Weird boost issues

[CupraStu]

Morning all hoping someone can help!

This morning my Leon did something strange, car was driving as it did when i picked it up in January slowed down on the approach to a roundabout, then come the other side of the roundabout i had 0.5bar boost and sounded like the dump valve wasn't working.

The car has following mods : Ramair filter, Forge Splitter Dump valve, Full Milltek non res with Toyosport downpipe and a remap by a guy who mainly specialise in Ford / Vauxhall's but does have a reputation for being good at what he does.

I've run an OBD11 check on it and ive got "17705 Pressure drop between turbo and Throttle Valve (check D.V.)"
Now i know doing research and my previous 1.8T experience that the Sp litter is not seen in the highest light. Usually the car will hit 1.4bar and then hold 1 bar but as said coming off the roundabout would not go past 0.5bar.

Ignition reset it and it was normal again however seemed to misfire and "hold the revs" when i parked up in my work car park idle was sat at 1300 for about 20 secs even though the car was hot and up to temp?!

Only other thing i would add is my car never has sat at 90 on the temp gauge, it seems to fluctuate between 70 and 90 quite a lot.

I've carried out a throttle clean and MAF sensor clean and also replaced the coolant temp sensor with a genuine one, before i got the car it also had a new turbo so cant see it being that.

Any ideas?

 

[mty12345]

Hi mate. The temp not staying at 90 is definitely the thermostat.

0.5 bar is limp mode, and that 17705 code is probably the cause. It's a pain in the ass on a lot of mapped cars and is caused by a glitch in the software. There is a certain parameter that needs to be changed during the remap. If not done then this code will often pop up on mornings when the temp is below 5C on start up. Turning the ignition back off and on again will clear it and it shouldn't happen again until you have another cold start. If it does happen at other times then you have a genuine leak, although from my experience you would usually get a code for 'mixture too rich' if that was the case.

Sticky revs i'm not sure..... did you recalibrate the throttle body with VCDS after cleaning it? If not it could be that. Hope thats some help.

 

[CupraStu]

Hi mate. The temp not staying at 90 is definitely the thermostat.

0.5 bar is limp mode, and that 17705 code is probably the cause. It's a pain in the ass on a lot of mapped cars and is caused by a glitch in the software. There is a certain parameter that needs to be changed during the remap. If not done then this code will often pop up on mornings when the temp is below 5C on start up. Turning the ignition back off and on again will clear it and it shouldn't happen again until you have another cold start. If it does happen at other times then you have a genuine leak, although from my experience you would usually get a code for 'mixture too rich' if that was the case.

Sticky revs i'm not sure..... did you recalibrate the throttle body with VCDS after cleaning it? If not it could be that. Hope thats some help.

Appreciate this! So if i was to get a actual remap from say REVO (only one in my home town of Inverness) they would already know about that issue and would be able to adjust the parameter.

I didnt take the Throttle valve all the way off so didn't think it would need a recalibrate, may see if i can find out how to do it on OBD11 as i dont have VCDS

 

[mty12345]

I can't say 100% that revo will have patched it, but i would definitely have thought so. Maybe drop them a email just to check. Other option would be to get a custom map done by someone like bill@badger5, then you could take advantage of the downpipe etc. Obviously it depends what part of the UK you are in though.

I managed to find a link to more info about the parameter that needs changing, you could go back to original guy and get him to change it for you.
As i understand it, it's as simple as changing the one value in FVPDKLDUS to a 0.
https://18t-tuning.co.uk/17705-pressure-drop-between-turbo-and-throttle-valve/