Have an '06 F150 5.4L 4X4 3.73 and have a question.

Since about Friday, I'm wanting to say the idle rpms and cruising rpms have been running low. When warmed up and at a stand still, the rpms are at the 2nd notch on the tach, which I'm guessing to be 400-600 rpms. When coming to work today the rpms were between 1000-1200 while cruising between 40-45mph. When accelerating then letting off the gas, the rpms almost automatically drop to 1K from 2K. Not sure if this is a good explanation, but I can go into further detail if need be.

Now I noticed this on Friday because it felt like the engine was so smooth that it wasn't even on and secondly the gas pedal feels a lot softer than normal. Plus the fact that I must use a little more brake to stop since the engine isn't providing as much drag/pull back when I let off the gas pedal. The check engine light hasn't come on and no codes have been thrown that I've noticed.

Question is, what is the typical rpm range when sitting at idle? What type of rpms should you being running at say 30, 40 & 50 mph with a setup like mine?

Just trying to narrow it down if there really is an issue and if so how to explain it to the dealership since it's still under warranty. Any insight would be appreciated. I'm taking the truck in either this week or next for an oil change/tire rotation,so I'd like them to look at this then, if there is a problem. Just doesn't feel like the truck is running right.

Last not, the shift between gears seems really soft and the rpms only drop about 100-300 rpms between the 1-2 and 2-3 shifts. The tach & rpms drop significantly when the TC locks up though.

 

Typical idle speeds will vary, but in general I think our trucks idle in drive (and reverse) between 500-550 rpm. Park and neutral idles are higher around 700rpm. However, the calibration has several adders, so if you're ac is on, it can add anywhere from 50 -125 rpm. There's adders for battery voltage, power steering inputs, etc. Also, when you take your foot off the accelerator and close the throttle, there's a decel fuel calibration that comes into play so it's always hard to say what is really going on.

But, Im guessing you have noticed a change in idle speeds?

 

The change in idle rpm speeds and cruising speed rpms is what has made me notice the change. I've since noticed the soft gas pedal and increased brake pressure over the weekend.

If memory serves me correctly, which it most likely isn't, when running 40-45mph, the rpms have usually been higher in the 1400-1600 range, not the 1000-1200 range. This is why I've asked for basic rpm specs when running at certain speeds, for comparisons sake. Now when accelerating from this 1000-1200 range, the rpms jump up to around 2K and basically hold there until I let off or the TC locks up. I'm usually really light on the go pedal, so seeing the jump in rpms from 1K to 2K seems uncommon in my experience. It's always been a slower more gradual increase in rpms.

I don't know. I think I'm being paranoid and the truck is running fine, but something in me says the truck isn't running the same based on my overall feel of the motor, gas pedal and brake pedal reactions. Any ideas on what could have potentially caused this change in idle speed? IAC? I've owned it since new (17 months) and the truck only has 14,700 babied miles. I'm very easy on my vehicles and notice even the slightest changes.

Any ideas on things to look for or potential causes, let me know. Otherwise she'll be going to the dealer for inspection.

 

Hey, just thought of this- how's your brake booster line, like the one just recalled on your vehicle? I wonder if that came off and that's why she's running differently and you're brakes seem sluggish...

 

I was thinking about that over the weekend, just couldn't determine how that'd effect the idle speed. Any idea on where to locate the booster line at?

Was hoping my dealer would perform this recall when I take the truck in for the oil change & rotation, but you never know if they have the parts in stock. Guess I'll have to give them a call to verify.

 

Okay, just went to Recall Information - Ford and input my VIN#. States "There are currently no recalls on this VIN."

Can this be correct or has Ford not updated their site since they won't be sending recall letter until later this month? Thoughts or ideas?

 

It's the line that comes off the brake booster, goes behind the intake manifold and connects somewhere hidden between the dash and the intake. Sounds like a bear to get to. They have to take off the injector rails (I believe) to fix. Used to have to pull off the intake. Not sure of all the dates, but the recall should have the build dates that are affected by this recall (I guess they took the clip off the line for a while).

It could affect it since the engine is sucking in air that the pcm doesn't no is there. I think it would make it run more rough and hestitate more, so probably not your issue

 

I'll have the dealer check it just in case. Someone here (maybe you) or on another site provided some detailed specs on the recall and my truck wasn't included. The recall summary for KC built F150's ended with 5/06 builds, where as mine was a 6/06 build. So I'm confused on if mine should be included or not.

Now the truck doesn't run rough nor hesitate, but I feel if the idle drops any lower then it will start to sputter or hesitate. That's how low the idle feels.

