Engine braking (lack of)

scro · Jun 8, 2005

Is it me, or is there real lack of engine braking?

This is my first contact with the mod motor, and I've been driving a Jeep for a few years - so I might be willing to accept that I'm just used to the tractor engine in my Jeep; but I don't think so.

Even if I tach it up to 4k or so (I may have tried 5k+ ), it just doesn't slow down much. I'm guessing it might be programmed in for torque management or traction control. Any ideas?

05Stangster · Jun 8, 2005

I take it you have a standard? I test drove the standard and noticed some engine breaking, but not what you would get from a Jeep. I think it is designed to alleviate as much engine breaking as possible for mpg purposes.

I have the Auto and it has engine braking when you take the OD off or down shift manually. Of course, you can't downshift too much - the computer won't let you.

crewwolfy · Jun 8, 2005

I've noticed this too. My little Nissan Pulsar (1.8L) had a lot more engine braking than the stang. Makes for smoother shifting, but feels strange.

DukeOfValencia · Jun 8, 2005

I've posted similar responses before, but I think it's because the computer keeps the throttle open even after you let off the gas. Ever notice that between shifts the engine doesn't rev down right away? Try reving a 66 Mustang and an 05 Mustang... if you let off the gas at the same time and at the same rpm the 66 Mustang engine will rev down faster...
I think the purpose is to decrease the emissions. It has something to do with when you down shift and engine brake you have a ton of unburnt gas going out the tail pipe... or something like that. I find it annoying and I hope someone with find a computer flash to remove that BS.

scro · Jun 8, 2005

RetiredGeneral said:
I've posted similar responses before, but I think it's because the computer keeps the throttle open even after you let off the gas. Ever notice that between shifts the engine doesn't rev down right away? Try reving a 66 Mustang and an 05 Mustang... if you let off the gas at the same time and at the same rpm the 66 Mustang engine will rev down faster...
I think the purpose is to decrease the emissions. It has something to do with when you down shift and engine brake you have a ton of unburnt gas going out the tail pipe... or something like that. I find it annoying and I hope someone with find a computer flash to remove that BS.

I was thinking the same thing about the computer keeping the butterfly open; but I did another search on the subject and found a post about it. Evidently it's the idle air bypass on the older 4.6 motors. They were using a restrictor plate on the IA to fix it. Could be the same here.

I'll look into that when I can. I really don't like staying on the brakes on long downhill grades.

nbk13nw · Jun 8, 2005

scro said:
I was thinking the same thing about the computer keeping the butterfly open; but I did another search on the subject and found a post about it. Evidently it's the idle air bypass on the older 4.6 motors. They were using a restrictor plate on the IA to fix it. Could be the same here.

I'll look into that when I can. I really don't like staying on the brakes on long downhill grades.

Has anyone running charge motion plates seen a difference?

Mossberg · Jun 8, 2005

My daily driver has more engine brake than the stang does.

BLK05GT · Jun 9, 2005

Mine has a 7 second delay, then it engine brakes. It makes it really tough to go 25 down a long hill. While going down the hill at 30 or so (with my foot off the gas), right at the count of 7 the engine braking kicks in, and it slows way down, so I have to tap the gas to "reset it", and back up towards 30 again, and the cycle repeats.

cleveland · Jun 9, 2005

You people need to learn your cars a bit more.

In an automatically controlled Mustang engine braking kicks down immediately unless you dont drop it to such a low gear as compared to the current one that it would cause damage to the engine. The computer controls this so you dont accidentally hit like 2nd or 1st gear from 5th or 4th when you are already at high revs.

You can drop it to 1st from 5th though but it will downshift to the next safest gear and so on from there.

-Dan

SLOW 97 · Jun 10, 2005

Dan, I think you've totally missed the point here. I think everyone here is well aware that if you're driving an automatic and manually select 1st or 2nd at 60 mph its not going to downshift into the computer sees a safe cehicle speed. Just like the federally mandated reverse lockouts that EVERY tranmission is required to have standard or auto. It wouldn't be pretty if you were able to select reverse while travelling forward not to mention fairly unsafe when your wheels lock up. This engine brake snafu has to have something to do with the torque management BS. I also drive an '04 VW GTI which has drive by wire throttle. I can't stand it! The computer can do whatever it wants with the throttle plate and that is annoying. If you've ever driven any diesel powered vehicle, there is little to no engine braking due to the fact there is no vacuum because there is no throttle plate. Im not sure what Ford's strategy in doing this is but, its probably emissions related or possibly to protect the gear train in the trans. Depending on who you ask, downshifting is not such a good idea. I believe it says in the owner's manual not to manually downshift. I do know that it does put a lot of stress on gear teeth from the gears being driven by the vehicles momentum, not the engine which loads the coast side (as opposed to 'drive' side) of the gear teeth. This is why you shouldn't do a reverse burnout are hammer on it in reverse. You could severe damage your ring and pinion becuase they are not designed to be loaded in that direction of rotation. Anyway, sorry for rambling on, but hope I could clarify some things for you guys. Hopefully the aftermarket can sort out the new engine mangement soon.

