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Sudden Acceleration from Stop (Move Over, Toyota!)

2007 Lincoln MKZ well maintained with 40K miles & under warranty. Once every 2 months or so, when car is still cool–within 5 miles of start–and idling with brake applied, engine will suddenly rev and car will start to accelerate from stop, despite heavy brake pressure. Only cure is to move lever to Neutral or Park and (1) tromp on accelerator pedal to bring engine speed back to idle or (2) turn key off. This is a dangerous & frightening problem, but it occurs very intermittently so dealer cannot duplicate. Dealer downloaded a computer-chip update, then changed battery, then searched Ford/Lincoln database…but has no idea how to address this problem. I opened a case file with Ford Motor (Detroit) and also filed a safety complaint with NHTSA in case I don’t survive the crash I know will happen. Any ideas, suggestions, or recommendations? Aside from this problem, I really enjoy the car.

Wireless throttles have become commonplace, and are deigned and manufactured for different makes of car by the same pedal manufacturers. I’m afraid you’re suffering from the same malady as Toyotas have.

You’ve done all you can short of trading the car. But the dealer hasn’t quite yet. Ask them of they can put an “event recorder” in the car for when this happens again. Point out to them that you like the vehicle, but you really want to get it resolved before an inevitable accident. Put a bit of fear in them.

Perhaps if it were me I’d get used to putting the car in neutral when stoped under the conditions that this tends to happen until it gets resolved.

This may be an Idle Air Control valve problem and this can occur without setting a code.

Your car has comparatively low miles for possibly going on 4 years of age and while some claim that induction cleaning is always a scam, that is not always the case.
If the problem is related to the IAC then cleaning may help. It’s also not a rare problem on any make of car.

Thanks for the great suggestion. I called the dealer immediately, but was told the “event recorders” are no longer in use because they proved unreliable. Also, I asked if the wireless throttle could simply be replaced. It seems that, due to legal restrictions, dealerships cannot replace a part unless they can first prove it is malfunctioning or unless the manufacturer issues a recall or at least authorizes the replacement. Otherwise, the dealership is de facto admitting liability and assuming responsibility for the entire situation. Hmmm… Anyway, thanks for the ideas. At least I now know about something called a “wireless throttle.” I could trade the car, but I don’t want someone else to be injured as a result of my buck-passing.

I didn’t think that Ford used IAC’s on any cars with throttle-by-wire. I know that neither of Lincolns have one. The main [only] throttle is used to control idle.

You are likely correct and no doubt know more about the MKZ than I do. A quick look shows a Technical Service Bulletin issued in 6/09 about a rough or dropped idle on these cars.
Think this problem could be related to that TSB? Maybe a dropped idle and the ECM is going nuts trying to compensate for it?

It could be, I haven’t seen this problem so it’s hard to suggest what to look at.

In any event…congratulations on your ability to reach down and put the vehicle in neutral. You have common sense to spare. Sadly, a lot of Toyota drivers lack the ability to accomplish this simple manuever.

How can I access online the Lincoln TSB you refer to (6/09) re rough or dropped idle? The dealer tells me he finds NO bulletin related to my problem, but this sounds very relevant. I found some online complaints from 2009 Ford Flex owners with the identical acceleration problem under same conditions as mine. Maybe there’s a defective part that’s used among several Ford/Lincoln/Mercury models & years.

The dealers are actually under no obligation to give you a copy of a TSB but I don’t see a problem with it. I’ve done front service counter work and had no problem with running off a copy of a TSB for someone. It’s public knowledge anyway which can be accessed on something like ALLDATA.COM but to get the details on that TSB would require a subscription. (25-30 bucks for a single car)

The TSB is designated 09-11-13 and was issued in June of 2009. Maybe you can hit more than one dealer up and find someone who is willing to run off a copy.
You can also contact FOMOCO online as they have as service oriented section (don’t expect much because car makers won’t say much of anything about details) and they can act as a go-between with you and the dealer who can’t seem to find this TSB.
Hope that helps.

(I ran into a problem some years ago with a few suspension components on my Merkur (German built Ford) in which some bushings were updated and of which the dealer was apparently oblivous. I printed off the pictorial, took it into the parts dept. and they wanted to know “where did you get this?” I got my parts though.)

It could be the brake booster.

Having recently purchased a 2010 Flex, I experienced a brief unintended acceleration incident. Actually it was the second occurrence within a week, the first occurring during a test drive of the same model vehicle from a different Ford store.

The first time, cold engine, waiting on traffic light, moderate uphill gradient, foot on break - engine rev’d up and pulled the vehicle forward about three (3) feet as I applied more pressure to the break peddle.

The second occurrence, warm engine, also waiting on traffic light, very slight uphill gradient, foot on break - engine rev’d up and pulled the vehicle forward about five (5) feet as I applied more pressure to the break peddle.

I have appointment with Ford dealer to run diagnostics, but obviously this is going to be difficult to track down.

My accelerations have not occurred on any incline (very flat terrain each time). I’ve now had six episodes. Dealer has had car four times but can do nothing because can’t find a problem. I suggest filing a report with the National Highway Traffic Safety Admin/NHTSA. Please let me know if your dealer discovers the cause. This could be a Ford/Lincoln/Mercury issues like Toyota’s. If you bought your Flex new, then at least you may be covered by a “lemon law.” I bought mine used so no such recourse. Good luck!

Have you checked to see if that could put an “in-flight data recorder” in for a week or two while you drive around waiting for your car to take off again? It might tell them something.

I see three TSBs that have something to do with the drive-by-wire computer reading of data.
–tsb 07-6-10 hesitation upon acceleration
–the aforementioned tsb 09-11-13 rough idle, idle drops
–tsb 09-13-10 runs rough or misses
All just TSBs , not recalls ( they can’t issue a recall unless they have the solution and the problem applies to a higher percentage of vehicles )
I see no recalls.

Your Ford dealer can print out all the TSBs you wish to read ( I can too, but this old dog is not adept at getting these into a format that I can post here ), But we’re still not sure if any of those will fix your issue. I bet it’s worth a try though, as most of them have to do with computer re-programming ( which you say they’ve done once already).

I think ALL ( Toyota, Ford etc ) of these accelerator problems are computer related. There’s just so much data crunching going on that it’s easy to believe that some data is getting mixed and mis-read. And THAT makes it even more scary. Just which ONE binary digit is out out of place in all that software code ?

Thanks for the suggestions. I spoke to the service mgr about all three TSB’s you mention. He said they’ve already run those diagnostics on my vehicle. (I just got it back from the Lincoln service dept…for the 4th time.) The dealer says the black-box solution has not proved satisfactory so they discontinued that practice. Hmmm… Ford Customer Service in Detroit wants to give me a pin#/voucher to purchase a new vehicle on an “X Plan” basis (no-haggle bottom line discount price). I asked whether that would prevent the next buyer of my vehicle from having this same problem. No answer to that question. Everyone (dealer, mfg.) is very nice and polite and eager to help, but no one can do anything until they actually experience the problem. My wife is now relucant to ride in my luxury 5-passenger Lincoln MKZ any more. Aside from this single issue, I really like the car. What a shame!

These may be the industry eye openers that prove just because a technology exists ( ALL computerized systems, accelerator, transmission, abs, cruise ) does not mean you must use it.
And therefore it’s time to revert back to mechanical operations for many automotive functions.
Much like airplanes, redundant systems can be powered by different sources ( vacuum, electrical, mechanical ) to allow the function of one if the other is down.

It still could be a brake booster vacuum leak.