Acceleration Problems?
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Junior User
Joined: Jan 2006
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Acceleration Problems?
Hello, My 98 explorer with the V6 sohc motor seems to be running rich and bogging slightly accross the rpm range. I have no check engine light and most everything has either been cleaned or recently replaced, including plug wires, plugs, air filter, pvc valve, fuel filter. The TB, MAF, manifold and injectors have all been recently cleaned.
The truck has 136k mi mostly highway on it. Most sensors are original including all 4 oxygen sensors, TPS, Air Temp Sensor, cam position sensor and air temp sensor. I have brought the truck to several dealers who claim there is nothing wrong with it and no codes show up. I do not think any of them have done a thorough OBD-II scan on it though, just a code check.
I feel the bog especially bad in the warmer weather above 70 f though it is still present in colder weather. Humid and wet weather also makes it worse. It is most prominent in the 3000-4000rpm range, between 1/2 and almost full throttle. It gets hung up for a few seconds around 3200rpm according to the tach and then moves on. I know it happens because the gas milage is particularly effected.
Ford Service is no help as they usually only address something when it is 80% inoperative. My truck is still very drivable and responsive with a 4.10 dif, so their test drives turn up nothing. It has been my daily driver for 5 years and I know how it is supposed to run...
Is there anything I could check to help with this problem? I am running out of things to do. I think the oxygen sensors might be getting worn a bit but would that effect acceleration?
Any help or suggestion would be appreciated.
The truck has 136k mi mostly highway on it. Most sensors are original including all 4 oxygen sensors, TPS, Air Temp Sensor, cam position sensor and air temp sensor. I have brought the truck to several dealers who claim there is nothing wrong with it and no codes show up. I do not think any of them have done a thorough OBD-II scan on it though, just a code check.
I feel the bog especially bad in the warmer weather above 70 f though it is still present in colder weather. Humid and wet weather also makes it worse. It is most prominent in the 3000-4000rpm range, between 1/2 and almost full throttle. It gets hung up for a few seconds around 3200rpm according to the tach and then moves on. I know it happens because the gas milage is particularly effected.
Ford Service is no help as they usually only address something when it is 80% inoperative. My truck is still very drivable and responsive with a 4.10 dif, so their test drives turn up nothing. It has been my daily driver for 5 years and I know how it is supposed to run...
Is there anything I could check to help with this problem? I am running out of things to do. I think the oxygen sensors might be getting worn a bit but would that effect acceleration?
Any help or suggestion would be appreciated.
Last edited by X-Power; Jan 23, 2006 at 12:52 PM.
Senior User
Joined: Nov 2004
Posts: 279
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From: Jacksonville, NC
Have you checked your IAC(Idle Air Control) Valve? Here is a link on how to check and clean. Hope this helps you.
https://www.ford-trucks.com/forums/s...hreadid=166103
https://www.ford-trucks.com/forums/s...hreadid=166103
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Junior User
Joined: Jan 2006
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Bulldog, I am a little confused. I thought the IAC only effected idle and not overall performance? I did have issues with it in the past but it was replaced with a new one.
I forgot to mention it but the truck idles smooth & steady but slightly weak between 400- 600rpm.
I first noticed this bogging effect when I drilled out the air box and used a K&N filter last summer. My MAF Sensor is brand new and has no oil on sensors, so that is not the problem. I replaced the old MAF when I upgraded to a Volant intake kit. I also reset the computer by disconnecting the battery several times.
The rich condition of the engine under hard acceleration has something to do with the increased air flow volume but I don't why, for some reason the computer does not seem to read it correctly and is running the mixture rich. Off idle to half pedal runs great, dip beyond that and the problem starts. Like I said it is a lot worse in warm, humid weather.
The problem did not seem to be present before I started messing with the intake. I did some upgrades to primarily increase the gas milage, which it has.
I forgot to mention it but the truck idles smooth & steady but slightly weak between 400- 600rpm.
I first noticed this bogging effect when I drilled out the air box and used a K&N filter last summer. My MAF Sensor is brand new and has no oil on sensors, so that is not the problem. I replaced the old MAF when I upgraded to a Volant intake kit. I also reset the computer by disconnecting the battery several times.
The rich condition of the engine under hard acceleration has something to do with the increased air flow volume but I don't why, for some reason the computer does not seem to read it correctly and is running the mixture rich. Off idle to half pedal runs great, dip beyond that and the problem starts. Like I said it is a lot worse in warm, humid weather.
The problem did not seem to be present before I started messing with the intake. I did some upgrades to primarily increase the gas milage, which it has.
Last edited by X-Power; Jan 23, 2006 at 05:41 PM.
