My observation of my MPT76 Turbo -- MPT owners come on in!!
09-09-2009, 05:54 PM
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My observation of my MPT76 Turbo -- MPT owners come on in!! Well, got my car running over the weekend. I had my pcm tuned for a basic idle speed density tune so I could check for leaks and etc before I take it to my tuner/dyno.
Couple of observations I made and wanna see if this is normal.
#1. I was thinking at idle a turbo was quite, not the case, this turbo has a nice whistle at idle, very noticable. I thought at first I had a vacuum leak, but none showed up.
#2. Blow-Off Valve (JGS 56mm) has lots of air blowing out of it at idle, not sure if that is normal, and of coarse if I unplug the vacuum port the valve shuts (did it just to see what happened, did not effect idle quality).
#3. Notice on the exhuast housing it is leaking a very small amount of oil from the area you loosen to clock it (13mm bolts). Not smoking at all, just noticed a small amount.
#4. On my boost gauge at idle, it registers no vacuum, is that normal?? I know the gauge is working when you burp the throttle a small amount it jumps to about 1psi then goes back to a little vacuum the shortly back to 0.
#5. With the Open 4" dump by the trans and the cam, it sound amazing!!!
Couple of observations I made and wanna see if this is normal.
#1. I was thinking at idle a turbo was quite, not the case, this turbo has a nice whistle at idle, very noticable. I thought at first I had a vacuum leak, but none showed up.
#2. Blow-Off Valve (JGS 56mm) has lots of air blowing out of it at idle, not sure if that is normal, and of coarse if I unplug the vacuum port the valve shuts (did it just to see what happened, did not effect idle quality).
#3. Notice on the exhuast housing it is leaking a very small amount of oil from the area you loosen to clock it (13mm bolts). Not smoking at all, just noticed a small amount.
#4. On my boost gauge at idle, it registers no vacuum, is that normal?? I know the gauge is working when you burp the throttle a small amount it jumps to about 1psi then goes back to a little vacuum the shortly back to 0.
#5. With the Open 4" dump by the trans and the cam, it sound amazing!!!
09-09-2009, 08:04 PM
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I have never seen a turbo make noise at idle or be pushing enough air to keep the engine out of vacuum at idle, seems like something is reading wrong there to me.
09-09-2009, 11:28 PM
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do you have your gauge ref from manfold ?
sounds like it is ref from turbo.
blow off valve will need a slightly heavier spring, just enough to keep it shut at idle.
sounds like it is ref from turbo.
blow off valve will need a slightly heavier spring, just enough to keep it shut at idle.
09-10-2009, 09:18 AM
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Here's how I have the blow-off and boost gauge hookup.
From blowoff valve to brake booster hose, in-between those I have a "T" which goes to boost gauge.
Thanks and I plan on installing the heavier spring in the blow-off valve.
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09-10-2009, 09:20 AM
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I thought the same thing about the turbo pushing enough air at idle to keep blow-off valve open slightly. I guess it is getting plenty of vacuum because if I disconnect the hose going to the blow-off valve it shuts while running.
09-10-2009, 12:22 PM
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Your BOV is working properly if it is the jgs unit. I thought the same thing but after doing some research and calling jgs this is normal operation. The air you feel coming out of the bov at idle is normal. This is a sign of an efficiant setup. If you where sucking air at the bov this would be a different story. If you blip the throtte while watching the BOV you should see it slam shut. This is becouse at idle the you are at full vaccum. As soon as the blade of the tb opens the vacuum goes away. As for the boost gauge you might have a slight leak in the feed line.
09-10-2009, 12:51 PM
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Your BOV is working properly if it is the jgs unit. I thought the same thing but after doing some research and calling jgs this is normal operation. The air you feel coming out of the bov at idle is normal. This is a sign of an efficiant setup. If you where sucking air at the bov this would be a different story. If you blip the throtte while watching the BOV you should see it slam shut. This is becouse at idle the you are at full vaccum. As soon as the blade of the tb opens the vacuum goes away. As for the boost gauge you might have a slight leak in the feed line.
Also, I noticed after turning it off, the boost gauge shows almost 1psi and stays their for awhile. Hopefully that means everything is sealed tight, I dunno.
09-10-2009, 03:19 PM
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Autometer machanical 30psi boost gauge. Only power is for the light. Stays at zero unless is slightly revved and when the revs come back down it goes to vacuum for a sec or 2.
09-10-2009, 04:10 PM
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How did you test for vacuum leaks?
If you are reading 0 vacuum at idle something is wrong or your gauge is bad. Autometer dosnt have the best quality control so I would lean in the direction of a bad gauge. Try another or pick up a vac gauge at autozone.
I wouldnt worry about the noise at idle. If you have a really short downpipe I am sure you are hearing it through the exhaust.
If you are reading 0 vacuum at idle something is wrong or your gauge is bad. Autometer dosnt have the best quality control so I would lean in the direction of a bad gauge. Try another or pick up a vac gauge at autozone.
I wouldnt worry about the noise at idle. If you have a really short downpipe I am sure you are hearing it through the exhaust.