300bhp/ton · Jun 10, 2005

05Stangster said:
I take it you have a standard? I test drove the standard and noticed some engine breaking, but not what you would get from a Jeep. I think it is designed to alleviate as much engine breaking as possible for mpg purposes.

I have the Auto and it has engine braking when you take the OD off or down shift manually. Of course, you can't downshift too much - the computer won't let you.

FYI - an internal combustion engine under down revving (ie engine breaking) will not be using fuel to do so, it is probably the most economical state the engien can acheive, this is because the trottle is closed and will not be injecting fuel into the cobustion chamber (or carb if old school).

Going down a hill with the car in gear (manual) and your foot off of the throttle is more economical than shifting to neutral and letting the engine idle while you roll down the hill, as at idle fuel will still be being injected into the combustion chamber.

Auto boxes work differently to manuals and dependant on make model behave differently too. Some will stay in as high a gear as possible and engine break when you lift off of the throttle (the GM400 3-speed auto box in my XJS does this). However some cars will drop the revs completely when you lift off, ie even at say 70mph at 3500rpm lift off the throttle on a level gradiant after a second or two it will drop to about idle rpm. This is what happens in a Rover 825i Sterling 2.5 V6 K-series engine and 4-speed electronic controlled gearbox.

I'm not sure how the GT auto box works but it is electronic controlled as opposed to vacuum/mechanical. Try finding a steep slope (driveway??) and lock the box in 1st and see if it will engine break ok.

DukeOfValencia · Jun 10, 2005

300bhp/ton said:
FYI - an internal combustion engine under down revving (ie engine breaking) will not be using fuel to do so, it is probably the most economical state the engien can acheive, this is because the trottle is closed and will not be injecting fuel into the cobustion chamber (or carb if old school).

The problem is that it doesn't seem to close the throttle... On an old carb engine the gas pedal is connected directly to the carb by a cable or a rod. You let off the gas, the carb closes, and the gas/air flow is restricted. However, it feels like the computer is keeping the throttle open even after you let off the pedal. It's most evident to me between gear shifts. It took me a little while to get used to shifting when the engine stays reved up even after I let of the gas.

scro · Jun 10, 2005

Looks like there aren't any definitive answers yet. It may take quite some time before someone figures it out. There are too many more important things to work on.

I mostly wanted a sanity check since I had no experience with the 4.6 engine. Thanks for all the replies.

BTW, mine is a manual trans. I can imagine you auto guys REALLY don't slow down when you lift throttle.

cleveland · Jun 10, 2005

Well, Im fine with the engine braking. It slows enough for me to make me lunge in my seat.

-Dan

300bhp/ton · Jun 11, 2005

RetiredGeneral said:
The problem is that it doesn't seem to close the throttle... On an old carb engine the gas pedal is connected directly to the carb by a cable or a rod. You let off the gas, the carb closes, and the gas/air flow is restricted. However, it feels like the computer is keeping the throttle open even after you let off the pedal. It's most evident to me between gear shifts. It took me a little while to get used to shifting when the engine stays reved up even after I let of the gas.

These new fangled electronic setups are sometimes beyond me. I have driven an auto 05 GT and didn;t really notice any difference from any other modern auto matic (Jag/Merc/Rover and so on).

However it should still be closing the throttle (as per the old carb setups) else you would continue to accelarate. If not then maybe there is a bit of a clitch with the ECU giving the electronic equiverlant of a sticky throttle cable.

official_style · Nov 15, 2005

i had the problem fixed. there is a seven second delay, before the engine braking will begin, i had it changed with a sniper tune to i think a 1 second delay. sooo much better!

hubec · Nov 15, 2005

As others have correctly posted it's due of the electric throttle thinking it knows how to drive the car better than the driver amnit: . It will EVENTUALY close but you have to wait for it. Most of us refuse to acknowledge it but our big - manly man - import crushing - V8 thundering super stangs, are designed sothat any old granny can climb in and drive to bingo. Either put up with it or get a tune. Mine will be taken care of when I get the SC installed .

Engine braking (lack of)

scro

05Stangster

New Member

crewwolfy

Member

DukeOfValencia

Member

scro

nbk13nw

Member

Mossberg

Active Member

BLK05GT

New Member

cleveland

SLOW 97

300bhp/ton

New Member

DukeOfValencia

Member

scro

cleveland

300bhp/ton

New Member

official_style

New Member

hubec

New Member

Similar threads

Engine braking (lack of)

New Member

Member

Member

Member

Active Member

New Member

New Member

Member

New Member

New Member

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency