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Truck sputters and jerks when low speed and stopped.


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fitzcali13
New User

Apr 8, 2014, 4:27 PM

Post #1 of 8 (2095 views)
Truck sputters and jerks when low speed and stopped. Sign In

I have a 1990 Ford Ranger 4x4 with the 4.0 v6 engine and automatic transmission. I bought the truck about three years ago and never had a problem except for minor oil leaks. Lately I've been having problems though. At low idle, around 400 rpm it sputters like it's trying to suck fuel even when it's on a full tank. When I drive it down the road the sputtering goes away. But when I come to a stop it starts sputtering and starts jerking, like it's trying to go without my foot on the gas. If I hold my foot on the brake and give it a little gas at the same time this problem goes away. I don't know what it could be. Any help would be appreciated before I end up replacing every part trying to figure it out on my own. Thank y'all.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 8, 2014, 10:39 PM

Post #2 of 8 (2055 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

400 RPM is about to stall and no surprise it's jerking or stumbling at that. Should be more like 650 or a bit more. IAC could be dirty or bad, vacuum leaks exceeding what it can cover.


Idle not adjustable so look at those two things first,


T



nickwarner
Veteran / Moderator
nickwarner profile image

Apr 8, 2014, 11:19 PM

Post #3 of 8 (2052 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

Will it do this if your foot isn't on the brake? Try putting it in park or neutral, take your foot off the brake and see if it starts to stabilize.


fitzcali13
New User

Apr 9, 2014, 6:32 AM

Post #4 of 8 (2039 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

Yeah it usually runs about 1000 rpm in idle. So it did go down. IAC means?

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fitzcali13
New User

Apr 9, 2014, 6:35 AM

Post #5 of 8 (2037 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

And yes when I do take my foot off of the break and put it in park the jerking does go away. But still sputters and stuff.

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fitzcali13
New User

Apr 9, 2014, 7:17 AM

Post #6 of 8 (2034 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

I've actually already replaced the AIC valve just two days ago.

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kev2
Veteran
kev2 profile image

Apr 9, 2014, 11:45 AM

Post #7 of 8 (2025 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

try shifting to N as you slow to a stop - does the 'bucking' go away in N?


nickwarner
Veteran / Moderator
nickwarner profile image

Apr 10, 2014, 12:39 AM

Post #8 of 8 (2008 views)
Re: Truck sputters and jerks when low speed and stopped. Sign In

Did you clean the bore when you changed the IAC motor? Big thing that causes issues is the back of the throttle plate, idle bleed holes in the plate, and the bore passages get coked up with carbon. Screws with the airflow. So take an old toothbrush and some carb cleaner and get it nice and clean. If you unbolt the throttle body to do it be sure to replace the gasket. But get it all cleaned up nice. Then see what you have. If the new IAC motor is in a coked up bore, it will act no better than the old one did.






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