Frustrated,, Turbo master

[Pruittx2]

After hanging my head to look, and then thinking tighten to boost, or loosen to unboost, and I've forgotten.

On my 94 GM4 turboMaster How to decrease boost?

I've got mo time to feel foolish for asking,, hell I started feeling that way shortly after buying my truck! lol

I loosened it like 2 full turns, and it still seems to hit 15 at half throttle. I do drive like an old man, so I'm always lookin at the boost. But when towing my small trailer and mower, It'll come to 15 pretty quick.

 

[Big Bertha]

The spring at 2" should be about 8 to 10 pounds of boost.

 

[NVW]

Loosen the spring for less boost.

 

[Pruittx2]

Excellent, thank you sir, that's what I was thinking,, and have done so,, but the gauge still seems to be hitting 15 @ less that 3/4 throttle. I have an International Diesel's rebuilt 6.5 and,, well Long Story, but I drive it easy, and don't want it to BLOW!!!

 

[bison]

Ah,you wont blow it if you keep an eye on EGT's.
15 psi boost is not that high.

 

[Pruittx2]

Head over to the Place,, and read some of my old threads on the reman engine. I'm thinking that 15 spikes are ok, for a few , but I don't need another boat anchor. Lol

 

[Acesneights1]

15 is pushing an older motor with factory HG's I think but I run 15 no problem with my 93 as it has ARP's. IIRC ChrisK1500 ran 18 and finally blew his at about 20 psi.

 

[tanman_2006]

I push 18 on mine, stock HG and TTY. Runs like a champ. Its vaccum controled still

 

[JiFaire]

If you're still hitting 15, Dave, keep backing it off. Watch your EGTs and look for black smoke, though ... if the boost doesn't back off, your gauge might be wonky... Your wastegate opens, right? The old ones can rust up and freeze, effectively welding them shut.

 

[Acesneights1]

I push 18 on mine, stock HG and TTY. Runs like a champ. Its vaccum controled still

That makes no sense. The factory ecm controlled vac system would never let it anywhere near that. It would de fuel.

 

[buddy]

If you're still hitting 15, Dave, keep backing it off. Watch your EGTs and look for black smoke, though ... if the boost doesn't back off, your gauge might be wonky... Your wastegate opens, right? The old ones can rust up and freeze, effectively welding them shut.

X2, my GM4 got really sticky, I took it aparts greased it and excercised it, and it started happening again a few months later. Although mine would open and then not want to close all the way. You will need to back off the spring a little more than someone with a stock PCM.

 

[buddy]

That makes no sense. The factory ecm controlled vac system would never let it anywhere near that. It would de fuel.

Although it can be told to boost that high and not throw codes pretty simply.

 

[Pruittx2]

I'll get out there in the morning, and check,, Long day, home for bout the last hour driving all day. 4hrs up north, unload ceiling pine boards for the family's cabin, and then driving back home. off to bed,,, peace

 

[great white]

That makes no sense. The factory ecm controlled vac system would never let it anywhere near that. It would de fuel.

You're right, on a stock PCM.

I'll better someone's been digging in the cupboards....

 

[Pruittx2]

OK,, So I go look this am,, and find the waste gate is apparently stuck shut,, can't move it with my hand. Hmmm,, hit it with some silicone spray,, and then a little bump on the end of a pry bar, and Pop! is comes un stuck. and moves with small hand pressure.

So like I said, I had thought that backing the nut off the stud would, decrease boost pressure. Sure enough, once wastegate was not stuck on it's seat, I drove it, to see I had like 5psi.

A couple test, and tightens, and I got it where I want it, only a hint of black haze, under heavy acceleration. Even this old dog can learn a few things,,