Help! Sags and Surges after APPS and FCA replacement.
09-25-2013, 06:19 PM
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Help! Sags and Surges after APPS and FCA replacement.
Hey guys, I thought I did my homework on this one.... guess not!
Just a few days ago, I noticed a slightly sluggish "sag" or "cutting out" almost as though I let up on the accelerator pedal slightly. Then in a couple of days it got more pronounced. Normally, not enough to move the tach more than 50-100 rpms.
Checked for codes:none.
I returned to factory settings (Smarty back to stock, and MP-8 all the way down) and see no change than when running the Smarty.
I read up on others that had [what I thought was] the same problem. It looked like a strong possibility I had a bad FCA and/or a TPS. So, I got them both on the way with the APPS arriving first.
I installed the APPS and saw no difference then the FCA arrived the next day, so I installed it this morning, just sure that I was good to go. NOPE!
Still there. Still sagging/surging almost like it loses fuel for a sec or two, then right back to normal. Does not seem to be terribly speed (mph) or rpm specific.
I am not getting any rpm spike like I would guess would happen with tranny slippage, nor any "hunting" for gears nor high revving like I read some others have...
Any Ideas?
Just a few days ago, I noticed a slightly sluggish "sag" or "cutting out" almost as though I let up on the accelerator pedal slightly. Then in a couple of days it got more pronounced. Normally, not enough to move the tach more than 50-100 rpms.
Checked for codes:none.
I returned to factory settings (Smarty back to stock, and MP-8 all the way down) and see no change than when running the Smarty.
I read up on others that had [what I thought was] the same problem. It looked like a strong possibility I had a bad FCA and/or a TPS. So, I got them both on the way with the APPS arriving first.
I installed the APPS and saw no difference then the FCA arrived the next day, so I installed it this morning, just sure that I was good to go. NOPE!
Still there. Still sagging/surging almost like it loses fuel for a sec or two, then right back to normal. Does not seem to be terribly speed (mph) or rpm specific.
I am not getting any rpm spike like I would guess would happen with tranny slippage, nor any "hunting" for gears nor high revving like I read some others have...
Any Ideas?
09-25-2013, 07:57 PM
#2
Cummins Guru
I would check the valve cover gasket wiring to the injectors first. Could have a bad connection if you still have the original gasket then replace it. Not a question of if it will fail but when it will fail. Have not seen any of the new updated gaskets fail yet. To check wiring connection I usually cut the plastic ties holding the wire to the gasket then the wire will come right off from the spot weld connection if the spot weld has failed. Ohm test will also show higher resistance in the wiring.
09-26-2013, 06:29 AM
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BigIron70, I did not realize the valve cover gasket was part of the wiring harness for the injectors. I was aware of such on older 7.3 Powerstrokes. I will check it out.
09-27-2013, 05:35 AM
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I had surging while driving down the road and replaced my apps to no avail. I found this link to trouble shoot the apps and found that my ECM connection was wet and causing issues.
http://articles.mopar1973man.com/3rd...the-app-sensor
http://articles.mopar1973man.com/3rd...the-app-sensor
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