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Exhaust Popping On Decel... Bad!

bluey33

By bluey33,
in Engines & Forced Induction

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bluey33 Experienced

bluey33

Posted
Posted

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.

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DVS JEZ Grand Master

DVS JEZ

Posted
Posted

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

bluey33 Experienced

bluey33

Posted
  • Author
Posted

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.

bluey33 Experienced

bluey33

Posted
  • Author
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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 Grand Master

JonnoHR31

Posted
Posted

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 Experienced

bluey33

Posted
  • Author
Posted

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.

bluey33 Experienced

bluey33

Posted
  • Author
Posted

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 :(

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