Lope on startup

[ved0303]

Hey everyone I am new to the forum. Things got pretty quiet at powerstroke nation so I'm hoping there is more action here!
Anyways, my '97 will lope on start-up almost every time, warm or cold. If you give it some throttle and hold it at a steady RPM for a few seconds then let off, it will then drop down to 450-500 rpm for a couple of seconds and then come back and idle normal for the rest of the drive. Any ideas what this could be? This is the only symptom. I have had the truck for almost two years and it has only started doing this in the last couple of months. It has a little over 200,000 on it. Any ideas? It is just really annoying right now and I am afraid it will eventually turn into a bigger problem...

 

[dm83]

Have you had any luck with finding the root cause of this problem? I am experiencing a very similiar issue.

 

[ghohouston]

Possibly the cps, or maybe the vss, bad icp sensor, I think I even read about a trans sensor on obs trucks causing lope on startup

 

[ghohouston]

Unplug your icp sensor and look for oil in the connector, if wet, its bad, replace the icp sensor, you also may try starting with the sensor unplugged and see if it goes away

 

[Patrick Feeley]

Are you running the Auto PCM with the ZF-5 speed? I've heard of some issues when doing that. With an auto trans truck, if you start the truck in neutral and it doesn't lope, it could be the Transmission Range Sensor. Cheers!

 

[ghohouston]

Are you running the Auto PCM with the ZF-5 speed? I've heard of some issues when doing that. With an auto trans truck, if you start the truck in neutral and it doesn't lope, it could be the Transmission Range Sensor. Cheers!

Thank you, trans range sensor is what I was thinking of

 

[Wes Lewis]

Sounds like it could also be the injector harnesses

 

[dm83]

Thanks for the input. Ill take a look at some of these ideas.

 

[ActionRick]

Try starting it in neutral if its an auto ...

 

[oneton]

are you running any tunes?

 

[ved0303]

So I ruled out the the transmission range sensor. I also changed the cps with no change. But the local Ford dealership was able to plug in their fancy machine thing and run some tests for free. They were not able to figure out the exact problem but they were able to rule out a lot of stuff, which was nice because a lot of the things they ruled out were the super expensive things... So I'm still dealing with the problem but at least I'm narrowing in. Hopefully this will help anyone else who might be having the same problem!

 

[yzrmbsg]

Mine does this in the cold, never had it do it when its warm, I think it may be due to glow plugs or hpop going out. Did your dealer rule those 2 out?

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