Been having low RPMs upon starting car, trouble starting now (need answer fast)

In My Humble Opinion
1

For a few months now, my car has had low RPMs for the first few seconds after starting it, then it revs itself up to normal RPMs. All this time, it has been driving totally fine. This morning I went to start my car as usual, and it wouldn’t start the first few times I tried–it just made stuttery and chokey noises. Eventually I tried mashing down the gas pedal while turning and holding the key, and it finally started. Then I held the gas pedal down a little to keep the RPMs up until the engine kicked in (about 5 seconds). Once I got to work, after turning off the car I attempted to start it again (just to see if the issue would repeat itself). It started perfectly normally. My drive is about a half hour, so the car was warm the second time.

What’s confusing to me is, yesterday it was starting like normal. I had to move it out and in of the driveway to shovel (we had a lot of snow this weekend which turned to rain last night, and today it’s about 34 degrees/still rainy). And there were no issues getting it started yesterday, even though yesterday morning it was much colder and snowier (just the low RPM issue that I’ve had for a while, now). The problem doesn’t appear to be electrical in nature, and my check engine light was not on at anytime during these shenanigans.

I won’t be able to take my car in for service until the weekend. I was hoping to suss out how much the repair might be, or what might be wrong. I plan to keep starting my car on every break I have (every few hours), and hopefully that will be enough for me to get it home. I don’t know if I will have the discipline to wake up every few hours overnight and keep starting it, but that’s my current optimal solution.

2

I’m tempted to think you’re worrying disproportionately much about this problem.

My first thought about “low RPMs for the first few seconds after starting it, then it revs itself up to normal RPMs” is that the idle speed controller (ISC) is sticking or sluggish. The fact that it would start at all seems to rule out a host of bigger problems. If this is what’s going on, you can get around it by holding the pedal down a little ways while starting, and then a few seconds more until it hits its stride.

It’s possible this morning’s no-start indicated a different second problem. But it’s also possible it’s just the ISC acting up worse. Flooring the pedal while starting is counterproductive, as in many cars that activates a “clear flood” mode that shuts off the fuel injection. So if it doesn’t start readily next attempt, try starting with the pedal just partway down and see how it does. If it starts okay that way, you can nurse it along without much trouble until you get it into the shop. Trying to start it every few hours strikes me as eminently impractical.

3

Thanks, Gary. I was in panic mode because I was a little late already, and I had called off on Friday because of the snowstorm. So I leadfooted the pedal and got it to start. And it worked, so I can’t complain! But I’ll try holding down the pedal just a little bit if it doesn’t start normally tomorrow. I’m greatly encouraged that it runs normally once it starts, it’s just starting from cold that seems to be an issue. Hopefully I can limp along to Thursday to get it really looked at, I was fortunately able to get that day off.

4

Yeah, in the old days it was the automatic choke causing the problem, though more often revving too high in my experience. This could be a sticky mechanical part, an electronic problem, or something that crops up this time of year, a bad reaction to the winter fuel mix. Hopefully it’s the latter, an aside from some rough starts in winter, there’s nothing else wrong. Good luck.

5

How about a leaky fuel injector leaving too rich of a mixture until cleared out? Flooring the pedal does just the job meant to do.

6

Is it possible you have a clog in your air intake? Like a dirty filter or something? Do you notice any RPM drop when stopped at a stoplight?

7

It’s not impossible. But if those are the primary symptoms of an air clog, I don’t think so. It doesn’t idle low except when I first start it. Once the RPMs get up to normal (they start in the 250-300 range and get up to around 750-800 after about 4-5 seconds), they never dip back down. I know what you’re talking about though, because I *have *had a car that idled dangerously low and sometimes stalled out at stoplights (my old crappy celica). This car doesn’t do anything like that. Until this morning, I haven’t ever had trouble with the car refusing to do what I need it to do. (knock on wood)

The only thing I am sure of is that we had a shitload of precipitation this weekend. Snow from Thursday til Saturday, and thunderstorms with a shitload of rain last night (bizarre January weather for the midwest). It was still drizzling this morning, but the skies have since stopped leaking. Is it possible that maybe something just got too wet? Maybe the failure-to-start problem has evaporated. It has thankfully started normally on all my breaks and lunch today.

