1G Car runs great with a boost leak

[Boatsaccle]

I very recently aquired a manual 92 eagle talon tsi and I’m having a funky issue. This car has been thoroughly trashed, but runs. When started it will go to 2k rpm’s for a few seconds and drop down only to start missing pretty bad and kind of idle surging and stumbling and almost dying and when you drive it when you go into neutral 3/5 time it will die. Starts right back up and same thing. But I’ve fould that when I manually open the blow off valve by sucking the vacuum hose on it and sticking a screwdriver in the opening to hold the valve open, it runs FLAWLESSLY. No missing, absolutely smooth idle. I’m wondering what could cause an issue like this. He told me it has a bigger turbo wheel and housing but that doesn’t appear to be true. Injectors look new and has aftermarket front mount intercooler kit. Any question and I’ll answer to the best of my ability. THANKS

 

[curt-s]

Need to know the whole build list. For all we know, the car was tuned with a boost leak. Possibly most important, ECU.

 

[Boatsaccle]

The guy I got it from said it had a tune but I highly doubt it. As the boost controller was hooked up to the blow off valve and he said it had a bigger turbo and it appears to be bone stock, I’m assuming this car is completely stock besides a front mount intercooler kit

And a full exhaust sorry

 

[CanadianTalonTC]

Got an under hood photo?

The stock 1g Turbo is a 14B and the 16g which is the most common upgrade looks basically identical (especially if you are new to dsms), so you may have it.

I would recommend pulling the ECU, opening it and seeing if there is Link in there by some off chance before proceeding.

Sounds to me like the BISS is in way tight or the ISC may be stuck. Basically the BISS allows air to pass, the further out you screw it the more air passes the plate and the higher the throttle goes. The ISC is there to control the idle at the proper RPM but it needs to have the BISS properly otherwise it can't stay within proper range.

I would recommend doing the entire idle setup procedure after ensuring there are no further boost leaks. Don't forget the O-ring on the BISS and the TB shaft seals as those are common places to leak.

 

[Boatsaccle]

Hey thanks I’ll give this stuff a look when I get home, I’ll put pictures up as well, thing is a real junker

 

[pauleyman]

The guy I got it from said it had a tune but I highly doubt it. As the boost controller was hooked up to the blow off valve and he said it had a bigger turbo and it appears to be bone stock, I’m assuming this car is completely stock besides a front mount intercooler kit

And a full exhaust sorry

Assume nothing. Your going to have to verify ecu. Injectors etc. For the purpose of idle turbo doesn't matter.

 

[Boatsaccle]

Assume nothing. Your going to have to verify ecu. Injectors etc. For the purpose of idle turbo doesn't matter.

Ecu is stock non eprom, so no link. Also injectors are stock.

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[CanadianTalonTC]

Boost leak test and idle reset procedure and go from there then .

 

[Boatsaccle]

So I hooked the bov up the right way, instead of how the previous owner had it, and now when it idles the bov kind of sits open and vents and in turn it idles good. Because before it was closed, and when I manually opened it, it would idle good. But now it sits open by itself and idles good and holds boost great and works like it should, I guess my question is, is that how it’s supposed to be? Is the bov supposed to be open at idle to run good? Because I know it’s supposed to close under boost and when you let off, it vents.

 

[Boatsaccle]

It should not be open at idle. What BOV is it?

Some cheap eBay one it looks like.

 

[CanadianTalonTC]

Some cheap eBay one it looks like.

Have you tried adjusting the spring on top to ensure it closes? If its recirculated it shouldn't really matter cause it's all metered air anyways though.

 

[Boatsaccle]

I’ve adjusted it but it only runs good when it’s open. If I adjust it closed then I get a lot of surge and it idles poopy

 

[pauleyman]

So I hooked the bov up the right way, instead of how the previous owner had it, and now when it idles the bov kind of sits open and vents and in turn it idles good. Because before it was closed, and when I manually opened it, it would idle good. But now it sits open by itself and idles good and holds boost great and works like it should, I guess my question is, is that how it’s supposed to be? Is the bov supposed to be open at idle to run good? Because I know it’s supposed to close under boost and when you let off, it vents.

Is this bov vented to atmosphere? If so it shouldn't be if you're running a maf.

 

[Boatsaccle]

Is this bov vented to atmosphere? If so it shouldn't be if you're running a maf.

Yea stock maf and it is vented to atmosphere. I’m putting a new afr gauge in it sometime soon so maybe that will tell me something.

 

[CanadianTalonTC]

Yea stock maf and it is vented to atmosphere. I’m putting a new afr gauge in it sometime soon so maybe that will tell me something.

You cannot vent it to atmosphere utilizing a stock MAF (Well, if you had link you could do a sketchy setup for it) You are losing metered air and it is not injecting correctly. There is more amiss if it's running well leaking air like this as you obviously know.

Step 1: recirculate that BOV. Especially if it's opening at idle.

Step 2: boost leak test

Step 3: reset idle per FSM.

Step 4: Come back here and report findings and let's get this thing running properly.

 

[pauleyman]

So I hooked the bov up the right way, instead of how the previous owner had it, and now when it idles the bov kind of sits open and vents and in turn it idles good. Because before it was closed, and when I manually opened it, it would idle good. But now it sits open by itself and idles good and holds boost great and works like it should, I guess my question is, is that how it’s supposed to be? Is the bov supposed to be open at idle to run good?

Its supposed to be open at idle.
you have multiple issues as discussed above. You must fix them.

Because I know it’s supposed to close under boost and when you let off, it vents.