Drive-by-wire throttles

[brianl703]

Connectors have improved quite a bit--you don't see any unsealed connectors under the hood anymore. The locking mechanism is usually more reliable and less likely to break.

I don't see why an APPS should take any more of a beating than say the brakelight switch or clutch pedal switch, based on where the one in my Saab is mounted.

 

[brianl703]

Originally Posted By: Patman

The ECM failed on my Corvette a few years ago but it was due to corrosion. The ECM is under the battery, and the OEM batteries have a history of leaking out acid. Plus I think the area that the ECM sits in was not sealed properly from the elements, so road salt got in there. So that failure was not the ECM's fault.

However, 12 hours after getting a new ECM, it died! The tech's said they have never seen that happen ever. This was two years ago and the car hasn't had any problems since.


I'd heard about those Delphi batteries and their propensity to leak. I don't think they're made anymore, since Johnson Controls bought Delphi, I've seen AC Delco batteries that look exactly like Johnson Controls batteries with removeable vent caps.

The replacement ECM may have been a rebuild that wasn't tested very well before being sent out.

 

[Doug Hillary]

Hi,
Brianl703- ECMs a tiny cost????

I know that they cost areond $6000 for both Cummins and DD units in this Country. I expect the Euro truck ECMs to be much more expensive that that - that (parts prices) is one reason why I have never purchased a new Euro heavy truck. Even though I once worked for Mercedes Benz in truck (Benz & FreightLiner) development!

A friend of mine here has a "new" boat and his Cummins ECM went out at 170hrs (about 15 months) - Cummins did not want to pay but eventually coughed up under "goodwill Warranty". Fitted, the package cost around $6000 too. The reason we suspect was "corrosion"

Regards
Doug

 

[brianl703]

What they charge you for a part in the parts department is often no indication of what it actually costs the manufacturer, particularly for those parts for which the factory authorized dealership is the only source.

For example, the stereo amplifier in my Saab 93--some dealerships want about $1000 for a replacement. I've had that unit apart and it has nowhere near $1000 worth of components in it. The most expensive part of that amp converts an optical signal to an audio signal. The actual amp part is about equivalent to the $20 car stereo boosters Radio Shack used to sell--a bridged chip amp running directly off the 12V supply.

Or..how about the blower motor resistor pack for a Chevy Suburban? It has about $12.95 worth of electronic components in it (couple of transistors, some caps, diodes, resistors) yet GM wants about $150 for a new one.

 

[JTK]

Originally Posted By: brianl703
I don't see why an APPS should take any more of a beating than say the brakelight switch or clutch pedal switch, based on where the one in my Saab is mounted.


I've seen reports of APPS issues with all the electronic throttle controlled vehicles I've owned; Isuzu Rodeo, Chevy Trailblazer and Chevy Cobalt. The throttle body on the Isuzu was stamped Aisin, I assume the Trailblazer and Cobalt are Delphi systems. Again, not a ton of issues, but they do happen. I would also assume anything attached to a gas pedal would see more of a workout than a brake switch. An APPS needs to be a pretty accurate devise. One burp from it and you are in "reduced engine power" mode & be lucky to get off the road.

Joel

 

[brianl703]

The dual potentiometer APPS setup used in the Saab 93 can have up to an 8.2% variance (at WOT) between the two potentiometers before it goes into limp-home mode. At idle it's a maximum 5.2% variance. This is from the service manual.

Any potentiometer can get worn out over time. They could use rotary optical encoder discs instead.

 

[Kestas]

When everything is added up for the life of all the vehicles, I wonder how much gas DBW throttles saved the public versus how much it cost to repair/replace the throttles that have gone bad. In my personal situation with my 95 Mercedes E320, I know it will be a net loss.

I'm starting to see a pattern with many automotive designs where a technology is introduced to save gasoline, only to cost the owner more when the unit needs to be diagnosed, serviced, and repaired. I believe the added cost of initial production and future repair of these features far exceeds the cost of gasoline that it saves. The only winner is the manufacturer, who scores points with the federal government on CAFE ratings. We should see more of this in the upcoming future. And with the car manufacturer's record of lack of robustness in their parts, and their attitude toward manufacturing parts to last only through warranty, things will get worse.

The goal should be low cost of owning and operating a vehicle, not just good gas mileage.

 

[Max_Wander]

^ it's true. It's all about the manufacturer gaining control over the running vehicle, for economy, drivability and self-repservation purposes. it has nothing to do with helping the driver, or increasing part reliability. If people have epileptic siezures on the pedal, dumbing down the surges is only enabling stupid drivers to reinforce their behaviour. Just wait until you new car guys have to replace a servo unit or potentiometer after you get the hesitation and stalling

 

[brianl703]

As if we've never had to replace a potentiometer to cure a hesitation or stalling problem on those older cars. Without a code, no less.

