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Old 05-27-2002, 11:30 PM   #1
AZScoobie
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Default Boost issues with the AVCR... Need help.

Some of you have read my post about running Cat free. I mentioned that I was having to reprogram the AVCR as I was making much more boost at the original settings.

I initialized the AVCR and started clean. No matter what I do I cant control boost at the high end of the RPM band. For example:

Boost set at 1.00. Duty starting at 40. I get .8 bar until about 5000 rpm where I meet the target of 1 bar. 1 bar is eclipsed pretty fast and boost heads on to 1.4 bar at redline. Of course I back out when this happends... If I use a duty of 50 I hit 1.0 bar faster but the top end over boost is exagerated. If run more than 50 I get a boost oscilation.

I have ran through the learning process many times on an open country road today doing long third gear pulls. It seems that I just cant get the boost down in the 5500 rpm + range.

I have adjusted about every setting there is to adjust. third or fourth gear just overboosts no matter what I do.

After realizing that the learn feature was no longer capable of mapping out my boost levels I started to manualy map the Duty. No luck... I need a 56 duty to get midrange boost to hit but then boost rises real fast and even a setting of 40 is not holding down boost in the high range in higher gears.

I have checked the lines, fittings and the Map sensor against the greddy map sensor. Everything jives. No leaks. Cars making power but it obviously does not like 1.4 bar so I need to do something. I have talked to friends that run the AVCR and I have read the manual again. I am starting to wonder if removing the cat has pushed my power over the edge of the wastegate and or BPM downpipe and or my AVCR is no longer up to the task of controlling my setup. If I turn the AVCR off I make .7 bar to redline with no rise at all.. That confirms there is no leak.

any idea's would be great. I am willing to try anything you suggest.

Thanks!

CT
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Old 05-27-2002, 11:37 PM   #2
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Don't have the time at the moment to go in depth but I am also using the AVC-r with no cats in the exhaust, but I don't have any problems hitting boost setpoint at 1.1 tapering to 0.9 at 7000 RPM. I also have Samco IC hoses, everything else stock besides the DP/UP. Are you running a bigger turbo?
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Old 05-27-2002, 11:47 PM   #3
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Quote:
Originally posted by Fubaru
Don't have the time at the moment to go in depth but I am also using the AVC-r with no cats in the exhaust, but I don't have any problems hitting boost setpoint at 1.1 tapering to 0.9 at 7000 RPM. I also have Samco IC hoses, everything else stock besides the DP/UP. Are you running a bigger turbo?
Yes. Big BB turbo with a full fuel system upgrade, uppipe, downpipe ect.. ect.. ect...

CT
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Old 05-28-2002, 12:51 AM   #4
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Maybe you need to play with you fb settings?

That's weird.. 19.9 psi shouldn't be too much for the avc-r to push back.. I know people say the solenoid sucks but I'm pretty sure it was said to be good til 24 psi or so at least.

I have the avc-r and a catless exhaust.. but I'm not running a bigger turbo. I'm running 1.1kg and generally don't see more than 1.14. Usually it's a temperature change that causes it.
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Old 05-28-2002, 01:14 AM   #5
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Quote:
Originally posted by lenyx
Maybe you need to play with you fb settings?

That's weird.. 19.9 psi shouldn't be too much for the avc-r to push back.. I know people say the solenoid sucks but I'm pretty sure it was said to be good til 24 psi or so at least.

I have the avc-r and a catless exhaust.. but I'm not running a bigger turbo. I'm running 1.1kg and generally don't see more than 1.14. Usually it's a temperature change that causes it.
I have taken the FB to the limits I am going to call Apex tomorrow and talk with there help line.

CT
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Old 05-28-2002, 01:52 AM   #6
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try turning the learn gear and feedback both off and then put all the start duties at 0 then start at 1 bar and make a few runs and see if that helps......I have the avcr also and wish I would've went with my original plans of getting the profec b.....but I just HAD to have the cool little blue box
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Old 05-28-2002, 10:31 AM   #7
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Yeah I have mine set at 1.1 but sometimes it goes up to 1.15. I don't mind though, there doesn't seem to be any problems. BTW, did all of you know that the AVCR doesn't read in bar? You have to multiply the number by .981 to get bar.

