PDA

View Full Version : Having issues with my G-valve, any ideas?



Clay
06-17-2006, 04:35 PM
Ok, a year or so ago I purchased a couple of "grainger" valves with the part numbers right from Gus' and Gary's web sites. No problems there.

Now, last night I went to the track and used the method taught to me by James Reeves to set the g-valve off the car. I set it to 11/12 PSI to start opening with no issues.

The g-valve was installed with all new hoses, so no leaks there. The pressure tap was from the turbo outlet nipple, then to the g-valve, then straight to the WG.

On the track something wasnt right. I could only get 5-7 PSI on the track. I turned it in 1 turn, and tried again, no better. There wasnt much adjustment left in the g-valve at this point either. I thought maybe my WG was bad, so I took the g-valve out, and was able to boost up over 10 PSI while parked in the pits holding the brake, slipping the clutch (while sitting on GRASS!) ;)

So I ran the rest of the night with out the g-valve, just WG connected straight to a vacuum source running 5 - 7 psi.

It almost seems like the spring in the g-valve it to weak and is opening up almost immediatley, or it has an internal leak where the halves screw together maybe. Anyone have any ideas what may be wrong?

Anyway, my options now are (a) get the g-vavle figured out or (b) buy a premade manual boost controller that will work *before* I touch it!!

clay

86Shelby
06-17-2006, 06:25 PM
Sure there's no debris in the valve causing boost to leak past? Can you blow through it?

Was there a boost spike, followed by it settling down at 5-7 psi? I'd lean towards a clogged or missing vent between the valve and WG actuator.

GLHSKEN
06-17-2006, 06:34 PM
1^^^^

Turbulence
06-17-2006, 06:51 PM
+2^^^^

I recall Gus saying he sometimes put a little lawnmower gas filter just in front of the G valve. I have had my valve get dirty causing the exact symptoms you describe. Looking at it I could see a bit of debris but nothing that looked like it would have any impact. Cleaned it with a Q-tip and alcohol, put on the filter and have had no problems since.

Martin
89 Horizon
90 Voyager TII rip

Clay
06-17-2006, 07:51 PM
well, Im not saying there wasnt some dirt, but it was a brand new valve, never been used, and I took it apart between runs and cleaned it, and it still didnt seem to work. There is a small (what ever size it suppose to be) vent hole. Ill clean it again and see what happens.

thanks,
clay

Clay
06-17-2006, 07:55 PM
also, do I need to have a restrictor in the line?? I dont have anything in the line but the g-valve

Clay
06-17-2006, 08:06 PM
Ok, one more thing and probably the reason it didnt work!

I went to gus' site and checked his layout. My vent hole was on the opposite side to what gus had. IE gus had it on the WG side, I had it on the intake side.

would this screw up the operation of the g-valve?

86Shelby
06-17-2006, 10:00 PM
Yes, having the vent on the intake side of the valve would cause an initial boost spike, then it would settle to minimum boost, 5-7 psi on most cars. The pressurised air can't be released from the hose between the valve and the wastegate actuator. So, it stays there and keep the wastegate open.

Marcus86GLHS
06-18-2006, 06:01 AM
yes that's your prob....your wastegate puck is staying open, make that vent hole change and you'll probably have it working right.

Clay
06-20-2006, 08:12 PM
well, I flipped it around and put a new check ball in it (I lost the old one after all this junk happened), and just tried it tonight.

Works like a charm now! holds a solid 13 PSI and boy oh boy is it fun to be back in the boost again!

thanks!
clay

Subliminal
01-24-2007, 11:51 AM
also, do I need to have a restrictor in the line?? I dont have anything in the line but the g-valve

I'm having terrible boost spike right now, and I'm curious about this too. My grainger is hooked up right, but I guess it could be dirty. I spike about 7 psi and then settle back down. Kind of annoying, really.