The drive-by-wire systems WILL give you a code if there's a problem with a potentiometer.

 

[Jett Rink]

I'm with brianl703 on this one. To me, this seems like a useful technological advance, particularly in diagnosing problems.

I've noticed one thing about BITOG, there seems to be a technophobe streak. On the one hand we marvel at the pretty advanced chemistry behind oils like German Castrol, Mobil 1 0w-40, Amsoil, etc. But the membership is a little paranoid about oil life monitors and drive by wire throttles. Just a strange combination of technophilia and technophobia.

 

[chrome]

I am not sure if this has been mentioned before, but DBW is also strongly tied in to a modern car's electronic stability control. This feature is being found in increasing more and more new vehicles, even in lower to mid level models.

Automotive engineers have found that having a computer controlled throttle works better if stability control was to be implemented. Trying to pull back x% of engine power when a mechanical throttle plate is wide open can be hard using just ignition and fuel control.

 

[brianl703]

I had a 1996 Ford Contour (no longer own it) that has traction control. The traction control uses a box inline with the throttle cable that can close the throttle plate. It's got some sort of mechanism in it that unspools to allow slack on the cable so the throttle can close. As I recall it's a pretty big box, at least 6" cubed. You can hear a motor running inside of it when the traction control kicks in.

 

[moribundman]

My '96 A4 quattro has a conventional throttle cable. Traction control is performed via ABS up to a certain speed (~ >/=35-40 mph? The system works seamless), beyond that the torsen and electronic differential lock take over that task. I have driven A4s that had DBW and they did not perform any better or safer than mine in terms of traction and the interplay of engine management and power distribution. However, I found throttle response of the conventional cable-operated throttle to be considerably more immediate and, uhm, well, responsive.

 

[XS650]

Originally Posted By: brianl703
As if we've never had to replace a potentiometer to cure a hesitation or stalling problem on those older cars. Without a code, no less.

The drive-by-wire systems WILL give you a code if there's a problem with a potentiometer.



Brian, that does put it in perspective.

 

[BuickGN]

Originally Posted By: brianl703
As if we've never had to replace a potentiometer to cure a hesitation or stalling problem on those older cars. Without a code, no less.

The drive-by-wire systems WILL give you a code if there's a problem with a potentiometer.



Understood but a TPS and such will give you poor idle, hesitation, and stalling but will not leave you on the side of the road.

 

[wirelessF]

In my 2001 Tundra it has a double throttle control, where it actually has a mechanical linkage, but actually connects to a sensor where it sent to the PCM then to the TB motor to open/close the butterfly valve. If the motor/sensor were to fail, by pressing the pedal all the way to the ground, it will partially open the throttle where it is now mechainally controlled and in "limp mode" because the throttle butterfly valve can't open all the way until the TB motor is fixed.

 

[Patman]

Originally Posted By: brianl703



I'd heard about those Delphi batteries and their propensity to leak. I don't think they're made anymore, since Johnson Controls bought Delphi, I've seen AC Delco batteries that look exactly like Johnson Controls batteries with removeable vent caps.





The original battery was an AC Delco actually.

 

[brianl703]

Yea, Delphi used to make AC Delco batteries. They don't anymore because Delphi doesn't make batteries anymore, having sold that business to Johnson Controls.

 

[ekpolk]

I don't disagree that there are a number of substantial benefits that are gained by using a DBW throttle linkage. What bugs me is when the engineers program in "we know better than you do what you need/want" features. When I floor it in any car, I want the throttle plate open, right now. I don't want the computer delaying for a few eyeblinks to see if I really mean it or not. When I lift off the gas in a manual to upshift, I want the rpms dropping off right now, not feathering down slowly to suit the engineers' profile of the cleanest possible event.

To the extent that DBW programming is at odds with what the driver expects, on a moment-by-moment basis, it can really spoil the pleasure of the driving experience. This was very much the case in my 03 V-6 Camry. Again, DBW has benefits, but until the engineers understand that we, their customers, can detect the conflicts they're programming into our cars, we're going to have problems.

 

[brianl703]

Originally Posted By: ekpolk
When I floor it in any car, I want the throttle plate open, right now.


My Saab does that.

Quote:
When I lift off the gas in a manual to upshift, I want the rpms dropping off right now, not feathering down slowly to suit the engineers' profile of the cleanest possible event.


This happened even before DBW. In fact I had a problem with a 1995 model car that kept the revs up after you pushed the clutch in. Guess what solved it? A new TPS.

Quote:
This was very much the case in my 03 V-6 Camry.


It's possible Toyota screwed up.