:OWell about 10 days ago I reinstalled my "customtuning" postally remapped ECU; and my initial feelings were "this is great!"

However,

Tuesday morning, after a night shift, we set off from Southampton to Cardiff with the car loaded up with the following:

me, the wife (driving), 3 kids, 2 dogs, a cat and enough luggage for a few days.

We were going fine, the car never missed a beat...UNTIL we pulled into Leigh Delamare services for petrol...

£20 of petrol later and the car simply refused to start! It turned over fine, but no sign of starting at all.

I tried a pathetic attempt at a roadside repair (check a few obvious connections, followed by last resort of disconnecting the battery for a few minutes to allow my remapped ECU to reboot) but to no avail.

Eventually we resorted to joining the AA, who initially charged £55 to join. WHen the repairman turned up an hour later, he tried exactl what I had before plugging in some sort of OBD reader and promptly told me "your ECU has a programming fault - I can't fix it."

He then upgraded us to AA relay, at another £100 in order to transport us and the car onto Cardiff, where we are as I write this.

As if that wasn't enough, I phoned custom tuning today to be told "what we did to your ECU couldn't possibly have caused what happened"

However, they agreed to restore the ECU back to its original state of tune, so I posted it to them again.

A few questions for you techie people there...

Will it work when I get it back?

If not, what do I do??

So their remap couldnt have possibly caused an ECU programming fault???

I smell something

So their remap couldnt have possibly caused an ECU programming fault???

I smell something

What is your expert opinion?

My, non expert opinion, is this...

Before the remap, the car was fine. No faults, driving fine.

Then I get a remap (which somehow involves them opening up the ECU to remove something and remap it - they wouldn't tell me what)

Less than 100 miles after the "remap" the car breaks down and the AAs OBD reader tells me there is a "programming error" in the ECU.

I think it MUST have been something they did.

Any idea why they might remove something to remap it??

This is your Octavia we're talking about? They shouldn't have opened your ECU or removed anything.

Yeah, it's my Octavia. I'm hoping they didn't do one of those "resistor" type mods you can buy on ebay for about £6

If they have had the ECU apart it sounds like either that's their way of remapping (taking the flash chip out and using a programmer to reprogram the chip) or perhaps they tried to bench flash it and the flash failed, meaning they had to resort to other more physical methods. The only way to know is to have a look inside the ECU and have a look at the soldering.

I'd suggest a word with Richard Washbrook as well (oscarli.com). He's the one that the tuners often send ECU's to for repair. Dunno if an ECU checksum error would behave like this....

Sure youve had a strong word with those concerned...

Bas

Was this the £95 special deal you wrote about in another thread?

I think Bengie summed it up in the last post of that thread, his words were "Good Luck".

If it had a checksum error the car wouldn't have started at all.. sounds like some dodgy soldering or something to me! Not that soldering is required!

You need to talk to Custon Tuning and find out what they did. most maps are done through the ODBII port if you take the car to them. If the ECU is removed they have tool that plug directly to the ECU, the only time they resort to bench flashing is if there are problems communicating via the OBD or the direct connection, so the ECU "MAY" have had issues but you need to check with them first. They really should not be allowed to refuse to tell you either. I would always be wary of anyone taking a soldering iron to my ECU

"Bench flashing" is with the ECU plugged into a cable, sounds like they've had to solder it for some reason.

As if that wasn't enough, I phoned custom tuning today to be told "what we did to your ECU couldn't possibly have caused what happened"

Bull****. It's a computer. Thery've just overwritten some of it's code with new stuff. That's like changing system or config files on a PC. If they've dissasembled part of it they could have damaged it. I'm not saying they *have*, but it IS possible.

could just be a checksum error. some cars start a few times with checksum error then they just wont start again till its corrected. if you have vag com or someone near you you may have a code saying internal checksumm error

also if vag com connects then the ecu is probably ok. if the ecu has failed normally vag com will connect.

if they have soldered you may have a leg thats lifted or even a pad. depends on how good there soldering is.

sometimes cars that have had revo or apr have to be soldered as even bench flashing doesnt always work

I think people are right with the checksum issue here. Ecus employ checksum protection, on MED7.5 ECUs it usually takes a few engine starts before it decides it's definately wrong.

