HELP!!!

[NBSTAHOE]

Ok this is kinda long…

I have a 02 Tahoe with 2WD. VIN Z.
I wanted to add some power to it, so I started with the TBSS swap. Followed some youtube videos to see what I was up against. Bought all the parts proceeded with the job. When I was done I crank up the truck and it’s making this horrible sucking noise. I’ve replaced the intake gasket twice. TB gasket. IAC. TPS. All new. But I keep throwing a EVAP code and that Noise is embarrassing. On a cold start the idle hangs for about 2 minutes then regulates. The noise goes away. I put it in drive, the noise comes back briefly then goes away. It’s intermittent. And present at low RPMs. Under load it’s not noticeable. But fuel economy sucks. And it won’t go past 3K rpms when going about 50-60. Checked hoses. They’re good. Sprayed carb cleaner. No change in RPMs but that noise is present. Somebody please help.

 

[Scottydoggs]

sounds like a huge vac leak. you got hydro boost brakes? or a vac booster? maybe the port for the vac booster has been left open on the new intake?

whats the code for the evap? maybe you got a broken line to it and thats the vac leak.

 

[tom3]

I use an old nurses stethoscope to pinpoint vacuum leaks. I pulled the end off and stuck the pipes into a short piece of garden hose. Can get right to the spot quickly. Good for exhaust leaks and other stuff too.

 

[NBSTAHOE]

sounds like a huge vac leak. you got hydro boost brakes? or a vac booster? maybe the port for the vac booster has been left open on the new intake?

whats the code for the evap? maybe you got a broken line to it and thats the vac leak.

Thanks for the response. It’s Vac booster and the code is P0440.

 

[NBSTAHOE]

I use an old nurses stethoscope to pinpoint vacuum leaks. I pulled the end off and stuck the pipes into a short piece of garden hose. Can get right to the spot quickly. Good for exhaust leaks and other stuff too.

Thanks I’ll look into it to trying to pinpoint it that way. Its like the noise is coming from the CAI. But if I remove it, the noise is coming from the intake itself through the CAI.

 

[Scottydoggs]

the 440 code is a huge vac leak. you need to look a bit harder for a busted line.

 

[Mudsport96]

What are you useing for a throttle body? I was under the impression it was a 3 bily vs 4 bolt pattern

 

[NBSTAHOE]

the 440 code is a huge vac leak. you need to look a bit harder for a busted line

Thanks I’ll recheck the lines today. Some are new required with the swap and some were just fine, but I’ll check again.

 

[NBSTAHOE]

What are you useing for a throttle body? I was under the impression it was a 3 bily vs 4 bolt pattern

I’m using a Holley Sniper EFI 8600081. A 4 bolt.

 

[Mudsport96]

Starting fluid. Run the truck, and spray around the intake. When you find the vacuum leak you will know.

 

[NBSTAHOE]

Starting fluid. Run the truck, and spray around the intake. When you find the vacuum leak you will know.

I’ve already tried that and didn’t notice any change.

 

[nick0789]

If you can, post a video of the engine running on a cold start (go through youtube and then embed the video here).

If it were me I would do the easy troubleshooting first, some of which you've already done:
1) check all connections / make sure the intake is torqued properly (inch pounds)
2) check all vacuum lines
3) do a smoke test with a cheapo cigar. Be sure to plug vacuum lines and put a glove or something over throttle body
4) put OEM throttle body back on and see if the issue persists. It's quick enough to swap without having to pull the whole intake again
5) check the EVAP lines

 

[Mudsport96]

I’ve already tried that and didn’t notice any change.

If you are introducing fuel (starting fluid) to an air leak, you have to get a change in idle, it is fuel and air. Carb cleaner doesnt have the bite it did 20 years ago use good starting fluid

 

[NBSTAHOE]

If you are introducing fuel (starting fluid) to an air leak, you have to get a change in idle, it is fuel and air. Carb cleaner doesnt have the bite it did 20 years ago use good starting fluid

 

[NBSTAHOE]

 

[NBSTAHOE]

I’m trying to figure how to post the video. I shared it from YouTube.

 

[NBSTAHOE]

 

[NBSTAHOE]

 

[NBSTAHOE]

 

[nick0789]

That dog is having a grand ole time!

Anyways, if it's not a major hassle to do so have you tried reinstalling the original air box and tube? I didn't pay attention in your original post to see that you have a CAI. Not that it's going to be your issue but I have read about the CAIs causing a lot of random issues with these engines when they are installed. Granted, they are usually from the MAF being installed backwards (doesn't appear to be in your case) or oil from the filter fouling the MAF ... but it would be super easy to confirm / rule out.