Dont bite my head off, coz i might be wrong, but it you have a pre cat lambda probe fault then it wont boost right surely, i change my down pipe recently and when i removed the lamda prob, i sprayed some wd40 on it to get it back in nicely, when i drove it down the road it wasnt boosting right until it burnt the wd40 off the lambda probe??? shouldnt you change the lamda?
 
Dont bite my head off, coz i might be wrong, but it you have a pre cat lambda probe fault then it wont boost right surely, i change my down pipe recently and when i removed the lamda prob, i sprayed some wd40 on it to get it back in nicely, when i drove it down the road it wasnt boosting right until it burnt the wd40 off the lambda probe??? shouldnt you change the lamda?

Im not too sure either but you may be right, lambda detects oxygen in the exhuast system, so if its faulty and detecting too much oxygen, or not enough, would it be possible for it to cut down the boost pressure or up the fuel to try and cure the problem. :confused:
 
Lambda may need replacing as he is getting a code but that may be down to his decat so changing the lambda might not take the code away. Only one way to find out and thats by changing it. However the leak needs sorting as that may mean he is losing boost aswell.
 
yeah but shouldnt he be getting a second lamda probe fault then after the decat then? the pre cat one wont bring the engine light on due to a decat surely because its before the cat, so it shouyld be reading right? Has he had the second lamda prob mapped out?
 
Maybe maybe not. The flow past it might not be right so its causing it to read wrong. Only way to find out is to fit another one anyway but he NEEDS to sort the air leak problem out. Changing the lambda wont take the air leak code away which also could be causing his boost and/or mpg problems.
 
this leak? is the the fault code secondary air system-leak detected? if so danny you need to check the vac pipe goin in to the egr valve, thats is commen for splitin and causes this fault to come on, the egr valve is under tou TIP. also commen for this fault is the secondary pump its self leaks or the impeller inside seizes. The pump is the big black thing in the way of your oil filter
 
ta lads am gonna try that now...

everytime i drive it now and hit full boost it goes in 2 limp mode and doesnt come out of it till i turn the car of...so i get one blast of 15psi...

Ive had that lambda code for nearly 6months and it was running fine...
 
A lambda code wont cause any boost loss so its not that. You've done the N112's bypass so what did you do to the secondary air injection system when you did it? I mean like did you take it off, leave it on there or even take half off and block the pipes?
 
A lambda code wont cause any boost loss so its not that. You've done the N112's bypass so what did you do to the secondary air injection system when you did it? I mean like did you take it off, leave it on there or even take half off and block the pipes?

Why wouldn't a lambda code cause boost loss???, if the ecu sees theres a fault with exhaust gas mixture then it thinks the engines not running right so cuts the boost down so its doesnt to any further damage until the fault is cured?
 
Ok i should re-phrase that. A lambda code (as thats all it is not actually at fault) wont cause a loss of like 6-8psi like it is on dans. Will over/under fuel of course tho but not cause as much loss in boost that hes actually getting atm
 
It could easily cause that much boost loss. You dont know its just a code and not a real fault. You are just assuming it because of the decat. If it has been overfuelling which from his mpg it has then it could have actually broken the lambda sensor. Too much fuel will smother the power. Too rich=less power.
 
ta lads am gonna try that now...

everytime i drive it now and hit full boost it goes in 2 limp mode and doesnt come out of it till i turn the car of...so i get one blast of 15psi...

Ive had that lambda code for nearly 6months and it was running fine...

So your new turbo is boostin properly now but your ecu thinks its overboostin and throwin it into limp? or am i miles off?
Would that not be the N75?:confused:
 
A lambda code wont cause any boost loss so its not that. You've done the N112's bypass so what did you do to the secondary air injection system when you did it? I mean like did you take it off, leave it on there or even take half off and block the pipes?

what you meant to do with it sure you said connect it to the dump valve vac line which is what i did when i did it. Is that that?
 
disconnect the pump?

All I did was put a screw in the vac line leading to pump...got a fault code once for it, cleared it and hasn't come back since