Engine idles but will not accelerate

I am wondering I know it sounds easy but could the air filter be plugged?

Get a engine vacuum reading @ idle let me know how maney inch if vacuum you have.

Retrieve the code and post it up. That may be the answer to your problems.

Also, you should do a full ignition tune-up (wires, cap and rotor) not just spark plugs.

I would recommend doing some testing. Replacing parts can waist a lot of money. Get the vacuum readings and fuel readings. If you can't rent them you might be better off paying a shop to do the testing

DTC P0171: FUEL SYSTEM TOO LEAN

1. Check the fuel pressure
Is fuel pressure OK?
YES - Go to step 2.
NO - Check these items:
If the pressure is too high. Check the fuel pressure regulator and the fuel return line.
If the pressure is too low. Check the fuel pump, the fuel feed line, the fuel filter, and the fuel pressure regulator.

2. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.

3. Check the Primary HO2S or Air Fuel Ratio (A/F) Sensor (Sensor 1) output with the scan tool. Does it stay at less than 0.3 V or more than 0.6 V?

YES - Replace the Primary HO2S or Air Fuel Ratio (A/F) Sensor (Sensor 1).
NO - Go to step 4.

4. With a vacuum pump, apply vacuum to the EVAP canister purge valve from the intake manifold side. Does it hold vacuum?
YES - Check the valve clearances and adjust if necessary. If the valve clearances are OK, replace the injectors.
NO - Replace the EVAP canister purge valve.

DTC P0420: CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD

1. Reset the ECM/PCM

2. Start the engine. Hold the engine at 3,000 RPM with no load (in Park or neutral) until the radiator fan comes on.

3. Except F23A4 SULEV engine: Test-drive at 40-55 mph (64-88 km/h) for approx. 2 minutes. Then decelerate for at least 3 seconds with the throttle completely closed. Then reduce the vehicle speed to 35 mph (56 km/h), and try to hold it until the scan tool indicates FAIL or PASS as the TWC test result.

F23A4 SULEV engine: Test-drive at 50-55 mph (80-88 km/h) for approx. 2 minutes. Then decelerate for at least 4 seconds with the throttle completely closed. Then accelerate to 55 mph (88 km/h), and try to hold it until the scan tool indicates FAIL or PASS as the TWC test result.

Is the test result FAIL?

YES -Check the three way catalytic converter (TWC). If necessary, replace the TWC.

NO -Intermittent failure, system is OK at this time.

This could be a pump going bad, low on fluid or the seals in the steering unit itself worn out. Normally when teh steering box goes it's hard to steer wehn cold then is ok after warmup.

You may have had a filter that needed to be replaced and when you run the system dry the pump sucks everything out that it possibly can to keep the engine running. Junk, sediments, etc collect and are now pushed in to the fuel line. Adding new fuel pushes it along until it gets to the filter. Yes, replace it and it is pretty easy to do yourself. After you replace it I would bet the fuel that leaks out when tipped is not very clean.

Hi 2fast2furious,

Check the transmisison fluid level and top up if necessary.

When engine is cold, the Idle Air Control valve would increase the rpm till it warms up sufficiently before it settles down to idling speed. That is normal unless after warming up the rpm is more than 800rpm, then you might have a vacumn leakage somewhere or the idle speed is out of adjustment.

When the rpm's shoot up does the engine lurch ahead? I am checking if the problem is guage or engine.

Check on the EGR valve. Sometimes it sticks. Then start looking for a vacuum leak, check coolant level and if full, bleed the air from the system. The Idle Air Control valve could be taken apart and cleaned as well.