Help! No Boost control!

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psipwrd

Member
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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Texasnick

New member
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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psipwrd

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





Look at that, no water temp sensor plug here either!
 
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l0ch0w

New member
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.
 
underscore

underscore

Well-known member
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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psipwrd

Member
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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Corey

Active member
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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psipwrd

Member
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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Corey

Active member
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?
 
underscore

underscore

Well-known member
psipwrd":3qbg015f said:
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...
Click to expand...

That almost sounds like TVIS got crossed with TVSV
 
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psipwrd

Member
I didn't check the CEL, had it towed to a shop. The mechanic said it's the distributor rotor. Waiting on parts and install...
 
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psipwrd

Member
I pulled my CELs and...wow...

12, 14, 22, 24, 31, 34, and 54. The mechanic didn't reset after changing the distributor rotor. I reset the codes tonight, drove for about 30 mins, and only 22 came back so far. I'll check the plug tomorrow and order the water temp sensor if that looks good.
 
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