96 Cobra Hellion 76mm Turbo Kit Install

[b00stin]

It sounds like a leak in either metered air before the throttle body or a vacuum leak after the throttle body. That's what might be causing it to stall out when coming to a stop. The car has the most vacuum at idle or when the throttle body is immediately closed (like when coming to a stop), therefore, if there's a vacuum leak, it's gonna be worst during these conditions.

It's leaking vacuum and metered air when coming to an idle, and it's leaking boost when you're getting into it.

I really think it has something to do with the way the PCV system is hooked up. I'm telling you, disconnect the PCV lines that connect to the turbo inlet pipe, boost tube between the turbo and throttle body, or intake manifold. (I'm not sure exactly where your PCV hoses are connected, but it's got to be 2 out of those 3.. all of which are metered air). When you disconnect them, the important thing is that you plug the bungs in the intake tract where both hoses connect. For the purpose of this test, it doesn't matter if the hoses coming from the crankcase don't connect to anything, just make sure they are secure from heat and moving parts. That'll eliminate the possibility of there being a vacuum/boost leak through the intake into the PCV system.

I recommend to eliminate any possibility of there being a metered-air PCV leak, either use breathers (little filters connected directly to the PCV valves on each valve cover), or you can run PCV hoses to a catch can with a filter on the top. That accomplishes the same thing, except it gives the oil vapor/smoke a single place to condense. Or, you could run both hoses into a T fitting to a single hose, and connect the single line before the MAF in the intake. Make sure to use an oil accumulator to reduce the likelihood of oil and smoke making the MAF dirty (which will throw a lean code because it's not reading accurately). It all depends on what state you live in and whether or not you have to pass an inspection or emissions test. If you aren't worried about emissions, just do breathers, or a catch can. That way, it's completely separate from the metered side of the intake.

The simplest setup by far is to just run breathers on each side and cap off the original fittings on the intake and boost tube where the PCV originally connected.

That eliminates any possibility of there being a vacuum/boost/metered air leak through the PCV system. Vacuum leaks are awful to track down, so having one less place for there to be a vacuum leak makes things a lot simpler to troubleshoot.

Oh, forgot to ask you. Is the check engine light on? If so, what codes is it showing? Do you have a boost/vacuum gauge? If so, how much vacuum is it showing at idle? If you have the gauge connected to the correct area in a vacuum line on the intake manifold, it should be reading around 20 in/hg at idle. If it's reading 15 or less in/hg at vacuum, I'd be suspicious of a leak.

Please, before you do anything else...plug the bungs where the PCV hoses connect to the intake tract and see how it runs. (don't plug the hoses coming from the PCV valves on either side of the engine. just let them hang loose for a test ride. It'll be ok if they are open for now. They are venting to the atmosphere, just like with breathers) But its very important you do this with both PCV hoses on either side of the engine. If I'm right, you'll notice an instant improvement in driveability. Smooth, steady idle, no hesitating, stalling, and no breaking up when you start to get in the boost. Do that and tell me what happens.

Good luck!

Homer

I will try this when i get home... i am reading 20 in of vacuum at idle. my question is if i cap off the upper portion (the pipe leading to the throttle body) that is the iac reference.. shouldn't that be connected? the only codes i have are for the rear o2 sensors which are deletedand secondary air injection which is also taken out. i also have imrc deletes installed.. not sure what kind of driveabilty issue that would cause low end.

 

[saleensonoma]

hopefully u figure this out and i was ready to drop c4 in my typhoon chasing vacuum leaks.

 

[saleensonoma]

Maybe this summer we can meet up. Im outside of toledo but go out to detroit/taylor watch some grudge nights and some friends earn money

 

[b00stin]

IUP99snake... i tried what you said blocking off the pcv...didn't help it... seems to only do it after the vehicle is at operating temperature. i even went as far as bypassing the turbo and installed my old intake pipe with mass air flow sensor on the end bypassing the whole setup and the car still wants to stall...it has a slightly erratic idle the idle will drop down to like 650rpm and bounce up to 1100 and then stabilize or idle kind of low like 650-700 rpm range and eventually stall out at idle...or when coming to a stop

 

[b00stin]

So now this leads me to believe its either an iac or possible dirty stock Maf from sitting around so long....

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[CBelleperche]

Your car is being a bitch Ryan, pull a Chris Brown and set her straight!!!

 

[b00stin]

Your car is being a bitch Ryan, pull a Chris Brown and set her straight!!!

im about to light her on fire lmao

 

[CBelleperche]

That's only a temporary solution!

