Exhaust Popping On Decel... Bad!

[bluey33]

33 gtst - clutch and full exhaust (bellmouth)

Had issues for a while when I fill up tank with fuel and start the car it won't idle correctly and hunts (sometimes stalls)

This issue I was always a bit whatever about it. Hit the throttle and she settles ok.

Major concern is:

I have had a very intermittent issue where the exhaust will pop when I decelerate with no throttle and then touch the throttle it will pop no matter how many times I go on an off throttle. Sometimes it will get so bad it will pop whilst decelerating down revs without touching the throttle.

Through the revs doesn't miss a beat.

Did it with 2 different motors in it. (blew motor) Only things that remained on change of engine was afm, tps, coils and loom. (fuel pump of course)

Cas, plugs, fpr, injectors all changed.

I got consult to find O2 sensor sitting at .3 when cold then when at temp sits around .1-.2V. Had a spare sitting around so tried that and it just read 0.0-0.15V. So I Bought O2 sensor and found readings Fluctuated from .28-.80V. Which a mates car also did. Got better fuel consumption of course.

Car still popped intermittently.

Tested for vac leak and all good.

Tested tps voltage and all good.

Also I originally had exhaust studs snapped so gathered that would cause popping. Changed all studs and gasket. Still popped intermittently.

It was very intermittent so hard to diagnose but of course now I am in QLD on holidays it is doing it a lot more then normal.

I have found that when I'm low on fuel it doesn't pop at all no matter how much I cruise or thrash it. I pull into servo and put fuel in and I pull out to check if it pops and it does.

So I am thinking fuel pump but why or can u guys think of something else?

Sorry for massive read but wanted to give as much info as possible.

I also understand if u all are not in the mood to think as it is Easter and u may be drunk or hungover.

[JonnoHR31]

Check the breather line from the fuel tank to the carbon canister, maybe a bit of fuels getting through when the tanks full.

[bluey33]

Cheers. Will check it out in morning.

[DVS JEZ]

Also check tps setting.

Did u keep the charcoal canister or remove it? If u removed it wat did u do with the lines? I had a mate route his breather line to the inlet manifold and wondered why it was running rich on decel and accell

[Stevoss]

Recirc stock bov?

[Manuel Kasko]

Wrap your exhaust in exhaust wrap and enjoy da flames brah

[bluey33]

Stock bov not blocked.

Exhaust wrap isn't needed for flames lol. It's stock and people think its off tap cause it blows flames.

Charcoal canister lines were put on as they were but will gO over them in the morning.

[Manuel Kasko]

Mine pops on the odd occasion after smashed my cat out.

Wouldn't mind knowing the cause as well

[Bsa]

No cat or bashed cat will lead to exhaust poping

[toffy]

^^^ . Beat me to it .

Edited April 7, 2012 by toffy

[bluey33]

Not my kind of popping though...

[Bsa]

Maybe make a recording of the sound

[bluey33]

Ok. I'll see how I go tomorrow. Will take it out and when it pops I will vent charcoal canister to atmosphere and see of that fixes it. If not will get recording.

[ima_slap_joO]

I had the same issue, as DVS said, double check the TPS again, if you have another unit try that.

Edited April 7, 2012 by ima_slap_joO

[bluey33]

Checked it couple times as that's what everyone thought it would be and didn't believe I checked it right. It is set at .43v and reads normal on consult when issue is happening.

I'm going to get stuck into it now and see how I go.

[JonnoHR31]

One way to check whether or not its the TPS is to turn the ignition off whilst on decel and see if it makes any difference. If everythings working as it should it shouldn't make any difference. Just make sure the motors hot first

[bluey33]

Yea that's still the same with ignition off.

I have vented charcoal canister to Atmosphere and it hasn't popped and carried on today.

Will hook canister back up tonight and see if it pops (of it does) then i will undo it to see if it fixs it.

Also found fuel filler fitting loose which is why fuel leaked last DECA.

[Bsa]

Do you have broken gaskets before the dump

[bluey33]

Just did manifold gasket as I had 8 snapped studs lol. All new genuine parts. Reused gasket to exhaust which was fine.

When it was popping I thought this was due to fix it for sure but didn't

[Bsa]

You mean head to manifold gasket or turbo to dump