Finding header/exhaust leaks
 

I've been researching DIY ways to find exhaust leaks without turning the car on, and many people online recommend using a shopvac and blowing into the exhaust (which I've done, along with spraying soapy water, and it works very well)

Just recently I've seen a couple people advising against this method because there is a possibility of blowing debris into open exhaust valves and possibly damaging valves or piston rings etc.
Now I'm a nervous wreck, but what's done is done and I haven't noticed anything as far as symptoms.

Is this a concern on our cars? And is there a better way to check for leaks at home without a smoke machine?

So why are you nervous?
Do you have a leak?
A lighter or a incense stick works.
Most leaks are caused by improper installation, used gaskets, improper torque, or warped flanges. Most of the time it is install error.

@swarb Just nervous I may have done some damage that isn't noticeable yet by using that testing technique.
I don't think I have a leak, but I have some random pretty high ST fuel trims at low throttle and I'd like to rule out exhaust leak. I haven't tested this new JDL header for leaks, but when I installed it I used proper torque, new gaskets, their lock nut kit, and the flanges were all flush when I measured.

Use a vacuum (suction side) and trace every joint with one of these
http://www.toolaid.com/sites/default...hoto%20300.JPG

Not everyone will have access to one.......but for difficult to find leaks in exhaust systems we will sometimes use the smoke machine that we use to find leaks in vehicles Evap systems. It fills the pipe(s) with a relatively dense smoke, and where theres smoke...theres a leak. Same principle as using a shop vac in reverse just lower pressure and well....smoke.

Depends on how high the STFT's are. Are you running e85?

http://datazap.me/u/joshbustos86/jdl...zoom=2452-2824

91 octane..suppose it could be the fuel as it does have 10% ethanol in it..

Stft varing widly with throttle load changes is totally normal this is the ecu keeping the fueling correct in closed loop operation.

ltft is the average of stft over a sliding window of time in each of the trim bands, this is the one you look at, your ltft look fine and your commanded afr and afr are following eachother under load.

stft will go to zero in open loop fueling mode again normal.

have a read of the maf scaling thread again it has explaination of fueling modes

if you had a leak the ltft would usually be high in the lower bands like way over 10% usually in positive direction as o2 sensor sees fresh air and ads ship loads of fuel to try to compensate for perceived lean condition

relax , have a beer it looks fine

^ Exactly