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lttldude9
New User
Oct 3, 2010, 12:07 PM
Post #1 of 4
(6904 views)
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Car sputtering on start
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Hello,
Thanks for taking time to help me out, I really appreciate your generosity. I have a manual 2001 Hyundai Accent, and when I haven't driven my car for about 12+ hours, and I start it, the car turns on and the engine starts. When I apply the gas pedal the car sputters, or it doesn't even go (almost feels like when you let the clutch up without giving it any gas, the car kind of jumps forward a bit ). When it's not sputtering, it stays in idol even as I push down the gas pedal. This will go on for a couple minutes, and every so often the car will lurch forward as if it's getting gas, but this is only brief and then it goes back to idol/sputtering. After a few minutes of this sputtering, giving it gas, and sometimes having the car turn off completely(stall out), the car will start getting more gas and picking up speed. Once the car starts running, its fine, and drives with no issues. I can even stop and turn off the car, come back an hour later, and it starts perfectly. It's only when it hasn't ran for a 12+ hours. What could be the issue? Any help is greatly appreciated thanks.
(This post was edited by lttldude9 on Oct 3, 2010, 12:12 PM)
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DanD
Veteran
/ Moderator
Oct 4, 2010, 4:45 AM
Post #2 of 4
(6880 views)
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Re: Car sputtering on start
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Fuel or ignition; hard to say without a first hand look see or performing tests; it’s not likely engine management (electronic) due to you not mentioning a check engine light; but that’s also a pretty wide open statement.
Fuel wise I’m thinking that there might be an internal leak allowing the fuel lines to siphon back to the fuel tank.
On a properly functioning system, a check valve that is incorporated in the fuel pump, holds a solid column of fuel between the fuel pump and fuel injectors. This will give the fuel system almost instant pressure when the engine is restarted. If this check valve is leaking internally, fuel will slowly siphon back into the tank. This now means that the fuel pump must fill the empty lines, purge all the air out via the injectors and then it can build pressure. During this filling, purging and pressurizing; the engine may start on the dribbles of fuel coming from the injectors; but not enough fuel to produce sufficient power to accelerate.
A fuel pressure gage would need to be attached and pressures tested before a 12 hour sit. When the engine is first turned off the running pressure should hold for at least 10-20 minutes. The pressure will eventually dissipate to where this check valve will contain the fuel in the system. On the restart, after its 12 hour sit; the fuel pressure should be back up to full pressure before the end of cranking to start.
Ignition wise, you may have a run down, worn out secondary system. As in burnt out spark plugs, high resistant ignition wires (spark plug wires) or one of the two coils is beginning to fail electrically or it insulation has failed allowing spark to ground rather then to the spark plugs. Why only after sitting for an extended time frame; a cold dried out (all fuel in cylinders has evaporated) engine requires much more voltage to jump the spark plug gap.
For the cost of plugs & wires; just replace them and see if things improve. A simple way of checking coil and or spark plug wire insulation is with a household spray cleaner bottle, filled with a salt water solution. Start the engine and lightly mist the ignition system with this salt water. You may hear or see spark jumping from any of the components; the engine may even stall if the insulation is bad enough.
As for the electronics there still might be an issue there, with one or more sensors; one that is still functioning within its parameters as to not trigger a check engine light; but is no longer accurate.
For example, an engine coolant temperature sensor may not be signaling an accurate signal to the computer; telling the computer that the engine is still warm, when in fact the engine is stone cold. To diagnose this; the use of a scanner to read computer’s interruption of the sensor’s input and a digital multi-meter to perform pin test on the sensors and compare finds to specifications.
Sorry not always a black or white answer to drivability issues.
Dan.
Canadian "EH"
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lttldude9
New User
Oct 5, 2010, 10:34 AM
Post #3 of 4
(6849 views)
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Re: Car sputtering on start
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Thanks for the feedback. I just replaced the fuel filter and nothing changed. Also I got the check engine light trouble code: P1128 which is Manufacturer Central fuel airmetering valve. Please note this trouble code has been on since I purchased the car (2 years ago), and this has only been a real problem for the past few months, so it may be unrelated. Next I am going to get the fuel pressure and decide if I need to replace the pump. Any advice?
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DanD
Veteran
/ Moderator
Oct 6, 2010, 4:10 AM
Post #4 of 4
(6827 views)
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Re: Car sputtering on start
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P1128 Sets when the ECM has seen long-term fuel trim at 10-15% lean for a period of 30 seconds or more. This is also a 2 drive cycle code; meaning the ECM has to see this on two consecutive drives. A drive cycle is the engine is started, engine up to temperature, driven X number of minutes, above X number miles per-hour and then stopped and engine turned off.
Causes for setting the code; anything that will make the computer think the engine is running to lean for to long, even after the computer has tried to compensate by adding more fuel.
Things like vacuum leaks, exhaust leaks in front of the O2 sensor, defective O2, dirty injector(s), low fuel pressure, misfires or the computer itself.
Vacuum leaks can be anything from a (fairly large) vacuum line cracked or off, intake manifold or its gasket, EVAP purge solenoid leaking.
Exhaust leak; between the firing of the cylinders a small vacuum is created in the exhaust system. If there is a hole in the exhaust, air will be sucked into the exhaust; the O2 sensor will react to this un-burnt oxygen and send out a lean signal to the ECM.
There more things but I could go on and on and not even touch on the cause of your car’s issue.
When you have the fuel pressure tested; it may test ok at approx 50psi; if the engine has not sat for the 12 hours; you’ll need the gauge attached during one of the car’s little fits.
Dan.
Canadian "EH"
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