AVC-R issues - inaccurate boost and PTB that sucks.
This has been installed for a while, and installed correctly. Voltage for sensors is correct, and I know how to tune the thing moderately well. This is on a car running a .50 trim setup.
Basically what I see occurring is a major discrepancy between boost on the unit itself, and boost actually on the boost gauge. For example, setting the boost on the controller to 1.15 will show a WOT readout of 1.68 but the boost gauge at WOT does not go above 15-16. This is with a duty cycle of about 40%. An increase in duty cycle will usually result in boost levels becoming more in-tune with each other at the expense of some really shitty part-throttle boost. Boost by gear works flawlessly.
My settings are as follows: Feedback is off, learn mode is off, duty cycle is static at 40%. The gear judge setting is based on 3,000 rpm "cruises" in all 5 gears and inputting the number associated with each gear (aka, it's accurate and not taken off of someone else's setting). Graph scale is typical: BS: 2.0kg/cm2, NE: 7000rpm, SP 300km/h. 4 - 8 - / on the car setting choice.
External wastegate is being used, so the unit is set up appropriately for that. Everything is secure and away from excessive heat. Points were soldered (durr).
So my main problems:
1) Boost on the unit screen is incorrect when measured with the REAL boost by my boost gauge (which IS correct).
2) Higher duty cycle = hardcore PTB. This leaves me with an all-or-nothing deal. By this I mean either I do not go into 50%+ throttle (or I go into 10+psi of boost), or I go full WOT and hang on!. This is OK for residential streets but I do not want to boost 15psi in 5th gear at 60% throttle passing a car on the freeway!
Car is DSP tuned, and tuned the right way. It's in no way tune related.
Boost gauge is brand spankin' new version of the VEI bi-directional gauge. Vacuum and boost are EXTREMELY close between both the VEI and my Aeroforce scan gauge, so it's the AVC-R's boost that is simply off.
I have been battling this for some time now, and really have no idea where else to try looking to correct it. Boost-by-gear works fine, but its boost is off since the units boost is off as well; however, it DOES work (can definitely see more boost in 3rd gear than 2nd with 25% correction).
I turn the unit to "OFF" and run simply off the 9lb spring in the EWG and all the problems disappear, which is REALLY making me want to move to a MBC and be done with it. Unfortunately I have been immensely spoiled with the boost-by-gear so I'd like to try to get this fixed first.
It's a long post, I know, but any help would be greatly appreciated.
Is the gauge digital or analog and are these picking vac pressure reference from near the same location (hooked up to the port on the TB spacer)?
The stock analog gauge is picking up vac and pressure signals under the dash pad which is several feet from the the intake manifold. the hose under the pad is hooked up to a port on the brake booster and there's a line from there to under the intake above the starter = You might be seeing difference if you have an analog gauge here and the AVC-R digital pressure sensor at the TB port.
Although I think the Aeroforce is using manifold pressure via MAP sensor.....there might be a response time in regards to using whats its displaying = it might be matching the Analog gauge because of a delay.
Was the AVC-R pressure sensor new installed by you using a new kit? More or less meaning you bought the AVC-R new and at some point near after the install you think it was reading correctly.
Some of what I found posted on the web with regards to how to hook up the solenoid based on internal or external wastegate did not seem to always match. Have an image of how you have the solenoid hooked up.......I do understand you are seeing an issue with the pressure sensor reading but there might be a couple of things happening.
Is the gauge digital or analog and are these picking vac pressure reference from near the same location (hooked up to the port on the TB spacer)?
The gauge is digital. Location is not the same. Vacuum used for the boost gauge is the stock location and tubing and the vacuum used for the AVC-R is at the throttle body which also goes to the blow-off valve.
Quote: Originally Posted by turbojack
Was the AVC-R pressure sensor new installed by you using a new kit? More or less meaning you bought the AVC-R new and at some point near after the install you think it was reading correctly.
The kit was brand new when purchased. There have always been discrepencies of some margin but it seems to be quite dramatic now.
Quote: Originally Posted by turbojack
Some of what I found posted on the web with regards to how to hook up the solenoid based on internal or external wastegate did not seem to always match. Have an image of how you have the solenoid hooked up.......I do understand you are seeing an issue with the pressure sensor reading but there might be a couple of things happening.
I have the solenoid based on what I read on here for an external wastegate - NC and COM are used. The former, IIRC, goes to the compressor housing then T's into the bottom part of the wastegate, while the COM goes from the top of the wastegate.
Although I'm not a 100% sure like I was a pro tuner but I think you want both items reading boost to be hooked up the same spot if you want to compare them. Kind of like using a piggy back and insuring that the grounds you use when installing are the same grounds points that the PCM uses and the factory sensors use, otherwise the readings in the piggyback will not be the same as what the PCM is seeing.
With the length of line between the intake manifold and the hook up at the gauge, I think you will see a discrepancy between that and whats being read directly behind the TP by the AVC-R pressure solenoid which is no doubt close to the TB. My understanding is that you ideally want to have electric pressure sensors getting vac/pressure readings to be sourced from just behind the TB plate/under the carb and the line from here to the sensor to be no longer then 1'. Same as for MBC's and for EBC solenoids.
IMO I would trust the readings of the AVC-R sensor over the boost gauge as it sounds like its hooked up as intended and outside of a voltage spike it should not be a problem.
Also, any chance the filter for the pressure sensor is fudged up with oil loaded crankcase vapors? As a test remove the filter and make a pull looking for a difference.
I did and things seem to be better. The readings on the AVC-R aren't as "off," I have it set to 1.45 bar, though, but WOT will only go to about 1.32 bar with boost at about 17-18 now instead of around 21-22.
PTB is still being an issue. It's just that once I hit 4+v on the TPS the car starts to fucking move like mad. I give it half throttle and hot it on the freeway and you can feel the car buck and I look at the boost gauge and boost is at like 11-12. The entire ignition system has like 200 miles on it with OEM parts minus copper plugs gapped at .32.
Did the TPS rewire and nothing changed. Vacuum is steady at 16 (have Crower turbo-grind cams from the 2.0l Neon). They're pretty aggressive, and tuned, btw.
All lines are secure with zip-ties, too. And of course now my wideband sensor takes a shit *grrr*.
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AVC-R issues - inaccurate boost and PTB that sucks.
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