There's not an issue with the ecu itself if vagcom can connect and read faults. The ecu is cycling and the processor is running but it's decided not to let the engine start.

Remapping software usually requires an element of checksum recalculation after modification. This envolves modifying some unused areas of the memory.

Kev

I agree about a checksumm error. Is yours a late model Octavia VRS? The last models still use a Bosch ME7.5_1 ECU but the checksumm calculation is very slightly different to the early models, anyone using "cracked" or out of date remapping software might still suffer from this problem.

Dont worry though, if its only software damage then it can be reflashed, although some tuning tools want communicate with a faulty ECU and it might need flashing on the bench in "boot mode"

If you need it sorting i will take a look for free, its not a big problem with the correct equipment.

Checksumm error!

That's what the AA man said.

I'm expecting the ecu back from Custom tuning tomorrow morning. If they've put it back to standard and it had a checksumm error, will it be fixed now?

(note to self - learn a bit more about reprogramming ecus...)

I think people are right with the checksum issue here. Ecus employ checksum protection, on MED7.5 ECUs it usually takes a few engine starts before it decides it's definately wrong.

There's not an issue with the ecu itself if vagcom can connect and read faults. The ecu is cycling and the processor is running but it's decided not to let the engine start.

Remapping software usually requires an element of checksum recalculation after modification. This envolves modifying some unused areas of the memory.

Kev

Thanks Kev, that sounds spot on. I've probably used the car about 10 times since the remap, so what you've said seems to fit in exactly. And I recall the AA man saying "checksum" because I thought he was asking me to "check something":rofl:

Guess I've got some comeback against customtuning then! (They can at least cover my recovery bill...)

sometimes cars that have had revo or apr have to be soldered as even bench flashing doesnt always work

Incorrect.... chips only need to be replaced if they've previously had a chip on them (usually the wrong chip i.e cheaper one that can't be flashed or if it's on an encryption board).

The only problem other companies have with our software and apr software is that they cannot flash an entire ECU as they will be using slave tools that have limited functionality, the ECU would just need to be flashed with a FULL stock file

I think people are right with the checksum issue here. Ecus employ checksum protection, on MED7.5 ECUs it usually takes a few engine starts before it decides it's definately wrong.

There's not an issue with the ecu itself if vagcom can connect and read faults. The ecu is cycling and the processor is running but it's decided not to let the engine start.

Remapping software usually requires an element of checksum recalculation after modification. This envolves modifying some unused areas of the memory.

Kev

Spot on! 10 ignition cycles or so iirc and the ECU will commit "suicide" if there's a bad checksum

Hi

But if it is checksum error , if it is put back to standard , wont the checksum error still be there????

Stored fault code

Sarah

As long as the original map that was on the ecu is flashed back, then the checksum calculation should be the same as before and once the fault cleared all should be well. However if a different version of the standard map is flashed back, then the checksum could still be different and a fault once again will be recorded.

Hi

But if it is checksum error , if it is put back to standard , wont the checksum error still be there????

Stored fault code

Sarah

Hi Sarah,

The ecu's checksum changes back to standard when the correct standard file is written back to the ecu. Ecu is cycled when the ignition is turned on and sees that there isn't a checksum problem anymore.

Diesel EDC16 are even more anal about their checksum to the point where nowdays there are meathods to remove the checksum calculation protection from the serial EEPROM.

Kev

UPDATE:

Just got the ECU back in the post, plugged it all in and it STILL won't start. The engine turns over fine, but just fails to fire up.

Any resident gurus have any suggestions what to do next? I'm stuck in Cardiff at the moment and have to be back in Southampton for work on Monday!

Pleeeeeeeease???

Can you read the fault codes and post them here?

If you can do without the ECU i'd be happy to take a look at it for you with no obligation if you could send it to us.

Kev

Can you read the fault codes and post them here?

If you can do without the ECU i'd be happy to take a look at it for you with no obligation if you could send it to us.

Kev

I don't have the facility to read the fault codes (don't have vag com) but the AA man said "Checksum error" - does it need to be more specific than that?

I can easily do without the ECU because the car won't go without it - the only problem is, I'm in Cardiff and you're in Peterborough, so anything you do to fix it (if it can be fixed) is going to ned to be simply a "plug and play" option. Does that cause a problem?? - I am really, really grateful by the way...