5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Acceleration Problem???

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Old Jun 28, 2011 | 10:48 PM
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RouteBurner's Avatar
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Default Acceleration Problem???

My 92 LX 5.0 does not respond : on hard acceleration it "gets quiet as if I took my foot off the accelerator" and does not pick up any speed but when I lightly press it will gradually pick up speed and change gear. Just put in plugs, cap and rotor less than 2 months ago, after a winter storage. It does not have a catalytic converter any longer, so I'm lost. Don't suspect fuel injectors, or fuel filter, because I can "gun" it in park and nuetral just fine so I know it is getting gas. Any ideas?
Old Jun 28, 2011 | 10:53 PM
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I would check the throttle position sensor to make sure it is funtioning, particularly at max throttle as applied by your foot.
Old Jun 28, 2011 | 10:54 PM
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TPS? Thanks, I will check that tomorrow after work. I still haven't picked up any "check engine codes yet".
Old Jun 28, 2011 | 11:00 PM
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Originally Posted by RouteBurner
TPS? Thanks, I will check that tomorrow after work. I still haven't picked up any "check engine codes yet".
so you ran a koeo/koer test?? or do you mean that the light isn't on therefore you assume no codes exist??
Old Jun 29, 2011 | 12:14 AM
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Yeah I koeo/koer tested it twice. Because I'm not sure the CEL still works. I haven't seen it on in over three years of summer driving.
Old Jun 29, 2011 | 12:17 AM
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codes showed 11 both times.....
Old Jun 30, 2011 | 04:00 PM
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No Go. I changed the TPS sensor. Still picks up speed and changes gears if I lightly press down on the gas. But as soon as I "gun-it" it stops accelerating as if I took my foot off the gas, and continues to be quiet with the accelerator fully pressed down. But whats strange is that in Park and Neutral it raises the motor just fine up to full throttle. Any other ideas?
Old Jun 30, 2011 | 10:38 PM
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The volume of fuel required when going down the road and sitting still....is different. Hook up a pressure gauge and watch it as you drive down the road.
Old Jun 30, 2011 | 10:47 PM
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Suck, Squish, Bang, Blow

It takes air, fuel and spark to run. It idles, so you know air and spark are present.

Bubba's right. Confirm fuel. Pressure first, then injectors. TPS comes to mind because it's a wear part. Corroded or mal-adjusted and it won't tell the PCM to deliver fuel. If it's OK, move on to fuel pressure and volume.
Old Jul 1, 2011 | 02:02 AM
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Next step, fuel filter and pressure test.



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