No response from accelerator pedal

[widman]

Today I drove my sister-in-law's Mazda2. Once in the morning on the 1.2 mile drive to the office the accelerator failed to respond until I stopped, turned off the engine and restarted it.

While driving it just goes into idle and stays there.

On the way home it happened 4 times. Each time it started responding after restarting the engine.

Any thoughts?

 

[Hermann]

Drive by wire failing is the most likely culprit. But with todays electric cars anything is possible.

 

[SatinSilver]

Has your sis in law said anything about the issue?

Be careful messing around with a ladys car. It's kind of like poking at a hornets nest.

 

[bdcardinal]

If it is fly-by-wire it could either be the pedal or the throttle body itself. FWIW I replace about 150 throttle bodies for every pedal I sell on gas cars.

 

[Cardenio327]

Widman, I think I read in one of your posts that standing water is driven through frequently in Bolivia. Could it be possible water has washed the dielectric grease out of some of the electrical connectors, causing corrosion and false contacts to begin to take place?

It is a standard practice on motorcycles that will be ridden in the rain or on long trips to disconnect every connector and apply a liberal amount of dielectric grease as a preventative measure. Usually not a problem on automobiles, but if they are driven through standing water, all bets are off.

 

[Falken]

If it is still under warranty take it to the dealer.

It is probably a TPS (throttle position sensor) but I can't tell you without a wiring diagram.

If you can hook it up to an OBDII scanner maybe you can test throttle %

 

[widman]

No warranty. It is a used Japanese version, converted to left hand drive.

 

[Tegger]

Originally Posted By: widman
No warranty. It is a used Japanese version, converted to left hand drive.

If it's anything like the North American throttle-by-wire system, then what you experienced is a result of the ECM/PCM having sensed a fault with the throttle control system.

The electronic throttle system is designed to default to idle unless every single parameter reports normal, every time. One single glitch, even transient, and the system immediately drops to idle and stays there until restart.

Another thing that will cause a drop down to idle in some vehicles (not sure about the Mazda 2) is if the brake pedal is touched while the gas pedal is depressed. If your foot briefly brushes the brake pedal sufficient to activate the brake lights, the system will immediately drop to idle. But I don't know if in this case the idle state would persist until restart.

If it's not an accidental brake-pedal press, then this means you may an electronic or mechanical fault somewhere in the system. Considering that you have a highly-modified vehicle, this may be tough to solve.

 

[widman]

Thanks for the explanation. Probably related to the check engine light then, although she says that's been on for months. (Typical female)

 

[Tegger]

Originally Posted By: widman
Thanks for the explanation. Probably related to the check engine light then, although she says that's been on for months. (Typical female)

You know, I was going to ask if the MIL was on, but decided not to on the grounds that it would be a too-obvious question...

Better have the code read!

 

[widman]

A loose wire

 

[andyd]

Originally Posted By: widman
A loose wire
That is all? Did you find it before replacing anything ?

 

[doitmyself]

Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?

 

[punisher]

Originally Posted By: doitmyself
Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?


1) Simple traction control
2) No extra cruise control servo and cables
3) No IAC to screw up or clean
4) Better adaptive idle control

 

[antiqueshell]

Originally Posted By: punisher
Originally Posted By: doitmyself
Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?


1) Simple traction control
2) No extra cruise control servo and cables
3) No IAC to screw up or clean
4) Better adaptive idle control



BUT when it fails....it costs a heck of a lot more to repair than a 30 dollar metal cable.

 

[SteveSRT8]

Originally Posted By: punisher
Originally Posted By: doitmyself
Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?


1) Simple traction control
2) No extra cruise control servo and cables
3) No IAC to screw up or clean
4) Better adaptive idle control


Note there are IAC's present on some DBW setups. Add to the list fewer stuck throttles. Overall it is a good thing.

Many cars that have poor response, etc., can be reprogrammed by the aftermarket for amazing improvements. Also you can sometimes simply pull a fuse and reset the adaptives once in a while.

 

[Tegger]

Originally Posted By: doitmyself
Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?

Easier to meet US emissions and CAFE regulations. Until electronic throttles, the throttle plate was the only thing the engine's computer could not control.

Any other features conferred by electronic throttles are byproducts, not reasons.

 

[MarkM66]

Originally Posted By: antiqueshell
Originally Posted By: punisher
Originally Posted By: doitmyself
Sorry for the "idiot" question, but what is the advantage of these systems over the simple, mechanical throttle cable?


1) Simple traction control
2) No extra cruise control servo and cables
3) No IAC to screw up or clean
4) Better adaptive idle control



BUT when it fails....it costs a heck of a lot more to repair than a 30 dollar metal cable.

And it's a pain when you're working under the hood, and want to give it some throttle..