Should I be seeing fault codes?

[jronnquist]

Hello everyone!

I just bought myself a HEX-V2 setup and plan to spend the next couple of weeks getting to grips with it so I can start diagnosing the issues with my car (Octavia Mk2 VRS 170 PD [BMN]). Don't worry, I have no intention of jumping on here every five minutes with a host of annoying questions that I can't be bothered to answer myself, but I have run into a mystery right at the outset that I cannot find an answer to anywhere and was hoping for some clarification from someone familiar with the VCDS system.

My car has some very clear issues. Since a full engine rebuild a couple of weeks ago it is drinking about 30% more fuel on average and there is very (VERY) little boost before 2000RPM. I'm confident that I can get to the bottom of this with a little study and time, but having run an initial scan I am getting zero error codes from the engine. I realize that there are many faults that will not produce error codes, but just to be sure I unplugged the MAF sensor and ran the scan again. No codes. I then unplugged the clip on the turbo actuator, and again, no codes. When plugged in both produce clear figures in their respective blocks, but shouldn't the fact that the ECU is getting no signal at all from these two components when unplugged produce error codes of some kind? I know the ECU effectively ignores the MAF sensor when it's unplugged and uses default values instead, but surely the absence of a signal is a serious "error" for diagnostic purposes, no?

ps. I should add here that the car has been mapped before someone asks. I have been told that some maps (bad ones, I guess) will block fault codes. But before I go down this route and have the ECU re-coded to default values it would be good to know if I should be seeing error codes based on the above in the first place.

 

[MasterTommy]

As a certain person who’ll undoubtedly be present 1 or 2 posts below this one would say:

FOD

Yes, you should flash your ECU back to stock before you can diagnose anything. You cannot calculate the sum of 3 numbers when you’re missing two of them. You can deduce their most likely values from other factors, but will never be sure.

 

[Uwe]

My car has some very clear issues. Since a full engine rebuild a couple of weeks ago it is drinking about 30% more fuel on average and there is very (VERY) little boost before 2000RPM. I'm confident that I can get to the bottom of this with a little study and time, but having run an initial scan I am getting zero error codes from the engine. I realize that there are many faults that will not produce error codes, but just to be sure I unplugged the MAF sensor and ran the scan again. No codes. I then unplugged the clip on the turbo actuator, and again, no codes. When plugged in both produce clear figures in their respective blocks, but shouldn't the fact that the ECU is getting no signal at all from these two components when unplugged produce error codes of some kind? I know the ECU effectively ignores the MAF sensor when it's unplugged and uses default values instead, but surely the absence of a signal is a serious "error" for diagnostic purposes, no?

Did you actually try to start the engine with any of these things unplugged? In some cases, just unplugging a sensor won't set a fault code unless the engine has been run, at least a for a bit...

-Uwe-

 

[jronnquist]

I did.

The car starts quite happily with both unplugged. With just the MAF sensor off it runs fine. With the actuator unplugged there's no boost at all (and some very strange sounds from under the hood). I only ran it like this for a hundred yards or so to see what would happen , but again, no codes at all.

 

[Uwe]

The car starts quite happily with both unplugged. With just the MAF sensor off it runs fine. With the actuator unplugged there's no boost at all (and some very strange sounds from under the hood). I only ran it like this for a hundred yards or so to see what would happen , but again, no codes at all.

I can't think of any reason why you'd get no fault codes then, except that they're suppressed in the software that's currently in your ECU.

-Uwe-

 

[Jack@European_Parts]

Hello and welcome OP.

Fascinating synopsis, now post an auto-scan please, than flash this POS to stock, run it and post the scan again.
JPPSG

http://forums.ross-tech.com/showthr...essional-Problem-Solver-Guide-quot-JPPSG-quot

THIS IS FUBAR WTF FOD! That isn't tuning either......ever ask why your first motor blew up?

http://forums.ross-tech.com/showthr...smelly-Garbage-can-dumped-on-Motorsports!-WTF

 

[jronnquist]

Fascinating synopsis, now post an auto-scan please, than [then] flash this POS to stock, run it and post the scan again.
JPPSG

Thank you for the link!

THIS IS FUBAR WTF FOD! That isn't tuning either......ever ask why your first motor blew up?

The remap in question was done by a reputable tuner and its purpose was to improve engine performance. I don't recall saying anything about alterations to the emissions hardware or software. That said, I still intend to have the ECU returned to stock.

But the questions still stands; Assuming nothing has been done to the engine or ECU, should unplugging the MAF sensor or wiring to the turbo actuator produce a fault code in VCDS? Unless I'm missing something, the answer must surely be either a "yes" or a "no".

