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Old 01-12-2018, 09:47 AM   #1
dytha99
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Default Snap crackle pop BOOM

'92 940 na Regina, 345k

No exhaust system from the cat back.

No signal from o2 sensor.

Car runs rich.

Whenever I decelerate from any speed over 30mph I hear snap crackle pop boom until I hit 30mph and lower or until I give it some gas.

What is causing these noises?



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Old 01-12-2018, 09:58 AM   #2
vwblue1967
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Pretty sure its not having an exhaust.
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Old 01-12-2018, 10:22 AM   #3
esmth
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Even with a working o2 sensor you'll hear a ton of that with an open downpipe

you're also cooking the cat running it like that!
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Old 01-12-2018, 11:22 AM   #4
EivlEvo
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Here is a video of my stock 87 244 with a busted exhaust just after the cat (which was probably completely destroyed).

This is just a vid of my drive home from work one day so nothing crazy, but you can definitely see the fireballs if you watch for the flashes (easier to see towards the end maybe).

This vid is queued up. You'll see one at 3:44 and 3:54 and 4:05 etc etc etc
https://youtu.be/W6kz79Hdaeg?t=3m34s

There's a good over-run of the popping when I get off the highway at 13 mins.

Best one at 13:20

Last edited by EivlEvo; 01-12-2018 at 11:28 AM..
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Old 01-12-2018, 12:11 PM   #5
Dirty Rick
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It is normal for a motor to cackle, fart, pop, bang, bark, even emit flame, on decell, especially without a baffle.

Overfueling or misfiring WILL overheat the cat to the point of destruction.
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Old 01-13-2018, 12:12 AM   #6
NotSoFresh
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Quote:
Originally Posted by Dirty Rick View Post
It is normal for a motor to cackle, fart, pop, bang, bark, even emit flame, on decell, especially without a baffle.

Overfueling or misfiring WILL overheat the cat to the point of destruction.
This is only normal on cars with carbs and high strung efi cars. Very few of the users here have cars high strung enough that they pop and spit fire normally (open headers/downpipes not included). That takes compression and cam overlap. Not factory stuff. If yours does it it is because it is running like crap.

The function of the o2 sensor is to tell the ecu whether the mixture is right. Without one you are dumping fuel into the exhaust which is exploding and popping. You are also likely running lean at times as well. O2 sensor delete will not make power, only rob it. The ecu needs to know how much fuel it needs to squirt to work properly. Put the o2 back and get working on ecu upgrades.
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Old 01-15-2018, 10:40 AM   #7
dytha99
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Quote:
Originally Posted by NotSoFresh View Post
This is only normal on cars with carbs and high strung efi cars. Very few of the users here have cars high strung enough that they pop and spit fire normally (open headers/downpipes not included). That takes compression and cam overlap. Not factory stuff. If yours does it it is because it is running like crap.

The function of the o2 sensor is to tell the ecu whether the mixture is right. Without one you are dumping fuel into the exhaust which is exploding and popping. You are also likely running lean at times as well. O2 sensor delete will not make power, only rob it. The ecu needs to know how much fuel it needs to squirt to work properly. Put the o2 back and get working on ecu upgrades.
Thanks. The o2 has not been deleted. However I'm going to replace it and have the exhaust kit that i put on welded up.



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