Help! No Boost control!

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Help! No Boost control!

Postby psipwrd » Sun Apr 22, 2012 4:09 pm

My ST185 CS looked bone stock, so I'm starting from scratch. I read the primer, and installed a boost gauge and boost controller, and still waiting on the FCD. 19psi vacuum at idle, check. I took the car out for a test drive and hit 7psi in 1st and 2nd, and over 17psi in 3rd-5th with my vacuum lines popping off. I replaced a smooth T (already on car) with a barbed T, turned down the boost, and about to go for another test run.

I'm wondering if the car was modded and demodded, and what to look for.

Why would I not hit fuel cut, even over 17psi? Help!

Before installing the boost controller, I was hitting 5-7psi in 1st and 2nd, and 9-11 in 3rd-5th.
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Re: Help! No Boost control!

Postby underscore » Sun Apr 22, 2012 4:12 pm

Not sure why you didn't hit fuel cut, but an RC/CS doesn't cut until 17psi
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Re: Help! No Boost control!

Postby psipwrd » Mon Apr 23, 2012 7:25 pm

After adding the barbed T, I hit fuel cut at 17-18 psi. Thanks!
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Re: Help! No Boost control!

Postby Texasnick » Mon Apr 23, 2012 7:58 pm

So I take it you're using an MBC with the T-VSV still active?

You aren't going to get consistent boost in all gears unless you block off the tvsv
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Re: Help! No Boost control!

Postby psipwrd » Sat May 19, 2012 8:48 am

I noticed my boost was inconsistent, I'll block the T-VSV, Thx!
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Re: Help! No Boost control!

Postby psipwrd » Sat May 19, 2012 10:24 am

I just blocked my T-VSV and now I got a CEL. It also hesitated/stumbled when boost came on.

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Look at that, no water temp sensor plug here either!
Last edited by psipwrd on Fri Jun 01, 2012 3:53 am, edited 1 time in total.
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Re: Help! No Boost control!

Postby l0ch0w » Sat May 19, 2012 12:51 pm

You dont want to block off the tvsv....

Make sure that you install the T for your boost controller between the reference line from the compressor housing and the wastegate actuator,not between the tvsv and the wastegate actuator.

Since you have a CS, the boost cut will not hit until 17 psi anyways...

If you want to go beyond that, then the fuel cut defender will come in handy.
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Re: Help! No Boost control!

Postby underscore » Sat May 19, 2012 2:42 pm

if you block off the TVSV incorrectly, or aren't using a manual controller, you'll make less boost than the ecu is expecting and likely overfuel.
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Re: Help! No Boost control!

Postby psipwrd » Sat May 19, 2012 4:32 pm

The line from the compressor is going into the bottom of the mbc, and the line off the side of the mbc is going into the wastegate actuator nipple (forward). The rear actuator nipple is capped as barely seen in the pic, and the nipple from the block is capped the same.

I drove the car to see what I was boosting in each gear and it died. It acted like it ran out of gas and now it will not start.

It ran fine with the TVSV connected, just boosted inconsistently. The TVSV immediately caused the CEL, and now...death...

I'm kicking myself in the butt for disconnecting it :bangshead:
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Re: Help! No Boost control!

Postby Corey » Sat May 19, 2012 5:11 pm

Can probably bet nearly every owner on here has disconnected the TVIS by capping it off like you did.

Maybe the caps are leaking? Try rubber fuel hoses with long bolts pressed into the ends. That may seal better than those vacuum caps :shrug:

What CEL codes are stored at the moment? Once you check them, try reseting the ecu to clear the codes and see if they return.

It sounds like a vacuum leak.

Also: Did you remove the electrical connector from the TVSV or just cap off the vac lines? There's no need to remove the connector.
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Re: Help! No Boost control!

Postby psipwrd » Sat May 19, 2012 6:18 pm

I just capped them, didn't disconnect the electrical connector. I'll go back tonight and reset the ECU and see if it starts. If not, I'm going to assume it's the fuel system since it's acting like it ran out of gas. It wouldn't let me boost more than 5 psi below 4k rpms, and a 7-10 above 4k. I had a fuel pump go bad on a supercharged car and it died just like this...
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Re: Help! No Boost control!

Postby psipwrd » Mon May 21, 2012 5:21 am

Is it possible it immediately went into limp mode with the TVSV disconnected?
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Re: Help! No Boost control!

Postby Corey » Mon May 21, 2012 5:37 am

It shouldn't.

With those lines capped off, and with no boost controller, all that happens is that boost will be about 5PSI in all gears.

If it is stuck in limp mode, its because of something else.

What code(s) is the ECU throwing out?
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Re: Help! No Boost control!

Postby underscore » Mon May 21, 2012 2:48 pm

psipwrd wrote:I just capped them, didn't disconnect the electrical connector. I'll go back tonight and reset the ECU and see if it starts. If not, I'm going to assume it's the fuel system since it's acting like it ran out of gas. It wouldn't let me boost more than 5 psi below 4k rpms, and a 7-10 above 4k. I had a fuel pump go bad on a supercharged car and it died just like this...


That almost sounds like TVIS got crossed with TVSV
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Re: Help! No Boost control!

Postby Corey » Mon May 21, 2012 2:55 pm

Good point ^
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