So when I first got my setup aI had a manual boost controller that only lasted me a few weeks until it started not being able to even remotely control the boost spike between gears on my 5AT. So I switched out to a different manual boost controller and that worked fine for a while but wasn't as precise as I would've liked it to be in managin the boost so I switched out to the Apexi AVCR like a month or two ago. I got everything dialed in as good as i possibly could and it was keeping everything in order and my boost was spiking from like .53 to .63 bar (7.5 to 9psi) between shifts which I got used to. Then all of a sudden the other day it started to do what the first MBC did and was spiking to like .66 or .67 bar between shifts and under the same settings was overboosting to like.56 in third and fourth gear sometimes. So basically I had to reconfigure it again and drop the duty cycle from like 42% down to like 38% just to get it to not overshoot the boost but when i shift it is still going way over what I am comfortable with. What could be causing this? Any input would be greatly appreciated.


Thanks,



D. Webb

 

temp change?

 

nah the temperature is still the same for the most part.

 

theres got to be a leak coming from some vacum line.

 

small changes in atmospheric conditions can require adjustment of any boost controller if you care about 100% consistency. Running a wierd turbo/wastegate setup like the rear mount you have isnt going to help with consistency either. The best controller is the latest HKS EVC, I would recommend that, and then at least you know you are doing everything you can do in the boost controller department to keep things consistent..

 

I've don't think changes in the atmosphere over the past week though would be causing me to have to lower my duty cycle by lik 4-5% and I also don't think it would be causing me to overboost so muych more while shifting. As far as the HKS vs. Apexi boost controllers goes, I've read a lot about it and they are the two top units on the market. The HKS just happens to be more popular with the 350z crowd presumably for the looks. It's deffinitely debateable which one is actually better.

 

I've used on my cars in the past the Greddy Profec-B or Profec-e01 with great success. AVC-R is a huge PITA to get nailed down right. BTW, you aren't "wearing down" the boost controller.

 

I didn't say thats what is happening. It just seems like that's whats happening. I actually have no idea whats going on. It was stable for about a month and then just went haywire

 

I have yet to see a spike out of the HKS boost controller. But let me ask you, are you seeing a spike, even with the boost controller off?

 

I dont think hes running the car with the boost controller off.

 

Are you saying you haven't seen any spikes between shifts on a 5AT with the EVC? I was under the impression from some other owners of 5AT's that this was inevitable to a certain extent... If thats they case I'll buy one tomorrow. Keep in mind its not spiking really when I run all the way through one gear just when I shift and keep it floored.

 

This is what GurgenPB told me and he seemed to have some experience dealing with it.

 

Just wanted to add Blitz SBC-iD is a top tier EBC...good luck with your issues.

 

So are you solely talking about boost BETWEEN shifts or overboost at WOT? These are two separate issues. Gurgen may be correct about the between shifts issue and may not be correctable. This is by far different than a boost spike or not being able to hold boost at WOT.

 

ok I guess boost spike wasn't the correct term to use then. not sure what is. but I am only talking about the boost going up for the duration of the shift

 

the avcr is a top notch boost controller, I doubt that's your problem as I'm running one on my 300 with no problems.

 

I've thought about that one because it is compact and a little cheaper than the other two.

 

do you have the gear learn mode on or off?

 

I've lowered the target boost to .45 bar (6.4psi) and turned the duty cycle up to 52% and that has got things back in line a little more. I also raised the feedback speeds in each gear except 1 and 2. wierd thing is happening now though. I'm still having a boost spike between 2nd and 3rd of like 1.5 psi but the boost spike between 3 and 4 which used to be similar is now almost nothing. what could be causing this?

 

I don't have the gear learn mode on.