Air bypass valve ?

Fostang · 07-31-2001, 05:26 PM

How do you know when the air bypass valve is no working properly? What are the symtoms of a car with a bad bypass valve. The car idles roughly and when accelerating it just sits on it's behind and doesn't get up. The tps sensor has been replaced and is working correctly what else could it be?

------------------
67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

Jeff7477 · 07-31-2001, 05:32 PM

Vacuum leak? checked vacuum lately?

Fostang · 07-31-2001, 06:07 PM

Vacuum is perfect.

------------------
67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

QuantumMotorsports · 07-31-2001, 09:42 PM

I have been having similar problems, but they are intermittent. Does your car also sometimes miss at idle and sound like it is almost loping like it has a cam? I am wondering if it isn't an ignition problem. Such as a bad coil, or TFI module. I have heard that they are known to go bad on 5.0s. I'm am trying to learn all I can about the EFI electrical system because as you can tell by now it has a huge effect on how the engine can run. I am planning on rewiring my entire wire harness soon because I have had many electrical problems since squirrels chewed my harness to bits and I had a ford dealer fix it. Never send a dealership to do a mans job by the way.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" offroad H pipe w/ 2 chamber flowmasters, T5 tranny
New E/T!!!
14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

Fostang · 08-01-2001, 02:40 PM

It tends to want to lope but today replaced the air bypass and sensor attached rechecked the timing and it ran fine now. Much more stable rpm's. But still seems to need more air. Maybe it's time to replace the throttle body and mass air.

------------------
67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

07-31-2001, 05:26 PM	#1
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Air bypass valve ? How do you know when the air bypass valve is no working properly? What are the symtoms of a car with a bad bypass valve. The car idles roughly and when accelerating it just sits on it's behind and doesn't get up. The tps sensor has been replaced and is working correctly what else could it be? ------------------ 67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Bad or Dirty Air Bypass Valve???	mimicons	Windsor Power	3	11-10-2002 08:02 PM
Qs about Bypass Valve install	Chipdog	Windsor Power	2	08-08-2002 08:17 AM
Powerdyne bypass valve install?	FASTFRANK	Windsor Power	3	05-11-2002 12:22 PM
throttle air bypass valve	87 GT MUSTANG	Windsor Power	1	03-27-2002 12:47 PM
Bypass Valve?	Chipdog	Windsor Power	1	07-18-2001 05:56 PM

07-31-2001, 05:32 PM	#2
Jeff7477 Registered Member Join Date: Jun 2001 Location: Lincoln, Nebraska USA Posts: 67	Vacuum leak? checked vacuum lately?

07-31-2001, 06:07 PM	#3
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	Vacuum is perfect. ------------------ 67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s

07-31-2001, 09:42 PM	#4
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	I have been having similar problems, but they are intermittent. Does your car also sometimes miss at idle and sound like it is almost loping like it has a cam? I am wondering if it isn't an ignition problem. Such as a bad coil, or TFI module. I have heard that they are known to go bad on 5.0s. I'm am trying to learn all I can about the EFI electrical system because as you can tell by now it has a huge effect on how the engine can run. I am planning on rewiring my entire wire harness soon because I have had many electrical problems since squirrels chewed my harness to bits and I had a ford dealer fix it. Never send a dealership to do a mans job by the way. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, Ported and Polished E7TEs, 2.25" offroad H pipe w/ 2 chamber flowmasters, T5 tranny New E/T!!! 14.626 @ 94.94mph, 2.194 60' time, a little better than last time. Keep in mind this thang is heavy (3590lbs) Finally 14s!!!!

08-01-2001, 02:40 PM	#5
Fostang Registered Member Join Date: Feb 2001 Location: Stockton, Ca Posts: 599	It tends to want to lope but today replaced the air bypass and sensor attached rechecked the timing and it ran fine now. Much more stable rpm's. But still seems to need more air. Maybe it's time to replace the throttle body and mass air. ------------------ 67'fastback-Edelbrock carb,intake,cam,valve springs.Rhode lifters, CompCam rocker arms, windage tray,cerama coated headers,dual flows with H-pipe, modded c-4,tci stall converter,perma cool electric fan,aluminum water pump,griffen aluminum radiator,accel 8.8 cable,wide cap distriburator,magnetic pick up,v-matic hurst shifter,edelbrock performer nitrous, carter electric fuel pump,ignitor coil,solid motor mounts,magna racing suspension,poly urathane bushings,under rider traction bars, comp. eng. s