Cobra bogs after I shift

Emmanueldsg

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Nov 26, 2020
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Brighton, Co
Hello there my cobra bogs sometimes when I shift fast from 2nd to 3rd at wide open throttle but it’s only sometimes, some other times it’s completely fine, and it won’t do it if I shift slowly. any ideas on what it could be. Cobra is fbo kenne bell on e85


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2000GTSTANG

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Nov 26, 2006
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Plymouth, MI
That's your return-less fuel system throttling down the pumps when you let your foot off the gas pedal during the shift. Once you get on the gas again, the pumps need to build fuel pressure so you get the bog.

Seems like the harder you push this type of fuel system, the worst it is. I had a Kenne Bell 2002 GT with a single pump on a boost-a-pump and running e85. It would do the same thing basically everytime you shifted quickly but would not if you could bang the gears fast enough or took your time to roll into the throttle after the shift.

You could see if the PPRV valve is still inside your gas tank, and delete it if it is, with a piece of submersible fuel line. The PPRV has been know to cause hesitation when shifting too. Some say you can try to tune it out but I never tried so YMMV.
 
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Emmanueldsg

New Member
Joined
Nov 26, 2020
Messages
3
Location
Brighton, Co
That's your return-less fuel system throttling down the pumps when you let your foot off the gas pedal during the shift. Once you get on the gas again, the pumps need to build fuel pressure so you get the bog.

Seems like the harder you push this type of fuel system, the worst it is. I had a Kenne Bell 2002 GT with a single pump on a boost-a-pump and running e85. It would do the same thing basically everytime you shifted quickly but would not if you could bang the gears fast enough or took your time to roll into the throttle after the shift.

You could see if the PPRV valve is still inside your gas tank, and delete it if it is, with a piece of submersible fuel line. The PPRV has been know to cause hesitation when shifting too. Some say you can try to tune it out but I never tried so YMMV.

Thank you, me and Danny Johnson were also thinking it’s the return less fuel system and I could also try the pprv delete


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01yellercobra

AKA slo984now
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Oct 5, 2005
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Cali
Depending on your fuel set up you should be able to tune it out. I did the PPRV delete on my 01 and funny enough I had the shift hesitation after I removed the blower. I had to tweak the tune to get rid of it.
 

NGO

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Jul 1, 2011
Messages
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Location
Indialantic, FL
That's your return-less fuel system throttling down the pumps when you let your foot off the gas pedal during the shift. Once you get on the gas again, the pumps need to build fuel pressure so you get the bog.

Seems like the harder you push this type of fuel system, the worst it is. I had a Kenne Bell 2002 GT with a single pump on a boost-a-pump and running e85. It would do the same thing basically everytime you shifted quickly but would not if you could bang the gears fast enough or took your time to roll into the throttle after the shift.

You could see if the PPRV valve is still inside your gas tank, and delete it if it is, with a piece of submersible fuel line. The PPRV has been know to cause hesitation when shifting too. Some say you can try to tune it out but I never tried so YMMV.

Perfect! That is a good explanation. This anomaly has occurred a few times, scares the crap out of me I am so worried of running lean. Thanks
 

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