I have an inspection scheduled for Thursday. Even if the problem doesn’t repeat itself, I’d like to get the low starting idle looked at. It could be a symptom of something that will manifest as a more direct problem in the future, and I’m going to be there to redeem an oil change groupon anyway. I’ll post back with the diagnosis. Thanks again for being so helpful!

8

Your drain back valve, or whatever they call it is shot. Fuel pump creates pressure, fuel injectors need pressure to work. Drain back valve keeps pressure in the system so that when you turn the key, it fires up instantly.

Drain back valve is shot, pressure drains out(back to the tank) at some unknown rate. It doesn’t start instantly. If it sits for 20 minutes, you may still have enough pressure for a good quick start. After a few hours, it may be crank, crank, sputter (low pressure not enough fuel), then start.

Its an easy check with a fuel pressure gauge. A garage is probably going to tell you that is something that is “wrong”, and “technically” there is something wrong. But its not a big deal, 3-5 seconds to bring up the pressure and your off and running.

Unfortunately that stupid drain back/back flow valve is usually attached to a lot of other stuff that costs a lot of money, like the fuel pump in the tank, so you have to change it all.

Could also be the pressure regulator bleeding back on the return line.

I figure as long as you aren’t smelling gas, and its pretty consistent(it may get worse) , nothing to worry about. Let it sit all day, it will fire up again, no need to go out and fire it up on your breaks.

9

Thanks, bubba jr! I am going to let it get cold overnight and see if the problem can be reproduced in the morning. The low idle (again, only at startup) has been a (recent) chronic issue, but I suspect the heavy precipitation and ambient moisture may have exacerbated it to the point of having difficulty starting. I don’t expect it to keep happening, /fingers crossed.

After doing some googling, I found out that the '06 Ford Five Hundred has a TSB out on the throttle body–when it gets dirty (a “sludge buildup”), it can cause a low idle. Would it be a good idea to print it out and take it to the repair shop with me? So they can check for the issue? Cleaning it would be cheaper than replacing it, anyway. I guess I should also mention that I’d like the fuel pump assembly looked at? Or should I just shut up and let them see what they find? God, this is gonna cost me a fortune x_x

I don’t know how to interpret all the details of a TSB, but the procedure appears to be 0.7 billable labor-hours. Here it is, for anyone who’s interested:

** TSB 09-24-12**
12/14/09
3.0L LOW IDLE/ELECTRONIC THROTTLE BODY CLEANING PROCEDURE
FORD:
2005-2007 Five Hundred, Freestyle
MERCURY:
2005-2007 Montego
ISSUE
Some 2005-2007 Freestyle, Five Hundred, Taurus and Montego vehicles equipped with the 3.0L engine may set a malfunction indicator lamp (MIL) code P0506 or P0505 or exhibit a low idle. This may be due to sludge buildup in the electronic throttle body (ETB).

ACTION
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

  1. Disconnect the negative cable from the battery.
  2. Follow Workshop Manual (WSM), Section 303-04 to remove the throttle body from the vehicle.
  3. Use Motorcraft® Choke and Linkage Cleaner, spray the throttle body plate and bore. Using a small, soft, solvent resistant brush clean the edges of the throttle plate and the mating surface of the throttle bore to remove all sludge build up. Reapply Motorcraft® Choke and Linkage Cleaner or equivalent.
  4. Clean with a lint-free cloth.
  5. Inspect throttle body gasket and replace if damaged.
  6. Follow WSM, Section 303-04 to install throttle body.
  7. Connect ground cable on battery.
    –
    Parts Block
    WARRANTY STATUS: Eligible Under Provisions Of New Vehicle Limited
    Warranty Coverage
    IMPORTANT : Warranty coverage limits/policies are not altered by a TSB.
    Warranty coverage limits are determined by the identified causal part.

