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Surge on Stage 1 K04 - Cured

Mark300zx

Active Member
Apr 24, 2008
1,455
8
Surrey/SW London
Here is an interesting post on adjusting the N75 valve, I no little about it, all I know is that I did it on mine and it eliminated the surging, but will bow to the wisdom of anyone who has experience of on LCRs?
 

JamJay

California Bound
Thanks, I'll have a look through :)

So to sum this up so far:

- 007 DV tested for sticking = Operates as normal, dumps pressurised air audibley.
- 007 DV replaced for OE DV = Boost not held as well, dumps very easily, rules out sticky DV as cause of surge.
- All hoses felt and checked with my eyes = No holes or spilts found.
- Actuator not opening up = Actuator is OE, never been touched and opens at 4 - 5psi.
- MAF Sensor fault = Was dying, max of 206g/s, new MAF reads 226g/s but still have surge.
- N75 not controlling boost = New N75 tried, car ran worse for some reason so old N75 reinstalled.
- TIP not fitted correctly = TIP refitted, again, still issue persists.

So on the list to try next:

- Boost leak test to make sure that I have none, causing surge and hesitation.
- Green temp sensor to rule out cause of hesitation.
- Throttle body clean and reset to rule out cause of hesitation.
- 007DV service kit to rule out cause of hesitation.
- Check spark plugs & coilpacks as cause of hesitation but doesn't feel ignition related.
- FMIC, car seemed to run MUCH better in cold temps.
- Stage 2 map & dyno time to rule out mapping issue with Stage 2 mods on Stage 1 code.

Anything else that I should check?
 
Last edited:

rsmith

Robbie
Apr 28, 2004
2,797
1
Tipperary, Ireland
Why not put on your old tip and see if you still have the problem, if you don't u need to tweak the map or run a boost controller to control the boost spikes, this still doesn't explain the big difference between the actual vs requested boost, u are getting more boost than the ecu requests, I can only guess the new TIP has meant your turbo should be running lower duty cycles to create the same amount of boost because of the increased airflow.
 

gulzar

LCR jabba'd
Oct 1, 2007
178
0
Why not put on your old tip and see if you still have the problem, if you don't u need to tweak the map or run a boost controller to control the boost spikes, this still doesn't explain the big difference between the actual vs requested boost, u are getting more boost than the ecu requests, I can only guess the new TIP has meant your turbo should be running lower duty cycles to create the same amount of boost because of the increased airflow.

i have to agree with this. maybe swap old one back in and see how you get on.

goodluck to u mate.
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
wondering how much more time/effort/money you will throw at this when fitting an unos mbc in parallel with the n75 will control your spike of boost instantly
 

traumapat

Leon Cupra IHI
Jul 24, 2005
5,925
4
sunny sussex
+1 jamjay the mbc will not cover up the problem its the fix fr the problem imho. Work fantastic on mine.

Thats fine if thats the case and the TIP needs an mbc to work properly. But is that the case?

So should all 3" tips be fitted with an mbc?

Personally Id remove the TIP to prove/disprove its causing the surge. If thats the culprit then fit an mbc and happy days.

As much as JJ must be pulling his hair out this thread has become a good testing and development piece. I think we`re all interested in this as the TIP sounds excellent and makes a solid difference.
 

sambryant

RoadRunner meep meep
Mar 26, 2009
4,848
2
Bristol
I personally think its the combo of the tip and map and to cure it you have a choice, new map or fit a mbc. Bill said to me a mbc would be best and he was right. Going stage 2 wont just cure it, the map needs to suit the tip.
 

JamJay

California Bound
I won't be throwing any more £££ away on this car, as said before it could be MAF or N75 both of which I have tried. The MAF was dying so that's £80 well :)cry:) spent and the N75 was a gamble but as it ran poop it clearly wasn't the issue but hey, such is life. The car also has a hesitation issue and for peace of mind/maintenance I will be boost leak testing the car, changing the black temp sensor for a green one, cleaning the TB and servicing the DV...a health check if you will which I was planning on anyway and are necessary for any 1.8T owner who loves their car.

