Boost controller

[Nitrous]

Anyone have a good picture of a stock boost controller setup? I was wondering where the bottom vacuum port went to or does it just stay open? I was also have a question on the waste gate, how much vacuum should it take to open it? How's the best way to test the wastegate and tell what turbo you have it it says Garrett on it? One last question, there's a long vac line that comes from the back of the manifold down the passenger fender well and up under the front bumper. I've pulled on it and it feels like it'shooked to something but I can't see it. I'll put the truck back in the air this weekend but I thought I'd ask about it. I was thinking possibly A/C vac canister...........................

Thanks

 

[Aeroking]

Re: Boost controller

the stock GM wastegate system uses an ECM controlled solenoid (bolted to the top of the compressor housing). You should have a vacuum hose coming off of the test port on the turbo compressor, going into one side of the solenoid. Then the other side of the solenoid has a vacuum hose running to the wastegate dampner. The pressure referenced from the compressor port, runs through the solenoid and pressurizes the wastegate dampner. The pressue on the dampner, pushes/pulls the rod on the wastegate.

The solenoid has a 2 wire connector on it from the main harness. The ECM sents electronic pulses to the solenoid to regulate pressure. The ECM is programmed to cut back boost if knock is present. Also it pulls boost for a couple other reasons.

So on a stock setup, to change the maximum boost, you change the rod length. which opens the wastegate more/less giving you more/less boost.


EDITED: vacuum line running down the fender is probably for the vacuum ball under the battery tray.

 

[Chest Rockwell]

Re: Boost controller

That long vacuum line you chased goes to the vacuum ball tucked up under the battery tray.

 

[stuckinUT]

Re: Boost controller

Looking at the boost solenoid from the front the lower port on the right is just a vent, it stays open. From the factory it had a foam filter clipped on, but a lot of times it has fallen off.

 

[Nitrous]

Re: Boost controller

This is great, thanks for the replies. I was really unsure about the vent line. I'm a nitrous guy so bare with me on the turbo questions. Should I be able to put light suction on the vacuum line and move the rod on the turbo or should it take more vacuum? When cruising about 30mph I hear what could almost be described as a growling noise similar to a bad bearing but not all of the time. If the wastegate was dumping too much air do you think this could be the noise I'm hearing? I've been through the drivetrain and everything seems to be in great shape now so I'm leaning towards the induction. Any comments on this?

 

[Nitrous]

Re: Boost controller

Ok, got the wastgate to move so no more issues there and the long vacuum line does go to the vacuum ball. There's a long hose under the oil pan off the front differential that looks like a vent line and it's rubbed in two and was tucked into the frame. Is there any particular place this hose goes or does it just hang high under the truck? I don't see any numbers on the Garrett turbo but it looks close to stock, is there any way to identify it?

 

[BoostedSUV]

Re: Boost controller

Ok, got the wastgate to move so no more issues there and the long vacuum line does go to the vacuum ball. There's a long hose under the oil pan off the front differential that looks like a vent line and it's rubbed in two and was tucked into the frame. Is there any particular place this hose goes or does it just hang high under the truck? I don't see any numbers on the Garrett turbo but it looks close to stock, is there any way to identify it?

I can't remember what my stocker said said but if it has "Garret and Mitsubishi" on it it's more than likely a stock one.

 

[Nitrous]

Re: Boost controller

No Mitsubishi on the turbo just Garrett. I thought Mitsubishi was the stock turbo. I do have Garrett cooler on it though.

 

[Richard Le]

Re: Boost controller

Which cracked vacuum line would cause one to overboost, the line from the turbo compressor or the line from the wastegate?

 

[pauly78]

Re: Boost controller

What happens if the two hoses on the control solenoid are reversed from what the above picture shows. I only recalled one hose on that solenoid when I put all of that back togther. After seing the photo I went and checked. They were both there...but reversed. Any ideas.

 

[BoostedSUV]

Re: Boost controller

What happens if the two hoses on the control solenoid are reversed from what the above picture shows. I only recalled one hose on that solenoid when I put all of that back togther. After seing the photo I went and checked. They were both there...but reversed. Any ideas.

they need to be in the right order otherwise you will have no boost control. One side supplies the boost pressure the solenoid and the other side feeds that pressure to open the wastegate. If they are in the wrong order the wastegate will not open. correct me if I'm wrong.

 

[pauly78]

Re: Boost controller

My symptoms regarding boost control are that the turbo would spool up quick on a cold engine. It took forever on a hot one. I am relying on the stock gauge at this point and seat of the pants feel but it was night and day. I know I know i need to use a computer to see exactly what is going on. I will in the near future, hopefully it will stay together until then.

 

[BoostedSUV]

Re: Boost controller

My symptoms regarding boost control are that the turbo would spool up quick on a cold engine. It took forever on a hot one. I am relying on the stock gauge at this point and seat of the pants feel but it was night and day. I know I know i need to use a computer to see exactly what is going on. I will in the near future, hopefully it will stay together until then.

at least put an aftermarket boost gauge in the truck! I had a vacuum line broken on my boost solenoid, I never new it and relied on the stock POS boost gauge. Well I ended up hanging a rod out of the oil pan because it was going over 20psi and I had no way of telling... Datamaster and laptop is great but put an aftermarket boost in gauge before anything else. Trust me! :tup:

 

[pauly78]

Re: Boost controller

thats on the list along with an A/F meter. I have a 3 pod a-pillar and the only thing in it is the chip selector. Got to do some more cash paying side jobs first.

 

[Luke]

Re: Boost controller

thats on the list along with an A/F meter. I have a 3 pod a-pillar and the only thing in it is the chip selector. Got to do some more cash paying side jobs first.

you mean Wide band O2 sensor right? dont use the A/F meters that splice into the O2 sensors, they re shit....

 

[BoostedSUV]

Re: Boost controller

I second that.. A/f meters are nothing more than a light show. I have an autometer a/f gauge in my truck because it was free but its a waste of time. I'm going to replace it with a wideband if you really want to buy an A/F gauge.