 

[Uwe]

But the questions still stands; Assuming nothing has been done to the engine or ECU, should unplugging the MAF sensor or wiring to the turbo actuator produce a fault code in VCDS? Unless I'm missing something, the answer must surely be either a "yes" or a "no".

No. But only because I'm being pedantic. Fault codes are not "in VCDS". They are in your ECU. VCDS only asks the ECU, "Hey, do you have any fault codes?" Then the ECU either answers, "Yes, I have this many, and here they are" or "Nope, I haven't got any."

Yes, your ECU should have fault codes when you unplug stuff like the MAF and then start the engine.

-Uwe-

 

[jronnquist]

Thank you!

The case made for remapping by those who do it, as I'm sure you know well, is that an engine manufacturer does not map for the highest possible performance, but strikes a balance between performance, longevity and the requirement to keep emissions down. The case I made to myself was that a modest power increase (about 20%) would be okay as long as I took good care of the engine. I was also told that my MPG would improve. I do a lot miles, so to my way of thinking if I'm burning less fuel, whatever emissions increase I'd be guilty of under the occasional speed run would be more than offset by the savings on long highway journeys. I do about 70 miles per working day, and most of them safely tucked in behind a semi at about 56 MPH.

I do not have the expertise to remap an ECU myself, but I understand enough about the system to appreciate that a good map takes a lot of work and a lot of testing to get right. The company that did mine was a reputable one. It wasn't cheap, and they had the car for an entire day to "test and adjust". That said, I can only go by my own experience, so if they have done a half job and simply shut certain things down instead of fine tuning them to work with everything else, they will have to answer for it.

 

[Jack@European_Parts]

Thank you!

The case made for remapping by those who do it, as I'm sure you know well, is that an engine manufacturer does not map for the highest possible performance, but strikes a balance between performance, longevity and the requirement to keep emissions down. The case I made to myself was that a modest power increase (about 20%) would be okay as long as I took good care of the engine. I was also told that my MPG would improve. I do a lot miles, so to my way of thinking if I'm burning less fuel, whatever emissions increase I'd be guilty of under the occasional speed run would be more than offset by the savings on long highway journeys. I do about 70 miles per working day, and most of them safely tucked in behind a semi at about 56 MPH.

I do not have the expertise to remap an ECU myself, but I understand enough about the system to appreciate that a good map takes a lot of work and a lot of testing to get right. The company that did mine was a reputable one. It wasn't cheap, and they had the car for an entire day to "test and adjust". That said, I can only go by my own experience, so if they have done a half job and simply shut certain things down instead of fine tuning them to work with everything else, they will have to answer for it.

Poor rationalization to vacate diagnostic stack items & critically needed as you can see for repairing a car or warning you, " hey sir I'm going to blow up now and spill your crankshaft on the pavement" because no error was displayed you indeed did?

No matter who the stupid awful unrepentant tuner is, setting flags to zero isn't an achievement and not a reason to justify the aforementioned you claim right?

Is the "reputable tuner" going to reimburse you for your engine repair or purchase, because that is what the reputable business would do & if they took away such warnings & without good service to inform you they were doing it, as part of their alleged kill program?

Way to go to defend the people that just shot you in the chest, however, no auto-scan and a clear ploy to spit garbage baseless opinions in the forum & that helps no one, unless your rationalized guidance is to help people kill their car, is it?

 

[jronnquist]

Poor rationalization to vacate diagnostic stack items & critically needed as you can see for repairing a car or warning you, " hey sir I'm going to blow up now and spill your crankshaft on the pavement" because no error was displayed you indeed did?

No matter who the stupid awful unrepentant tuner is, setting flags to zero isn't an achievement and not a reason to justify the aforementioned you claim right?

Is the "reputable tuner" going to reimburse you for your engine repair or purchase, because that is what the reputable business would do & if they took away such warnings & without good service to inform you they were doing it, as part of their alleged kill program?

Way to go to defend the people that just shot you in the chest, however, no auto-scan and a clear ploy to spit garbage baseless opinions in the forum & that helps no one, unless your rationalized guidance is to help people kill their car, is it?

With all due respect, you seem to be reading things into my posts that I have neither stated, nor implied.

I say the tuner is reputable because I spent a great deal of time finding one and settled on the business most highly recommended by customers on independent forums, including members of the UK's Skoda forums. I am not prepared to condemn them publicly until I have established that they have indeed botched my car. Should that turn out to be the case I will be as militant as yourself in addressing the issue with them. I have discussed the situation with the owner and he has assure me they will re-flash the ECU back to stock if I take the car back in.

