Deceleration popping at exhaust with new MSA Premium exhaust

[Crashtd420]

I hope its common as i have already leaned the mixture to 1.5 turns clockwise and retarded the timing to 10 btdc and still pops at the exhaust when decelerating. In view of this, the lean or richen the mixture or advancing or retarding the timing at the distributor with the MSA PREMIUM EXHAUST SYSTEM will not eliminate the deceleration popping as others have recommended. Maybe one of the gaskets provided by MSA is not sealing correctly.

How are you leaning the mixture?...

Is this just happening at idle or while driving.....

Someone please correct me if I am off but it sounds like he's adjust the air fuel screw on the carb. I believe that only effects idle and the initial transition off idle... if you up on the rpms and it's happening while decelerating you need to adjust your jetting....

A run on a dyno or an air fuel gauge might be worth looking into.... that can tell you when your running rich or lean...

[datzenmike]

Carb is basically at idle when decelerating. High manifold vacuum and only enough gas for idle or a small amount more.

[racerx]

Have u called me a and see if its common to do the? Maybe they should of called it popping premium exhaust aystem

[racerx]

Meant have u called msa to see if this is common?

[racerx]

The if he thing too is have you asked,other z owners or join their forum and asked about msa popping noise

[Crashtd420]

Mike that's what I don't know so thanks...

Been doing alot of reading about tuning lately, but I have a lot to learn...

[MikeRL411]

Back in the '50s, that's the 1950s not the 1850s, I would tune my 49 Mercury slightly rich.  I cut the tail pipe short, welded on a "baloney" exhaust over the shortened tail pipe to the rear bumper and drilled a hole.  Inserted a spark plug [lawn mower plugs were just fine] in the hole and hooked up a Model T Ford coil [wooden crate housing and all sold by Sears], installed a push button switch to the battery.  When someone followed too closely I would speed up a bit.  If the car kept following too closely, I would let off the accelerater, wait a second and push the button.  The tongue of flame would clear all the bugs off his radiator and windshield and for some reason he would stop driving on my tail.

Edited May 7, 2017 by MikeRL411

[jalexquijano]

Well honestly my mechanic had removed the anti backfire valve, and emmission devices that where fastened to the balance tuve. He also removed the air galley. I dont know if the smog pump was removed or not by Previous Owner. I do believe so as the engine block had the blank space to bolt the compressor bracket to fasten the AC Compressor. Anyway, if i dont have the air galley installed any longer and it forms part of the emission system, even if i source a NOS Anti backfire valve if installed it would not cause any effect to avoid the deceleration popping at the exhaust. Any other way of preventing the deceleration popping at the tailpipe?

[datzenmike]

I think it would have an effect. When the AB valve opens, intake vacuum will suck air in. Dilutes the mixture making it much leaner. Will also drop the vacuum.

[Ranman72]

a performance exhaust will have a more free flow design with less back pressure and when decelerating will be more prone to popping it is not an uncommon thing 

as mike said the stock exhaust probably did it to some extent too but was muffled by a quieter exhaust 

[jalexquijano]

okay! but i removed the air galley which was rotten and forms part of the emission circuit and i think i dont have a smog pump any longer. As i wrote in my last post, even if i sourced an anti backfire valve how could i make it work as it depends on the other parts of the emmision system to work correctly and those parts were removed also.

[KoHeartsGPA]

If it only makes popcorn while deceleration, don't worry about it anymore and enjoy the classic life!

[jalexquijano]

i just want to know if it will still pop if i get better pipe to pipe gaskets and manifold to downpipe gasket, replace the ones provided by MSA and seal them with red high temperature RTV gasket maker?

[Cheetahking]

My experience - went from a stock exhaust to a resonator only never heard a thing before, and after it pops a lot on decel.  only change was exhaust - you are just hearing it now.  The rest of the tuning stuff you are going after may be worthwhile - but won't necessarily stop the noise!

[racerx]

Jalex, did u get touch w msa to see see if its normal?

[jalexquijano]

whom shall i talk at MSA?? i read in another fórum that their gaskets were not of good quality and they are prone to leaking.

[datzenmike]

You're 3 pages into this and it's not going away with a gasket change.

 

This popping is the new normal.

[racerx]

Most products have a tech line you can contact. If not like i said earlier have you gone on line or any z forum and inquired about msa exhaust to see of they had the same popping noise. We are giving you advised since u asked are you checking off the advised that are given. I have a feeling its a normal thing with the popping.

[Ranman72]

if you think or even have a question about the gaskets being crappy quality then replace them 

dont use form a gasket or anything of the like on the exhaust it wont help 

[mhub91]

Dude it's normal. Get over it lol

[jalexquijano]

Just talked to a seller at MSA and he says its not normal. He argues that the car is running rich or it has ignition problems. I told him none of that. I lowered the mixture and it still backfires on deceleration. I advanced to 16BTDC and retarded to 11 BTDC and still the same.

[mhub91]

IBTL

 

[datzenmike]

Just talked to a seller at MSA and he says its not normal. He argues that the car is running rich or it has ignition problems. I told him none of that. I lowered the mixture and it still backfires on deceleration. I advanced to 16BTDC and retarded to 11 BTDC and still the same.

 

Of course he will say that. ALL low restriction 'performance' exhausts make noise... it's what they do best.

[Ranman72]

sell it and put the stock one back on 

or ask msa for a refund 

you obviously are not satisfied or happy with it 

IBTL

[mhub91]

FYI, all vehicles do this when you alter the exhaust.

 

I work at a performance shop. Just a few weeks ago a installed a massive cat back on a 2016 F150 low rider. It popped and crackled when engine braking.