Car runs horrible after FP Intake install..

[my98GST]

It idles really bad, it has been running realy rich, and wants to die occasionally... Would this be becuase I don't have the charcoal canister line and the valve cover line not plugged in to the intake?

 

[definitiveno]

It would definately be if you weren't rerouting your blow off into it.

 

[CTP_MADDOG]

my guess is you are not rerouting your bov.

 

[my98GST]

Yeah my bov is recirculated... Same as before with my Injen intake, except the FP doesn't have the three bungs for the carbon canister and the valve cover breather.. The only things that I changed was my exhaust manifold and the intake.

 

[definitiveno]

Manifold you say? Details.

 

[my98GST]

DNP manifold... The car makes like a popping noise at idle almost like its camming but sounds like its missing but its not missing... it wants to run like poo before WOT and then runs like a raped ape at WOT which makes me thing it would run even better if it was running properly all the way around.....if that makes sense. Also it wants to back fire more now. I think it is the valve cover breather hose cause my buddies popped off on his gsx and it started doing the same thing.

 

[kenamond]

DNP manifold... The car makes like a popping noise at idle almost like its camming but sounds like its missing but its not missing... it wants to run like poo before WOT and then runs like a raped ape at WOT which makes me thing it would run even better if it was running properly all the way around.....if that makes sense. Also it wants to back fire more now. I think it is the valve cover breather hose cause my buddies popped off on his gsx and it started doing the same thing.

At idle, the PCV valve is open, and the IM sees a vaccuum, so it will draw air in through the VC and in through that VC breather on the side. Normally, the VC breather connects to the intake pipe, so it is pulling air from the intake pipe which is downwind of the MAS. End result: in your case, you're pulling extra air into your motor at idle which has not been metered by the MAS, and you're running lean at idle.

Under boost, the PCV valve closes, so the leak goes away.

If you cap your VC breather, however, you end up pressurizing your crankcase under boost (blowby and valve leaks), and you might blow seals or pop your dip stick tube.

You could do a very simple test. Start your motor, put your thumb over the VC breather or breather hose and see if the idle improves.

Also, make sure your intake pipe couplers are sealed including the recirc hoses.

A boost leak test might not be a bad idea if you've tinkered at all with the BOV, IC pipes, etc. (anything between the compressor and the intake side of the head).

Do a search for folks who have modded their intake pipes to add a nipple for whatever they needed.

That's my guess.

 

[spyderturbo007]

Did you remember to plug your MAS back in.

 

[2gAWDTalon]

X 10 on the Mas connector. Not recirculating your blow off valve willnot make the car run like crap in the way he is describing it. Not recirculating will make it run like crap for a second when you shift and sometimes areound town when you shift. Not running the PCV valve to the intake or the other breather will also have zero ill effect on the way it runs. Most DSM's have those two tits on the valve cover rant to a catch can, so how do you figure that could be his problem? Check that MAS connector, it is a easy mistake. I did it one time, we were boost leak test my car before heading to the track and got in a hurry. Anyway a couple block down the road and I pulled over to see why it was running like doodie/check engine light on and sure enough... I forgot to plug in the MAS.

 

[my98GST]

Yup the mas is plugged in...

 

[spyderturbo007]

I know this might sound stupid, but did you try swapping out the intakes for the one that was working? Is it possible that you damaged your MAS during the installation?

Did you cover the honeycombs with anything to protect it during the installation and then forget to remove the cover? And don't even think about asking why I posed that question.

 

[kenamond]

X 10 on the Mas connector. Not recirculating your blow off valve willnot make the car run like crap in the way he is describing it. Not recirculating will make it run like crap for a second when you shift and sometimes areound town when you shift. Not running the PCV valve to the intake or the other breather will also have zero ill effect on the way it runs. Most DSM's have those two tits on the valve cover rant to a catch can, so how do you figure that could be his problem?

At idle (he's having problems at idle) in the stock setup, the PCV is open, and the motor is pulling air from the intake pipe (which is downwind of the MAS, so the air is metered), through the VC breather line, into the VC, in through the PCV, and into the IM. If you leave this open to the atmosphere, the motor will pull unmetered air into the motor, and you'll run lean at idle. Under boost, the PCV closes. He's running fine under boost. That's why I'm suggesting this - it's pretty easy to put a thumb over a hose. The motor will still run a bit rough at idle if you block the VC breather, because the ECU is expecting that extra air coming from in through the PCV, but it's a few psi vaccuum more and 100rpm difference, but it won't run as rough as he's seeing.

Folks who run both VC nipples (breather and PCV) to a catch can are defeating the purpose of their PCV system. It relieves crank case pressure due to blow by, and it ventilates the crankcase gasses which include exhaust and fuel/air mix so that it doesn't settle in the oil. There are setups which give you what you want (no oil in your intake pipe or IM from the VC breather or PCV valve) while maintaining the PCV system functions I just mentioned.