The car has never failed to start or broken down in the 68,000 miles that I have owned it, and it certainly didn't "blow up". The issue with the engine was oil loss, not performance. I opted to go all out and replace the piston rings, turbo, valves, stem seals, and the oil pump tensioner partly to cover all possible causes, and partly to take advantage of the fact that the engine was out and accessible. The oil loss issue has been resolved, but post rebuild the engine has developed some new issues, and I bought the VCDS setup to diagnose them. It was only when I noticed the lack of expected fault codes that I considered the remap may be responsible.

So to be clear; if the ECU with stock maps behaves as it should, I will waste no time raising hell with these people for hacking rather than remapping my ECU, whether the oil loss issue or the problems after rebuild are a direct result of this or not. I share your indignation at the prospect entirely. I just want to establish that it wasn't something I messed up myself during the rebuild before I go in with all guns blazing. I think that's a fairly reasonable approach, don't you?

 

[Jack@European_Parts]

With all due respect, you seem to be reading things into my posts that I have neither stated, nor implied.

I say the tuner is reputable because I spent a great deal of time finding one and settled on the business most highly recommended by customers on independent forums, including members of the UK's Skoda forums. I am not prepared to condemn them publicly until I have established that they have indeed botched my car. Should that turn out to be the case I will be as militant as yourself in addressing the issue with them. I have discussed the situation with the owner and he has assure me they will re-flash the ECU back to stock if I take the car back in.

The car has never failed to start or broken down in the 68,000 miles that I have owned it, and it certainly didn't "blow up". The issue with the engine was oil loss, not performance. I opted to go all out and replace the piston rings, turbo, valves, stem seals, and the oil pump tensioner partly to cover all possible causes, and partly to take advantage of the fact that the engine was out and accessible. The oil loss issue has been resolved, but post rebuild the engine has developed some new issues, and I bought the VCDS setup to diagnose them. It was only when I noticed the lack of expected fault codes that I considered the remap may be responsible.

So to be clear; if the ECU with stock maps behaves as it should, I will waste no time raising hell with these people for hacking rather than remapping my ECU, whether the oil loss issue or the problems after rebuild are a direct result of this or not. I share your indignation at the prospect entirely. I just want to establish that it wasn't something I messed up myself during the rebuild before I go in with all guns blazing. I think that's a fairly reasonable approach, don't you?

You are new, however, you should be forewarned I am an antagonist asshole.
I never stated anyone was anything, nor did I ask who the alleged tuner is, now did I?

I'm just here asking questions and putting things in perspective, yet still you have presented no "HARD DATA" being an auto-scan & to help resolve your question to authenticate all the aforementioned behavior, now did you?
That asked, so they are credible by people shooting their mouth off in forums and you are just merely trying to ascertain if you are at fault right, but need to ask questions like should my car report DTC's, WTF doesn't this answer all the aforementioned very quickly?

If you have no warning & where you normally would have such an MIL or DTC, then why wouldn't this be a reasonable reason for your motor to smoke the rings from over fuel fat mixtures applied & to mask over advanced timing maps I suspect and pushing hard into detonation with most likely CF ignored or misfires too, contaminating the oil with fuel as a solvent?

 

[Uwe]

I am an antagonist asshole.

Quoted for truth.

But we love you anyway.

-Uwe-

 

[jronnquist]

Okay, that's fair enough.

And I see your point. If they have simply blocked DTCs from showing up or deactivated warning lights then we have a serious problem. The place that did it is up in Bristol (about a 2-hour drive from here) so it's going to take me a couple of days to make the trip. Once I have this sorted I will record some basic block info and post.

 

[Jack@European_Parts]

Okay, that's fair enough.

And I see your point. If they have simply blocked DTCs from showing up or deactivated warning lights then we have a serious problem. The place that did it is up in Bristol (about a 2-hour drive from here) so it's going to take me a couple of days to make the trip. Once I have this sorted I will record some basic block info and post.

Don't even tell me the alleged tuners name, really don't care which one it is.

You should post the data you see and codes you dont see reported by the ECU for each device unplugged and video it, right?

Then have ECU flashed to stock or get second stock ECU and do the same and watch what does and doesn't report for comparison, right?

Post it here or on YouTube and than if you find what you and I are suspecting, let the tuner know first without fully embarrassing them & that they owe you or you will take them to task with naming them to TUV, MOT, & the court of public opinion, right?

Hope those questions help you surmise a path of proper documentation and hey did you know unless you have a MOT or TUV exemption approval, that tuning is illegal in the UK too, "technically" speaking of course?

https://www.gov.uk/getting-an-mot/the-mot-test

NostraJackAss has used Omnipotent asshole powers with extra ball baked beans to Question!