2000 AMK 8L S3 Boost Issues.....!!!

AWDMk1

AWDMk1

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Hi,,

My 2000 AMK 8L S3 has an uprated K04 from CR Turbo's that was fitted about 18 months ago. The car has only done about 10 miles in that time as I've had it SORN'd and garaged while I've had the use of a company car. I've started using it again last week and the power delivery is not as it used to be.....

The S3 has a custom JabbaSport remap, Forge 007p, Forge Induction, FMIC etc. etc. and was last rolling roaded at 293bhp (at JabbaSport). The problem I have now is that the car only boosts to 0.4 bar until it gets to around 4 / 4.5k revs and then it will start to climb gently until it maxes out at 0.75 bar at around 6k revs. The car used to make considerably more boost than that and would regularly reach 1.5bar +, needless to say it's sluggish and nowherere near as much fun to drive!

I'm pretty confident that turbo is fine, as I say it was fully reconditioned and uprated by CR Turbos a little while back and hasn't been used since. I suspect / hope that it is something that may have come about as a result of the car standing unused for so long? I can't hear any boost leaks when driving though can't rule that out entirely..... Also the turbo was replaced because the previous unit failed so there was quite a bit of oil being burned through the exhaust, not sure if this could have caused issues with something either?

Any thoughts or opinions on likely culprits would be greatly appreciated!!!

Cheers,

Paul
 
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Scan for fault codes first... sounds like its in limp mode for some reason...

What you are also seeing is boost creep... actuator pressure is low for an 'uprated' K04... normally specify a 0.8bar actuator on hybrids...

Could also be the wastgate that an issue... need to log the car to see what boost request is... if its requesting more than 0.5bar (typically 2300mbar or more in requested boost) then its possible the turbo is the issue... actuator bar may have come loose and the wastegate could be open all the time...

Fault codes then logging...

<tuffty/>
 
<tuffty/>,

Thanks for the response, appreciated your thoughts, when I say uprated K04 it is, I think, a bog standard K04 when it comes to everything but the bearings so the actuator pressure is probably as per the day it left the factory...

I'll get it plugged in and see what fault codes come back and go from there.

Thanks again.

Paul
 
chinese hotside?
stuck wastegate?

had that on CR hybrid...

or n75 not working... so actuator pressure + creep perhaps what you are seeing
 
Our of interest I unplugged the n75 on the way home from work, took it for a blast and it was exactly the same with it unplugged, no difference whatsoever, still peaked at bang on 0.4 bar beneath 4k revs then increased past that slightly after 4.5k which as tufty and badger have suggested is probably boost creep? Not sure if that helps the diagnosis, still doesn't sound like it has a boost leak but the MAF could be at fault I guess. Filled it full of fresh fuel when I started using it and I've done 100 miles now so I don't think it's that.... I guess fault codes are still my best port of call for now?

Appreciate the thoughts though, keep 'em coming if you have any more ideas please!

Cheers,

Paul
 
In limp mode or a fecked N75 I reckon... the fact your boost did exactly the same suggests the N75... (obvs fault codes will help...) just remember though that now you have driven with the N75 disconnected there will be a fault code for it (N75 open circuit or something)

Fault codes will help the diagnosis for sure...

<tuffty/>
 
Just to resurrect this one, unfortunately I haven't had the chance to get the car plugged into vagcom to get fault codes yet so have been putting up with 0.4 bar max boost which isn't the end of the world given I'm only using the car got a short commute each day at the minute. Anyway.... Surprise surprise pulled away from a roundabout today and it boosted straight to 0.75 bar, it has in car adjustable boost so turned that up to full, found a nice stretch of road and it boosted straight to 1.7 bar which is higher than its ever boosted before and potentially a little higher than it should boost? In car boost gauge / turbo timer logs highest boost which was always 1.67 after about 15k miles and was done when the previous owner had it. Long story short after a couple of miles it reverted back to 0.4 bar max. Feeling a bit inspired I took the n75 off soaked it in wd40 for half an hour, put it back together and it was boosting to 1.55 bar but once again it reverted back to 0.4 after a few miles. Also at one point before it reverted when on wot it hit about 1.5 bar and the engine warning light came on though it still drove fine, pulled over and restarted the car and the warning light was gone.

