TDI de-cat, will it make it idle funny? **SORTED**

[Cupra_Red]

my fr 1900 tdi has been de-cat, and all silencers cut out, no idea why was done when i bought it

will this make the car idle up and down and create boost at idle?

it has not been mapped.

it makes boost then shuts off idles tidy then itl make boost again ??

 

[Seatmann]

It shouldn't, there's loads of them with straight throughs and no problems, are the revs dancing about a bit?

 

[Cupra_Red]

yes its also creating boost at idle.....

 

[Cupra_Red]

it it correct to think the cat is also used to cause back pressure to stop the over run on the turbo? if this is true then thats why im having massive boost spikes

 

[Seatmann]

If the revs are dancing about and your engines a PD then it could be the timing belt not tensioned properly or the coolant temp sensor on any tdi. The straight through wont cause that, just makes more noise including a dv type noise when letting off on the throttle.

 

[Martin_FR]

Running a milltek turbo back exahust (with back box) and Iv had no issues with idle

VAG COM scan show any fault codes logged?

 

[uzi_cupra]

you should not be getting any crazy boost spikes with the decat in place, and as for your revs jumping i'd say its either temp sensor or could be something to do with the maf.

 

[Cupra_Red]

Maf makes no diff unplugged or plugged in

Temp is all fine on the gauge it does not drop and then shoot back to 90 it sits at 90

Just about had enough of it!

It does not bring a single fault code up

 

[Cupra_Red]

Also the revs don't jump realy, it just starts spoiling at idle rev's then will stop boosting and start again and so on

 

[uzi_cupra]

hmm maybe check WOT on vag com in 3rd/4th it should be between 70-80% if any lower or higher then might just need to adjust the actuator (could cause the problem-but not common)
does the problem happen all the time?i cant seem to think what it could be apart from whats mentioned.(it has been serviced yea?)

 

[Cupra_Red]

car has full service yes, had new turbo in 2010 by seat

happens all the time, can be driving come off the power and u can hear it still spooling up

it makes 0.5 bar of boost whilst its having a mad minute at idle and like i say it will drop back to normal idle after no set time....can still boost for few mins or it will do it for few seconds

 

[Mr_Dave]

By creating boost, do you mean that the turbo spools when idling? Or do you actually see the revs jumping up and down?

My ex-beeza never did anything funny with revs, but even with a stock system they start spooling the turbo.. There is a reason but I forget what..

 

[Cupra_Red]

By creating boost, do you mean that the turbo spools when idling? Or do you actually see the revs jumping up and down?

My ex-beeza never did anything funny with revs, but even with a stock system they start spooling the turbo.. There is a reason but I forget what..

revs dont go up it just starts boosting and then boost drops off and then boosts agin and so on....

 

[Martin_FR]

When mine is left idling for a few minutes I hear it start to spool and does so for a while. Has always done it
Maybe this is what yours is doing and is just natural for the PD130's? Is it actually causing you any problems?

 

[Seatmann]

I wonder if it's a new thing to protect the turbo because normally leaving a tdi idling is bad for the turbo due to lack of oil getting round the bearings.

 

[samussamus1]

Seatmann, idling is good for the turbo as oil is going around the bearings still yet the turbo is not spinning very fast, this is why people install turbo timers

 

[samussamus1]

oh and for the idling boosting thing, thats normal on a pd130, sometimes it happens, sometimes it doesnt, i can be slowing down with the clutch down, and you hear the turbo spool quite loudly....its normal as long as your revs are normal.

 

[Martin_FR]

Seatmann, idling is good for the turbo as oil is going around the bearings still yet the turbo is not spinning very fast, this is why people install turbo timers

Iv heard both good and bad. Good for it letting oil circulate after a long / hard drive but then again heard idling for long periods isnt good.

Obviously at idle your oil pressure isnt as high as when your driving really is it

 

[samussamus1]

Ah I see your point, best person to ask is a turbo specialist

 

[Martin_FR]

He doesnt actually mention the idle speed rising so im thinking its just the boost noise hes hearing? If so I reckon thats perfecty normal, and it probably isnt making much boost but just hearing the spool. And getting paranoid about a decat affecting things.