Boost problems, help please!

[Didster]

I've recently bought a Stage 2 Ibiza Cupra with a RR printout at 274.5bhp and 285ft lb. The mod list is as long as my arm including K03S hybrid, Live map, N249/SAI delete with resistors, turbo-back Milltek, TIP, Forge 007P etc.

But anyway, I was wondering what sort of boost levels the car should see at this spec with that amount of power and how it would behave tailing off etc?

Also have a very odd boost fluctuation issue whereby if I load the car up about half way and watch the boost gauge it'll hit 10psi then fall back to 5, then 10, then 5 etc. I've done some vagcom logs if anyone would like to see those.

I genuinely thought it was the N75 valve but today having tried an MBC bypass on the N75 with no change I'm stumped now. Few people have said it could be the actuator?

Need your help 1.8T gurus! I'm pretty clued up on these engines but this one's got me!

 

[ibizacupra]

are you sure its remapped?
sounds like ecu is trying to pull back when its seeing more boost than its expecting.

got access to vcds to log the car? check faultcodes etc etc

 

[Didster]

Definitely remapped. I have logged the car and requested boost vs actual boost is massively different and under load mid-throttle it'll boost to say 10psi, then back to 5-10-5 etc. Full boost is only 17psi too even in 5th so something's a miss.

 

[ibizacupra]

logs?

 

[Didster]

Logs are here in PDF format:

Full throttle from 2000rpm to 7000rpm

Half throttle pulls to show fluctuation

Boost Pressures Req vs Actual

Maybe you can help make head or tail of it?

I think it was mapped by a company called Viper Performance?

 

[ibizacupra]

has it done it since remap?
if not, consider trying another N75 and smoke test to confirm no leaks

 

[Didster]

To be honest I bought it remapped but the guy who owned it said it was feeling slightly slower than usual and thought the lumps in the boost were down to the software but I'm not so sure.

I've tried 3 other N75s and MBC and nothing changes it. Gonna check for leaks tomorrow using the smoke tester at a friend's garage. What do you make of the logs Mr Badger?

 

[Didster]

Still not managed to get into the garage for a boost leak test BUT have done a few more live data logs with vagcom and you can see what I mean totally from these graphs I captured:

You can see I'm not reaching the boost levels I'm supposed to be and the fluctuations at half throttle are clearly visible too.

Any ideas guys?

 

[Hobbiniho]

what spring is in the 007p?

 

[Didster]

I haven't actually looked tbh but AFAIK it's the yellow one?

 

[ibizacupra]

as for not achieving requested, logging 118 n75 duty cycle will confirm.
erratic boost fluctuations could be several things, including remap.. but leaks, n75, MAF all could influence this fluctuation.

 

[Didster]

I'm sure I've logged 118, what do I look for in the log and if I log the MAF what will indicate a problem there? Thanks

 

[Hobbiniho]

has it still got the pcv? worth checking for split/leaking pipes

 

[k123]

Looks like a boost leak from the graphs....worth getting someone to rev it to 4k while you scrabble around at the front of the car listening for hissing noises?

Very different engine but I just spent an age going through everything before finding it was a boost leak in the intercooler:

seatcupra.net/forums/showthread.php?t=373959

 

[ibizacupra]

smoke test for the win..

I would be lost without mine finds all sorts of leaks quickly

LOTS of customer drive in completely unaware its leaking like a seive.... and when they see smoke pouring out of various perished and split pipes, their comments of "its driving ok" are Confirmation, thats no gauge of it being "ok" at all !

 

[Didster]

Well smoke test has shown no leaks at all. I have noticed though, unplugging my MAF doesn't seem to do anything and if anything the car drives slightly better? OK this doesn't effect the way the car boosts but is that an indication of a nackered MAF too? Maybe this car has more than one issue?

 

[Didster]

Right OK, small update.

Yesterday I had it smoke tested again properly and we found 2 big leaks in the pipework which we've now rectified, also got it on the rollers at Dynotech in Erith.

We found the car is running dangerously lean so have unplugged the MAF to rectify this for the time being for safety. It's only running in the 10s AFR wise with the MAF disconnected so no worry of bore wash!

Also the fluctuating still hasn't gone and I'm at a real loose end now. I have noticed that my actuator is quite easy to move though so wonder if this has anything to do with it?

 

[ibizacupra]

Right OK, small update.

Yesterday I had it smoke tested again properly and we found 2 big leaks in the pipework which we've now rectified, also got it on the rollers at Dynotech in Erith.

We found the car is running dangerously lean so have unplugged the MAF to rectify this for the time being for safety. It's only running in the 10s AFR wise with the MAF disconnected so no worry of bore wash!

Also the fluctuating still hasn't gone and I'm at a real loose end now. I have noticed that my actuator is quite easy to move though so wonder if this has anything to do with it?

what crap smoke test was your prior one to find 2 x big leaks this time?

lean when maf connected, rich when not? under reading maf then?
logged g/s on it vs boost?

if maf's scaled 1:1 then rule of thumbe guide of g/s divide 0.8 = bhp *should* approximate.

when maf's replaced, fueling should correct.. IF the maps not wonky for whatever reason.
To rule out hardware from software, MBC for boost control, and if its all smooth on mbc it points to software, once all your leaks and didgy maf are ruled out and there are no residual faultcodes left.

 

[k123]

I couldn't undo the security torq screws on my MAF since I don't have the correct bit.....got a pleasant surprise though when I found it pretty easy to undo both screws with grips around the edge of the screw head.

No damage afterwards and was able to give it a proper clean once in there....whilst laughing at how pointless it was using MAF cleaning spray while it was still assembled!

 

[Didster]

lean when maf connected, rich when not? under reading maf then?
logged g/s on it vs boost?

if maf's scaled 1:1 then rule of thumbe guide of g/s divide 0.8 = bhp *should* approximate.

A little confused here, what blocks do I have to measure to check the MAF readings and are you talking about requested boost or actual?

What readings mean it's ok?