Low power from a dead stop

[Xjeepowner]

I’ve got a little over 9000 miles on my 2.7 Bronco and just noticed that when I floor it from a dead stop it accelerates very slowly till it gets about 15 then it seems to get full throttle, I tried turning off the traction control, tried sport with both 2h and 4a and nothing makes a difference. It won’t even spin the tires on the dirt till it gets to about 15 or so. Once it’s moving it runs great. It has no trouble pulling the long grades in Colorado and New Mexico. It’s getting great gas mileage from Durango Co. to Moab for Bronco Safari It got 21 mpg and it’s an auto with sas.
Any ideas?

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[mikec426]

This happens to me periodically. I remember watching a video a while back about the 2.7L engine and that you need to give the turbos a workout now and then. So when I notice it, I put her in Sport mode and haul ass a few times and it seems to go away for a while.

 

[Xjeepowner]

I’ll give that a try and see what happens. Thanks

 

[Bikeric]

My Bronco got 14.2 mpg’s before I went to Moab. 1,100 miles on the highway averaging 75 with a few spirited jaunts above 90mph got me up to 16.2 mpg. I think our engine’s just need a little extra cleaning to function at 100%.

 

[CatMonkey]

The turbo has to spool up before it can make any power, which is hard to do from 600 rpm. You might try power braking and seeing if that does anything for you.

 

[GI_Jo_Nathan]

This is why I like manuals.

 

[LSU Jonno]

Happens to me occasionally too. It’s actually scary when I’m trying to gun it to pull out some times and it just won’t move. There is like a one second delay between gas pedal movement and vehicle movement which seems forever when trying to pull out quickly.

 

[Lil Red Broncette]

This is why I like manuals.

My manual doesn't seem to avoid this.

 

[Lil Red Broncette]

I’ve got a little over 9000 miles on my 2.7 Bronco and just noticed that when I floor it from a dead stop it accelerates very slowly till it gets about 15 then it seems to get full throttle...

I don't know if this is something new on your vehicle or something you noticed. The way you wrote it, it sounded like maybe you didn't really try just flooring it suddenly before.

If recently discovered verses a definite change, it may be a normal behavior.

There are two things at play when you floor it suddenly from idle.

First, as someone else mentioned, there is the response delay from the turbo. There isn't much RPM so there isn't much boost available.

Second, and quite annoying when you notice it, is a software delay built into the gas pedal response. Although your foot goes from zero to full throttle in a half a second, the throttle controller algorithm effectively ramps up the throttle command to the engine controller.

So your full throttle input may have been a half second from zero to full, but the engine control gets something like two seconds from zero to full with the first bit of it especially slow.

There are modules one can by that lets you tailor the throttle response and effectively eliminate the delay. I've seen people commenting this is the best thing they have did.

I don't know if on your climate control the fan control acts like mine, but mind has a long delay that is annoying. I can change fan speeds and instead of just changing immediately it smoothly ramps the fan to the new speed. I expect someone thought that would be a cool "feature" but to me the delay is annoying. It isn't so bad changing it in the middle of the range, but if the fan is at very slow it is particularly slow at changes. That tells me that mathematically the algorithm they use limits the change by a proportion of the settings. Thus when slow it can only change very slow, but when faster it can change faster.

The throttle seems to act a bit like the fan control although not nearly as slow.

I understand why they built this throttle response delay. But in some cases it is annoying and limits the driver's ability to find the best response.

The throttle response delay doesn't bother me so much in my bronco with the automatic trans, but it really bugs me on the one with the manual trans. I believe the reason is because on the automatic I stay on the gas and the vehicle handles the shifts. With the manual, if I am taking it easy no problem, but when I go to accelerate hard, the time spent in first gear is so short it doesn't get ramped all the way up and then it resets when I let off throttle to go into second and once again have the throttle response delay.

 

[Lab00Rat]

I've noticed this too. Only seems to happen to me when I have a double stop sign. The second stop-to-go has a very uncomfortable acceleration. Last week I had to abort the merge because it's a fast traffic merge and the traffic doesn't let up. The Bronco practically sputtered the acceleration after the second stop. Very unsafe situation. Not sure what's causing this, and I'd like to know if it's driving habit or software related. This did not always happen. It wasn't till I was 8k miles or better. I know it should not happen because I use this double stop sign path twice a day, every day. It only recently started happening.

I've owned trash vehicles that sputter at acceleration, and they usually cost me about $1k growing up. I've not had that happen on a $60k high-end vehicle before. Meh, maybe I need to re-think what a high-end vehicle is.

 

[JerryC]

What octane of fuel are you using? If not 91 or 93 you may want to try that.
I have a manual and do not notice this, but it has only had 93 octane fuel since day 1.

YMMV....

 

[bradcd]

While I haven't experienced this, you could try pulling the fuse for the ECU/fuel map for a few seconds. Sorry, I don't know the fuse number or location. It may reset all back to stock parameters. It's helped previous vehicles I've owned when the computer nerfs itself down too much for economy.

 

[Jazer]

Turbo lag + fly by wire tech, it's not going to be instantaneous.

 

[khill007]

that! It’s turbo lag, and this rig has it bad! Would like to hear about any mods out there that eliminate?!?

That is all!

 

[Fly by Nite]

That's just how turbos work. They rely on exhaust pressure to spin the compressor side to produce the boost that makes more power.... and you don't get the exhaust pressure until you're putting a load on the engine. It's not instantaneous, there's going to be a delay. It can be reduced by using smaller turbos that spool (spin) up faster, but that also limits peak power. Ford sized everything for low low-mid range torque, not max hi-rpm HP figures. There's always a compromise.

If you want instant power, a crank-driven supercharger would give quicker response. But they also use some of the engine power to make that boost. Turbo's use exhaust gas which is basically 'free', and doesn't sap engine power to make it.

You can reduce turbo lag with Nitrous Oxide injection (NO2 or NOS). It will increase initial power with the extra O2 and fuel, which will in turn increase the exhaust pressure and bring in the turbo boost sooner. The main downside is you need to keep filling the consumable NO2 tank.

Driving style can be optimized to bring the boost in faster.... As mentioned, 'power braking' puts a load on the engine while vehicle is stopped.... it builds boost while sitting still so it's there when brake is released and gas is mashed.

Automatics are typically better with turbos since they keep a more constant load on the engine (which produced turbo boost). Manuals tend to lose boost when letting off the gas when shifting gears.

In the older days of turbos ('78-80's) it typically took 2 seconds from 'flooring it from a stop' to 'full boost' .... but boy, when the boost hit, it sure felt good! It did take a lot more technique to time that power surge, particularly when coming out of turns.

Another way to get rid of that lag is to replace that turbo motor with a big V-8. That's gonna be a big project.

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