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Only 5psi Boost-cut with NS vac reduction!?!

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Old 08-13-10, 10:08 PM
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Question Only 5psi Boost-cut with NS vac reduction!?!

Here's an odd bit:

After doing a full vac reduction and running NS, I'm hitting only 5psi before boost-cut.

Any thoughts/ ideas?
Old 08-14-10, 03:49 AM
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What ecu? Mods ?
Old 08-15-10, 09:59 PM
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Stock AT ecu and PCMT (with the ABP sensor directly wired from one unit, to another).

No major mods: Apexi mid-pipe and exhaust, Apexi dual filter intakes, HKS Turbo-Timer...

No joke. That's it. Only other thing is that I did a vac reduction and it's running NS.
Old 08-16-10, 10:56 AM
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Same problem over here.. someone help!
Old 08-16-10, 12:06 PM
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2 questions:
1. How do you KNOW it is boost fuel cut?
2. Where does your boost gauge get its signal from?

The attached is a table showing boost fuel-cut values.
Attached Thumbnails Only 5psi Boost-cut with NS vac reduction!?!-max-boost.jpg  
Old 08-16-10, 12:22 PM
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Wow. Good point, Dave.

1: ) When my gauge reads 5# the engine kind of "Cuts out" for a second... Perhaps I wasn't saying it right, but since it only does it at the 5psi marker, I figured it was a pretty safe bet.... Possibly fuel-cut, now that you've pointed it out?

2: ) Both the gauge and the BOV are pulled from nipples on the front (left?) of the UIM, immediately after the TB. Originally they were pulled to each of the two nipples on the backside of the UIM (By the bolts), but was cleaning up and swapped 'em.

At first I thought it was solely the vac-reduction, but it did it before I did it.

Not really sure.... Mebbe I should also check the FPR vac line?
Old 08-16-10, 12:28 PM
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What is your rpms when this is happening?
Old 08-17-10, 12:04 AM
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LOL. Funny you asked that. I was thinking about that, today, and couldn't remember any kind o f consistency in the tach department.

You got theories?
Old 08-18-10, 08:28 AM
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Drove the car, lastnight and no correlation between the tach and the boost gauge... I think I'm also going to recheck the remaining vac lines, since it pulls up to -0+ then holds, piddling around that point, but not pulling up in to boost.
Old 08-18-10, 08:52 AM
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Since we don't know what you did (nor can we see it), the first think you are going to have to do is recheck your work. Was the car performing like this before your work?
Old 08-18-10, 08:56 AM
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That's the odd thing. It had problems, but DIFFERENT ones. THOSE are sorted out, but now this.

*headbeat*

This started off because the car sat for a couple of months after being ridden hard and put up wet.... The latter IMMEDIATELY after the former.

It started, but was running like pure-grain ***. Turbos got replaced (to ANOTHER set of shitty, NS, stocks - owner's a cheap ***), and problems ironed out...

Then the ECU issue...

THEN the 'cut' issue...

Now the questionable boost issue.

I know that it isn't anything major, just mildly time-consuming.
Old 08-20-10, 11:53 PM
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Well, even though the FD is FS (see sig), this is an oddity, still.

Just got done reading a couple posts, related and maybe I should check the WG or such? It's doing the same 'sticking' that the other posts suggest...

Since I've got the reduction done, I'm fairly positive it's not a solenoid issue, heheh.

Well? Anyone?

ANYONE?!
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