 

I know what you mean about the recall, my 04 was built in June2004 and the recall starts with trucks built June18! How do I know that they put the right (old) hose on mine

Guess, I haven't been much help, maybe someone else will be better...

 

Yeah, these recalls seem to be hit or miss sometimes. I'll have the dealer check the recall on my truck, just to be on the safe side.

You've been great assistance, I'm simply looking for suggestions since I don't know what would/could be the cause.

Now do you think the idle issue could be due to bad gas? I was just under 1/2 a tank, so filled up the 16 gallons at Shell. Since then, gas pedal isn't nearly as soft, but still softer than normal and the tach/rpms seem to have improved slightly, but also not back to normal. Now the brake pedal still is a little squishy, so that may be due to recall, I'm unsure. I wouldn't think even bad gas would make that significant of a difference, but I'm going to run this tank out and refill again and see if the problem continues.

Of course anyone else with thoughts/ideas/suggestions, send them in. Thanks again!

 

After driving the truck all last week and this weekend, the problem is still there. Hopefully this will describe more of the nature of the issue(s). I'm unsure if there are two problems causing my issues or if it is all related to one issue.

As previously stated, the brake pedal is very soft and requires me to use a lot more effort to stop the truck. I'm thinking this may be related to the brake booster recall, but I'm truly unsure.

The other issue is the running of the engine. It seems very smooth, more than normal. Looks like base idle rpms are correct, but when accelerating it does not look/feel right. Keep in mind I am very easy on the gas. When accelerating, the rpms almost instantly jump up to 2K and hold there thru each gear. At each shift point it may drop 100-200 rpms until the TC locks up. Once the TC locks up the rpms instantly drop to 1000-1200. Being observant of my trucks performance, I hardly ever get the rpms up to 2K, mostly just during highway on ramps when trying to get up to speed. Otherwise in normal day to day city driving this used to very uncommon and would only get to maybe 1800 rpms. Also, this has cause a lack of power or slow acceleration even though the rpms are staying at 2K. I was on the highway yesterday and had no problem keeping speed, but when acceletating it did feel sluggish and lacking power.

If I have it, could this brake booster vacuum leak be causing both the brake and rpm/acceleration issue? What else should I look at? I've taken a quick look at the throttle body, IAC and MAF/MAS and all look good, none seem coated or to contain build up. I am simply lost to the potential cause.

Now I will be trying to schedule warranty work tomorrow, so hopefully I can take the truck in this week. Would just like some ideas on items to have the dealer check into. Any suggestions would be helpful. Thanks!

 

Truck's scheduled for warranty service tomorrow at 7am (MST). We'll wait to see what they come back with. Hope they don't wait all day to get to her then call me late afternoon stating they want to keep her overnight.

We'll keep everyone posted, if anyone is reading this. Kind of feel like I'm talking to myself.

 

Dang, still no replies.

Truck is at the dealers. Looking at the drivability issue, brakes and oil change/tire rotation.

Took the truck for a ride with the shop foreman. Nice guy and really seemed like he knew what he was talking about.

He said he could notice something was slightly off, nothing significant, but was going to do a thorough check of all systems. Not sure if he was saying this to blow smoke up my you know where or not, but we'll see when I pick the truck up this afternoon.

 

Okay just got a call from the service advisor.

So far they have found nothing, no problems. Kind of figured, this has always been my experience with drivability issues. The owner notices the issue/problem since they drive the vehicle day to day, but service dept can't find a problem.

Now I'm okay with this as long as they sign off that the truck has a clean bill of health. The problem I have is the dang service advisor and trying to sale parts not needed. He just stated that the normal maintenance schedule at 15K miles is to replace the fuel filter. Looking at my owners manual and Fords website, they don't recommend fuel filter replacement until 30K miles.

This is upsetting, but typical, since the service advisor lied right to my face or ear saying it is a Ford recommended service at 15K. This chaps my hide and kind of makes me want to take the truck to another stealership or to at least work with a different service advisor.

Just providing an update though. Service advisor said they might want to keep the truck overnight, which is no problem. I'd prefer they take their time and investigate all avenues. So we'll see if I get her back tonight or tomorrow, and whether or not the symptoms have been cured.

 

You mentioned a "soft gas pedal", and since it's "drive by wire", and I'll assume it happened in conjunction with the harder to stop aspect (which would be from lower vacuum, and lower idle) kindly ask them to reflash your PCM, or at least mention it to them so they note it. Your TPS runs through a circuit in your PCM also.