Ok so my boosted L61 is popping allot on decell / engine brake....
It did this allot when I would have en exhaust leak. But as far as i can tell there's no leak.
And from my experience it would need to be a decent sized leak to cause the pops im hearing on decell.

Does anyone know what esle other than an exhaust leak can cause loud pops on decell?

Mine is N/a and does that since i can remember. Its usaully caused by a lean condition. which is usally what the computer sets the car to do on decel. So check your tune or your wideband to see what your A/F ratio is on decel



]:-> 287 TimeSlips In Hand. Car Still Runs Strong... 3 Differentials Later ]:->

mines stock with just a header, exhaust, and intake, and i have no popping.

It has done this since I got my car. Stock exhaust it did it. Catback magnaflow it did it. Now that I'm boosted, it still does it. All on decel.

It's fairly normal for modified cars to do that. You can some times make it less noticeable with a resonator or a straight through muffler in the center section of the car.

My Car does this every time I let off the gas on decl, and after I let off on WOT it blows a big backfire and a flame

I have 2.5" exhaust to a 30" Resonator to a flowmaster 40. It's all on an ecotec with the Saab Turbo setup.

K well I had ignition issues before....
The icm, (Compression sense timing module... Which i HATE) would fail every 6 months....
The issue was resolved by grounding the icm to the head/block ground point, and re running the connections between the icm and ecm.
Makes me wonder if theres something wrong with that again.....

Also I feel like a noob for not knowing, but
does the fuel cut out on decel?

NeedTurbo wrote:K well I had ignition issues before....
The icm, (Compression sense timing module... Which i HATE) would fail every 6 months....
The issue was resolved by grounding the icm to the head/block ground point, and re running the connections between the icm and ecm.
Makes me wonder if theres something wrong with that again.....

Also I feel like a noob for not knowing, but
does the fuel cut out on decel?

I am not sure. I know it severely leans it out, but I don't know if it completely shuts off the injectors or not.


BTW, since I removed my muffler, mine pops under deceleration too. I think its a normal characteristic of our cars, but the stock muffler muffles it.


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Yes, noob, the search button is for you...

i doubt the fuel would cut out completly, the charge in the cylinder would get so hot so quick. idk, but thats just my guess



horsepower is the force that determines at what speed you hit the wall, torque is the force that determines how far you take the wall with you after you hit it.

02 silver cavy wrote:i doubt the fuel would cut out completly, the charge in the cylinder would get so hot so quick. idk, but thats just my guess

The fuel DOES cut out completly on decel (under certain conditions). If you have no fuel burning how is it going to get hot?

Bump.

So the fuel cuts out under certain conditions?
Or does it just lean out alot?
OR
Do some ppl just think it leans out when really it's just reburning the blow by from the pcv?

(Tom) S/C Fire wrote:

02 silver cavy wrote:i doubt the fuel would cut out completly, the charge in the cylinder would get so hot so quick. idk, but thats just my guess

The fuel DOES cut out completly on decel (under certain conditions). If you have no fuel burning how is it going to get hot?

injectors do shut off...

+1 for Tom

Yeah i've always had the popping on decel noise aswell. Slightly noticable with stock 02 sunfire gt exhaust, now very noticable with magnaflows.


How to we rid it!?

K so the injectors do shut off,

So what is igniting causing the pops?
I'm thinking either excessive blow by, or small coolant leak into the chamber?

No, it is a normal characteristic of our cars... Deal with it.


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Yes, noob, the search button is for you...

I have the same problem, but I noticed a decrease in power when my car started to do that! Could it be the plugs?


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

its the DCFO, its more noticable on aftermarket exhausts, you can turn it off if you like in hp tuners but id reccomend against doing so it saves alot of gas being on



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

DCFO? So if I"m not worried about gas, does that mean I can tune more HP out of the car?


"FRIENDS DON'T LET FRIENDS DRIVE STOCK"

This is normally caused by and exhaust leak...

or overly large exhaust

My pops on decell are related to my Icm and coil packs failing.
I'm working on a complete rewire solution for the l61 icm as we speek. I'll post the results when im done with that.

You can check if your problem is similar.
Find someone with a l61 and swap their icm and coil pack in.

If the pops go away completely, you may have a short in on of your lines ran to your icm/coil packs.

The short will cause a new icm and coil pack to progressively fail.
So a new pair will run good for maybe a couple weeks, then slowly start to fail.
Some signs of this may be hesitation, pops on decell, loss of power.
Though all those symptoms are universal for many problems.

the popping noise is simply your fuel mixture igniting after it exits the cylinder and is in the exhaust, or whats left of it anyways. the reason you hear it when you have a significant exhaust leak is because it is not being muffled by the cat/muffler/resonator. a bad coil or ignition module could cause it if it were sending a spark at the wrong time.

My car used to do that until I put a resonator in it..... now I just get this gurgly sounds wich I personally think sounds cool.

And I have a big problem about this deceleration fuel cut off thing...

If it completely shuts off the injectors..... than why is fuel being burnt on decel?... I can hear my damn exhaust..... it's loud enough.... I know damn well the injectors are firing.... shutting the injectors off completely would do the same damn thing as turning the ignition key off. Also... It wouldn't make sence for it to lean way out either.... because that would burn the engine.

So what the hell is really going on?

Im thinking it just leans it out to where theirs much less fuel but still in the safe zone..... at least thats the only thing that makes scense to me.

Anyone that really knows what there talking about care to chime in?

well the only chiming in I can do, is what I told you...

if it were the coil packs failing then you would here it on stock cavs with stock exhaust too right? some stock cavs have failing coils but they never make the pooping sound.

I dont have any popping sound because I am running 2" exhaust and It doesnt have any leaks....

P.S. I make enough power to run 12.4 in the quarter...
I had coil go bad on my eco and it still didnt pop...

Thanks the input. I guess?

Like I said before my specific problem is related to my coil packs AND icm failing.

In my situation, a new coil pack and icm will 100% not pop at all.
Ones that are failing will pop progressively more.

And as i said in my post exhaust pops can be cause by more than one thing.

As far as rewiring the icm power supply.
You can easily wire it to the battery using a relay tapped into the ignition. For switched on run purposes.
I tested this last night and it works 100% fine.

All other wires can be directly ran straight from the icm to the pcm, ex cam out, timing 1, timing 2.
Wiring diagrams from Chiltons helps alot for this.