Any one have weird boost issues after downpipe install?
 

I have read somewhere a while back that installing a downpipe can cause weird boost issues on the stock sequential system since the ecu doesn't control it based on boost but rather ECU maps. So some mods like a DP could cause boost patterns to be off.

My boost goes as follows

3rd Gear WOT
>1500- 4500RPM, 0-14PSI on primary turbo
4500RPM< Boost immediately drops to 5psi and holds to about redline.

Now I'm not blaming it entirely on the dowpipe but if it could help narrow it down that would help.

I did just get done re- doing the wiring harness, fuel injectors, vacuum lines etc. I am thinking solenoids are likely culprit.

When doing the DP you likely didn't put the charge control actuator lines back in properly or the actuator itself isn't working

Quick test start the car and see if the rod pulls in

At idle the rod is pulled in all the way. I'm going to see if replacing the solenoids helps, now I start to understand why people steer away from the twins in favor of a single turbo.

I do however love the response the twins have so I will try my best to keep them going.

There is nothing wrong with the twins, or your downpipe. Listen to Fritz. Also, check your vacuum lines. One that slipped off can cause loss of boost.

The second butterfly valve on the crossover tube. Disconnect the vacuum hose completely and go for a drive, it will be a lot laggier but you should get full boost with the secondary. if this happens, you know which solenoid is being a POS.

There are a lot of people that think the nipples on the LIM are vacuum, they are not, they are simple pass through that do not have any access to the LIM vacuum or boost. They are directly connected to the hoses on other side of the LIM.

Sounds like you have your vacuum lines routed incorrectly after you reinstalled the y-pipe after installing the downpipe.

Solved. I don't know what did it but I replaced 1 leaking check valve, replaced the top vacuum chamber and one loose vacuum hose. Car feels great.

Good job. Its always nice to solve a mystery like that one :)

:icon_tup::icon_tup:
I've found it's always a vacuum line open rather than a solenoid inoperative.
Another sequential setup saved.

I do love the twins and have come to believe people give up to easily and trust me, I could see why. After I spent all winter waiting on parts and funds I finally got it all back together and was incredibly frustrated to see no boost from my second turbo, so I dug in it two more times to find out I had overlooked simple stuff.

One of my check valves, the one by the throttle body coming off the TB was leaking, my Y-pipe coupler had a big crack, after sorting those two out I was getting full boost and the biggest grin.

I have thoughts of getting the BNR twins, but that might just stay on paper. I love the power and sometimes it feels like too much. I don't plan on 1/4 racing or street racing but to rather enjoy the car for what it is and maybe occasionally auto-x it but given my height 6''5' it might not be easy :D

I don't think any one cares but this is what the car looked like for two monthts

https://cimg9.ibsrv.net/gimg/www.rx7...df3693dd00.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...6bd57fad80.jpg


What it looks like right now and the proud owner.

https://cimg6.ibsrv.net/gimg/www.rx7...6e5281b224.jpg

You can have any beer you want as long as it's a Corona (I know, I know)

https://cimg7.ibsrv.net/gimg/www.rx7...2488a0ba6d.jpg