Startup/Idle Problem

[GSXDNA]

So I just took my car to the dealership to have the TPS replaced. Got the car back today, everything was running great. It was even idling better than it ever has (constant 1000rpm).

Then, when I got home, I decided to try out my boost leak tester that I just built, because I had the feeling I had a leak somewhere. Just for the heck of it, I also disconnected some of the intake/intercooler piping just to have a look around and observe the overall condition of everything. When I took off the tubing from the turbo to the air box, I noticed all this gunk and buildup in it. So, I took it inside, washed it out with warm water, and let it dry outside in the wind for about 30 min.

Other than that, all I did was disconnect and reconnect the piping from the intercooler to the turbo, and from the throttle body to the BOV. (By the way, the stock 2G BOV is starting to leak at less than 5psi)

After I reconnected everything (and yes, I triple checked everything - it's all connected and tight), when I go to start my car up the RPMs go to about 2k (as they are supposed to), but then drop down to like 200 and almost make the car stall for a few seconds, then they go back up to a lower 600-700 or so. However, I took the car out for a ride and it's running phenomenal. It's definitely pulling harder than it was before I messed with it.

But what could be causing this idle issue? Could there just be some excess water in the piping that just needs to dry up? Should I be concerned?

 

[solo92s10]

did you disconnect the intercooler piping after you did the boost leak test? It sounds alot like a boost leak and if you disconnected the pipeing after the test then the test was worthless as the leak is often inthe piping/couplers.

 

[GSXDNA]

did you disconnect the intercooler piping after you did the boost leak test? It sounds alot like a boost leak and if you disconnected the pipeing after the test then the test was worthless as the leak is often inthe piping/couplers.

I'm not quite sure I understand what you're saying. When I did the boost leak test, i forced air into the intercooler, flowing to the TB. I suspected the BOV to be the culprit from the beginning, so I disconnected the recirc valve on the BOV and heard air start to hiss out from it as soon as I put any air in the system.

However, the car was idling fine at startup BEFORE the boost leak test. Also, if it is a vacuum or boost leak causing this startup problem, why would it be pulling so much stronger now?

Also, I added engine coolant, but I'm sure that has nothing to do with anything.

 

[16g-2ndgen]

your right, a vacuum leak and or boost leak would not make the car pull harder. it seems like it is surging. have you checked for cracks? (if stock ### rubber sh*t). is the blow off valve recurculated? becouse it will do the exact same thing that you have said your talon is doing.

 

[GSXDNA]

your right, a vacuum leak and or boost leak would not make the car pull harder. it seems like it is surging. have you checked for cracks? (if stock ### rubber sh*t). is the blow off valve recurculated? becouse it will do the exact same thing that you have said your talon is doing.

The car is completely stock, so yes - all rubber sh*t. And as mentioned, it was starting up fine before I disconnected and then reconnected the piping. What do you mean by surging? How would a crack in any one of the lines have a different affect than having a leak?

 

[TurboDSM610]

Well you can start by spraying starter fluid on your vaccum lines while your car is idling. If the idle gets rough u got a leak. But it sounds like you got a vacuum leak or boost leak.

 

[GSXDNA]

Well you can start by spraying starter fluid on your vaccum lines while your car is idling. If the idle gets rough u got a leak. But it sounds like you got a vacuum leak or boost leak.

It's weird though, because after I've been driving the car around for a few minutes, idle is great (900rpm). There seems to be no difference whether the engine is hot or cold when I start it. However, since I reset the ECU, upon start-up RPMs will struggle to even reach 200-300 initially for the first few seconds. Then, they will raise to about 500 or so, until finally leveling off at 900-1000 after a few minutes.

If it were a boos/vacuum leak, wouldn't the idle problem be there after startup as well? I obviously messed something up, I just can't find it.

 

[TurboDSM610]

Have you checked the ECU for leaky capacitors cause that could cause idling issues as well.

 

[GSXDNA]

Have you checked the ECU for leaky capacitors cause that could cause idling issues as well.

I haven't because the startup issue wasn't present until i started messing with the piping.

You know what...I wonder if the problem is in the piping from the intake box to the turbo. That's the only pipe I messed with that wouldn't cause issues under boost if it were cracked/leaky, but could potentially cause problems at startup. I'm going to go take a look at it right now and see.

 

[GSXDNA]

Ok, so I can't think of any other possible potential cause to this problem, other than the intake tube. So, I took it off again and very carefully examined it. On the stock intake between the airbox and the turbo inlet, there are three small hoses that are connected to the main tube. Then, I remembered that the one tube on the bottom (the smallest of the three) had to have the sealant/glue connecting the smaller hose to the large tube taken off in order for me to get the large intake tube out. I examined the connection to see how snug it was, and there was a little bit of play, possibly causing a very very small vacuum leak. So, I went to the store and bought some sealant and applied it. I guess in the morning we'll see if that was it or not.