So, I was driving and my gas pedal lost all resistance. I could floor it, with no increase in speed, or even RPMs. Basically, I just could just limp along at 30 mph or so. This happened once, and I immediately had it towed to the dealer. The dealer has been unable to replicate the problem, so they say they can't do anything to fix it. It's not an accelerator cable issue, as my car does not have one of those. Is this likely to be a case of some spontaneous electrical problem and remission? Any ideas?
OT - Question for the Board's Car Experts
- Thread starter lawmatt78
- Start date
The 335i, like many other cars, has a "drive by wire" accelerator assembly. The pedal travel is regulated by a solenoid which has a built-in position sensor to send pedal position to the throttle body assembly on the engine.
If it's only happened once and the dealer won't (or can't) reproduce the problem, then you should probably wait until it happens again and return the car to the dealer.
Another possibility is that you misjudged the perceived pedal resistance (that it was fine) and that the car simply suffered some kind of fault and went into what's called "limp home mode", where engine output is reduced. If that's the case, the issue has nothing to do with your accelerator pedal and is more likely related to an issue with fuel the fuel injection system or one of the various sensors that controls ignition timing.
I've only owned one BMW, it was a long time ago and one of the reasons I won't own another is because all my friends who do own them have never had good things to say about their dealer service network. Try another dealer, if it's even remotely convenient.
If it's only happened once and the dealer won't (or can't) reproduce the problem, then you should probably wait until it happens again and return the car to the dealer.
Another possibility is that you misjudged the perceived pedal resistance (that it was fine) and that the car simply suffered some kind of fault and went into what's called "limp home mode", where engine output is reduced. If that's the case, the issue has nothing to do with your accelerator pedal and is more likely related to an issue with fuel the fuel injection system or one of the various sensors that controls ignition timing.
I've only owned one BMW, it was a long time ago and one of the reasons I won't own another is because all my friends who do own them have never had good things to say about their dealer service network. Try another dealer, if it's even remotely convenient.
That's really weird, that there were no fault codes in a standard ECU pull. In fact... I kinda don't believe them.
I'd definitely try another dealer.
You can read your own fault codes for about $20 and an app for your phone. Get a Bluetooth ODBII reader for the ODBII port on your car from amazon. Install an app (Torque is one) on your phone. Have the phone connect to the reader via Bluetooth and you can read codes yourself - and monitor most everything else with your smart phone. Might be an option if you are so inclined.
This is one of the reasons I stay at least semi-active on the Audi forums. There's always somebody close by who has the full-blown diagnostic analysis software kit on a laptop and they're more than happy to meet up for a beer and run your ECU codes.
If you have such stuff (or access to somebody who does) you can also change a lot of things on the car to make it more interesting / convenient / user friendly. One example - there's always a code that will allow you to open (or close) all your windows and sunroof, remotely, with your key fob. On the newer Audis there are codes that allow you to change the information that's presented in the MFD on the instrument panel.
AKA "limp home".
It just doesn't make sense, because there's NOTHING that can happen to put the car into a reduced power mode and not throw an error from the ECU. I think his dealer is being unhelpful.
I think it's indicative of the "sh!t-for-brains" mechanics they have nowadays. I had an issue with my Saturn where certain environmental factors would throw it in low power mode (and this mode limped along at 5mph!) which was finally traced back to a sensor that wasn't sealed properly when the dealership replaced. But it took a second dealership with a good mechanic to actually find that.
I had a similar problem with my 328. I parked it and drove later that day and it drove fine. A week or so later it did it again. Went to the dealer and they said the car needed a "software update". Everything has been fine since.
Don't know if you have Autozones in Oregon, but you can borrow an OBDII reader from them for free. Only takes a few minutes to run a diagnostic. Bring the code back in and they'll look it up for you.
Had the same issue with the same car after buying it in 2013. The error it threw was a "drivetrain malfunction", and then it went into limp mode. I figured it was a software glitch. Never happened again, and the car has been perfect since. Other owners have experienced the same thing. If the dealer hasn't found anything, hopefully it won't recur.
Initially I would say Mass Air Flow sensor but that doesn't just go away and data would be collected on computer as well as O2 sensors
It is very possible that the dealer is unable to see the problem. I had the exact same problem on the QEW, after flooring it. Got to my destination in limp mode. Started the car the following morning, and it was like nothing happened. Never had a problem since, and it's been close to three years. Recently returned the car as it was a lease.
Your theory on the fuel or fuel injection system is an interesting one. At least one poster on the bimmer boards had some of his injectors replaced. Problem is, BMW uses the drivetrain malfunction - limp mode message to mean almost anything. Another poster had a transmission problem. Waiting till the problem reproduces and then taking it to the dealer, as you suggested, is probably the thing to do. The car could very well be fine.
My first A4, back on '05-06, would do this periodically - the early VAG EA- series motors were known for eating coil packs and injectors. The exorcised that demon sometime around the introduction of the gen 2 EA-888. My wife's '10 A4 has never had any mechanical issues. But the codes were always really specific - they would point you right to the component, down to the specific cylinder.
Just pull out the choke and throttle ,pump the gas pedal a bit and she should be good to go,by golly.