New map was on the cards anyway, Stage 2 was always planned so it's not money down the drain by any means. MBC will come shortly after this if the surge continues with the new code then it's all done :). The key right now is not not place the car under heavy load in higher gears and drive it sensibly, if I need to use it that is.

I will still post up more logs as and when I get the chance, some 115/118 logs very soon I hope back to back with the new N75 so I can see what's going on there.

If someone could post a diagram for DIY installing and fitting MBC with N75 then that would be great :)
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
Thats fine if thats the case and the TIP needs an mbc to work properly. But is that the case?

So should all 3" tips be fitted with an mbc?

Personally Id remove the TIP to prove/disprove its causing the surge. If thats the culprit then fit an mbc and happy days.

As much as JJ must be pulling his hair out this thread has become a good testing and development piece. I think we`re all interested in this as the TIP sounds excellent and makes a solid difference.

nope.. its not the case
it was fine for 3 weeks, then something happend to tge car and now its overboosting well beyond the maps request
mbc will cap the spike... is what I am saying

50+ TIPs out there... It is not the cause.

I cant recall but has block 060 been logged when the surge has been seen? ~(to confirm if the throttle is opening fully or not.) - remembering surge is the engine inability to consume air and it pulsing back into the compressor (due to inadequate flow/restriction/excess volume at that given moment etc etc)
 
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JamJay

California Bound
When fitting an MBC, what should I set it at on stock rods?

I've just done a conversion for my boost and i'm spiking about 22.5psi (2540mbar, 10mbar less than the ECU will stop reading at so I'm still within the ECU range), that doesn't seem too high does it? So, if I was to set an MBC to 24psi (which I think Sam's is set), it in effect wouldn't even work, right?

Using this calculation sourced from VWVortex: (your boost value -1010)*14.7/1000

Actual Boost...

2540mbar max - 1010 = 1530mbar
14.7/1000 = 0.0147

1530 * 0.0147 = 22.491psi


ECU Requested Boost...

2290 max - 1010 = 1280
14.7/1000 = 0.0147

1280 * 0.0147 = 18.816psi


A request of 18.8psi seems a little on the low side, what are LCRs supposed to boost to, 21/22psi max requested?

I'm still learning here so does anyone know what this means? It's looking to me like the ECU is mapped to request a certain amount (which was suitable at the time of mapping - stock LCR) and now that it has the TB exhaust & 3" TIP allowing it to create boost much more freely, it cannot control it any longer. I find it weird how it doesn't throw me into limp mode though as I am clearly over boosting at the turbo however the car is only mapped to consume air thrusting into it at 18.8psi.
 

ibizacupra

Jack-RIP my little Friend
Jul 25, 2001
31,333
19
glos.uk
aim for 2400mb - I would'nt be too sure that 10mb is'nt its actual max reading..

your only on stage 1 remember for your requested boost & this is dependant on who's map is on there as to what level its set to ask for

limp on stock file would be +/- 250mb, but this limit is often moved away to not work when remapped
 

wild willy

Full Member
Aug 4, 2003
2,323
0
Wales
Jay,
the highest the map sensor can read is 2540mb, it canot measure anything above it so when you see vagcom measurements of 2540 odds are its actually a fair bit higher. Personally on stock rods you don't want to go past 1.40bar (2400mb measured). Many people on standard tips are boosting well into the 1.6bar+ region which is a bit of a lottery as to when the rods are going to bend. SOOOOOOOOOOOOOOO fit the fecking mbc and be done with it and enjoy your mean machine. :)
 

JamJay

California Bound
Thanks you knowledgable folk :)

I've found a diagram for plumbing in the an MBC on Audizine...I think, I've been all over the web with this problem but I've learnt a lot. I'm going to order a Forge UNOS on pay day along with a FMIC.

MBCN75.jpg


One thing though, should I install the UNOS before stage 2 to cap this all now and then before Stage 2 map remove it and see how it runs as this looks like a map problem? If I find that it still surges after the map then reinstall the MBC set at 2400/20.5psi?
 
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