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Engine unresponsive when cold.

928 Views 10 Replies 5 Participants Last post by  Farmer Z
Hey fellas, I got a bit of a problem here that I need a little help on. When my truck is cold, usually the first drive of the morning, the throttle acts very funny. It is unresponsive and bounces around. If I step on it hard enough the problem goes away. It only does this for the first few miles. It will usually start doing it around freezing or below.

Here is what I did today. When it was cold I left it in park and slowly pushed the pedal down. Then engine would start to climb, then stop climbing while I kept pushing, then it would jump to where it should be. It would climb normal, then maybe fall a little bit, climb up, pause again, maybe drop a little, then finally at about 2000 it seems to run fine.

But the odd thing is that if I leave it on the block heater or drive a few miles it works fine.

I hate to admit it, but I'm thinking the apps is going. It has a new vp44, lift pump, and injectors. What ideas do you have.

99 24 valve cummins
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Discussion Starter · #2 ·
by the way, this may be in my head, but when I pump the pedal before starting (wipe the pot). It seems to help. So that too leads me to possible bad apps. I also have the occasional TC lockup hunt, but normally cleaning the battery post fixes that.
 

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Discussion Starter · #4 ·
well I regularily check the codes. It hasnt thrown any for the apps. And I don't think it would because it just varies a little bit, it's not a full dead pedal, just enough to drop engine rpm. Is it common for an apps to do this or is it more common for them to flat out die? Why would the cold affect it?

Thanks again.
 

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my truck has been doing the same crap and gets worse the colder it gets!! i have been told a couple times that my edge causes this until it warms up?? i have no idea! but i have a 2 month old apps being my last one went out and its done it before and after so thats prob not your cause??
 

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Discussion Starter · #6 ·
Well I guess I can rule out the apps and you can rule out your chip because I don't have one. And I think we can rule out the vp44 since mine also did it after replacing it. I have a couple friends also with 24 valves that do the same thing. some people just say it's that engine, but I'd like to get down to the cause......mainly just because I can, haha.
 

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yea i too have heard of others doing this also! someone on here mentioned cleaning the map sensor which i havent done yet? prob get around to it this week? it may just be the nature of the beast? it seems to stop if i kick truck into high idle for 5 or 10 mins prior to driving!?
 

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Discussion Starter · #8 ·
Yeah my guess is some sensor. MAP or IAT, something that can be responsive to the cold that would give an immediate change in fuel delivery. It also needs to warm up very quick. The question is which one. ha.
 

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Unless Im missing something, sounds like you need to let it warm up before driving. Im sure you wouldnt want to hop out of bed and start running; well your cold engine doesnt like to either.

The little quirks you have may be just part of the VP itself. Let it warm up to normal operating temperature before you go doggin it.

If you do, then I dont know:hehe:

The rare times Ive started and gone, its doggy as hell and if I had to get it going it would be unresponsive then take off. Thats only happened MAYBE twice on each truck. I always let them warm up before I go anywhere
 

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If i get on the truck after 2 mins of normal idling(850rpm) the truck can act up especially the closer to 0F it gets, but if i run the high idle switches then the truck works fine, i let the truck idle away on 3 cylinder high idle till the truck's temp gauge starts moving past 140, usually its warm int he cab by then, but that is what i do.
 

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Discussion Starter · #11 ·
I found the problem fellas, thanks for the help. I replaced the apps and now she works beautifully. The cold was affecting the POT.
 
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