this is a tricky one , ( for me anyway, and i'm a mechanic)... put a td05 18g from harvey on my 2006 2.5 wrx in may this year had it mapped and was running great holding 20 psi(1.4 bar) from 3rd to 5th. noticed about 8 weeks ago only running 17 psi and over fueling car was holding back on full throttle at about 5000 rpm, got the map checked and adjusted a few things , (don't ask me what the mapper did it) ,..
was fine for 2 weeks then was over boosting and getting fuel cut at high revs at 25 psi, had map checked again and fitted a 3 port boost soleinoid, has been fine for a week until last night , on motorway noticed only boosting at 16 psi in 2nd 17 in 3rd and 18 in 4th and 5th.... no idea why after it's been mapped it changes after a few days ... please can someone shed some light on this or if someone has had similar issues please let me know .....

 

just to add the car has fuel pump ,sti top mount, full decat ,cosworth panel filter. and cometic headgaskets...

 

It is some thing that is failing slowly. It would appear your mapper is mapping around the failing sensor or problem and not diagnosing it. Buy ay, i know **** all about mapping!

Is it possible for you to do a fault code check. Or your mapper?

 

no fault codes stored, have spoke to my mapper and he has just informed me that my ecu will reduce boost when air temp gets close to 0 degrees... going to see what happens when warm weather arrives..

 

As i said above, i know sweet FA about mapping.

But what i do know is, my car makes 'more' boost when the air temp gets down to 0 degrees, not less. Due to the cold air being denser.

You will be back at the mappers sooner rather than later, as when whatever it is, deteriorates even further your problem will return, and at some point you should recieve a CEL or an error code. Unless of course the mapper has adjusted the tolerances beyond the recommended levels.

You would be well advised to locate the problem, rather than masking it with a tweak. Perhaps a second opinion is in order.

 

+1

 

ok guys thanks for the input , i'll have another look

 

ok, just for a update , i went out on sat and the outside temp was 4 degrees , the boost is back and pulling like a choo choo, so my mapper was right, he said 2006 models onwards have a saftey feature on them to reduce the boost in cold temps .... he also said he can change the map to get rid of this if i want .... just thought i'd post this incase any body else worried !!

 

Good news mate