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Rough idle then dies


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I have a 1999 cummins. Once the engine has already been warmed up if I go to start it sometimes it starts a very lopey idle, which stumbles on for a few seconds and then dies. I was showing a bad tps error code. I have replaced that and no longer have the check engine light on. My wait to start light sometimes takes a while to come on, but that has been that way for several years. I have a FASS lift pump installed and I can hear it running. After sitting for a few hours to cool it will start up. Help please

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It was doing this before I installed the new tps, which I got from TMB service or Tims. I just went outside and tried to start it and it began to do a runaway, was able to turn the key off before it past 2000 rpm. Tried to start it again after and same lopey idle for about 5 to 10 seconds and then stalls

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Did you follow instructions and got it set at certain voltage and then had your batteries disconnected for at least half hour and then with key on slowly press acc pedal and depress slow shut key off and do that two more times and then start? Do a proper adjustment of new sensor and reset and see if it helps, if not maybe other issue, crank or cam sensor etc.

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Sounds like there is still a APPS issue. Like Alex said earlier, double check what the voltage signal is and make sure it is correct. There should have been instructions with your new APPS to set the voltage correctly. You might also try the reset procedure and see if it makes much of a difference.

 

What is your fuel pressure both at idle and WOT? Just trying to help rule some other things out.

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It's only doing this when it's already warmed up. The new tps was installed correctly. I don't have a fuel pressure gauge but the fass pump is running good. When it's cold it starts right up and drives fine with no error codes. Once warmed up it will not start and remain running. My EGT gauge ticks on and off in time with the lopey idle of the engine. It's as if it's being turned on and off, but a couple of times a second.

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Timbo's APPS doesn't have a voltage to set. You can mount it and do a APPS reset be good to go. The adjustment process only for taking slack out other than that it has no bearing on the performance of the Timbo's APPS sensor.

 

As for diagnostics for the rough idle and dies.

 

  • What is your fuel pressure at idle and WOT at highway speeds.
  • Any error codes present? Check with OBDII reader.
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Timbo's APPS doesn't have a voltage to set. You can mount it and do a APPS reset be good to go. The adjustment process only for taking slack out other than that it has no bearing on the performance of the Timbo's APPS sensor.

 

As for diagnostics for the rough idle and dies.

 

  • What is your fuel pressure at idle and WOT at highway speeds.
  • Any error codes present? Check with OBDII reader.

 

 

When I did my Timbo, it came with instructions on how to set the voltage by back probing the signal wire. I think I still have the instruction sheet it came with. I can post up the specs if you want. 

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  • 4 weeks later...
  • I don't have a fuel pressure gauge, but I can hear the fass pump running when it is doing the lopey idle. No error codes are coming up on my obd scanner but the check engine light does come on. A couple of times when it has done this I have been able to get it to start by plugging in my scanner and pressing the red button to clear any codes ( eve though it shows zero codes ) and then it will start. This doesn't work every time though.
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