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Old 01-13-2007, 10:15 PM   #1
NOTORIOUS VR
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Join Date: Jan 2007
Location: Germany
Posts: 9
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Default issue w/ boost spikes? i think?

Hey all...

First of I'm new to the site, although not new to cars I haven't done a lot (actually anything) on Supra's in general.

I have a friend here in Germany that has a MK III Supra 7MGTE..

Anyways... Yesterday I upped the boost for him... I checked out the FAQ's on the forums here, and seen that 10psi should be ok for a stock motor (as far as I could gather).

The motor is compleatly stock except for a HKS head gasket (supprise, supprise).

Anyways... I used a plain old Air Pressure Regulator (mainly used for regulating air compressors, etc) as I've used them before on other turbo cars, and they're a cheap but effective way to manual boost controllers.

Last night I upped the boost using a boost guage to around 10psi (.7 BAR), and it was a cool night, and the car ran GREAT. Pulled very nice, never went into overboost (or fuel cut) except for once while I was trying to dial it in. But after a bit of tinkering the boost stayed at a solid .7 BAR.

Anyways... I had brought the regulator inside the cabin, but then later decided (for sometimes obvious reasons) that it would be better in the engine room away from people that would have the urge to tinker.

So w/ the regulator LOCKED all I did was disconnect the hoses, pull them back out to the engine bay, cut them shorter and reconnected.

It was ok for a few passes, but soon in 3 and 4th gear the boost wasn't stable anymore for some reason. Sometimes is would boost less, sometimes way more then .7 BAR and would hit fuel cut. It was quite random, and come and go. Sometimes fully stable boost, sometimes less/or overboosting would occur.

I then turned the regulator down because I thought maybe, just maybe the hoses being shortened might have something to do w/ it. But again, at first the boost was lower, but then went to a solid .7 BAR and I thought all was well... but again, shortly after every so often it would start to overboost and hit the fuel cut.

I'm quite perplexted w/ this situation. Like I said above, I've used this regulator before w/o issues on numerous cars (including another supra from a buddy in Canada) so I find it hard to believe that it is causing this, especially since it ran great the night before (where the air was actually a lot colder/denser).

One more thing is, the connector going to the AFM is VERY loose, by that I mean the plug does clip on but the while part (connector) that is supposed to be solid on the AFM itself is loose, and u can wiggle it up and down, side to side. Now I was only made aware of this today where my buddy showed me that, and u can hear clicking when u move the connector up and down.

Sorry for the long read, but I wanted to give as much info as possible

Cheers!

Last edited by NOTORIOUS VR; 01-13-2007 at 10:43 PM.
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