagnostics. Apparently Porsche won't reimburse now if they don't find anything, so basically, it has to be broken or throw a code or you'll be paying to get something looked at should they not be able to duplicate the problem.
Normally I blow off the surveys because it's a waste of time to just rate all 5 stars. Doesn't help Porsche, doesn't help the dealer and takes my time to submit a worthless evaluation. This time, I'll be brutally honest, though they are focused mostly on the dealer who seems to be doing what they can.
09-19-2019, 11:20 PM
#6368
09-20-2019, 07:27 AM
#6369
Unlike Skiahh now that it is in the 50's in the AM here mine is driving great. It is a 14 though and I believe the one he's seeing the lag in is a 15. The response has been typical of what I would expect from a diesel engine, not instantaneous but, predictably consistent.
09-23-2019, 11:46 AM
#6370
This weekend I installed a new fuel filter and drained the whole filter canister (water removal procedure, but just decided to drain the whole thing to be safe as its not that much fuel). It wasn't clear from the service records when the filter had been replaced, and if the previous owner had done the water removal at all.
The filter was pretty bad looking, and I didn't see any clear water separation in the canister, but drained it anyway. The car seems to be running will a little more pep and a little less lag, but it could be psychological or weather related.
Just bringing this up for those of you that go through the carbon cleaning process might want to throw this in too. Its cheap ($20-30 for a filter), and takes about 10 minutes. Couldn't hurt to start fresh on the fuel side, if you're spending the time to clean out the air side.
The filter was pretty bad looking, and I didn't see any clear water separation in the canister, but drained it anyway. The car seems to be running will a little more pep and a little less lag, but it could be psychological or weather related.
Just bringing this up for those of you that go through the carbon cleaning process might want to throw this in too. Its cheap ($20-30 for a filter), and takes about 10 minutes. Couldn't hurt to start fresh on the fuel side, if you're spending the time to clean out the air side.
09-23-2019, 01:23 PM
#6371
This weekend I installed a new fuel filter and drained the whole filter canister (water removal procedure, but just decided to drain the whole thing to be safe as its not that much fuel). It wasn't clear from the service records when the filter had been replaced, and if the previous owner had done the water removal at all.
The filter was pretty bad looking, and I didn't see any clear water separation in the canister, but drained it anyway. The car seems to be running will a little more pep and a little less lag, but it could be psychological or weather related.
Just bringing this up for those of you that go through the carbon cleaning process might want to throw this in too. Its cheap ($20-30 for a filter), and takes about 10 minutes. Couldn't hurt to start fresh on the fuel side, if you're spending the time to clean out the air side.
The filter was pretty bad looking, and I didn't see any clear water separation in the canister, but drained it anyway. The car seems to be running will a little more pep and a little less lag, but it could be psychological or weather related.
Just bringing this up for those of you that go through the carbon cleaning process might want to throw this in too. Its cheap ($20-30 for a filter), and takes about 10 minutes. Couldn't hurt to start fresh on the fuel side, if you're spending the time to clean out the air side.
10-26-2019, 08:37 PM
#6373
Intermediate
So I am beginning to wonder, as Cayenne Diesel owners, will we face similar problems as those unfortunate owners of GM Diesels with Bosch Components?
https://www.cnet.com/roadshow/news/g...s-diesel-fuel/
https://www.detroitnews.com/story/bu...el/1943084001/
Whereas, the lawsuit claims US diesel fuel is thinner compared to a thicker blend sold in Europe. Knowing the fuel is thinner, it provides less lubrication, which in turn creates air pockets. When these air pockets form in the fuel injection system, metal directly contacts metal. The alleged end result is metal shavings pumped into the fuel system and engine with major damage inflicted.
"The pump secretly deposits metal shavings and debris throughout the fuel injection system and the engine until it suddenly and catastrophically fails without warning," the lawsuit claims. "Such catastrophic failure often causes the vehicle to shut off while in motion and renders it unable to be restarted, because the vehicle’s fuel injection system and engine component parts have been completely contaminated and destroyed."
I've read numerous posts about Volkswagen diesel owners seeing metal shavings in their oil, and wondering why...
Concerning!? What do you think?
https://www.cnet.com/roadshow/news/g...s-diesel-fuel/
https://www.detroitnews.com/story/bu...el/1943084001/
Whereas, the lawsuit claims US diesel fuel is thinner compared to a thicker blend sold in Europe. Knowing the fuel is thinner, it provides less lubrication, which in turn creates air pockets. When these air pockets form in the fuel injection system, metal directly contacts metal. The alleged end result is metal shavings pumped into the fuel system and engine with major damage inflicted.
"The pump secretly deposits metal shavings and debris throughout the fuel injection system and the engine until it suddenly and catastrophically fails without warning," the lawsuit claims. "Such catastrophic failure often causes the vehicle to shut off while in motion and renders it unable to be restarted, because the vehicle’s fuel injection system and engine component parts have been completely contaminated and destroyed."
I've read numerous posts about Volkswagen diesel owners seeing metal shavings in their oil, and wondering why...
Concerning!? What do you think?
Last edited by alterniTECH; 10-26-2019 at 10:11 PM.
10-28-2019, 12:57 PM
#6374
So I am beginning to wonder, as Cayenne Diesel owners, will we face similar problems as those unfortunate owners of GM Diesels with Bosch Components?
https://www.cnet.com/roadshow/news/g...s-diesel-fuel/
https://www.detroitnews.com/story/bu...el/1943084001/
Whereas, the lawsuit claims US diesel fuel is thinner compared to a thicker blend sold in Europe. Knowing the fuel is thinner, it provides less lubrication, which in turn creates air pockets. When these air pockets form in the fuel injection system, metal directly contacts metal. The alleged end result is metal shavings pumped into the fuel system and engine with major damage inflicted.
"The pump secretly deposits metal shavings and debris throughout the fuel injection system and the engine until it suddenly and catastrophically fails without warning," the lawsuit claims. "Such catastrophic failure often causes the vehicle to shut off while in motion and renders it unable to be restarted, because the vehicle’s fuel injection system and engine component parts have been completely contaminated and destroyed."
I've read numerous posts about Volkswagen diesel owners seeing metal shavings in their oil, and wondering why...
Concerning!? What do you think?
https://www.cnet.com/roadshow/news/g...s-diesel-fuel/
https://www.detroitnews.com/story/bu...el/1943084001/
Whereas, the lawsuit claims US diesel fuel is thinner compared to a thicker blend sold in Europe. Knowing the fuel is thinner, it provides less lubrication, which in turn creates air pockets. When these air pockets form in the fuel injection system, metal directly contacts metal. The alleged end result is metal shavings pumped into the fuel system and engine with major damage inflicted.
"The pump secretly deposits metal shavings and debris throughout the fuel injection system and the engine until it suddenly and catastrophically fails without warning," the lawsuit claims. "Such catastrophic failure often causes the vehicle to shut off while in motion and renders it unable to be restarted, because the vehicle’s fuel injection system and engine component parts have been completely contaminated and destroyed."
I've read numerous posts about Volkswagen diesel owners seeing metal shavings in their oil, and wondering why...
Concerning!? What do you think?
A good diesel fuel additive is your friend.
10-28-2019, 02:54 PM
#6375