Unresponsiveness of GM Electronic Throttle Bodies

Status
Not open for further replies.

Nick1994

$100 site donor 2024
Joined
Feb 19, 2013
Messages
16,645
Location
Phoenix, AZ
I've always had a hard time with how unresponsive electronic GM throttle bodies are. Well, at least the older ones. And I'm a GM guy! The ones I have driven have no power off the line, It's like they fall flat on their face. From a stop if you floor it, it slowly creeps up the RPMs but once they get moving they have plenty of power, no complaints there. So 20mph+ if you stomp on the gas they'll move down the road in a hurry. The cars that have done this to me are: 2002 Chevy Trailblazer LTZ (4.2), 2-2003 Chevy Silverados (5.3), 2005 Chevy Tahoe (5.3), and a 2006 Isuzu Ascender (4.2). On any of these vehicles, they won't even chirp the tires when taking off at all, and traction control isn't even kicking in.

I've towed trailers with the Trailblazer & the Ascender, and while the Trailblazer had MUCH more power towing (3.73 gears, probably higher gears in the Ascender), they both have no power off the line, but do just fine once moving.

My comparison to this is my previous 1996 Chevy C1500 Silverado 5.7L, which would lay down 2 black stripes that were probably close to 15 feet long. It always had power right off the line (it had an actual throttle cable).

It makes it really annoying driving in the mountains too because when giving it a little more gas, sometimes they'll just hop down to 2nd gear and scream up the mountain, it's too hard to "feel" when it's going to shift. So what's up with it?
 
If you delivered full available torque to that 4L60 (minimal tip-in management), what do you think would happen to durability?
 
Originally Posted By: Ramblejam
If you delivered full available torque to that 4L60 (tip-in management), what do you think would happen to durability?

Sometimes when pulling out onto a highway it's nice to be able to actually move, especially when other cars are coming. Also especially when there's a trailer behind you.
 
Originally Posted By: Nick1994
Originally Posted By: Ramblejam
If you delivered full available torque to that 4L60 (tip-in management), what do you think would happen to durability?

Sometimes when pulling out onto a highway it's nice to be able to actually move, especially when other cars are coming. Also especially when there's a trailer behind you.


If it bothers you to that degree, get the thing tuned.

Both brake torque limit, and ETC tip-in limit can be modified to your tastes.
 
THIS! I have had this issue as well, and is still my biggest complaint with GM vehicles. It only gets worse with the transmission tuning. The Pontiac has these issues, and my Camry is the exact opposite. Just imagine it with these new turbo engines.
 
My son lives in Phoenix and has all of his cars 'tuned" by various shops.

My 2008 Trailblazer with the 5.3L V8 will lay down 2 black stripes and it has 118,000 miles on it. It has had NO chipping or software mods.
 
My rental is a 2016 Impala with a 3.6L and the throttle body is really weird. The Fords I have driven with them and my Volvo did not have any issues whatsoever with throttle response.
 
I still remember a midsize pontiac (G3?) I rented that did this to me. 0-25 was a prayer then it would perk up and then perk up again at 45+.

I can imagine fooling some really stupid people on test drives who think the top 20% of the pedal gives them so much 50-75 passing power, only to find it was all an illusion.

On the flipside my electric throttle HHR makes some nice snappy shifts with power cuts in the right milliseconds. As an end-of-life car user I like the idea of anti-abuse programming forced upon previous owners.
wink.gif
 
Originally Posted By: Ramblejam
If you delivered full available torque to that 4L60 (minimal tip-in management), what do you think would happen to durability?



Off the line in 1st gear...Probably nothing, 1-2 shift also. Though ALL torque is routed through the Forward Sprag that is known to "Wad" up.
The 2-3 shift & any Downshift from 3rd or 4th to 1st or 2nd at full tilt really needs Torque Management for the 3-4 Clutches to live.

I do agree with you, Most folks do not understand the massive Torque Rise available right off idle, And a "Bad" tune can hurt the transmission. A good tuner can give you better drivability buy modifying the TM tables & allowing the trans to live, Some just turn the TM off.....Not good.
 
I guess I'm lucky I was on the tail end for cable driven throttle bodies since my 02 Silverado 5.3L has a TB cable. Throttle response is wonderful off the bat, until its conservative gear shifting programming kills the fun.
 
Last edited:
In a drive-by-wire system, I think it may have to do with the programming in the ecu, or how linear the signal from throttle actually is. It is pretty common for potentiometers to not be nice and even in resistance, especially in a automotive environment. Most systems are running 2 pots, and averaging the signal controlling the throttle plate. As they drift, so does the throttle position.

They are not quite as predictable as a cable.
 
Just an FYI, most "throttle by wire" throttle bodies can actually move the throttle plate very quickly. It is the programming that is problematic.
 
Originally Posted By: Ramblejam
If you delivered full available torque to that 4L60 (minimal tip-in management), what do you think would happen to durability?



This is exactly the reason, and it can all be mitigated with aftermarket tuning. All the Toyotas I have driven were the worst for this.
 
WTLY

Nothing a few keystrokes with trusty EFILive and/or HPTuners software can't workaround.
I'm no computer guy but it's easy (and fun!) even for luddites.
smile.gif


Ironic how my 48 IDAs and Quadrajets feel so 'responsive' when properly tweaked.
But with the ever-present aroma of hydrocarbons wafting from their respective tailpipes.
 
I noticed the throttle response difference between the Yukon and Trailblazer. The Yukon feels so much more responsive. Just goes to show you the software makes a ton of difference.

A tune would fix that easy. PCMofNC does tunes for a good price and you can pick the shift firmness as well and everything else you want.

Also anyone with a 4L60E, for better 1-2 shifts the vette servo mod is awesome.
 
Can't be any worse than the Kia Rio I just had as a rental. At one point pedal input did absolutely nothing for what felt like an eternity... When I had to cross lanes in fast traffic.
 
I found Hyundai and Kia to be the worst, the tip in is real aggressive and after that the little engine doesn't have much more to give.
 
Sometimes with my Envoy, there is a lag when you floor it. Granted, I never floor my cars off the line, only at highway speeds when the engine's turning over 2,000 rpm.

When I had them, my '05 and '07 Grand Marquis' were particularly bad with TBW. The '07 was better, the '05 had issues corrected with a tune.
 
I drove a brand new Silverado about 4 months ago that had this problem. The one thing I always loved about GMs vs. Fords was that nice "smack" off the line. This truck did not have it.....at all. Maybe it's a CAFE thing.
 
I always figured it was torque management and emissions. Tip-in on my Toyotas is ridiculous, yet when you clutch the Camry it is slow to unwind. Sometimes I wish my Tundra was more "managed" like this, as it can be tough to feather the throttle when on dirt or snow.
 
Status
Not open for further replies.
Back
Top