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Jul 1, 2021 | 02:03 PM

Zoo Keeper

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5th Gear

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From: Long Island N.Y.

major bogging

Hello corvette fans,
I have a problem that i can't figure out. 1990 base corvette that i changed the fuel pump, fuel filter, fuel regulator, TPS, MAP sensors, O2 sensor disconnect the neg for 4 hrs.I also changed plugs, cap rotor and wires. The car idols (little rough) as soon has i go to accelerate it just bogs and sometime back fires when let off. If i slowly bring up the rpms, the engine runs rough. Has anyone ever had this problem please help

Jul 1, 2021 | 02:22 PM

Vetteman Jack

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Jul 1, 2021 | 02:52 PM

ctmccloskey

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Welcome to the Corvette Forum Zoo Keeper!

It says that you replaced the TPS on your L98. Did you reset it after putting the new one in?

Why did you need to disconnect the Ground wire for 4 hours?

When you first start your engine the Corvette is in "Open Loop" using stored data in place of real data and as the engine and Oxygen Sensor warm up they start sending a signal used to control the air-fuel ratio. Once the Oxygen sensor is warmed up it will then allow the engine to switch over to "Closed Loop". In Closed Loop the engine is using data from the Oxygen Sensor, MAF Sensor and the engine's Coolant Temperature Sensor to more accurately calculate the fuel ratio.
My question is does your Corvette go from Open Loop to Closed Loop or is it stuck in Open Loop?

Just so you know, if it is stuck in open loop it the engine will run poorly. Kind of sounds like what you might be describing.

Are you using a stock type fuel pressure regulator or an adjustable? What is the fuel pressure while idling? All the vacuum lines connected?

Jul 1, 2021 | 11:14 PM

JD1964

Burning Brakes

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Have you checked the injectors? Testing the resistance with ohm meter is easy. One bad injector can throw it all outta whack. Computer might try and compensate for a lean condition caused by a misfiring injector. It will then richen up the working injectors and add to the problem.

Jul 2, 2021 | 09:55 AM

Zoo Keeper

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5th Gear

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From: Long Island N.Y.

thanks for your input. i set the tps @ .54vdc. the crazy thing is i never got a check engine light.\ ever! I put my scanner on and nothing shows. I broke down the first time with the same thing and got it flat bedded home. When they took it off the vette ran great for about a month. Then it happened again. I changed the fuel pump and filter and ran great for one day. Now were back to the same thing, this is where were at now. I pulled the Neg. cable off for 4 hrs to try to reset the ecm.
John

Jul 2, 2021 | 09:58 AM

Zoo Keeper

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5th Gear

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From: Long Island N.Y.

John,
the injectors were changed 7000 miles ago by the last owner

Jul 2, 2021 | 01:22 PM

ABD87

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Time is also a function of failure for the injectors. Mine were ten years old or so (I think) when I replaced them on a whim trying to solve a problem similar to yours.

Jul 2, 2021 | 03:39 PM

Mrvettenick

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Has anyone checked fuel pressure when it bogs? Also, I would disconnect and plug the vacuum line to the EGR valve to see if it gets better or stays the same.