[KaiserN54]

Some time ago, Shiv reviewed some logs of mine for some fuel system issues- and he opined that my turbos spooled very slowly in response to throttle input- in part because I don't hit peak boost until 4500 RPM's or so. He suggested my wastegates are beginning to fail. I really, really don't want to spend money on the turbos. They do have 72k on them so they are probably pretty worn out. But as of yet, I am still hitting 18.5 PSI and holding it, and I have no boost error codes yet....any thoughts?

[KaiserN54]

bump

[Ilma]

Why don't you log Boost Control Setpoint to see what the boost target is and then compare to actual boost?

Your boost curve looks ideal......but I can't say whether 1 second to reach peak boost is too long or not.
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[Ilma]

Considering you started your log at around 4K rpm....hitting peak boost by 4500 doesn't seem off to me.

[KaiserN54]

Originally Posted by Ilma

Why don't you log Boost Control Setpoint to see what the boost target is and then compare to actual boost?

Your boost curve looks ideal......but I can't say whether 1 second to reach peak boost is too long or not.
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Okay, heres a new log, from 2500 RPM, and with Boost control setpoint. How does it look? Car feels really laggy- slow as hell until maybe 3500, where it picks up. Is this normal for an aggressive e85 tune?

[Ilma]

Here's how mine looks

Compare setpoint to boost and then compare both to my throttle position lower down.

Mind you I am not stabbing the throttle in these runs which I think you are in yours (would be nice to see Throttle and DBW throttle superimposed on the same plot).

If you are slamming the throttle open.....then yes, Shiv is right and you have slow wastegates. You could try upping your Boost Contol Gain to 55 and see if the situation improves.

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[KaiserN54]

Tried adjusting the settings you suggested- doesn't seem much better. How soon after "stabbing it" should I stong boost kicking in? Heres a log.

[JamesM3M5]

I have a JB4 customer with underboost faults, 79k miles on his car. No vacuum or boost leaks, everything works properly. His WGs are REALLY LOOSE, so he is going to have me adjust them back to spec. The WG shafts are sadly loose in the turbine housing, too, so they won't last a whole helluva lot longer.

He also has never had the carbon cleaned. Hopefully those two items will cure the slow boost response.

You can also try to continue up with the boost control gain up to 60 or 65. But I would recommend getting the WGAs and boost control system checked as well. Vacuum leaks on the WG control side could be delaying the response time of the WGAs and slow boost response.

[KaiserN54]

Originally Posted by JamesM3M5

I have a JB4 customer with underboost faults, 79k miles on his car. No vacuum or boost leaks, everything works properly. His WGs are REALLY LOOSE, so he is going to have me adjust them back to spec. The WG shafts are sadly loose in the turbine housing, too, so they won't last a whole helluva lot longer.

He also has never had the carbon cleaned. Hopefully those two items will cure the slow boost response.

You can also try to continue up with the boost control gain up to 60 or 65. But I would recommend getting the WGAs and boost control system checked as well. Vacuum leaks on the WG control side could be delaying the response time of the WGAs and slow boost response.

I may try upping the BGA some more as you suggest. I have 72k so i'm guessing they are pretty well done and I don't know if is it wise to pay a couple hundred now for adjustments and testing when these approaches are nothing more than band-aids. If im going to have to spend the $ either way, there is no sense in adding to the cost by dragging it out.