Engine runs rough when attempting to accelerate

BILLY MONK

MEMBER
2007 FORD F-150
5.4L
V8
4WD
AUTOMATIC
109,000 MILES

Short term fuel trim (b1-s1) is at 99.3 and does not change on live stream data and the rest of them vary from 5-15 percent. Runs rough when you try to accelerate. Any idea of what might cause this? There were some trouble codes but they have been cleared and have not any come back yet.

5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Can you get a couple pictures of the scan tool screen so that we can see what you are referring too?

Also, what are your short and long term percentages? Also, what are the o2 sensor voltages?

Sounds like you either have an injector issue on that side or a misfire. Basically, this is saying that this bank has too much fuel. Either that is due to a misfiring plug and the fuel is not being burned or there is too much fuel from a leaking injector.

Any chance the codes were misfire codes on that bank?

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let's start with this info and go from there.

Image (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Monday, April 26th, 2021 AT 8:55 AM

BILLY MONK

MEMBER
5 POSTS

It did have a misfire code. Spark plugs are new. The fuel trim on that bank is 99.3 and never changes. It idles okay. Runs terrible going down the road. I don't remember exactly what the O2 sensor voltage was but it was in the range of what it should be.

Was this

answer

helpful?

Yes

No

Monday, April 26th, 2021 AT 6:29 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. That is good info. However, we are going to need to double check the o2 voltage if that is possible?

The reason is, the voltage is going to give us real time data as to what the engine is doing (rich/lean).

The short term fuel trim is giving the same info but is a calculation so we just need to compare that to the voltage. So this means if the short term fuel trim is maxed out but the voltage is correct then that is conflicting information which would point to a control module issue but we need to confirm which is correct to determine that.

Thanks

Was this

answer

helpful?

Yes

No

Monday, April 26th, 2021 AT 8:26 PM

BILLY MONK

MEMBER
5 POSTS

Okay, I'll get that information as soon as possible for you. Not my vehicle, but when get time I have a question about my f-150. 2005 5.4 L. Engine. It's about same as the other one. Idles good. Bad on the road. Sometimes it runs perfect for a few days, but the next day it will not hardly make it up a hill. It has new plugs(about 3 months old). Only code it has is a fuel rail pressure sensor circuit. Never been any other code. Any information would be appreciated. One other thing it runs better when overdrive is off. Thanks.

Was this

answer

helpful?

Yes

No

Tuesday, April 27th, 2021 AT 12:27 AM

KASEKENNY

MECHANIC
18,907 POSTS

We need to keep each post to one vehicle and one issue just because others will not find the solutions to them if they are under different headings or vehicles.

Let's get the fuel pressure of that vehicle at idle and then while you are driving and start a new post with that information and we can work through it.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

It may not be a fuel issue but it sounds like it and the fact that you had a pressure code means we need to rule it out and go from there. Thanks