MSP Vacuum Pressure w/ boost/vac gauge

callITaDAY · May 18, 2011

Hey guys, I just put in a boost/vac gauge and my vac reads 7ish inHg. I ran the vac line off of the bypass valve, and thought that might be the problem. I then ran it off of a line that attaches to the cold pipe i think, and it gives the same reading. Do I have a vac leak or am I just being stupid and have the hose run wrong?

hornsfan10609 · May 18, 2011

You may have a leak, it should be run off of the vacuum line that runs from the top of the intake manifold and has a T, then goes to the bypass valve and the wastegate. Unless you have a vacuum block in which case it should be run from there.

91Protege · May 18, 2011

Any main vac line off the intake should give you intake vacuum, where did you run the boost feed line from?

callITaDAY · May 19, 2011

I T'd the line that connects the cold pipe to the intake manifold maybe? Im not sure, the line connects to the top of the cold pipe along with a plug with some wires.

hornsfan10609 · May 19, 2011

Unless it was re-routed for some reason the line should run to the wastegate, there is no reason for it to be on the cold pipe.

And if you reused the stock vacuum lines that may be why, they need to be replaced by now.

jeffmsp · May 19, 2011

fyi the best vac boost source is typically the hose going from the IM to the brake booster. You will need a proper T fitting with smaller prong for the vac line to do it right and make sure you T in closer to the IM as there is a 1 way valve in the line and you want to be on the side closer to the IM. almost any part store will have the proper T fitting.

Maxx Mazda · May 19, 2011

At idle you should be pulling at least 20" of vacuum at idle.

Protegebuddy · May 19, 2011

MassJDM · May 19, 2011

if its lower than 20 in hg then the wastegate actuator diaphragm is probably bad. but u may have another leak somewhere.

callITaDAY · May 20, 2011

MassJDM said:
if its lower than 20 in hg then the wastegate actuator diaphragm is probably bad. but u may have another leak somewhere.

Should I replace my whole wastegate?

91Protege · May 20, 2011

Yes if its bad, I used a smoke machine and smoked my brothers and it was just leaking out. If your wastegate is bad it also wont be boosting right

hornsfan10609 · May 20, 2011

You can pull off the vacuum line to the wastegate and blow into it to test it. If it passes air it's certainly bad, if it doesn't it may not be. Some say this isn't a completely reliable test but that's how I found out mine was toast.

callITaDAY · May 20, 2011

It reads boost though. If I'm in second gear with the pedal to the floor it'll read 6.5lbs. If I'm idling and rev it up though it just goes to 0 and then back to vac. The vac level has changed, it now reads around 10 haha. I have no idea whats going on...

Maxx Mazda · May 20, 2011

You have a leak. The turbo will spin faster to compensate and hold your original level of boost.

callITaDAY · May 20, 2011

Damn. How to I figure out where my leak is?

91Protege · May 20, 2011

Smoke Machine. We use all the time at work.

callITaDAY · May 20, 2011

So I have to take it to a shop?

paniaguae640 · May 21, 2011

man just pull one hose at a time and then with your finger plug the disconnected side and if that changes the vacuum on the gauge then there you go

shane02pro5 · May 21, 2011

DIY boost leak tester google it

paniaguae640 · May 21, 2011

not even, my way is easy. that is how i found out my leaks and fixed them; now im running -23 vacuum

MSP Vacuum Pressure w/ boost/vac gauge

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