Hello everyone
I have an 89 EF Hatch with d15b2 DPFI I put a turbo on
I have a boost gauge and AF Gauge
I'm also running a Spa turbo FMU for fuel, My wastegate is set to 5psi and I run a boost controller, The issue I'm having is that the car won't boost over 1psi the turbo spools relatively quick and doesn't take too much time to hit 1psi but it won't go past.
I checked all the gaskets and charge piping to make sure there's no leak as well as the vacuum lines. Oddly enough when i reference the Intake Manifold for boost initially it gave me a vacuum reading under the 1 psi or not. for now, I run it after the boost controller it T'd it off from the wastegate so I could get an accurate reading.

I understand that the d15b2 is a terrible motor for boost even more so with DPFI before everyone gets up in arms about it. I'm currently building a d16y8 that's going in it and bought the turbo kit brand new as I'm planning to transplant it to the d16 when it's done.

Any help would be greatly appreciated

 

Does it have a blow-off valve? Is the vacuum line connected correctly?

 

The bov was connected I got 1 psi. I've since disconnected it just to test if it'll change anything.
I connected it to a vacuum port after the throttle body and had my boost gauge on a port next to it the boost read vacuum even "under boost" and the BOV i have has only a single port for a positive pressure reference

 

BOV needs positive pressure to hold it shut.

External wastegate?

 

Yes I have an external wastegate, the thing Is from my understanding you want the bov connected after the throttle body. But the ports produce vaccum even at full throttle so I'm confused on where to reference the bov unless I was to tap into the turbo reference. But that wouldn't make much sense.

 

BOV will need to use intake manifold vacuum. This way it will see boost pressure (to keep it closed) on load and vacuum at decel (to open it).

Is your wastegate a dual or single port?

 

Maybe the tandem valve is not actuating? It acts kind of like a choke on a carburetor, so I could see that preventing you from getting much boost. As a test, you could try temporarily pinning the tandem valve open to see if you get more boost - low end power/response will likely suffer, though. If you do pin it open and get more boost, maybe try repairing the tandem valve system (cracked vacuum line, busted diaphragm, etc.) so that it opens at higher manifold pressures. Just a thought.

 

That's a solid recommendation! Wouldn't have thought of that myself.

 

It's a single port. So it only can reference boost to close it the issue is that for some reason the reference ports after my throttle body only supply vaccum even under boost the only way I know this is cause there was 2 ports I used and my boost gauge was only reading vaccum even under acceleration so I can't seem to figure it out and I don't wann reference the turbo cause that defeats the purpose of having it release the boost

 

Is that the dropshot valve? Or something different. Do you happen to have a picture cause I'm not sure what that is.

 

I got to see this turbo set up if your still using the dpfi air horn that’s too badass. You can upgrade your injectors with injectors from an rx7

 

maybe Dax is talking about the bypass valve that opens when the motor is hot enough. Take off your air horn on top of your throttle body and you can see a throttle plate or butterfly undo the two screws and take that one off. The throttle plate that is connected to the gas pedal is under that one. Leave that one there lol

 

I'm assuming the "air horn" is that black cover that's says dpfi on it. So you're saying there's 2 butterfly valves one is like a choke and the other is the throttle correct?

 

Correct

 

Alright, so what I'll do tonight is reconnect the bov and the boost gauge to the Intake Manifold and remove that butterfly valve and go from there

 

dpfi turbo I’m here for that lol please post some pics. I would recommend you also that you torque down again your throttle body nuts that hold the throttle body to the IM. Also any vacuum nipples that aren’t needed be pulled out entirely and some metal dowels be sized matched and tapped in. Maybe you can pull the nipple for the map sensor hose and put a newer gen map sensor where the iat sensor goes. To eliminate your boost blowing off that hose as well. What oil are you using. I heard turbo guys before say they use rotella 15-40. I use rotella T5 15-40 in my Dohc zc 10k plus miles no issues. I live in CA it’s warm all year.

 

Currently, I'm using Rotella T5 5w-40 I use it on all my cars. I have a Z31 turbo I've been driving for 10k miles with no issues. So, I'll remove the choke plate re-torque the Throttle Body to the IM and I'll plug off the unused vacuum lines for now then tap them later thanks for the idea. as far as the MAP I'm going to leave it stock cause I'm gonna be slapping in a fully built d16y8 with its own MAP sensor. I'm not trying to dump really too much money cause it is only a d15. But the turbo kit was compatible and the d16 won't be ready for a couple of months so i figured why not do what what everyone gets triggered about a turbo d15 with dpfi.

 

BINGO! That fixed it! I got home took off that valve. Cleaned up the vaccum lines a bit a boom made boost no problems. Thanks guys for all your help really appreciate it. I can't tell you how happy I am that I got it running right. This was a good practice run before I set up the turbo on the new motor

 

Glad that fixed it. Now please post a pic, lol.

 

for real dis ***** wack if we can’t get a pic

 

 

There you go guys

 

Lit Ima post it on my ig

 

I also threw a b7 cam in it cause the motor is actually a B1