any ko4 - gurus - help needed after conversion!

[olethalb]

right chaps, i was on scn a while back with my old ibiza cupra and you chaps seem to know whats what! i sold it to get a sensible bora 2.0 8v 115bhp

- after a short time i got bored of the lack of power and dropped a golf gti AUM 1.8t lump in with s3 everything - inlet, injectors, tb, 4 bar fpr, ko4, dp, charge pipe and maf etc etc

ever since the conversion i'm having boost issues and cannot get my head around it, basically when you put your foot down it boosts to 20 psi then drops to 8 then up to 18 and so on - boost guage up and down feel and hear the power surging!

IF ANYONE HAS AN IDEA OR KNOWS WHAT COULD CAUSE THIS AS I'M OUT OF IDEAS...

i've replaced all boost hoses with silicon items
silicon forge TIP
changed MAF
changed N75
new forge actuator with uprated spring
new forge 007p with uprated spring
changed vac lines
plugs
coilpacks

somebody please please help and sort this fappin thing out!

thanks, olly

http://uk-mkivs.net/forums/t/272991.aspx

 

[pekingprawn]

sounds like a boost solenoid issue. i've just done a similar conversion in a golf but i rid myself of all the n112 and n249 valves etc so i wouldnt have these issues.

also could be MAF or lamda probe issue perhaps? although i do confess i'm not an expert. who did the mapping? i chucked on a decat and extended my pre cat lamda cable to reach and got rid of post cat lamda as my decat doesnt have a hole for it. im yet to get the car mapped properly but custom code will be coding out the second lamda probe to avoid issues.

not sure but it could perhaps be a MAP sensor issue too? Could also be a loose electrical connection or connector for any of your valves or sensors. I'd check your wiring etc

 

[m0rk]

do you have access to vag-com?

Would be interesting to see what boost is being requested, and delivered & what the N75 is being told to do.

 

[monomoz]

Dont know if this is worth a go but that sounds just like what my a3 1.8t does when i run it on crap fuel. It hits the knock sensor and backs off the igniton timing, then back up to the knock limit and backs off again... doesnt seam to do it on super unleaded though.. might not work but its worth a go????

 

[olethalb]

sounds like a boost solenoid issue. i've just done a similar conversion in a golf but i rid myself of all the n112 and n249 valves etc so i wouldnt have these issues.

also could be MAF or lamda probe issue perhaps? although i do confess i'm not an expert. who did the mapping? i chucked on a decat and extended my pre cat lamda cable to reach and got rid of post cat lamda as my decat doesnt have a hole for it. im yet to get the car mapped properly but custom code will be coding out the second lamda probe to avoid issues.

not sure but it could perhaps be a MAP sensor issue too? Could also be a loose electrical connection or connector for any of your valves or sensors. I'd check your wiring etc

i already removed n112 and n249 before the engine went in, it has a decat and the second lambda is being written out at the end of the month.

i've changed the n75 with another c and tried an h, it's got a new map sensor in it too, changed the maf twice. all wiring was checked when i fitted the engine. it has been suggested it's the remap and to be honest it looks like that is all that is left.

mork - i do have vagcom but it's budget - non registered and i'm not up to speed with it either.

thanks for the replies though chaps.

 

[olethalb]

mono - may be worth a try - possibly a crap map though with wrong or too advanced timing??

 

[pekingprawn]

mapping / fuelling might be out. i havent got my map finished yet and i have to leave my MAF disconnected otherwise my car fully shits itself.

out of interest what fuel pump and FPR you running?

just for the sake of running the car around, im running a 3 bar pump, LCR injectors and 4 bar fpr so it overfuels a little rather than becoming lean. just before mapping though i'll be running a 4 bar fuel pump and 3 bar FPR with the LCR injectors.

also, it could be your MAF internals. You need to run the 3 inch MAF with whatever element the map is expecting. so with me thats a 3 inch BAM MAF with AUM (golf gti) MAF internal element, but even when i run that my car shits itself because its not mapped properly yet.

i'd get it to the tuner and mapped up and then see where your at with it. good luck, nothing worse than these conversion ghosts!