Conversions & Swaps LSX Engines in Non-LSX Vehicles
Sponsored by:
Sponsored by:

Apparent Throttle Response Latency

Thread Tools
 
Search this Thread
 
Old 09-23-2017, 10:46 AM
  #1  
TECH Regular
Thread Starter
iTrader: (1)
 
sprech's Avatar
 
Join Date: Feb 2014
Location: Metro Denver
Posts: 429
Received 5 Likes on 4 Posts
Default Apparent Throttle Response Latency

I'm just now getting the Firebird on the road and am trying to shake all of the weirdness out of it. What I have noticed is that there appears to be a latency/delay in depressing the throttle pedal and the engine revving. Is this normal or should I be trying to hunt down an issue?

Engine/PCM from 2003 Silverado SS which I believe is an E38, but don't recall off the top of my head.
Old 09-24-2017, 05:51 PM
  #2  
TECH Senior Member
iTrader: (7)
 
Project GatTagO's Avatar
 
Join Date: Mar 2003
Location: The City of Fountains
Posts: 10,166
Received 1,439 Likes on 908 Posts

Default

I am assuming this is DBW....if so, there should be ways to tune the throttle response.

Andrew
Old 09-24-2017, 06:45 PM
  #3  
TECH Junkie
iTrader: (1)
 
Michael Yount's Avatar
 
Join Date: Jun 2015
Posts: 3,108
Received 464 Likes on 350 Posts
Default

Throttle response should be crisp/clean -- all DBW's that I've driven, if you didn't know they were DBW, you couldn't tell in normal driving. So I'd say you have a problem you need to track down. Seems like most problems come from the pedal assembly being incompatible with the computer being used. Mine were matched - worked like OEM from first start.
Old 09-25-2017, 11:25 AM
  #4  
TECH Resident
iTrader: (56)
 
TomM's Avatar
 
Join Date: Feb 2009
Location: Baytown, Texas
Posts: 853
Received 27 Likes on 16 Posts

Default

Originally Posted by sprech
I'm just now getting the Firebird on the road and am trying to shake all of the weirdness out of it. What I have noticed is that there appears to be a latency/delay in depressing the throttle pedal and the engine revving. Is this normal or should I be trying to hunt down an issue?

Engine/PCM from 2003 Silverado SS which I believe is an E38, but don't recall off the top of my head.
Don't think you have the E38 in that year, I think they came out in 2007.......

Check for a vacuum leak all around, then go from there...

T,
Old 09-25-2017, 01:53 PM
  #5  
TECH Regular
Thread Starter
iTrader: (1)
 
sprech's Avatar
 
Join Date: Feb 2014
Location: Metro Denver
Posts: 429
Received 5 Likes on 4 Posts
Default

Originally Posted by Michael Yount
Throttle response should be crisp/clean -- all DBW's that I've driven, if you didn't know they were DBW, you couldn't tell in normal driving. So I'd say you have a problem you need to track down. Seems like most problems come from the pedal assembly being incompatible with the computer being used. Mine were matched - worked like OEM from first start.
The pedal is from the donor vehicle


Originally Posted by TomM
Don't think you have the E38 in that year, I think they came out in 2007.......

Check for a vacuum leak all around, then go from there...

T,
Will do.

Originally Posted by Project GatTagO
I am assuming this is DBW....if so, there should be ways to tune the throttle response.

Andrew
Yes, DBW.
Old 09-25-2017, 07:53 PM
  #6  
TECH Junkie
iTrader: (1)
 
Michael Yount's Avatar
 
Join Date: Jun 2015
Posts: 3,108
Received 464 Likes on 350 Posts
Default

Have you set yours up with a check engine light? I think a vacuum leak will light the CEL -- at least it does on mine (08 Corvette ECU). Have you pulled codes? And just to be certain -- did you pull the motor/ecu/pedal yourself?
Old 09-26-2017, 03:01 PM
  #7  
TECH Regular
Thread Starter
iTrader: (1)
 
sprech's Avatar
 
Join Date: Feb 2014
Location: Metro Denver
Posts: 429
Received 5 Likes on 4 Posts
Default

Originally Posted by Michael Yount
Have you set yours up with a check engine light? I think a vacuum leak will light the CEL -- at least it does on mine (08 Corvette ECU). Have you pulled codes? And just to be certain -- did you pull the motor/ecu/pedal yourself?
I believe the CEL was installed with the Dakota Digital VHX gauges via the OBDII. There currently is no CEL indicated.

I didn't do the motor pull, the shop that did it, does these a lot and I as told that it was the same pedal and it looked to be. That being said, I cannot guarantee it.
Old 09-26-2017, 03:38 PM
  #8  
TECH Junkie
iTrader: (1)
 
Michael Yount's Avatar
 
Join Date: Jun 2015
Posts: 3,108
Received 464 Likes on 350 Posts
Default

Given what sounds like just a hint of uncertainty about the presence of a functioning CEL (it should come on during ignition on and then go out once the engine starts) and a bit of uncertainty around pedal compatibility --- I'd pull the codes. I found it pretty easy on mine - a $9 wifi/blue tooth dongle and a free (or less than $20) app that not only gives you a ton of operating info but also usually lists codes and allows you to reset them.

On mine I discovered that the ecu compares what it's seeing via the mass air sensor to what it calculates using the Map/Bap sensor -- and if those two things don't mesh -- it sets a code/CEL. This enabled me to discover I had a slight air intake leak somewhere between the mass air sensor and the throttle body. Smoothed some inlet piping surfaces, greased elbows, tightened clamps, etc. -- and no more leak, no more CEL. A vacuum leak would, I think, set the same type of code. So -- seems to me that pulling codes is a reasonable next step to determining why the throttle response seems abnormal.
Old 09-26-2017, 08:25 PM
  #9  
TECH Regular
Thread Starter
iTrader: (1)
 
sprech's Avatar
 
Join Date: Feb 2014
Location: Metro Denver
Posts: 429
Received 5 Likes on 4 Posts
Default

I'll check it out. The CEL does illuminate when they key is in accessory position, but does not light up when running. I am pretty sure everything is toght on the intake side as I just reinstalled it (the issue was happening prior). I am not sure what the rules for the MAF are as far as location with respect to the air cleaner, distance from throttle body, etc. mine is probably 10" from the 90 to the tb and the air filter is hooked directly to it. I've seen differing info about location etc. I'll also have to double check on a vacuum leak in the system as well.

Thoughts on the tb servo not doing what it should to open the butterfly or is its operation pretty binary?

I'm actually looking at the Edge CTS2 for PID display. I had one in my F350 and really liked how customizable it was.



Quick Reply: Apparent Throttle Response Latency



All times are GMT -5. The time now is 11:05 PM.