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Engine bogs between gears

Old Jul 14, 2020 | 10:28 PM
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Engine bogs between gears

ok so I have a 90 iroc with a 5.7 tpi. The car idles and runs awesome however when the car is about to shift from first to second its like the car is dragging an anchor. After shift its fine as long as I'm not hard on the throttle. Lite throttle. Good response. Full throttle good response. In the middle enging bogs down. Does the same from second to third but not third to fourth. Have replace the tps and iac. Fuel pump and filter are new. Transmission is also brand new 700r4 stock converter and had the TVcable professionally adjusted. Any ideas would help
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Old Jul 14, 2020 | 10:59 PM
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Re: Engine bogs between gears

Originally Posted by Tim Eaton
ok so I have a 90 iroc with a 5.7 tpi. The car idles and runs awesome however when the car is about to shift from first to second its like the car is dragging an anchor. After shift its fine as long as I'm not hard on the throttle. Lite throttle. Good response. Full throttle good response. In the middle enging bogs down. Does the same from second to third but not third to fourth. Have replace the tps and iac. Fuel pump and filter are new. Transmission is also brand new 700r4 stock converter and had the TVcable professionally adjusted. Any ideas would help
Hows your fuel pressure?
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Old Jul 14, 2020 | 11:16 PM
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Re: Engine bogs between gears

Thats on my list to check tomorrow. I've read lots of different numbers of what it should be. But no definite answer to what it should be. I have noticed the last couple days that I have some type of whining/whisling coming from under the upper plenum but all my vacuum lines are attached and unbroken
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Old Jul 16, 2020 | 06:39 PM
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Re: Engine bogs between gears

Ok so I checked the pressure. Key on, not running its 40 to 41 psi. Car running its about 46 to 47 and under power its almost 50. Do those numbers sound ok?
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Old Jul 16, 2020 | 08:46 PM
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From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Engine bogs between gears

key on, engine off around 43.5 psi is normal 41 isn't very far off. That's meaning that the regulator has no vacuum to it.
If it's running, Vacuum will drop the fuel pressure down lower, 36-38 range. That way when you open the throttle and vacuum drops the fuel pressure goes up and at WOT it will be around 43 psi.
So those numbers don't make sense. What is causing those numbers? I currently have no idea other than a bad gauge and that doesn't really add up either.
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Old Jul 17, 2020 | 08:13 AM
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Re: Engine bogs between gears

Yeah, probably get your fuel pressure under control. Too rich can cause bogging just as easily as too lean.
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