ScionFred

iTrader: (1)

On my cable-controlled throttle Dakota the hesitation was definitely caused by the TPS not responding quickly enough to manual throttle plate opening. On the XB I'm not even sure if it uses a TPS or relies on the drive-by-wire throttle pedal position. If there is a TPS on the TB, tweaking it may help alleviate the hesitation. If the delay is in the drive-by-wire system, that will require another approach. In either case, there are electro-mechanical sensors that can possibly be tweaked a bit. It's my understanding that such sensors have acceptable limits of operation which may be less than ideal. For instance, my Dakota TPS had an acceptable voltage range for closed throttle. Raising the voltage output to the upper limit of that range resulted in much quicker throttle response.

FWIW, I stumbled on a thread in the TC forum where someone claimed to improve throttle response by adding a piece of foam rubber between the upper throttle pedal stop and the pedal arm. This could potentially cause the DBW throttle sensor to react faster due to the removal of some play in the throttle pedal. When I have some time I'll play around with some ideas.

NemoTC

many drive by wire car have that problem, but not all are calibration problems I used 2 washers welded togheter right behind the sensor on the pedal, and it respond a little better

eyeeatingfish

Could you elaborate on this modification?

J-

eyeeatingfish

What i also dont like is that when you take your foot off the accelerator there is a delay in the engine powering down. This means when I shift out of gear the engine stays at higher RPMs or maybe even revs higher because it is delayed in getting gas.

Jan06xB

Maybe you should get some lubrication on the linkage - sound like maybe your gas pedal is sticky - you can just take your foot off the gas sooner before you push the clutch in. Even the xB has that delay when letting off the gas - helps make the shifts smoother.

eyeeatingfish

I want my car to do what i tell it to do, not to wait a second then do it.
Its kind of dangerous to have a slow to react accelerator. In an emergency the half second can make a difference.

As far as when you shift out of gear and it revs up because its getting the delayed gas but no longer in gear, that just burns extra gas and makes people think you cant drive stick.

Jan06xB

Well the throttle plate is moved with a motor so if the plate is sticky then some cleaning may help other than that the only thing I hear here in SL was that sometimes a grounding kit improves throttle response - possibly by having a better ground the motor on the throttle runs better and the TPS (Throttle Position Sensor) signal had less noise on it. Other than that the only other delay in the system is going to be the ECU that is calculating the throttle response and just maybe it can not run any faster to respond to the throttle input from your pedal. Maybe if the ECU was over clocked?? Heh heh now that would be funny if that worked. Only other way would be some sort of a thorttle closer linkage when the gas pedal is released and maybe an injector shut off during shifting.

eyeeatingfish

I called toyota cooporate headquarters and the customer service lady didnt really do anything other than "document" my case. She didnt seem to have any explanation about the delay (not surprising, as customer service doesnt design the software).
She really didnt offer any solution to the problem. She referred me back too the Hawaii dealer despite me telling her twice that I spoke to the Hawaii dealer and they had no solution. The hawaii dealer only related that if toyota came out with an update they could then use that to adjust my car.

I dont really expect them to spend thousands designing and distributing a whole new software based on my complaint alone though. I dont know if anyone else reported this issue to them.

Im just annoyed because an acceleration delay could be a safety hazard. A half second can make a big difference in a car crash.

J-

No doubt, where I live there is a intersection I have to take everyday with no light with very few gaps in traffic, a slight delay there can cause you to get hit. There's areas like this all over.

memebag

I've been driving my xB2 for a week now and I haven't noticed any delay.

eyeeatingfish

I have standard, im not sure if it is present in automatic models too.
try putting it in neutral and tap the gas pedal. You should notice a delay for the rpms to bounce up.

I also notice that in mine, if i shift out of gear real fast, the engine will continue to get fuel for that slight delay and rev up the engine to higher rpms because there is now no resistance.

Jan06xB

If you are driving a standard then just rev the engine a little before you think you have to take off . . . even 1500rpm will help with the response without wasting a lot fo gas if you don't go right away. If you have an automatic then power brake it a little - left foot on the brake and right foot on the gas or you can heal toe it with your right foot. There is a little bit of a delay in the throttle movement to maintain proper air/fuel mixtures in the engine as the air rushes into the intake plentum which has a high vacuum at idle/no load. Calculating the exact A/F mixture when teh throttle is snapped wide open is probably too hard to program into the ECU so they just open the throttle slowly and avoid the problem. IN the old days an accelerator pump was use to squirt gas into the engine by the carburator and often resulted in flooded engines and a lot of wasted gasoline.

eyeeatingfish

I am sure they designed it that way for a reason. Better air to fuel mixture? seems like a likely possibility, and yes in normal driving you can adjust the timing, however, when it comes to emergencies, I dont want to wait that extra 1/2 second for my engine to respond. I sure as heck wouldnt want my brakes to be a half second late.

Jan06xB

Yeah I hear ya on the brakes for sure and as a guy found out in his girlfriend car the brakes cutting out is no fun either. Just think how hard it is for us manual tranny drivers to do a quick down shift and then nail the gas to avoid something compared to an automatic that does the downshifting for you. You have to just get used to the delay and learn to avoid those situations if at all possible.
The only other thing to check is to make sure that the throttle motor is not binding or sticking and maybe try driving another same make car (you should update your profile so we can tell what you are driving) and see if it is your car only or they all do it when you drive the way you do. Oh and try a Prius takeoff at a stop sign or light with the engine isn't even running . . . talk about a delay! YIKES!!

TrevorS

iTrader: (1)

I notice the same problem with manual upshifting. I normally ease off the throttle the same time I release the clutch (depress the pedal), however, with the xB2, that results in an rpm surge when I shift up. I find it really annoying! The solution appears to be to release the throttle a little before depressing the clutch pedal. Of course, that is counter to any manual shift car I've ever driven -- including my Eclipse !

bugtoxb

as far as ur delay on the auto, i have noticed it seems to take off better if u use the manumatic put it in first and shift it, it seems to work better plus it wont shift as fast.... i am in georgia right now, u could drive like them down here and just pull out and hope their brakes work......... aka southerners cant drive! O and if it rains.... forget trying to get anywhere!... and they should make a seperate highway for tractor trailers! ok im done with my rant. I appologize

Jan06xB

The same works for the 1st gen xB - there is a slight throttle hold when shifting there too. So I back off the gas then push the clutch in and shift quick and sometimes hit the gas before letting the clutch out too.

skittelbrau

This pretty much explains what the system is. There are no moving parts that connect the pedal to the engine. Hence the name "drive-by-wire". The person who posted the washer mod is right on track.

Jan06xB

The 1st Gen xB is throttle cable and there is some delay but not as bad. If you want to feel the opposite effect try driving an electric vehicle - talk about instant response!