OPERATION DESCRIPTION TIME
092412A 2005-2007 Five Hundred, 0.7 Hr.
Freestyle, Montego: Clean The Throttle Body Plate And Bore Includes Time To Remove And Install The Throttle Body, And Check DTCs (Do Not Use With Any Other Labor Operations)

DEALER CODING
CONDITION
BASIC PART NO. CODE
9F991 49

10

The very best thing you can do in addressing the problem with the shop is the same as the very best thing you can do in addressing a problem with your physician: DESCRIBE THE SYMPTOM(S) and let the expert see to the diagnosis. If the shop is competent, you’re not going to teach them anything they don’t already know; if they’re not competent you’d be better off going to a better shop than trying to guide this one in the process.

All of us here, including me, have the disadvantage of not being with the car. We can only go on the given description of the symptom, without being able to observe it firsthand or do any testing to zero in on the cause(s). It could be something mentioned in this thread, or it could be something different yet. That said, I’ll share my doubts about some of the suggestions made, particularly with regard to the ongoing low idle for a few seconds then idling normally.

This could be a sticky mechanical part, an electronic problem, or something that crops up this time of year, a bad reaction to the winter fuel mix.
All reasonable possibilities, thought with the latter two I’d expect it to act up for more than a few seconds.

How about a leaky fuel injector leaving too rich of a mixture until cleared out?
I’d expect it to run rough, not just have a low idle.

Is it possible you have a clog in your air intake? Like a dirty filter or something?
No. This would show up under acceleration or at high speed long before it would affect idle speed.

Your drain back valve, or whatever they call it [check valve] is shot…Could also be the pressure regulator bleeding back on the return line.
Not for the ongoing problem where it starts right up but idles low.

I found out that the '06 Ford Five Hundred has a TSB out on the throttle body–when it gets dirty (a “sludge buildup”), it can cause a low idle.
Maybe not impossible, but very unlikely it would only affect the idle for a few seconds.

Now, if you want to say “I saw there was a TSB on throttle body sludge and I wondered if that could be it” or “a friend suggested it might be [something],” that’s okay, but first describe the symptoms. As an auto repair pro, I find it amusing that customers seem to think I wouldn’t know about, or at least be able to find out about, something they’ve run across. Then again, no one (including me) knows everything, and there’s no harm done so long as the customer doesn’t persuade the shop to do a repair that doesn’t fix the problem. Occasionally these guesses are right, but the best bet is having a competent professional sort it out.

11

Gary T, I always appreciate your expertise in my car trouble threads. :slight_smile: But, I’m less concerned about technical incompetence than I am about getting ripped off. Which is why I always try to diagnose an issue before I go in. I don’t think my tax refund will have cleared by Thursday, so I’m going to have to prioritize the most necessary repairs (since I also think I’m having an issue with my brakes and my left front tie rod).

Thankfully my car did not have any trouble starting this morning. I’ll still mention it to them, of course. But I’m not as panickedly-concerned about it as I was yesterday. Probably going to do brakes first, then tie rod, then address the idling issue.

12

Understood. The auto repair industry has not done itself any favors in terms of building a reputation for integrity.

The reason I stress competence is that lack of it – usually lack of full competence rather than having none at all – is the root of many of the problems people have with getting their cars fixed. There are many situations where customers end up paying more than they should not because of any intention to soak them but because the shop doesn’t have the skills and knowledge to effectively and accurately determine what repairs are needed. Then having sold a repair that didn’t solve the problem, they cover their butts by saying it needed that as well as this other thing, rather than take responsibility for a misdiagnosis. Of course an honorable shop won’t have customers paying for the shop’s mistakes, but shops that make a lot of mistakes won’t stay in business if they don’t pass the cost on to the customer. From my vantage point, lack of competence goes hand in hand with ripping people off.

ETA: Glad to hear it started for you today.

13

Dunno if this helps, or not, but, my vehicle, in moist weather, for some unknown reason, collects moisture on the coil. This results in an arc, and effects my cars performance quite often as you describe. lt also causes it, at times, to stop. Now, in wet weather, before starting the vehicle, i get a rag, or towel, and wipe the coil off. Problem solved!
Of course, I could be misunderstanding your symptoms.
Another thought…
I think you should take it by AutoZone or one of those parts stores that will give you a free diagnostic check, before going to a shop. Also, I hate to be the bearer of bad news, but, if the internet says about .7 billable hours, expect the price to be about 10 billable hours. Ask me how I know!
Good luck!
hh