Backfire& Bogging

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Feb 6, 2012
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I am having backfiring and bogging issues. It happens when the car is up to temperature. It is bogging in the mid-range around third gear. It's very responsive at WOT but backfires sometimes. Can anyone please figure out what's happing in this tune?
 

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a91what

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Mod Dude
Apr 6, 2011
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Can you elaborate on the issue? when does it happen? on tip in? after a gear change?

I see some lean spots at part throttle in the mid range, other than that the O2 appears to have a laggy response.

It is most definitely lean by more than a whole point on AFR. can you verify fuel pressure
 

[email protected]

Active Member
Feb 6, 2012
108
15
28
54
Can you elaborate on the issue? when does it happen? on tip in? after a gear change?

I see some lean spots at part throttle in the mid range, other than that the O2 appears to have a laggy response.

It is most definitely lean by more than a whole point on AFR. can you verify fuel pressure
It happens when I launch it hard sometimes. I get a backfire around 4500 rpm. I notice when I drive it around town at low speeds shifting I am hearing and feeling light popping. Bogging It's not necessarily consistent. Fuel pressure was at 50psi. I turned in down to 42psi with vac off.
 

[email protected]

Active Member
Feb 6, 2012
108
15
28
54
Can you elaborate on the issue? when does it happen? on tip in? after a gear change?

I see some lean spots at part throttle in the mid range, other than that the O2 appears to have a laggy response.

It is most definitely lean by more than a whole point on AFR. can you verify fuel pressure
I need to do another data log. I found that a rubber cap off the t -body was cracked and letting some Unmetered air In the system. Vacuum leak. Let me do another log and see if that fixed anything.
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
10,551
6,694
214
32
Hillsborough county
If you backed the fuel pressure down then thats the issue. dropping the pressure from 50 down to 42 psi makes the injector act smaller and requires a fuel trim.
 

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Feb 6, 2012
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When you inquired about the fuel pressure I noticed it was a bit high so I thought. The log was was with it at 50 psi. I will try a new log at 42psi and see if that improves anything tomorrow.
 

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Feb 6, 2012
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I drove it around today. It did not appear to bog as much. I did not notice the same backfiring but some. Please check and see if it looks better. My laptop disconnected a couple of times but managed to get an assortment of data logs.
 

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  • CurrentTune.msq
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  • 2021-09-07_17.40.27.mlg
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  • 2021-09-07_17.49.02.mlg
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  • 2021-09-07_17.52.15.mlg
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[email protected]

Active Member
Feb 6, 2012
108
15
28
54
Can you elaborate on the issue? when does it happen? on tip in? after a gear change?

I see some lean spots at part throttle in the mid range, other than that the O2 appears to have a laggy response.

It is most definitely lean by more than a whole point on AFR. can you verify fuel pressure

I need to do another data log. I found that a rubber cap off the t -body was cracked and letting some Unmetered air In the system. Vacuum leak. Let me do another log and see if that fixed anything.

If you backed the fuel pressure down then thats the issue. dropping the pressure from 50 down to 42 psi makes the injector act smaller and requires a fuel trim.
I drove it around today. It did not appear to bog as much. I did not notice the same backfiring but some. Please check and see if it looks better. My laptop disconnected a couple of times but managed to get an assortment of data logs.
 

Attachments

  • CurrentTune.msq
    117.8 KB · Views: 8
  • 2021-09-07_17.40.27.mlg
    1.3 MB · Views: 1
  • 2021-09-07_17.49.02.mlg
    361.6 KB · Views: 0
  • 2021-09-07_17.52.15.mlg
    828.6 KB · Views: 0