Dyno'ing with an Exhaust Leak ?

[tim510]

Hey Fella's


Im planning on getting my car dyno'ed on the weekend and ive got and exhaust leak just after my dump pipe (80cm from the turbo) where the flanges are meeting...the dump pipe is not quite right and does not fit square up to the rest of the exhuast


my question is, will the A/R meter be thrown out by this leak?

if they put the sniffer up the rear muffler, will this leak cause issues to the read out because of the leak up the line?

thanks


tim

[sssgtr]

Your A/F ratio shouldn't be thrown out by an exhaust leak. Nor the sniffer. You should be fine.

[tim510]

thanks sssgtr,


i wondered if the extra oxygen would change the reading...but i spose the exhaust is pushing fumes out and not sucking anything in

[GSRman]

hmm you could whack a couple of fat gaskets in there for the session..

[Artsi]

YES - leak in exhaust system can/will throw off oxy sensor. My parent's Volvo started behave funny, loss of power and bad fuel economy.

Local dyno bech operator knows heaps on Volvos. He right away suspected exhaust side leak. Sure enough, there was a miniscule leak problem at exhaust gasket between cylinder head and header.
That miniscule passage let air into exhaust piping, thus fooling oxy sensor to think engine is running too lean.

Swapped gasket. Problem gone.


Assumption is totally wrong on exhaust side experiencing only positive pressure pulses, thus it possibly could not suck in air. It can and it will.
Whenever there is a positive pulse travelling in piping, it'll be closely followed by a negative pressure pulse/wave. That negative wave is the culprit in drawing air into exhaust system.

-A.

[EXQS_ME]

there is a chance it could throw the reading out, but i guess it depends how big the gap is.. Ive had a car dynoed with a leak and its afr's were on the head anyways, but it was a very small leak.

nothing a roll of heat tape couldnt fix for an hour :)

[RB26DETT]

gasket glue qill fix the problem, i had the metal gaskets im mine and it leaked like a siv so i put some gadket glue on wither side of the gasket and wola no more leaks

[tim510]

i think it will hit it with some silimax blue-poo


should close the gap


the leak is after the turbo, before the turbo everything is fine