02 Boost spike/surge?
22 April 2020, 01:40 AM
#1
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02 Boost spike/surge?
Not sure what the issue could be called, but I will try my best to describe it.
So basic rundown of the current state of my Frankenstein
new ej207 w/205 heads (blew my old motor sadly
CGC 'VF34' monstrosity that isn't actually a VF34, uses same Garret parts, not sure exactly what it is...
Catless up pipe
3inch TBE
STI pinks
tuned to 17.5 psi
The car has always had a surge/spike since I had the stock turbo fail and replaced, even after a tune. After recently doing the exhaust and fuel mods, I had it re tuned to ~17.5 psi and it spools a fair bit faster now, full boost around 4-4.5k, about 1k sooner. IT holds this boost 'til redline. My tuner remarked that he was happy with the result, but that it boots to around 18psi before settling. Ok, no worries. As the weather has gotten colder, and perhaps as I have adjusted to the new setup, I am noticing a distinct surge/spike in the boost that you can see on the gauge and feel in the butt dyno. So the boost will initially climb to around 18-19psi, then drop to around 15-16psi, then build again where it remains roughly consistent depending on gear (gear ratios are very long). Some times it is more noticeable than others, some times it repeat this twice before I run out of gearing, from what I can tell. I am not sure if this is something to be concerned about or not.
I am still running the factory BCS, the waste-gate had to be specially fitted and made to work with the new turbo at the time for whatever reason. I'm wondering if this is an issue with the limitation of the factory BCS or wastegate at this point
Perhaps I should also mention, I recently installed a PTP turbo blanked. I was running without a heat shield for a long time (i know....) due to a mechanic discarding it and insisting it would be fine to run without. Seems to be doing a great job keeping temps down, intercooler is now cold to the touch after giving it the beans. When I installed it, I wrapped the wire around the downpipe and what I think was the wastegate. It was a PITA to install, frankly, I hope the wire is not interfering with the wastegate operation.
To add, I don't throw any CELs when this happens. It occurs only at WOT
Any advice would be much appreciated
So basic rundown of the current state of my Frankenstein
new ej207 w/205 heads (blew my old motor sadly
CGC 'VF34' monstrosity that isn't actually a VF34, uses same Garret parts, not sure exactly what it is...
Catless up pipe
3inch TBE
STI pinks
tuned to 17.5 psi
The car has always had a surge/spike since I had the stock turbo fail and replaced, even after a tune. After recently doing the exhaust and fuel mods, I had it re tuned to ~17.5 psi and it spools a fair bit faster now, full boost around 4-4.5k, about 1k sooner. IT holds this boost 'til redline. My tuner remarked that he was happy with the result, but that it boots to around 18psi before settling. Ok, no worries. As the weather has gotten colder, and perhaps as I have adjusted to the new setup, I am noticing a distinct surge/spike in the boost that you can see on the gauge and feel in the butt dyno. So the boost will initially climb to around 18-19psi, then drop to around 15-16psi, then build again where it remains roughly consistent depending on gear (gear ratios are very long). Some times it is more noticeable than others, some times it repeat this twice before I run out of gearing, from what I can tell. I am not sure if this is something to be concerned about or not.
I am still running the factory BCS, the waste-gate had to be specially fitted and made to work with the new turbo at the time for whatever reason. I'm wondering if this is an issue with the limitation of the factory BCS or wastegate at this point
Perhaps I should also mention, I recently installed a PTP turbo blanked. I was running without a heat shield for a long time (i know....) due to a mechanic discarding it and insisting it would be fine to run without. Seems to be doing a great job keeping temps down, intercooler is now cold to the touch after giving it the beans. When I installed it, I wrapped the wire around the downpipe and what I think was the wastegate. It was a PITA to install, frankly, I hope the wire is not interfering with the wastegate operation.
To add, I don't throw any CELs when this happens. It occurs only at WOT
Any advice would be much appreciated
Last edited by Taz_devil; 22 April 2020 at 01:45 AM.
22 April 2020, 06:40 AM
#2
I don't know about the mappings side, but if you want to check that the wastegate arm moves physically, you can connect a bike pump (or a compressor) to the wastegate hose connector, e.g by using a little bit of silicone hose. You should be able to see the wastegate arm move when pressurised.
If you use a compressor, make sure to set the pressure down to about 1 bar.
Also, the wastegate flapper arm will not move "all the way" around to 90 degrees from its usual position. My actual wastegate arm only moves about 10-15mm from closed to open, for example, which is too little to move the flapper to fully open, but it should work anyway, as long as it's not ridiculously little movement.
If you use a compressor, make sure to set the pressure down to about 1 bar.
Also, the wastegate flapper arm will not move "all the way" around to 90 degrees from its usual position. My actual wastegate arm only moves about 10-15mm from closed to open, for example, which is too little to move the flapper to fully open, but it should work anyway, as long as it's not ridiculously little movement.
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