Turbo Guru required ASAP.
#32
OP and pwderhound
datalog your cars, upload it to datazap.me and post here.... some tunes seem to have a boost to max to around 6000 rpms then boost drops off and then there is an overspike
I have seen it on my old GIAC tune, my old Eurodyne tune, my mate's Proto tune... my problem was solved by Tim who tunes my car and with a MAFLESS set up seems to disappear for everyone I talk to
but datalog it and lets look at things like IDC% etc
datalog your cars, upload it to datazap.me and post here.... some tunes seem to have a boost to max to around 6000 rpms then boost drops off and then there is an overspike
I have seen it on my old GIAC tune, my old Eurodyne tune, my mate's Proto tune... my problem was solved by Tim who tunes my car and with a MAFLESS set up seems to disappear for everyone I talk to
but datalog it and lets look at things like IDC% etc
#33
Racer
#34
#37
Race Director
My two cents' worth is I think this is the key:
I have seen it on my old GIAC tune, my old Eurodyne tune, my mate's Proto tune... my problem was solved by Tim who tunes my car and with a MAFLESS set up seems to disappear for everyone I talk to.
Based on reading through the thread my diagnosis would be the MAF is just not able to deal with the extra air flow brought about by the tune/changes to the engine. Just like a tuned engine can overwhelm the clutch so too can it overwhelm the ability of the MAF to measure the air being consumed by the engine.
The above is tempered a bit by some lingering concern about the car's fuel system being able to supply sufficient fuel under all conditions.
I do not know at what HP levels the stock fuel system begins to prove inadequate. Also, this assumes the stock system is in perfect working order. The Turbo fuel delivery system is rather complex and there's a lot to go wrong.
I have seen it on my old GIAC tune, my old Eurodyne tune, my mate's Proto tune... my problem was solved by Tim who tunes my car and with a MAFLESS set up seems to disappear for everyone I talk to.
Based on reading through the thread my diagnosis would be the MAF is just not able to deal with the extra air flow brought about by the tune/changes to the engine. Just like a tuned engine can overwhelm the clutch so too can it overwhelm the ability of the MAF to measure the air being consumed by the engine.
The above is tempered a bit by some lingering concern about the car's fuel system being able to supply sufficient fuel under all conditions.
I do not know at what HP levels the stock fuel system begins to prove inadequate. Also, this assumes the stock system is in perfect working order. The Turbo fuel delivery system is rather complex and there's a lot to go wrong.
#38
^somewhere above 550 crank assuming one has installed a 5 bar fpr i would imagine fuel ( or lack thereof ) can become an issue, which this reads like so i'm with you on that. but it does not read like a maf issue to me, but i'm "guessing" too.
..and mac, the quote you referenced was from a contributor, not the op. i don't believe the op is mafless? he indicated in his original post, he has already replaced the maf. even still, that doesn't sound like maf issues at all. or not any i have had, should say.
..and mac, the quote you referenced was from a contributor, not the op. i don't believe the op is mafless? he indicated in his original post, he has already replaced the maf. even still, that doesn't sound like maf issues at all. or not any i have had, should say.
#39
My log
Gents, here are two runs i've just completed.
The highlighted yellow shows me in 3rd flooring from 2.5k rpm and holding there.
The green shows me simulating how i can get the boost up there. You'll see my foot is at 45% is then i put it down a little then it's when I back off slightly i get the boost to start ramping up then I can put the foot down again (this area in red text in the green background.
Hope this helps you guys to help me.
The highlighted yellow shows me in 3rd flooring from 2.5k rpm and holding there.
The green shows me simulating how i can get the boost up there. You'll see my foot is at 45% is then i put it down a little then it's when I back off slightly i get the boost to start ramping up then I can put the foot down again (this area in red text in the green background.
Hope this helps you guys to help me.
#40
#41
what fuel are you running?
looks like a mess IMO...car is making plenty of boost, ign. timing is jumping around pretty bad (because way to advanced to begin with on boost), and is pretty lean...
Just had another look at it in the 'yellow' area, boost is definitely low during WOT pulls...I still think N75 isn't operating correctly, the boost flare when letting off makes me think wastegates are tight enough
Edit again, noticed a few post above you mentioned the oil filler cap...
Fix that then re-log...could VERY likely be your issue, you ARE leaking boost on the manifold side...
looks like a mess IMO...car is making plenty of boost, ign. timing is jumping around pretty bad (because way to advanced to begin with on boost), and is pretty lean...
Just had another look at it in the 'yellow' area, boost is definitely low during WOT pulls...I still think N75 isn't operating correctly, the boost flare when letting off makes me think wastegates are tight enough
Edit again, noticed a few post above you mentioned the oil filler cap...
Fix that then re-log...could VERY likely be your issue, you ARE leaking boost on the manifold side...
#42
what fuel are you running?
looks like a mess IMO...car is making plenty of boost, ign. timing is jumping around pretty bad (because way to advanced to begin with on boost), and is pretty lean...
Just had another look at it in the 'yellow' area, boost is definitely low during WOT pulls...I still think N75 isn't operating correctly, the boost flare when letting off makes me think wastegates are tight enough
Edit again, noticed a few post above you mentioned the oil filler cap...
Fix that then re-log...could VERY likely be your issue, you ARE leaking boost on the manifold side...
looks like a mess IMO...car is making plenty of boost, ign. timing is jumping around pretty bad (because way to advanced to begin with on boost), and is pretty lean...
Just had another look at it in the 'yellow' area, boost is definitely low during WOT pulls...I still think N75 isn't operating correctly, the boost flare when letting off makes me think wastegates are tight enough
Edit again, noticed a few post above you mentioned the oil filler cap...
Fix that then re-log...could VERY likely be your issue, you ARE leaking boost on the manifold side...
You think the timing is bad? it's a softronic tune.
#43
#44
993GT, i'm receiving mixed messages ref the boost leak check.
When applying a test 20 psi at the intake manifold and the engine TDC should there be pressure at the oil cap or not?
If yes then I agree fixing that leak may help but if pressure is not meant to be there then it's just a symptom of another problem.
When applying a test 20 psi at the intake manifold and the engine TDC should there be pressure at the oil cap or not?
If yes then I agree fixing that leak may help but if pressure is not meant to be there then it's just a symptom of another problem.
#45
You don't want timing jumping around like that, it is compensating for detonation/knock..ie very aggressive tune or the fuel you are using is inadequate....worth a re-log after fixing the boost leak.
Yes oil cap holds air pressure, if it's leaking you have a boost leak. Intake manifold has a large air line going to the oil tank.
Yes oil cap holds air pressure, if it's leaking you have a boost leak. Intake manifold has a large air line going to the oil tank.