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Title: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 21, 2025, 06:26:18 AM Hi.
Anyone measure pressure before fmic with bigger turbo (or maybe k04 hybrid)? I move my map sensor to place before fmic and have weird readings. It is possibile i have that "restricted" inlet hose? 2.5" inlet pipes. Or i cant mount sensor in that place? I have 2550+ readings over 5k rpms with 0 WG opened. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on June 22, 2025, 11:16:18 PM you confusing things?
mapsensor between turbo and fmic = hot side = usually higher pressure inlet pipe = no pressure = should have as less vacuum as possible 0% WG = no N75 working = base pressure = spring pressure only usually you should have a good fmic (google bar plate vs. fin tube) with now pressure drop on the intake side of your turbo you should have as no restrictions. your turbo is happy if you have no high pressure on the pressure side and no high vaccum on the inlet side. please tell us about your problem again. logs? Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 24, 2025, 04:28:19 AM you confusing things? mapsensor between turbo and fmic = hot side = usually higher pressure inlet pipe = no pressure = should have as less vacuum as possible 0% WG = no N75 working = base pressure = spring pressure only usually you should have a good fmic (google bar plate vs. fin tube) with now pressure drop on the intake side of your turbo you should have as no restrictions. your turbo is happy if you have no high pressure on the pressure side and no high vaccum on the inlet side. please tell us about your problem again. logs? I change two smic to fmic and regenerate k04-023 to hybrid stage 2 and have mounted map sensor after turbo - before intercooler. And now make logs and map readings over 5k rpm hit map limit (2550+) but have mounted gauge in mainfoald and show 1.3bar so difference is 0.2 bar + and my question is : It is normal? I ask only because I dont want blow up brand new turbo. I know here are many people with great knowledge. So first I must move map sensor before throttle plate after intercooler back and should measure pressure before additionally? Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on June 24, 2025, 04:41:25 AM 0.2bar pressure drop over the fmic is good and totally fine
mount the pressure sensor on the cold side where it has to be and start logging Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 24, 2025, 08:20:21 AM 0.2bar pressure drop over the fmic is good and totally fine Ok thanks for advice :)mount the pressure sensor on the cold side where it has to be and start logging I mount it back and start logs and tune forward. May ask one question? Should I change MAF to the brand new if isbstill OEM? Car is from 2002. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 30, 2025, 07:10:01 AM Ok I move sensor back after intercooler and before throttle.
And now maybe you can give me a tip what can cause that insane boost in mainfoald. First log is with unpluged hose to WG. Second is with connected and it is posible that turbo can handle high boost without N75 opened on high rpm-s? Sorry for my english :( i know it's bad. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on June 30, 2025, 07:45:18 AM unplugged hose or unplugged connector on your n75?
working as designed i would say you have to tune your boost pid tables add throttle plate to the logger Title: Re: Boost before fmic + k04 hybrid stage2 Post by: fknbrkn on June 30, 2025, 07:50:27 AM this caused by faulty wastegate flap or poor quality turbocharger at all
n75 also could be the reason Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 30, 2025, 08:00:18 AM unplugged hose or unplugged connector on your n75? Unpluged hose. It should only open on spring or I in mistake?working as designed i would say you have to tune your boost pid tables add throttle plate to the logger Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 30, 2025, 08:06:07 AM this caused by faulty wastegate flap or poor quality turbocharger at all Can you explain? n75 also could be the reason Can poor quality turbocharger make to much boost ? Wastegate flap is new and is still K04 Hybrid so size is same as K04-023 Yes N75 could be reason and I buy brand new pierburg and wait to receive it. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on June 30, 2025, 08:17:02 AM If you unplug the hose it will make all the boost it can possibly provide.
