spfi acts like carb w/bad accelerator pump

[MilesFox]

jims 88 spfi 4wd 5spd d/r wagon acts like a carb with a bad accelerator pump. when you rev it up, it makes somewhat of a "popping" noise, and has no torque. just like a vacuum leak, but it idles normally. once you get enough momentum, it drives fine, as long as you ease into the gas. if you put her down at rpm, it will stumble.

 

i read once on the board about a solenoid that will stick open, something to do with air introduction.

 

it has almost 200,000 miles. we have that little $100 for a spare, if that may be it. but could it be something on the throttle body? the amount of "vacuum leak" seems more than what that little component will allow.

 

and also, could it be the brake booster. you can tell it works when the motor runs, and when you step on the brake while idling, it will make popping noise or want to stall out.

[86subaru]

also the car sat for 6 months without a hood , and aleast another 6 months just sitting . :

[MilesFox]

bumpity bumpity:banana: :wave:

[86subaru]

bump ,any help ? thanks

[TomRhere]

Don't know much about FI systems, myself, but sounds like it's running lean.

Sitting with no hood on it, could've cause some corrosion on the wiring connectors, giving false signals to the ECU.

Could be the coolant temp sensor is bad, or faulty. ECU has to know the temp of the engine to give proper pulse timing to the injector(s).

Would a bad O2 sensor cause a lean condition? Where as the O2 sensor is telling the ECU that the engine is running rich, causing it to lean-out the engine.

 

Lean air/fuel mixture will cause backfires thru the intake, so can improper ignition timing.

 

Have you checked for vacuum leaks, everywhere?

[86subaru]

no we have not , may change the 02 censor ,thanks