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Does your car have a throttle hang on upshift?

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Discussion Starter · #1 ·
I'm starting this so as not to drag another thread further off topic.

Please post in the poll, let's see if we can get some data points together and figure this out. Some users (myself and XCNuse) swear it exists, others think we're nuts.

Be aware that the poll has points for auto and manual, as I don't believe the automatics will or can notice this since the transmission will damp out a lot of it. This primarily seams to be an issue with the manual equipped cars.
 

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Discussion Starter · #3 ·
To me, there's no debating it. And you ca rule out mods cause my car is mechanically stock. When upshifting from 4th to 5th at full throttle, the engine revs UP when you take your foot off the gas and push in the clutch.

I've heard of some automakers doing nonsense like this (Fords 1st gen focus comes to mind, had a port in the throttle body that kept the revs from dropping quickly to smooth shifting and throttle) to help make the car smoother when cruising on the highway. Whyever the condition exists, it's freaking annoying. I've driven all manner of manual equipped vehicles with cable throttles that don't do this.
 

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I just don't get why sometimes it does it, othertimes it doesn't.

I've mostly still experienced it when I load the throttle moreso than cruising, and that's when it will hang or even blip up. It HAS to be something electronic / ECU related.

And yes, it's definitely something unrelated to mods as my car always did it since I got it; I can even remember asking my dad why it was doing it like the first week I got my car.

"Smooth" shifting I disagree with, because I have to wait on the car. I don't know anyone that spends 1-2 seconds to shift.
That said, the shift from 4-5 is awkward, but it isn't that bad.. so I don't get it.
 

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On the auto front it doesn't happen however, I have noticed this while in manual mode. I thought it was transmission related and it freaked me out enough not to drive in manual mode. Good to know. Weird thing to do.
 

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Discussion Starter · #7 ·
And we can remove the auto options, that's just silly.
See below. The whole point of the poll is to accumulate data points for comparison. If this phenomena doesn't exist in autos, there must be a reason why and a difference that can be exploited.

On the auto front it doesn't happen however, I have noticed this while in manual mode. I thought it was transmission related and it freaked me out enough not to drive in manual mode. Good to know. Weird thing to do.
And that's what I thought.

Regarding the reason why, bare in mind that enthusiasts/people used to driving standards are not the norm. The average driver does not/can not shift as quickly or precisely as someone practiced can. By holding the throttle open between shifts, it gives the ham fisted a chance to slot into the next higher gear without the revs dropping and the car lurching when the clutch is released. I know it sounds silly, but our cars were designed for 90% of drivers, not 10% that know how to handle them properly.

All that being said, there's two possible mechanisms for this; electronic/ecu, and mechanical. Depending on what others say when they chime in, if we see a random distribution I'll lean towards a mechanical solution (port in the throttle body, it being blocked by carbon over time may explain why some don't have this). If it leans heavily towards people agreeing with me, then I say it's electronic, and in that case it almost has to be related to the ecu programming. If that's the case, and we can turn Dynotronics onto searching for a solution, that would be epic and another positive result from their tuning.

I'm just hoping people take noticed of this poll and contribute their feedback to give us some data.

Nuse, do you still have a spare throttle body lying around? It may be worth taking a look at it to see if there's a bypass port that can be blocked off. Of course, the ECU could also be feathering the Idle Control Valve to accomplish this same thing. Can't recall what car, but I remember working on one a long time ago that had a dashpot under the throttle wheel so that the throttle would slowly close that last 25% instead of slamming shut. The same thing could be accomplished electronically through manipulation of the IAC.
 

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Not sure if this is related, but I have kind of the opposite issue -- I get throttle surge from time to time. It pretty much only happens on a cold start (read: it doesn't have to be cold outside; cold start = engine is cold). But I'll drive up to a stop sign, push in the clutch (with foot clearly off the gas), and the engine will momentarily rev up another 500-1000 rpm, instead of dropped when the clutch pedal goes in.

Not sure if this is related, or if it's even and issue (might have something to do with the warm-up of the car).
 

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I get it as well; it's... I don't know if it's the same concept as this, but I know exactly what you're talking about Branden.

Even when it (the engine) isn't that cold; every morning driving out of my driveway just blipping first gear it just kind of hangs around for a second or so for no reason.

It was particularly awful this morning too. It's got to be related.. somehow.
 

