More S3 1.8T Tuning questions/problems

[Niffty951]

Hmmm I've been chasing this problem round the car now all week. Ran perfectly when it was first mapped. The car seems to go like a rocket in the lower gears (almost all of the time) but once you get past third (4th,5th,6th) it seems to have massively reduced boost?!

It also occasionally does the same thing in lower gears (just doesn't get up on that wave of boost like it should) and occasionally works correctly in the higher gears? But rarely.

I've replaced coil packs, plugs, oil (why not), DV valve (now Forge007p), MAF and found a cracked vacuum line which I repaired. The car is now smooth as silk but still the underlying problem remains. I really want to get this ironed out before I continue my mission to try and get a little more from the car.

Any suggestions welcome? I'm stumped.

[Niffty951]

Forgot to mention before its asked. All replacement parts were genuine.

Edited by Niffty951 on Tuesday 11th August 15:29

[PJR]

It only did this since it was mapped? Who mapped it? Was it a generic off the shelf job? Either way, i'd give them a ring and see what they suggest.

P,

[Dr G]

Could be they've simply cranked all the settings up to 11 and the ECU has said no! Running it on proper fuel?

[S3 Nattie]

Have you got VAG COM, it will save all your trial and error as to what is causing your problem.Did you reset the ECU once you changed the parts you said as there maybe a stored error within the ECU which has now been rectified. Have you checked the lines around the N75 or N249 valves as these control your waste gate and boost.

Edited by S3 Nattie on Saturday 8th August 03:17

[Tame Technician]

Best speak to the tuning company who remapped it. They should know whats up.

But I'd guess - Charged air temperature too high causing ECU to reduce boost pressure, to avoid detonation.

If your tuning company agree, Buy a bigger intercooler.

[Niffty951]

Tame Technician said:

Best speak to the tuning company who remapped it. They should know whats up.

But I'd guess - Charged air temperature too high causing ECU to reduce boost pressure, to avoid detonation.

If your tuning company agree, Buy a bigger intercooler.

Cheers for all the comments above. Done a scan of the error codes and nothing came up but the new MAF sensor seems to be reading low according to Awesome Gti.

I will change that first but failing that I'm very confused?! I found one leak in one of the vacuum lines around the n75 but have fixed this, might be another somewhere.

Interesting comment of the air temperatures I hadn't thought of that but given the weather lately in UK and that the car is only very modestly tuned here I'm sure its not a problem yet. I will be very worried if it is.

I've spoken to the guys that did the map and they are sure it'll be the maf. Seems suspect to me that the new unit would be failed but until I've tried replacing again I can't be sure. My thoughts are that if there's a leak I can’t see somewhere after the maf sensor on the intake pipe into the turbo it could be reading low as its drawing air through the hole/gap/leaking part?

Edited by Niffty951 on Tuesday 11th August 15:30

[Niffty951]

A little more of a note on the symptoms as I've now driven it a lot further.. it is definitely aggressively backing off the boost so that the car feels like your driving into a serious headwind then if you leave your foot down long enough it eventually (about 5200rpm usually) clears out and boosts properly (very well).

You can also sitting in sixth gear get the car to accelerate very hard by being very gentile on the throttle. There's a tiny thin sweet spot on the pedal which allows it to accelerate but any more or any less throttle application results in instant loss of boost and back to 'fighting the headwind'

That’s the best way I can describe it really. hmmm

Edited by Niffty951 on Tuesday 11th August 15:31

[Colonial]

Try replacing the N75 with a N75J.

The other thing is that the standard induction hoses may be collapsing in on themselves. Pretty common issue and fixed by replacing them with upgraded items such as Forge or Samco

[Niffty951]

Colonial said:

Try replacing the N75 with a N75J.

The other thing is that the standard induction hoses may be collapsing in on themselves. Pretty common issue and fixed by replacing them with upgraded items such as Forge or Samco

^^^ That is a very very interesting one! My intercooler hose keeps pulling itself off (not completely off but trying) the metal pipe that goes around the plastic cover on top of the engine. I've checked and its not leaking, came to the conclusion that it should be under pressure not vacuum so couldn't be pinching together but it is very flexable. Which hose is it that causes the problem and how can this be if its under boost?

I'm also replacing the MAF again today just to be sure.

[Colonial]

Niffty951 said:

Colonial said:

Try replacing the N75 with a N75J.

The other thing is that the standard induction hoses may be collapsing in on themselves. Pretty common issue and fixed by replacing them with upgraded items such as Forge or Samco

^^^ That is a very very interesting one! My intercooler hose keeps pulling itself off (not completely off but trying) the metal pipe that goes around the plastic cover on top of the engine. I've checked and its not leaking, came to the conclusion that it should be under pressure not vacuum so couldn't be pinching together but it is very flexable. Which hose is it that causes the problem and how can this be if its under boost?

I'm also replacing the MAF again today just to be sure.

I am not sure of the science behind it, but it works. It's the intercooler hose that is the main issue. But I also have the linkages being updated once I take the front end off the car. Really makes a difference and I 100% say do it as your next port of call.

Just on a side note, a good way of keeping the coilpacks in good working order is to remove that plastic cover as well as heat is the main cause of the coilpack issues

[nonuts]

Replacing a N75 with an N75J will most likely cause limp mode, I wouldn't bother especially if you're already having issues.

