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gattaca
Premium
join:2003-05-28
USA

2001 Mercury Sable - Nearly stalls when starting cold

»www.youtube.com/watch?v=BG5VpJ08 ··· VpJ08T7E


Notice that immediately after starting, the RPM drops and the engine stutters before picking up again.

This usually happens during cold starts, and otherwise runs fine.
Sometimes the car will stall out entirely and I'll need to restart it, which other times, it won't stall but it will continue to idle roughly until the car has about a mile to warm up.

If this happens, and I am driving the car while it is idling rough, the engine rocks the car and it has a jerking motion moving forward.

Any ideas? It's done this since I bought the car a few years ago, hasn't gotten better or worse.
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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
Does it only happen when idling? If so I'd say the idle air control motor is the culprit. If not, have you done a tuneup (plugs, wires) yet? Which engine do you have (Vulcan or Duratec)?


gattaca
Premium
join:2003-05-28
USA

1 edit
said by cowspotter:

Does it only happen when idling? If so I'd say the idle air control motor is the culprit. If not, have you done a tuneup (plugs, wires) yet? Which engine do you have (Vulcan or Duratec)?
It's the Vulcan engine.
It does this only when idling. If I give it a little bit of gas, it seems to smooth out. Sometimes all it will take is to give it a little bit of gas, and the engine will rev-up suddenly and then smooth out. Other times I'll have to drive it a mile or so.

When it has warmed up to the extent that it smooths out, the engine first increases in RPM (as shown in the video) and then slows down to a normal, smooth idle.

I'll try to get a high-quality audio recording of what the engine sounds like when it idles rough. It sputters and there is a noticeable increase in exhaust smell when around the back of the vehicle.

EDIT: Previous owner did new spark plugs around 35,000 miles ago, not sure about the wires.
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master1000

join:2001-02-22
Fort Pierre, SD
I will second the IAC as the probable culprit.
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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
I'd try replacing the IAC. It's a simple part, just 2 or 3 bolts. In case you don't know what it is, it's the silver cylinder that sits on top of the engine on the right side. Advance/Autozone should carry a replacement.

After you replace, you may want to pull the negative battery cable just to let the computer re-learn the idle. It may have been making adjustments to try to compensate for the bad IAC.


Cho Baka
Premium,MVM
join:2000-11-23
there
kudos:2
It was eons ago, but I had success cleaning an IAC to solve a problem like that described.

Might be worth a try.
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18

2 edits
reply to gattaca
minutiae removed


StNickless

@tmodns.net
That vehicle will have a sticker on the throttle body warning you not to use cleaners on it.
Remove air intake bellows and you will see it.
Most Fords have that self same sticker.


gattaca
Premium
join:2003-05-28
USA
said by StNickless :

That vehicle will have a sticker on the throttle body warning you not to use cleaners on it.
Remove air intake bellows and you will see it.
Most Fords have that self same sticker.
Indeed I did see a sticker warning me not to clean the throttle body. Any input on this?
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Doctor Olds
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1970 442 W30
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1 edit

1 recommendation

reply to StNickless
minutiae removed


StNickless

@tmodns.net
The sticker says not to clean it PERIOD, it does not mention the word harsh or anything like that.

It has nothing to do with teflon coating.

It has to do with the bushings on the throttle shaft that will swell and cause the throttle to stick, usually at wide open throttle.

Ever had a throttle shaft out of a throttle body?

Leave that to us that have the special fixtures and jigs with the attendant guides and reamers to do such work PROFESSIONALLY.
That is, unless you want to pay me later to fix your screwup.


gattaca
Premium
join:2003-05-28
USA
reply to gattaca
Click for full size
Thanks for the help thus far everyone.

I took a closer look at the IAC valve and throttle body. The IAC did look to have some carbon buildup that could be preventing it from functioning properly, but I didn't have a chance to get a picture of it.

I also removed the air intake from what I believe to be the throttle body (don't know much about what I'm doing, but going off of the help here as well as searching Google) and it looked clean to me (see attached...)
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Its a Secret
Please speak into the microphone
Premium
join:2008-02-23
Da wet coast
kudos:3
reply to gattaca
I wonder if this may be a case of a dirty TPS (throttle position sensor)? I've seen this type of symptom previously on other Ford's, and have to wonder. Yes, they can be cleaned, unless the unit is defective.

Just a thought, perhaps.
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
kudos:18

1 edit

1 recommendation

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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
FWIW I have cleaned the TB on a Taurus multiple time using that cleaner without any ill effects. No swelling, no sticking. I know a lot of people (taurus car club) who have done the same.

Why don't you take the air intake hose off of the TB and take some pics of it, including with the valve fully open so we can see what the backside looks like. Take some of the IAC as well with it off the TB.


Doctor Olds
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join:2001-04-19
1970 442 W30
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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
No, I hadn't heard of that. I don't even think my Duratec had a gasket on the IAC. The first time I removed it there wasn't one and I never had any driveability issues. The mounting surface was shaped in such a way that it looked like it would provide some kind of a seal. I've seen some people mention the presence of a paper gasket but never any redesign or aluminum spacer.


Cho Baka
Premium,MVM
join:2000-11-23
there
kudos:2
The engine in question is a Vulcan.
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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
I know. I haven't ever pulled an IAC off of a vulcan before so it could involve a different gasket/mounting setup.


gattaca
Premium
join:2003-05-28
USA
reply to cowspotter
said by cowspotter:

Why don't you take the air intake hose off of the TB and take some pics of it, including with the valve fully open so we can see what the backside looks like. Take some of the IAC as well with it off the TB.
Will do.
Can't tonight, but I should have some pictures up by tomorrow.
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gattaca
Premium
join:2003-05-28
USA
reply to gattaca
I don't have time now to upload the pics, as I have to head off to class.

However, I will say that it went a lot easier than I expected. There DID appear to be buildup on the engine side of the throttle body plate, which I cleaned gently with Teflon-safe cleaner and a soft toothbrush. I also cleaned the IAC valve and used the appropriate cleaner on the MAF sensor.

It may be too early to tell, but the immediate results are that the engine starts much quicker and idles smoother. I'll have to wait for it too cool down sufficiently to see if the problem is really fixed, but early signs seem promising. Thanks for all the help everyone, and I'll try to post the before/after pics later.
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cowspotter

join:2000-09-11
Ashburn, VA
kudos:2
A cleaning of the IAC may be all that was needed. Keep an eye on it. If you do need to replace it Rockauto has 3rd party replacements for $45, Motorcraft for $64 so it's not a really expensive part.