# What is wrong? Motor hesitates below 1500 RPMs **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** hesitation, sensors, ford, gasoline\ **Created:** [April 9, 2009, 6:18pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927 "2009-04-09T18:18:03Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![GenuineOne](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@GenuineOne](https://community.cartalk.com/u/GenuineOne)\ **Post date:** [April 9, 2009, 6:18pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/1 "2009-04-09T18:18:03Z")
I sure hope there is someone out there who can help me, along with three different shops(!) narrow this problem down. I own a 2001 Ford Super Duty F250 with 5.4L GAS motor V8 3/4 ton pick up. When driving normally and acelerating normall around 1000-1500 RPM, the engine hesitates like it’s not getting air or fuel. At 2000 RMP it runs normally. Symptoms not so bad when engine is cold. I took it to three different shops who ran thorough diagnostics; no data came up and no codes came up. Fuel filter & air filter were replaced; injectors were cleaned; mass air flow sensor was cleaned. Problem still exhisits and all three shops are stumped. --And these are highly recommended shops, not po-dunk. Help, recommendations anyone? I need my truck as it’s my only vehicle and am so worried ☹ ---
**Author:** ![bennyandthejets](https://avatars.discourse-cdn.com/v4/letter/b/b487fb/32.png) [@bennyandthejets](https://community.cartalk.com/u/bennyandthejets)\ **Post date:** [April 9, 2009, 8:08pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/2 "2009-04-09T20:08:42Z")
If you google your problem you might get a solution. I remember something about a computer issue, where the dealer can change the fuel management parimeters or something by loading different software to the PCM or ECM to fix a hesitation problem. I know for a fact that is the case on the newer 5.4 engines, I’m guessing it might be the same for yours as well. ---
**Author:** ![GenuineOne](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@GenuineOne](https://community.cartalk.com/u/GenuineOne)\ **Post date:** [April 9, 2009, 9:49pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/3 "2009-04-09T21:49:39Z")
Thank you, I will try google and calling the Ford dealer. Are you saying you believe the software in the PCM or ECM might be corrupt somehow? ---
**Author:** ![bennyandthejets](https://avatars.discourse-cdn.com/v4/letter/b/b487fb/32.png) [@bennyandthejets](https://community.cartalk.com/u/bennyandthejets)\ **Post date:** [April 9, 2009, 9:57pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/4 "2009-04-09T21:57:57Z")
I’m not saying corrupt, but maybe not just right for your altitude, or local fuel properties, or engine sensor settings or a number of other inputs the PCM looks for. ---
**Author:** ![GenuineOne](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@GenuineOne](https://community.cartalk.com/u/GenuineOne)\ **Post date:** [April 9, 2009, 10:26pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/5 "2009-04-09T22:26:45Z")
Thanks again, have you heard of Throttle position sensor or EGR position sensor? ---
**Author:** ![UncleTurbo](https://avatars.discourse-cdn.com/v4/letter/u/e9a140/32.png) [@UncleTurbo](https://community.cartalk.com/u/UncleTurbo)\ **Post date:** [April 9, 2009, 11:35pm UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/6 "2009-04-09T23:35:00Z")
If you have coils on top of the spark plugs you may have a bad coil(s). They don’t throw a code immediately, not until the missing is so bad the motor runs very poorly. Gentle acceleration in the rpm range you are noting is a symptom. ---
**Author:** ![hellokit](https://avatars.discourse-cdn.com/v4/letter/h/6a8cbe/32.png) [@hellokit](https://community.cartalk.com/u/hellokit)\ **Post date:** [April 10, 2009, 2:31am UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/7 "2009-04-10T02:31:52Z")
Everyone wants to wade in with a particular part and be able to rapidly determine that that’s the cause of the problem. This kind of approach isn’t that productive. One needs to gather all of the information surrounding the problem one can: weather, speed, driving conditions, and how the symptoms presented themselves. When something doesn’t perform as it should, one needs to know how it PROPERLY functions. Every function has to be checked, step by step, to determine IF it is correct. What are the symptoms? Are they: when accelerating, the engine hesitates in the 1,000 to 2,000 rpm? The hesitation is not as severe when the engine is cold? The hesitation, or misfire, is much less above 2,000 rpm? When the gas pedal is depressed for acceleration, the throttle position sensor (tps) tells the engine computer of that. The MAF (Mass Air Flow) Sensor tells how much air is going into the engine. The air intake temperature sensor, and the engine coolant temperature sensors tell the engine computer their info. The engine computer, then, commands more fuel to go with the increased air intake. The repairer needs to know what the values of the sensors should be, and measure those values. S/he needs to measure the output actuators, controlled by the engine computer. Whichever value is off, needs to be evaluated further. In particular, do a voltage check of the tps, as it is being moved. Voltage spikes, or ohm irregularities can cause the fuel flow to flutter similarly. Irregular values from other sensors can cause stumbles. Also, irregualar action from actuators can be a problem. ---
**Author:** ![topdeadcenter](https://avatars.discourse-cdn.com/v4/letter/t/a6a055/32.png) [@topdeadcenter](https://community.cartalk.com/u/topdeadcenter)\ **Post date:** [April 10, 2009, 2:39am UTC](https://community.cartalk.com/t/what-is-wrong-motor-hesitates-below-1500-rpms/28927/8 "2009-04-10T02:39:57Z")
Is the check engine light On? How does it idle? Throttle position sensor or dirty throttle plate most likely…