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I just posted in another thread where my gen car has similar issues. I think it might be part of the warm-up cycle, but it usually will stop doing this before the engine is warm. I've only noticed it the past couple months, too, so I'm wondering if there's some maintenance I'm missing (cleaning something fuel-related, etc).
 

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In for the deets:

I have an 07 2.3L mtx hatch touring leather moonroof
mileage: 135k
recent maintenance: oil change & filter (spin on conversion), new ngk plugs (iridium IX), new air filter, new waterpump, all new fluids, JBR lower rear mount, new OE top mounts, all factory parts otherwise
 

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For a point of reference again on the Automatic - Manual mode. When I drive the A3 with the 6 speed auto, manual OD Tiptronic, this never happens.

I'm a manual guy myself, but we have one car and the wife doesn't drive manual..
 

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I have this same issue but I think it is a combo with my clutch going out also. I didn't noticed it until about 70k but I am at 110k now. I drive a 2005 SP23 manual. The 4th-5th ratio is really weird, I feel like I have to wait for the car so I can shift. I think I have a clutch issue also because I began to feel it in the early gears first and now it's totally random. I still get it the most when getting on it from 1rst to 2nd gear, which makes me think my clutch is also a major factor.
 

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Discussion Starter · #14 ·
I have this same issue but I think it is a combo with my clutch going out also. I didn't noticed it until about 70k but I am at 110k now. I drive a 2005 SP23 manual. The 4th-5th ratio is really weird, I feel like I have to wait for the car so I can shift. I think I have a clutch issue also because I began to feel it in the early gears first and now it's totally random. I still get it the most when getting on it from 1rst to 2nd gear, which makes me think my clutch is also a major factor.
If it comes and goes, and you feel like the clutch is variable, consider bleeding the clutch line. That's on my to do list. A little air or water vapor (build up over time) will make for a clutch pedal that sometimes feels okay, and other times feels like Hell.
 

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I can tell you there are no ports in the throttle body. Idle is controlled solely by the throttle plate itself. Usually holds itself between 9-15% to idle depending on conditions.... unlike cable throttle cars which have a throttle that goes to 0% at idle... it has a stepper motor with normally 30-60 increments or steps that is its own port that allows air in to control idle.


I need to renew my photo bucket account, bit I have a logging screenshot of the throttle pedal vs throttle body % and you can see the TB has no problem keeping up at all times, except when upshifting it smooths out the throttle shutting and reacts slower by 0.5+ seconds. Will repost it tonight once I renew my account hopefully.
 

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Discussion Starter · #16 ·
except when upshifting it smooths out the throttle shutting and reacts slower by 0.5+ seconds.
And it is this 'smoothing' that we're referring to. Holding the throttle open even an additional half second annoys some drivers.
 

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DBW issues are talked about on every car that has one.
Our Mazda is an automatic and it's not an issue since the car is so unresponsive with the auto trans anyway.

The DBW on our 2006 Acura TSX with a 6 speed manual is terrible. It's a huge issue with TSX owners. The ECU was only recently cracked by Hondata. So far custom ECU tuning has had marginal affect on it.

The 2011+ 5.0L Mustang has an excellent DBW system even with a manual transmission. I pretty much defy anyone to tell that it is DBW.
Of course there are upgrades for the Mustang DBW system also.
ECU Tuning, and replacing the plastic stepper motor gears for more precise metal/brass gears.
 

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This is 100% an ECU/DBW issue. As far as I know it's commonly done to reduce emissions during upshifts. There is always a little bit of blow-by from the combustion in the cylinder to the crankcase, so under high load crankcase pressures become very high. When the throttle is closed quickly cylinder pressures drop, but the crankcase is still pressurized, so there is actually some blow-by of crankcase oil into the cylinders, where it's partially burnt and shot out the exhaust. That's bad for the cats, and causes lots of emissions.

It's also why a lot of cars will emit a big puff of white/blue smoke upon lifting. Turbo cars are even more prone to this because the pressures are higher.
 

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Had the same issue. This was on a 2008 Mazda5 with manual trans. Made driving a pain in the ass sometimes. Felt like I was slipping the clutch on every upshift because of the RPM's hanging.

Feel it sometimes on my current 5 which is an auto if I have to use manumatic mode. 1st to 2nd is the worst when I see it. Seems to hold forever.
 

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And it is this 'smoothing' that we're referring to. Holding the throttle open even an additional half second annoys some drivers.
That's what I was implying...

I upgraded my account so here is the screenshot of what I was talking about:

 
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