Slow boost spool on AAN GT2871R

Durr McDanks · October 24, 2015, 12:43:08 AM

I have a gt2871r with a .63 AR running 440cc injectors on an AAN (inline 5 20vt 2.2l). I am having some problems with late spool. I hit full spool around 4500 rpm's when it should be about 3500-3700 rpms. I attached a log below to give you guys a better picture. I have not messed around with the timing too much so I am not sure if the solution to my problem is to throw more timing down below. I have also pressure tested the system and found no major leaks. I am running version 1.5.3. Thanks in advance.
https://drive.google.com/file/d/0B953i4woSzc9dlJwazZER1ByazQ/view?usp=sharing

Leonhard · October 24, 2015, 08:20:23 AM

Boost refDC settings seems good to me,
have a look at the wastegate valve, a leak is often causing late spool. This wastegate-assembly is easy to check and maintain.
Also check the N75 valve, if it's leaking, the control pressure rises even with 100% refDC.
late spark should'nt causing late spool this much, resulting higher egt is even better.
Activate the EGO closed loop control, you are running quite rich.

regards :)

Durr McDanks · October 24, 2015, 10:33:54 PM

I vacuum tested the external wastegate top port today with a mighty vac at 20 in hg and I was losing about 1 in hg per min. I understand that this can cause slower spool time but is this a minor or massive leak? I also tested the n75, even though it is fairly new, and I was receiving an accurate ohm range and it was clicking when being jumped.

Kamuto · October 24, 2015, 10:43:37 PM

Quote from: Durr McDanks on October 24, 2015, 10:33:54 PM
I vacuum tested the external wastegate top port today with a mighty vac at 20 in hg and I was losing about 1 in hg per min. I understand that this can cause slower spool time but is this a minor or massive leak? I also tested the n75, even though it is fairly new, and I was receiving an accurate ohm range and it was clicking when being jumped.

what boost wastegate spring holds without ecu boost controll? or what is the mechanical boost? maybe your spring is just too weak, so backpressure is opening it :)

Durr McDanks · October 24, 2015, 10:45:35 PM

1.9 bar spring from 034 motorsports and I have an adjustable perch and cranked it down a little more and saw no difference in spool time

Durr McDanks · October 25, 2015, 12:31:45 AM

I am starting to believe that the valve seat is worn out in my wastegate. If I take off the wastegate and test the bottom port with an air compressor and the valve guide is worn I would feel air leaking past the valve below .9 bar correct?
http://www.efiexpress.com/catalog/product_info.php?products_id=56

Leonhard · October 25, 2015, 08:27:41 AM

yes, even if the valve guide is worn and control pressure is leaking, this spring should withstand the exhaust gas pressure as long as the valve seat is intact.
Disassembling the wastegate will show the seat condition.

Quote from: Durr McDanks on October 24, 2015, 12:43:08 AM
I have also pressure tested the system and found no major leaks.

...there should'nt be any leaks at all between Compressor-outlet and intake-manifold ;)

Kamuto · October 25, 2015, 10:23:45 AM

Quote from: Durr McDanks on October 24, 2015, 10:45:35 PM
1.9 bar spring from 034 motorsports and I have an adjustable perch and cranked it down a little more and saw no difference in spool time

1.9 means it can hold 1.9 with ecu control, without it it will usually hold something like 0.9 or something

Durr McDanks · October 25, 2015, 07:13:43 PM

I took apart the wastegate and the diaphragm is fine. The valve and seat looked like they would seal but the seat just popped right out of the wastegate. I am not sure if that's normal or if the seat is suppose to be pressed in. I would assume the seat has to be pressed in because every time the valve lifts that would mean the seat would rest on the exhaust manifold and rattle and then the valve might not seat properly the next time it comes down leading to a leak.

Leonhard · October 25, 2015, 09:32:49 PM

The seat is not pressed in, that's normal. It is holding in place by the bolts.

Durr McDanks · October 25, 2015, 10:13:12 PM

Dang, thought I had found something. Also, I do not have a gasket between my wastegate and manifold. I was reading that this is normal but I also see gaskets online for this. Should I buy a gasket or is this unnecessary?

Kamuto · October 25, 2015, 11:34:15 PM

Quote from: Durr McDanks on October 25, 2015, 10:13:12 PM
Dang, thought I had found something. Also, I do not have a gasket between my wastegate and manifold. I was reading that this is normal but I also see gaskets online for this. Should I buy a gasket or is this unnecessary?

there is no gasket :)

Kamuto · October 25, 2015, 11:35:15 PM

Quote from: Durr McDanks on October 24, 2015, 12:43:08 AM
I have a gt2871r with a .63 AR running 440cc injectors on an AAN (inline 5 20vt 2.2l). I am having some problems with late spool. I hit full spool around 4500 rpm's when it should be about 3500-3700 rpms. I attached a log below to give you guys a better picture. I have not messed around with the timing too much so I am not sure if the solution to my problem is to throw more timing down below. I have also pressure tested the system and found no major leaks. I am running version 1.5.3. Thanks in advance.
https://drive.google.com/file/d/0B953i4woSzc9dlJwazZER1ByazQ/view?usp=sharing

btw, how your exhaust looks?

Durr McDanks · October 26, 2015, 01:19:07 AM

I have a 3'' exhaust system all the way thru with a wagner tuner rs2 EM. I check for pre turbo leaks with some soapy water and found nothing.

Kamuto · October 26, 2015, 01:48:38 AM

Quote from: Durr McDanks on October 26, 2015, 01:19:07 AM
I have a 3'' exhaust system all the way thru with a wagner tuner rs2 EM. I check for pre turbo leaks with some soapy water and found nothing.

that's really really strange, you must have full boost like 3200rpm or something with that size turbo..

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Slow boost spool on AAN GT2871R