I appreciate vagcom was and still is the best advice but given that I'm unlikely to get the opportunity to do that soon (as I don't have it personally) and the above what is the opinion on changing out the n75 and banking on that being the culprit? Mine seems to be a "C" so if I was to change it is a like for like swap best?

Thanks,

Paul
 
AWDMk1 said:
Just to resurrect this one, unfortunately I haven't had the chance to get the car plugged into vagcom to get fault codes yet so have been putting up with 0.4 bar max boost which isn't the end of the world given I'm only using the car got a short commute each day at the minute. Anyway.... Surprise surprise pulled away from a roundabout today and it boosted straight to 0.75 bar, it has in car adjustable boost so turned that up to full, found a nice stretch of road and it boosted straight to 1.7 bar which is higher than its ever boosted before and potentially a little higher than it should boost? In car boost gauge / turbo timer logs highest boost which was always 1.67 after about 15k miles and was done when the previous owner had it. Long story short after a couple of miles it reverted back to 0.4 bar max. Feeling a bit inspired I took the n75 off soaked it in wd40 for half an hour, put it back together and it was boosting to 1.55 bar but once again it reverted back to 0.4 after a few miles. Also at one point before it reverted when on wot it hit about 1.5 bar and the engine warning light came on though it still drove fine, pulled over and restarted the car and the warning light was gone.

I appreciate vagcom was and still is the best advice but given that I'm unlikely to get the opportunity to do that soon (as I don't have it personally) and the above what is the opinion on changing out the n75 and banking on that being the culprit? Mine seems to be a "C" so if I was to change it is a like for like swap best?

Thanks,

Paul
Click to expand...

The N75 is a plastic valve... soaking in WD40 will not do much more than potentially weaken the plastic....

Adjustable boost controller? light comes on? the clues are there dude... has this been mapped for this? might have been worth mentioning this at the beginning...

Boost controllers like this are usually fitted as a sticky plaster to boost control... don't get me wrong I used to run an MBC but I knew the mapping and I knew the hardware so I knew where the limits were... 1.7bar on an engine with no rods (assuming you have no rods as this wasn't mentioned above) is a little risky...

Turbo timers are a waste of time and technically illegal...

I would be turning the boost down to a safe limit (18/20psi max) grab a full copy of VCDS and start logging to make sure timing and fuelling is ok... based on what you have said so far it sounds a little iffy to me...

<tuffty/>
 
Jabbasport fitted the in car adjustable boost and the turbo timer / boost gauge when they did the mapping. Not sure how the turbo timer could be illegal but then again I've never really thought about it. Not saying jabbasport are the best in the world but it's all been done to a high standard by them as a package and it's not been cobbled together. I agree 1.7 bar on standard rods is potentially pushing it a little, I thought the n75 could have been sticking which may have caused the lack / spike in boost...
 
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AWDMk1 said:
Appreciate your opinion tuffty and not being arsey but it does say that the car has a custom jabbasport remap etc. etc. etc. in the original post. They also fitted the in car adjustable boost and the turbo timer / boost gauge when they did the mapping. Not sure how the turbo timer could be illegal but then again I've never really thought about it. Not saying jabbasport are the best in the world but it's all been done to a high standard by them as a package and it's not been cobbled together. I agree 1.7 bar on standard rods is potentially pushing it a little, I thought the n75 could have been sticking which may have caused the lack / spike in boost...
Click to expand...

Sorry dude but a custom jabbasport map means nothing... I am not going to go into details but I am aware of how Jabba map cars and how they manage boost control...

Turbo timers are illegal as by law you cannot leave a car unattended while the engine is running...

