Removing Exhaust Manifold / Air pump on TBI

[liftedchevys87]

I have a 1987 Chevy v10 5.7L TBI. Its bone stock right now and I was going to run headers and remove the air pump. Does anyone have experience with this and know what problems I might run into? I know I have to plug off some vacuum lines to the TB, but what else?

[VileZambonie]

I usually cut the a.i.r. pump bracket too to clean up the look. That big round bracket with nothing there looks stupid. Just tape back the harness connector or cut it and carefully wrap it back in the loom. Once you've removed everything it's pretty self explanatory. One thing though, if your truck is equipped with downstream a.i.r. you'll need to plug the pipe going into the cat.

[GP3624]

What exactly does the air pump do other than add air to the exhaust for the cats to work, I have no cats on mine so removing the air pump wont cause any issues correct?

[VileZambonie]

What year is your truck?

[Layne]

The truck won't throw any codes with the air pump removed?

[liftedchevys87]

I thought the air pump fed unburned gas fumes from the top of the exhaust manifold (unburned fuel is less dense so it rises) into the throttle body....not 100% positive though.

[Layne]

It Air Injection Reaction so I think it's just pumping air.

[VileZambonie]

It works differently by year and application but here's a generic description of an electronically controlled system with carb

The Air Management System provides filtered air, under certain conditions, to the exhaust manifold to continue the combustion process after the exhaust gases have left the combustion chamber. This continued combustion aids in reducing HC and CO levels in the exhaust and also helps in maintaining ideal catalytic converter operating temperatures.

SYSTEM OPERATION
This system consist of a belt driven air pump, internal drilled passages in the cylinder head or manifolds, piping and hoses, electric air control valve and check valves. The vane type air pump supplies air through a centrifugal filter fan to the electric air control (EAC) valve, Fig. 11. On 1987 V6-262 and V8 engines, an electric air control valve with relief tube (ECT) is used, Fig. 12. The electric air control valve directs air to either the exhaust manifold ports or the air cleaner, which also acts as silencer.
On all engines except 1987 Federal V6-173 engines, at cold engine coolant temperatures or at wide open throttle conditions, the Electronic Control Module (ECM) will energize the electric air control valve solenoid, directing the air to the exhaust manifold ports. At higher engine coolant temperatures, the electric air control valve solenoid is de-energized, directing air to the air cleaner. Also at higher engine speeds, air is directed to the air cleaner through the pressure relief valve even though the solenoid may be energized. During engine deceleration, a rise in the manifold vacuum signal to the electric air control valve, will cause the valve to direct the air to the air cleaner. When the engine is operating in the closed loop mode, air flow should be to the air cleaner, with no air flow to the exhaust ports.
On Federal 1987 V6-173 engines, the Electronic Control Module (ECM) will energize the electric air control valve whenever the engine is started, directing air flow to the exhaust ports. Air flow will only be directed to the air cleaner during deceleration.
On all engines, the check valve(s), which is located on the air injection pipe, will prevent reverse exhaust gas flow into the air pump in the event of a air pump drive belt failure or exhaust system afterfire. When the engine is operating under a rich condition or if the service soon lamp is illuminated, the electric air control valve solenoid will be de-energized.

1985-87 MODELS W/HEAVY DUTY EMISSIONS

DESCRIPTION
The air injection system used on vehicles with heavy duty emissions utilize increased air flow over other models to reduce CO and HC emission levels. The AIR system provides additional oxygen to continue combustion after the exhaust gases leave the combustion chamber. This system diverts air from the exhaust manifold at increased engine speed or when a malfunction is detected in the system.
The AIR system used on vehicles equipped with a 6-292 engine consists of an air pump, air filter, air control valve, check valve, silencer, control module and injection nozzles.
The AIR system used on vehicles equipped with V8-350 or V8-454 engines consists of two air pumps, air filter, two air control valves, a control module and injection nozzles.

SYSTEM COMPONENTS

Air Control Valve
This valve is a high flow electric air control valve that is equipped with an electric solenoid to combine electronic control with normal diverter valve function, Fig. 11.
With ignition ``On'', the solenoid is energized through the control module and the air control valve operates like a diverter valve directing air to the exhaust manifold. During engine deceleration, when there is a rise in manifold vacuum, air is directed to the air cleaner or silencer even though the solenoid is energized. The solenoid is de-energized when there is a malfunction of the electrical circuit or high engine RPM over a prolonged period.



Deceleration Valve
The deceleration valve is used with the AIR system to help prevent backfiring during high vacuum conditions, Fig. 17. Vacuum draws the mixture valve diaphragm down and opens the valve allowing air from the air cleaner to flow into the intake manifold.

[Whodatjrock]

I have a 87 with the 5.7 350 TBI. I let a "shop" install my headers and exhaust pipes with no cat's. I keep getting the check engine light after the truck warms up? I think they removed my Air Pump also. The truck runs fine but I cant get the check engine light fixed.

[VileZambonie]

Did you check for dtc's? Jump a&b terminal in the data link connector

[Blue 82]

My (tbi) truck ran fine arond town after the header install
But within 5 minutes on the highway at cruise speed the Check Engine light would come on
Pullled the code and found it was the EGR valve
Pulled the air cleaner off and found I had knocked the vacuum line off
Plugged it back in and so far so good.

[zieg85]

Thanks Vile for the post, I learned a lot.