It's the TIP that's common to collapse on remapped cars, that's the other side of the turbo from the one you're seeing on the top of the engine. The TIP is at the back on the right hand side the airbox goes into the top of it past the MAF.

A new MAF shouldn't be faulty, I'd be having serious words with whoever remapped your car.

[Niffty951]

Well as suggested above the new new maf didn't solve the problem (now seems worse than ever) so I'll be making the call to Angel in a minute. Thanks for advice again and I will report back on what they say / when I find out what it is and sort it.

[Adamantium]

apologies if this has been asked as I've skimmed this thread, see if you can check your boost pressure whilst driving to see what its doing.

[Niffty951]

Not been asked yet. I have a gauge at home which just needs wiring up so I'll fit it tonight and have a look. I'm interested to see if its over boosting at times because it nearly took my head clean off my shoulders when I pulled out in third to overtake someone the other night! Felt way WAY too brutal to be correct!

I've spoken to Angel who said they're almost sure its not the map because its not a consistent fault. If it boost correctly sometimes it suggests something is sticking. They have suggested N75 which I have on order to collect tomorrow. I've also taken it upon myself at this stage to rule out a boost leak or crushing pipe anywhere (went a bit crazy actually - this is really bothering me!) so I've ordered every single boost hose, a new TIP and a full vacuum kit with all new clamps from SFS.

I'm planning at the same time to bypass the N249 thingy just to rule that out. Can I confirm on that point that I'm blocking the feed from the vacuum tank to the dv, running a line from the dv to the intake manifold directly and adding a T piece in the line to go to the fuel pressure regulator? Is all that correct? I'm leaving the N249 valve in so the ECU shouldn't get upset, it just wont be able to actually control the DV anymore.

If all of this doesn't solve my problem then having done already the DV, MAF (x2), coil packs and plugs... I think I'm going to burn the car and buy a van!

Edited by Niffty951 on Tuesday 11th August 15:32

[nonuts]

N249 is a safety feature of sorts, I've thought about removing it in the past and thought overall it's a bad idea especially if things aren't already working 100%.

Have you checked the pipes going to and from the valve immediately under the plate that supports the dipstick? I guess you'll check them all when replacing so at least that will be ruled out.

Did your car work properly before it was mapped? If so I'd be pretty angry at their attitude!

[Niffty951]

nonuts said:

N249 is a safety feature of sorts, I've thought about removing it in the past and thought overall it's a bad idea especially if things aren't already working 100%.

Have you checked the pipes going to and from the valve immediately under the plate that supports the dipstick? I guess you'll check them all when replacing so at least that will be ruled out.

Did your car work properly before it was mapped? If so I'd be pretty angry at their attitude!

It was absolutely fine before the map, wonderful in fact.. but adding 50hp worth of strain and extra boost does tend to bring out any faults that were previously not detectable. I cannot honestly blame the map until I've exhausted every other possibility. If I do find that the remap is to blame having replaced every other possible part in the engine then I will be speaking to them very seriously about a refund as its now cost me £865 just in parts relating to finding the engine fault and £579+vat for the Haldex controller that failed interestingly at exactly the same time as the map was done?! Can't think that it could have been in any way to blame but it did fail on the same day as I had the map done (rear diff just kept twitching like crazy till I replaced the controller). A real pity because the map transformed the performance and enjoyment of the car for the first 24hrs till the fault occurred and I wouldn't want to go back to a standard car now ever.

Edited by Niffty951 on Tuesday 11th August 15:32

[Colonial]

Does the power seem to cut out around 4,500 and then come spluttering back in an intermitment fashion?

If so I can tell you with 96% confidence that it is just the pipes collapsing as mine had the same symptons and replacing them with Forge items cleared it up.

The extra power from a map causes older ones to collapse in on themselves and it is not a fault of the chip/map itself.

[phumy]

Sorry, but you really dont have a leg to stand on when you start mentioning that youve had to spend XXX on this and XXX on that, all because you decided to put extra stress and strain on your engine, then you will try to get some recourse from the tuning company. All they can do is tell you whats wrong with it and that would have been my very first port of call, but now you have started to rip into everything and decided to change the lot, you might do that and still not clear the fault.

You really should go into this with your eyes wide open and realise that your putting extra wear and tear on all the systems on your car and eventually something will give up the ghost or go pop.

Edited by phumy on Wednesday 12th August 02:47

[Niffty951]

phumy said:

Sorry, but you really dont have a leg to stand on when you start mentioning that youve had to spend XXX on this and XXX on that, all because you decided to put extra stress and strain on your engine, then you will try to get some recourse from the tuning company. All they can do is tell you whats wrong with it and that would have been my very first port of call, but now you have started to rip into everything and decided to change the lot, you might do that and still not clear the fault.

You really should go into this with your eyes wide open and realise that your putting extra wear and tear on all the systems on your car and eventually something will give up the ghost or go pop.

Edited by phumy on Wednesday 12th August 02:47

Phoned them several times and followed their suggestions as to why its not working. First they thought DV then MAF then N75 same as anyone else would really. Can't not replace the parts and ask them to diagnose, so all the obvious options needed to be ruled out.