hooptie02

Alright, so I bought my 2002 s10 4.3 2wd about 3 weeks ago and have had nothing but trouble ever since... Most problems are bearable but this one has me worried. When I've been driving for a good while (2+hrs) my truck's throttle looses most of its responsiveness and will sputter pretty pathetically. I recently bagged the truck and had to relocate a black plastic box (originally located above the driver's side rear wheel believed to be some sort of emissions system) to directly behind the cab on the passenger's side above the exhaust. I believe that this might be causing the problem.

3 questions:
1.) What is the actual use of the black box?
2.) Do I need it?
3.) What else could be causing this problem?

jackyshaikh

Answers to your question

1.) What is the actual use of the black box?

Ans-the black box is EVAP canister itlimits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent valve to atmosphere. The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge valve ON, open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent valve OFF, open, fresh air will be drawn through the valve and vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon. The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge valve into the intake manifold to be consumed during normal combustion.

2.) Do I need it?

If it is damage,leaking,clogged you may.

3.) What else could be causing this problem?

If you have this kind of symtoms

[hr]


Hesitation, Sag, Stumble [/align]






Checks

Action


DEFINITION: The vehicle has a momentary lack of response when depressing the accelerator. The condition can occur at any vehicle speed. The condition is usually most severe when you attempt to make the vehicle move, for example, from a complete stop. The condition may cause the engine to stall if the condition is severe enough.


Preliminary Check

Refer to Symptoms - Engine Controls .


Fuel System Checks
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Check the fuel pressure. Refer to Fuel System Diagnosis .[/align][align=left]



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Check the throttle position (TP) sensor for binding or for sticking. The voltage should increase at a steady rate as the throttle moves toward wide open throttle (WOT).[/align][align=left]



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Check the manifold absolute pressure (MAP) sensor response and accuracy.[/align][align=left]



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Check for water contamination in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .[/align][align=left]



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Check the canister purge system for proper operation.[/align][align=left]



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Perform the fuel injector coil test. Refer to Fuel Injector Solenoid Coil Test .[/align][align=left]



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Perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Tech 2 .[/align][align=left]



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Check for low fuel pressure after a cold start, or during a moderate or full throttle acceleration.[/align]


Ignition System Checks
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Check for damaged spark plug wires.[/align][align=left]



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Check for fouled spark plugs.[/align][align=left]



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Check for proper ignition system performance. Refer to Distributor Ignition (DI) System Diagnosis .[/align]


Additional Checks
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Check the Service Bulletins for calibration updates.[/align][align=left]



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Check the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.[/align][align=left]



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Check the exhaust gas recirculation (EGR) valve operation. [/align][align=left]



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Check for a restricted exhaust. Refer to Restricted Exhaust in Engine Exhaust.[/align][/align]I hope this may help to isolate the problem.[/align]

steverap

I dont think the evap canister should be above the exhaust. Could very well be the problem.