 

[IUP99snake]

IUP99snake... i tried what you said blocking off the pcv...didn't help it... seems to only do it after the vehicle is at operating temperature. i even went as far as bypassing the turbo and installed my old intake pipe with mass air flow sensor on the end bypassing the whole setup and the car still wants to stall...it has a slightly erratic idle the idle will drop down to like 650rpm and bounce up to 1100 and then stabilize or idle kind of low like 650-700 rpm range and eventually stall out at idle...or when coming to a stop

Bummer. You asked about the IAC reference line.. Don't disconnect that. It can look like a PCV line.. Im assuming you just disconnected the PCV lines and not the IAC line..

Ironically, I just got rid of my breathers and installed new PCV valves and hoses, connecting them to the metered intake vacuum port and also the blower intake pipe to fix the lean codes my car was throwing. It wasn't necessarily the breathers that were causing the problem, lots of people have breathers.. But it was the tune. My tune is extremely finicky.. I did exactly the opposite of what I told you to do, which fixed my problem.. Nevertheless, capping off the provisions for the PCV on the intake and boost tube is a good way of eliminating possible issues.. Best of all, it didnt cost you anything and you now know one more thing that isnt causing the problem..

I'm out of ideas.. Take it to the tuner and let them sort it out.. I know it's tough to have to do that.

 

[CBelleperche]

The damn tuner didn't know what to do with it....

 

[LaserRed01GT]

I THINK I have the solution to your problem... You're running a blow thru maf in the location of a draw thru style... That MAF needs to be in the piping right before the throttle body. I used that exact MAF on my 99 DIY turbo build. Hope this solves your problem man.

 

[CBelleperche]

No dummy he is running a draw thru, just like Hellion does... With any FI setup you can run blow thru or draw thru

 

[b00stin]

Yeah this mass air flow sensor is definitely a draw through sensor bud

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[CBelleperche]

I THINK I have the solution to your problem... You're running a blow thru maf in the location of a draw thru style... That MAF needs to be in the piping right before the throttle body. I used that exact MAF on my 99 DIY turbo build. Hope this solves your problem man.

Your car never ran did it? Cause if you are saying things like this and installing a DiY turbo kit, you need to give your car to someone that knows what lefty loosey righty tighty is.... Just saying

 

[encasedmetal]

if your car is stalling only at temp but not before it's either one of 2 things or both.
1. as the car gets to temp things expand- especially your throttle blade which most people set the throttle screw before the car is to temp. so once it reaches temp and expands your TB chokes off the car and the IAC valve can't do it's thing. try and log ISC duty cycle, TB absolute and ISC integrator and I'll be able to tell you where to go on that.
2. fueling. for instance- when first tuning my car under cold start conditions- it would idle like hell at 19-20 afr until it warmed up, once at temp it idled right at 14.7-14.8 afr. big difference. so make sure you're logging while at temp and then your maf transfer tables can be scaled correctly.

other thoughts from previous posts- never ever put your pcv air before the maf- I saw this earlier in your thread and is a big ****ing no no. pcv will also have dick to do with your vacuum. and plus if your seeing 20# vacuum at idle you do not have vacuum leak. my car sees almost 0 vacuum with my cams and runs like a ****ing champ.

 

[b00stin]

The pcv is routed the way hellion sets it up after the maf

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[encasedmetal]

The pcv is routed the way hellion sets it up after the maf

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I thought so , but someone had posted to route it before and use an oil separator.

 

[LaserRed01GT]

No dummy he is running a draw thru, just like Hellion does... With any FI setup you can run blow thru or draw thru

I know you can run both "dummy"... I just thought it looked identical to my blow thru style maf.. I apologize for trying to be of help. Oh and here's a vid of my Mustang after my turbo install and tune.. It did in fact run.. very well. 1999 Mustang GT Turbo Highway Pull @ ~4PSI - YouTube

Again I apologize, I don't know everything about this stuff I just know some of the things that I've learned over the past 4 years of research for my own setup. Good luck finding the issue....

 

[IUP99snake]

I know you can run both "dummy"... I just thought it looked identical to my blow thru style maf.. I apologize for trying to be of help. Oh and here's a vid of my Mustang after my turbo install and tune.. It did in fact run.. very well. 1999 Mustang GT Turbo Highway Pull @ ~4PSI - YouTube

Again I apologize, I don't know everything about this stuff I just know some of the things that I've learned over the past 4 years of research for my own setup. Good luck finding the issue....

You didn't deserve to be called a dummy by the dummy. This isn't kindergarten. We're all trying to contribute and no one here is a dummy.

 

[brian97cobra]

interested to see the outcome of this...

good luck OP