1997 7.3 PS - acceleration lag
Thread Starter
|
New User
Joined: Nov 2012
Posts: 7
Likes: 0
1997 7.3 PS - acceleration lag
I had something a little strange happen yesterday and today.
I was stopped at an intersection, took my foot off the brake and hit the accelerator, nada, truck was in gear and engaged moving forward very slowly but zero rpm change. Just nothing, then after about 5-10 seconds it hit and the the RPMs went up and away I went. This kept happening at every stop. Between stops it kept at a constant RPM and no issues. It seemed like every time I hit the brake it killed the accelerator and it just stopped working. I confirmed this later on the freeway when someone cut me off and I had to hit the brakes hit the accelerator to go around and nothing.
I've had some strange electrical issues with fuses controlling my shifting etc. So my first thought was that I have a bad accelerator switch/sensor. It's not stalling, it stays idling at a constant so I'm pretty sure it isn't the CAM sensor.
I had it on the back tank and decided to switch it to the front and it stopped, I switched it back to the rear tank and it hasn't done it again but I'm just waiting for the other shoe to drop. Is there a chance that this has something to with the tank switch? I'm having trouble believing it's that easy. Any ideas?
I was stopped at an intersection, took my foot off the brake and hit the accelerator, nada, truck was in gear and engaged moving forward very slowly but zero rpm change. Just nothing, then after about 5-10 seconds it hit and the the RPMs went up and away I went. This kept happening at every stop. Between stops it kept at a constant RPM and no issues. It seemed like every time I hit the brake it killed the accelerator and it just stopped working. I confirmed this later on the freeway when someone cut me off and I had to hit the brakes hit the accelerator to go around and nothing.
I've had some strange electrical issues with fuses controlling my shifting etc. So my first thought was that I have a bad accelerator switch/sensor. It's not stalling, it stays idling at a constant so I'm pretty sure it isn't the CAM sensor.
I had it on the back tank and decided to switch it to the front and it stopped, I switched it back to the rear tank and it hasn't done it again but I'm just waiting for the other shoe to drop. Is there a chance that this has something to with the tank switch? I'm having trouble believing it's that easy. Any ideas?
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
It sounds like your IVS is going bad. There are two devices on the accelerator pedal. On is a throttle position sensor (TPS) that tells the engine computer (PCM) how far you're pushing the pedal down, and the other is an idle validation switch (IVS). If the IVS isn't opening and closing like it should, the PCM will ignore the TPS signal and leave the engine at idle. It could be as simple as an adjustment, but I think you probably need a new IVS. You could install a jumper to test the theory (Bypassing the IVS) but I would only do that as a test and I wouldn't advise leaving it overridden. That switch is the safety that stops the truck from running away if there should ever be a problem with the TPS.
I had a truck at work that did this once and pumping the accelerator would un-stick the switch for a while. You have to let the pedal rise to the top of its stroke, but opening and closing that switch repeatedly may get the contacts to make and solve the problem temporarily.
I had a truck at work that did this once and pumping the accelerator would un-stick the switch for a while. You have to let the pedal rise to the top of its stroke, but opening and closing that switch repeatedly may get the contacts to make and solve the problem temporarily.
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
It sounds like your IVS is going bad. There are two devices on the accelerator pedal. On is a throttle position sensor (TPS) that tells the engine computer (PCM) how far you're pushing the pedal down, and the other is an idle validation switch (IVS). If the IVS isn't opening and closing like it should, the PCM will ignore the TPS signal and leave the engine at idle. It could be as simple as an adjustment, but I think you probably need a new IVS. You could install a jumper to test the theory (Bypassing the IVS) but I would only do that as a test and I wouldn't advise leaving it overridden. That switch is the safety that stops the truck from running away if there should ever be a problem with the TPS.
I had a truck at work that did this once and pumping the accelerator would un-stick the switch for a while. You have to let the pedal rise to the top of its stroke, but opening and closing that switch repeatedly may get the contacts to make and solve the problem temporarily.
I had a truck at work that did this once and pumping the accelerator would un-stick the switch for a while. You have to let the pedal rise to the top of its stroke, but opening and closing that switch repeatedly may get the contacts to make and solve the problem temporarily.
What he said ^^^^^^^
It's your IVS (idle validation switch) on the go peddle. With your foot off the go peddle the IVS is actuated telling the PCM your foot is not on the peddle and to, just idle. If you push on the go peddle and the IVS does not disengage the PCM will ignore the TPS (throttle position sensor) and continue idling. If you look down there you will see a push button type switch, that's the IVS. You can also push the go peddle by hand and hear the switch actuate / De-actuate. They get dirty down there by the floor so just clean it up a bit and the problem will probably go away.
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
If i recall correctly Ford has discontinued the part, but this one is reported to fit the bill as a direct replacement. Get it while you can, the quantity is limited.
SS22BW32-330Y CUTLER HAMMER/EATON | Buy SS22BW32 330Y | Onlinecomponents.com
SS22BW32-330Y CUTLER HAMMER/EATON | Buy SS22BW32 330Y | Onlinecomponents.com
Post Fiend
Joined: Dec 2009
Posts: 15,505
Likes: 18
From: Livoina,La
Trending Topics
Thread Starter
|
New User
Joined: Nov 2012
Posts: 7
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Thread
Thread Starter
Forum
Replies
Last Post
plgebbia
1999 - 2003 7.3L Power Stroke Diesel
22
Jul 12, 2013 10:54 AM