Throttle Pedal Becomes Unresponsive
Thread Starter
Teching In
Joined: Oct 2017
Posts: 6
Likes: 1
Throttle Pedal Becomes Unresponsive Motor is on an engine stand. I can start the motor, if I play with the throttle it's all good but couple seconds after letting off the throttle, the throttle becomes unresponsive and idle gets rough, going into limp mode. It's a DBW, I switched out the TAC Module and throttle body and same thing. What do you think is causing this? Thanks.
Launching!
Joined: Aug 2015
Posts: 206
Likes: 11
From: Duvall, WA
Second on checking for codes.
There is some kind of logic in the DBW ECU which checks that the power it thinks the ECU is making roughly correlates with what it should be making based on the throttle position. If the difference is too large, it will lock the throttle in the "park" position until you key-cycle it, because it thinks there is a potentially dangerous DBW malfunction. It could be that. It could also be a lot of other things.
There is some kind of logic in the DBW ECU which checks that the power it thinks the ECU is making roughly correlates with what it should be making based on the throttle position. If the difference is too large, it will lock the throttle in the "park" position until you key-cycle it, because it thinks there is a potentially dangerous DBW malfunction. It could be that. It could also be a lot of other things.
Last edited by lemming104; Apr 7, 2020 at 02:58 PM.
Staging Lane
Joined: Oct 2015
Posts: 89
Likes: 3
From: Northern Idaho
Second on checking for codes.
There is some kind of logic in the DBW ECU which checks that the power it thinks the ECU is making roughly correlates with what it should be making based on the throttle position. If the difference is too large, it will lock the throttle in the "park" position until you key-cycle it, because it thinks there is a potentially dangerous DBW malfunction. It could be that. It could also be a lot of other things.
There is some kind of logic in the DBW ECU which checks that the power it thinks the ECU is making roughly correlates with what it should be making based on the throttle position. If the difference is too large, it will lock the throttle in the "park" position until you key-cycle it, because it thinks there is a potentially dangerous DBW malfunction. It could be that. It could also be a lot of other things.
TECH Enthusiast
Joined: Sep 2005
Posts: 618
Likes: 3
DD cruise... I have that exact same problem, ECU and DBW senses a difference in voltage and shuts down the throttle. In my case, it is caused by a Dakota Digital cruise control. Throttle only shuts down when cruise is engaged. I just need time with a mutli-meter to figure out where the problem is. I just hate working under the dash.
.
One of the things that both DD and Rostra said I needed to do was hook the ground from the cruise to the same ground in the harness that hooks in the throttle harness.
Also they were very emphatic about the quality of the grounds. A DD tech sent me instructions about how to do voltage drop tests on each ground.
I did all of that as well as remove all connectors from anywhere in the cruise worrying and replace with soldered connections.
The cruise worked much much better than every. No surges.
But after a couple months it happened again. I have yanked the DD and replacing with one that does not hook through the pedal wiring. In middle of that install so I can't report how it's working out yet.
Thread Starter
Teching In
Joined: Oct 2017
Posts: 6
Likes: 1
I was later told because I don't have all the sensore installed, the ECU is not reading the right information so it goes into limp mode and shuts the throttle down. I am in the process of trying to connect the sensors. The hard part is hooking up the O2 sensors. I only have the exhaust manifold, no where to put the O2 sensorrs.
TECH Enthusiast
Joined: Sep 2005
Posts: 618
Likes: 3
That sounds about right. Typically those sensors are in the exhaust pipe right after the header collectors.
Is there a reason you want it need to do this on an engine stand?
The buns for oxygen sensor are easy and inexpensive to come by. If you really want to run it on the stand you could have a muffler shop make you exhaust piped that drop down and weld O2 buns on to put the sensors on. I have no idea how viable that would be.
Is there a reason you want it need to do this on an engine stand?
The buns for oxygen sensor are easy and inexpensive to come by. If you really want to run it on the stand you could have a muffler shop make you exhaust piped that drop down and weld O2 buns on to put the sensors on. I have no idea how viable that would be.