Quote:
Originally posted by lenyx
Maybe you need to play with you fb settings?

That's weird.. 19.9 psi shouldn't be too much for the avc-r to push back.. I know people say the solenoid sucks but I'm pretty sure it was said to be good til 24 psi or so at least.

I have the avc-r and a catless exhaust.. but I'm not running a bigger turbo. I'm running 1.1kg and generally don't see more than 1.14. Usually it's a temperature change that causes it.
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Old 05-28-2002, 11:02 AM   #8
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I don't know what to say, I've had not problems with boost controll with the AVC-R. Which turbo are you using?

Did you try setting the Duty cycle for the high rpms to the minimum? Did you change 4th and 5th gear start duty to a negative number? If so, I think you have a defective unit.


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Old 05-28-2002, 11:29 AM   #9
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Notice I didn't say bar in my post

Quote:
Originally posted by kenshiro
Yeah I have mine set at 1.1 but sometimes it goes up to 1.15. I don't mind though, there doesn't seem to be any problems. BTW, did all of you know that the AVCR doesn't read in bar? You have to multiply the number by .981 to get bar.

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Old 05-28-2002, 01:36 PM   #10
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Quote:
Maybe you need to play with you fb settings?

That's weird.. 19.9 psi shouldn't be too much for the avc-r to push back.. I know people say the solenoid sucks but I'm pretty sure it was said to be good til 24 psi or so at least.
For everyone that says the solenoid sucks or can't handle more than ~20 psi, these guys below are running up to 31 psi on the AVC-R on a race setup R-33 GTR pushing 800+ hp.

http://www.exvitermini.com/r33specs.htm

It kind of sounds like the wastegate is getting stuck or not opening fully at higher boost. Course, why should it happen now with the catless exhaust and not before...? What about adjusting the wastegate itself? Perhaps you could set it at ~16 psi and run it without the avc-r enabled. I have no idea if the wastegate could be adjusted that much though.

Good luck man
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Old 05-28-2002, 02:52 PM   #11
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The only other thing I can think of, is you're using a DP with a splitter in it which has been known to cause WG sticking if the tongue doesn't match the turbo depth (or on other BPM version, even the correct one would do this).

-C
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Old 05-28-2002, 09:21 PM   #12
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Quote:
Originally posted by TypeC
I don't know what to say, I've had not problems with boost controll with the AVC-R. Which turbo are you using?

Did you try setting the Duty cycle for the high rpms to the minimum? Did you change 4th and 5th gear start duty to a negative number? If so, I think you have a defective unit.


Yes I have played with the start duty. and the FB and I have set the duty low at higher RPM's. I am starting to think the Turbo cant flow the exhaust through the wastegate after the uncorking of the exhaust when I removed the cat.

Just a few min ago I had it set at 1.0 kg. It made that at 5000 rpm and then ramped right up to 1.2 bar by 6500. I dont know what else to try. This happend the second I pulled off the ramps when I took the cat out. I am going to put the cat on again and see if it goes back to normal.

CT
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Old 05-28-2002, 09:23 PM   #13
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Quote:
Originally posted by TypeC
The only other thing I can think of, is you're using a DP with a splitter in it which has been known to cause WG sticking if the tongue doesn't match the turbo depth (or on other BPM version, even the correct one would do this).

-C
I checked clearance before we bolted the turbo/downpipe in the car. I could move the wastegate full open manualy and I had room. Anything is possible. I think its just flow.

CT
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Old 06-02-2002, 03:21 PM   #14
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Any updates? Did the cat re-install help? Very curious.

Paul
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Old 06-02-2002, 03:58 PM   #15
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Quote:
Originally posted by midlifecrisis
Any updates? Did the cat re-install help? Very curious.

Paul
Well. I noticed something esle. All the while I have been reading my electronic Greddy 52mm boost gauge. The AVCR and the greddy read the same at 1 bar. But if I go past that they read different. The AVCR will read 1.2 when the Greddy reads 1.4. Not sure what to trust.

CT
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