Either your Intake is collapsing or your wastegate is pushed open because of weak WG spring. Unplug the N75 connector and log basepressure please. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 30, 2025, 08:46:56 AM If you unplug the hose it will make all the boost it can possibly provide. Ok but why if I disconnect N75 it work ok but if I unplug hose to WG it isn't work?Either your Intake is collapsing or your wastegate is pushed open because of weak WG spring. Unplug the N75 connector and log basepressure please. If I unplug hose only spring is used to build boost so I should have low bost on all RPM-s range? Why unplug connector change basepressure read? Title: Re: Boost before fmic + k04 hybrid stage2 Post by: fknbrkn on June 30, 2025, 09:25:16 AM mid-range overboost could be fixed with PID tweaking but high-end where it pulls 1.4+ boost with 0% wgdc caused by non-machined wg port usually
another words: this hybrid sucks try to bore out wg port for a bit Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on June 30, 2025, 10:19:40 AM mid-range overboost could be fixed with PID tweaking but high-end where it pulls 1.4+ boost with 0% wgdc caused by non-machined wg port usually Ok I try sort it out because I think I am missunderstanded. If I unplug N75 (cable) I have 0.4 bar to 0.6Bar at end RPM's (7000)another words: this hybrid sucks try to bore out wg port for a bit If I unplug WG hose i have spool peak (weird) boost ~(2Bar) and then goes down to 0.6Bar (6500rpm) If I have conected all as it should (N75 etc) I have boost higher than I should even with 0% N75 so it isnt only turbo problem because in other causes boost it isnt very high. Only with N75 connected boost when reach 1.4 bar is still high to 7k rpm's. In other situatons with N75 not connected properly over 5k rpm's I have 0.6 bar so why you tell me this turbo is bad? Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on June 30, 2025, 01:14:14 PM Ok but why if I disconnect N75 it work ok but if I unplug hose to WG it isn't work? If I unplug hose only spring is used to build boost so I should have low bost on all RPM-s range? Why unplug connector change basepressure read? please learn how a turbo and n75 works Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on July 17, 2025, 08:26:40 AM Thanks guys for any advice and I read and check how n75 work and now I know if i let boost presure goes straight to WG then it opens when spring cant hold WG closed anymore.
But i have weird behavior in high rpms and its totally make blow my mind. Have few logs and can give me a feedback why i have opposite behavior? I have brand new pierburg N75 and still same things happen Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on July 17, 2025, 08:40:18 AM Thanks guys for any advice and I read and check how n75 work and now I know if i let boost presure goes straight to WG then it opens when spring cant hold WG closed anymore. Sorry something went wrong and no attachment add.But i have weird behavior in high rpms and its totally make blow my mind. Have few logs and can give me a feedback why i have opposite behavior? I have brand new pierburg N75 and still same things happen. As you see if I have more WG %DC i have pressure lost on high rpms and 0DC.csv file have locked DC to 0 on high rpms but boost goes high and low and again high. Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on July 18, 2025, 12:31:50 AM Tell us something about your Intake System. Looks like something is collapsing.
You can reduce boost up top. 1,5bar at redline with a small k04 ?! Title: Re: Boost before fmic + k04 hybrid stage2 Post by: Dejw0089 on July 22, 2025, 11:16:09 PM Tell us something about your Intake System. Looks like something is collapsing. Intake system is build with 2.5" aluminium pipes connected with silicones.You can reduce boost up top. 1,5bar at redline with a small k04 ?! TIP is silicone. Now i make short connection on n75 line (bypas n75) and make linear boost from 3k to 7k i have 0.5bar and goes up to 1.2 bar (no oscilations) So why with n75 pluged in with 0 DC have weird oscilations everytime on same rpms (6000) and when N75 have 85DC have 0.4 bar over 5k Title: Re: Boost before fmic + k04 hybrid stage2 Post by: aef on July 23, 2025, 12:45:50 AM As i said there are three possibilities
your tip is collapsing and blocking the whole intale or your wastegate is pushed open because of too much exhaust gas or your system is leaky because engine is moving too much on high load set CWMDAPP to 10 and KFLDRAPP to 0 on wot and log then set it to 10% fixed duty and log then set it to 20% fixed duty and log .... set it to 95% and log... this might help you to find the problem(s) |