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Engine Brake


SiriusProjects

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Can someone explain to me how the engine brake works? I'm sure I read something about it in the 350z user manual.

 

I only ask because when I am driving down a hill, I'm not really applying any acceleration. I just put the car into a low gear and this to a degree maintains a particular speed with me just holding my foot in the same position on the accelerator without applying any pressure. However, in these situations i do feel the car hesitate a few times on a downhill run and i assume it's what is known as the engine brake kicking in, but at the same time I wonder if the hesitation is being caused by some problem or something.

 

Am i right in thinkiing it is the engine brake or could it be something else?

 

Thanks.

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There isn't actually an engine brake (except for in some trucks/diesel engines) ~ it's just a term used to describe the effect caused when you're off the throttle & the vehicles rolling faster than the engines rpms. Like when you downshift from a higher gear to a lower gear at speed coming to a stop at traffic lights for example.

 

The friction in the drive train/vacuum on the engine basically causes the engine to slow & the vehicle in turn (won't happen when you're not in gear as you're just free wheeling then).

 

Hope I've explained it correctly as that's the way I understand it. :thumbs:

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I think I know the sensation you're describing. I'm sure it has to do with the fact the Zed is RWD and the fact that you are being pushed rather than pulled by the front wheels.

What planet are you from? Engine location and driven wheels has nothing to do with engine braking: Please don't confuse the OP anymore than he already is!

 

GMballistic explains it best, although diesels do engine brake as well just nowhere near as much due to them working via compression rather than spark.

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I think I know the sensation you're describing. I'm sure it has to do with the fact the Zed is RWD and the fact that you are being pushed rather than pulled by the front wheels.

What planet are you from? Engine location and driven wheels has nothing to do with engine braking: Please don't confuse the OP anymore than he already is!

 

GMballistic explains it best, although diesels do engine brake as well just nowhere near as much due to them working via compression rather than spark.

 

Yeah, but it doesn't sound like the OP is actually talking about engine braking though? Incidentally, I do understand the concept.

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Yeah, but it doesn't sound like the OP is actually talking about engine braking though? Incidentally, I do understand the concept.

Given there is no engine brake in the Zed, then what else could he be talking about? Off the gas, no power being applied, downhill, same speed. Engine braking, 100%.

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I think the OP is referring to engine braking, as others have said. I think the braking that the OP is getting at is when the engine cuts the fuel to the injectors because the hill incline is accelerating the car enough so the engine doesn't have to. (I may be wrong :surrender:). I sometimes find that as the fuel combustion turns on and off you can feel the car pulse which may lead the OP to think that a brake is being applied.

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Okay, it seems like I'm not quite clued up on these things. My zed has done it since I bought it and I wasn't really that bothered to be honest. I was on my way to work this morning on my normal route which involves going down a hill under a railway bridge and it hesitated a few times and I just thought, sod it, I'm going to ask on the forum and find out what others think. It's not a problem at all on flat roads, it literally only occurs when I'm going downhill.

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Hmmm... being serious for a change, it sounds like some form of fueling issue, perhaps being caused by a shift in gravity of going down hill. Are you particularly low on fuel when this happens, and are the hills quite steep?

 

Alternatively does it ever do it round bends? It sounds like the TCS may be cutting in and switching power from the wheels momentarily. What tyre sizes are you running?

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Hi marzman. No, I had over half a tank of fuel in the car today and the hill in question isn't that steep. I'm running 18" wheels, they are the factory fitted ones that come with a GT4.

 

It's weird though because I swear the car runs better some days than it does others. One day it can be running as sweet as a nut, but the next it can feel quite lumpy.

 

I would also like to say as well that during my time on the forum it has become obvious that many of you are mechanically proficient as well as drivers of cars. Perhaps I am in the minority, but whilst I can drive, I know very little mechanically. Yes, I can check the oil and the coolant levels, etc, but that is the limit of my knowledge. This is perhaps evidenced in the amount of posts I have put on the forum since joining. So whilst any questions posed might seem pretty ridiculous to most of you, they are genuine queries from someone who simply wants to learn more about how things work and the best way of doing that is to ask.

Edited by SiriusProjects
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Is the car fully warmed up, have you checked the oil level recently? Are your services up to date? It's hard to know what's causing your problem as the description is rather vague. Might be worth getting a mechanic to drive it and see what they think

 

 

Sent from my iPhone using Tapatalk

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