Rule 123
https://www.gov.uk/general-rules-all-drivers-riders-103-to-158/control-of-the-vehicle-117-to-126
and...
Leaving a vehicle unattended while the engine is running - PistonHeads

On your private property of course you can get away with it but left anywhere that is deemed public and you can be charged with 'quitting'

The fact that its boosting then reverting back to 0.4 bar is because its going into limp mode as the map you have does not like the boost its seeing.. it would seem apparent that its not been mapped for the boost you are trying to attain with your controller... this is not the first time I have seen this on a jabba map..

VCDS is still something you should be doing... I would be checking for fault codes and also checking fueling and timing pull too...

Set it to a sensible boost level and I suspect it won't keep dropping into limp

<tuffty/>
 
I see your point on the turbo timer, news to me but logical enough when you think about it and I must admit its annoying at best....! I had misread your earlier response apologies, I now see you were asking if the car was mapped for the adjustable boost controller, which I believe it was. I guess what is puzzling me is that it never had any of these issues before the new turbo was fitted, hence i'd not considered mapping issues as it was always ok on this map. I guess VCDS is the way forward and then go from there..... See, I got there in the end!!!
 
So.. if I understand this correctly... it was mapped as a K04 and now has (essentially) a K04 hybrid on it? (thats normally what uprated implies)

By definition if its a larger compressor (which it will be) then it will flow more for the same boost level... your map is now out of sync with the spec of the components you now have...

You haven't mentioned injectors... assuming you are still on stock injectors then jabbas normal trick is to modify a std 3bar FPR with a hammer to make it a 4(ish) bar FPR to increase fuel pressure and fueling capability... this would potentially suggest that with the hybrid you now have your fueling is going to be somewhat lacking especially if you continue to run at 1.7bar boost... std injectors are pretty much maxed out at 280-290hp... hybrids are typically 330hp units... std injectors even at 4bar are not enough... then of course there is the state of the fuel pump... seeing lots of these failing due to age these days and increased fuel pressure won't help...

Sorry for appearing to be negative but I have seen at least 2 cars recently with similar setups and similar issues...

<tuffty/>
 
It was mapped on a k04 yes and has since had a new turbo from cr turbos. I ordered an 'uprated' k04 from them, essentially this was a standard k04 with updated bearings (I believe that was the extent of the changes). This new turbo lasted about 5k miles before problems with oil passing the seals so it was removed, returned to cr and rebuilt free of charge. I didn't get to see it before it was fitted after being returned but it 'should' be another k04 with updated bearings and that's it. That said its bizarre that it boosted straight to 1.7 bar today when it never did that on either the original or the previous cr turbo. The injectors are standard too.

I always thought jabba had a decent reputation but I'm from VW roots and was into g60's etc previously and that's where they started. I think your VCDS advice was best as a starting point, are any of the eBay options out there worth considering or are they all rubbish?
 
Ah ok...

TBH I wouldn't put it past CR to have supplied a hybrid turbo... its plausible that something got lost in translation but if if you are running an EBC then you can turn it down to a sensible level...

I am not suggesting Jabba have done anything wrong but its difficult to gauge whats going on at the moment without logging the car and seeing any codes that may be there...

As for VCDS... I have written some info in a thread linked to in the FAQ thread of the stickies.. its also the link below my build thread link in my sig... have a read...

If full blown VCDS is a little too much then an ebay lead and VCDS light will work although you can't log past block 20 IIRC unless you register it for $99... you will need blocks 031 and 115 at least to see wahts going on with fuel and boost (as in what the map is expecting to see)...

<tuffty/>
 
Ok... had an epiphany this morning and it dawned on me that this behaviour is typical limp mode but of course thats reliant on the ECU still having control of the N75 and potentially the N249 too... you haven't indicated that you have an N249 bypass but you are running an EBC... this means the only thing the ECU has left it can control with is the throttle cutting load... don't know why I didn't think of this last night... sorry..

Normally an EBC comes with its own valve and you either leave the N75 electrically connected to keep the ECU happy and plumb in the EBC valve or run the EBC in parallel to act as a cap on the N75...

The fact that yours seems to boost to 1,7bar then drop down to 0.4bar limp mode style confuses me now as this suggests ECU intervention but for that to happen the ECU needs to have a degree of control over boost which I now don't know from your description if it does or not...

