have been having a problem for a while with boost and mpg and cold starting..I have replaced maf,idle control solenoid,today coolant temp sensor,also clean boost solenoid etc..checked all pipes for leaks..Today i noticed that the person i bought the car from has welded in the lamba which i was gona change(so need another)then noticed an exhaust leak in the downpipe..what affect would this have??

 

anyone??

 

If the lambda is in the down pipe and its leaking then i would have thought it upset its readings.