VCDS should shed a bit more light on the situation but also some pics of the engine bay and specifically the N75 might help

<tuffty/>
 
AWDMk1 said:
Jabbasport fitted the in car adjustable boost and the turbo timer / boost gauge when they did the mapping. Not sure how the turbo timer could be illegal but then again I've never really thought about it. Not saying jabbasport are the best in the world but it's all been done to a high standard by them as a package and it's not been cobbled together. I agree 1.7 bar on standard rods is potentially pushing it a little, I thought the n75 could have been sticking which may have caused the lack / spike in boost...
Click to expand...

why an ebc?
whats wrong with n75 control?

could be your external controller... who knows!
 
Tuffty - thanks again for your thoughts, any and all help is appreciated!

I'm not sure if I am confusing matters slightly so just to clarify when I say it has in car adjustable boost which was fitted by Jabbasport - this is basically a small black box about an inch or less square with a black dial on it, no fancy display or anything like that. It basically sets boost from 0.75 bar minimum to approx 1.7 bar maximum so is this actually an EBC or is it just a MBC but inside the car? Sorry if that's a ridiculous question....!

The turbo timer is a compact Greddy item, all it does is monitor the boost level, calculates a cool down time, logs this peak boost reached and allows you to program a warning which will cause it to flash and beep annoyingly when it reaches whatever boost level you have set the warning at.

The N75 is still in situ as is the N249 and I will take a couple of pics so you can see what it looks like at the moment.

Badger5 - In answer to your questions I have no idea at all..... the car was at this spec when I bought it a few years back, to be fair it has ran well up until the point that it needed a turbo and was garaged for a while, this issue has only arose since I started using it again.

Just to add further information on the way to work this morning it quite happily boosted past 0.4 bar, it was set to low boost on the in car dial and I was in traffic but I saw 0.6+ bar without any issues..... if I turned the boost back up and gave it the beans on the way home it is quite likely to revert back to 0.4 bar max though. The confusing thing is I have done 600+ miles in the car since starting to use it again and for 590 of those miles it has never went past 0.4 bar other than some boost creep at higher RPM and it's only since yesterday that it seems to have intermittently boosted as I would have expected it to. This is why I thought a faulty N75 was the likely culprit but that is my limited knowledge and possibly putting 2 and 2 together and coming up with 7.....!
 
jabba's ebc of sorts is a trick on map sensor and is wired to ecu.. tricks ecu.

bespoke to jabba in terms of how they choose to map with it.. no one else will map with it in place as its fooling Map sensor and driving n75.

ecu's reverting to a limp mode... Any codes? VCDS is required or code reader to see them as minimum else any help/advise is limited severely..

possible n75 malfunction and or pipes to and from it.

swapsies and see
 
I've followed tuffty's link and ordered a VCDS cable so I can get some error codes. I appreciate all of the help so far but think it's a bit of a waste of everybody's time without me being able to provide more specific details. Once the cable arrives I'll get some codes and post an update but in the mean time thanks again for the help and advice.

Cheers,

Paul
 
your welcome. (and a refreshing change to have someone who does'nt keep poking about in th dark without vcds etc)<< good move
 
I have no where near as much knowledge as tuffty and badger5 however I just noticed you mentioned the engine management light flashed on when you had the boost turned up to 1.7bar.


Could this be an indication of a faulty coil pack? I thought the EML flashed on when a misfire was detected?


Just a thought as I was reading through - I had similar issues when I first brought an S3 - turned out to be faulty n75, boosted stupidly high once then went straight into limp mode until the car was turned off and back on again.
 
russwuss, my comment re: the engine management light was misleading...!!! It was actually the traction control light that came on, in my panic and having seen neither lights in a long time I thought it was the engine management light. Doh!

I'm leaning toward the N75 as the culprit, the car boosted past 0.4 bar again this morning without issue at one point then peaked out at 0.4 bar under exactly the same circumstances a few minutes later, nothing had changed so it appears to be something intermittent now.

The VCDS cable should hopefully be with me before the weekend so I will be able to get error codes soon to help confirm either way.
 
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