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high rpm's on start up and lope idle cold
Ill try and include as much information as I can, but this could get long so I'll apologize in advance. The story starts all the way back in the fall when the temps started to drop, and on a cold start in the morning the truck would start normally, but when it started it seemed like it started at 1100-1200 rpm's then would drop back down and settle into a normal low idle. I didn't think too much of it due to the weather turning cold, and I figured the truck was giving it a little more juice to get it to flash up. Shortly before this all started to happen I switched to 0w40 syn oil. A couple thousand km later it started having a random fuel knock on a cold start. I watched it with a scanner showing the balance of each cylinder and it couldn't isolate it to any specific hole. It would still start with it's "normal" roar, then would have this random knock for a minute or two, then run normally the rest of the day. Flash forward to the new year when I blew the head gaskets. I tore it apart and found the number 8 injector lower o-ring was torn. I thought this might be my issue with the high rpm's on start up. During the cylinder head job I also sent my ficm into ed at ficmrepair.com (steller guy by the way) where he switched me out with a 4 pin and uploaded a PHP atlas 80 tune. When it was all up and running the roar at start up still existed but the random fuel knock was virtually gone. You can still hear it a little bit after a long cold soak when its not plugged in. This is Canada, it's cold. So when I say cold I mean like -25 ish (degrees C). I chalked the little bit of random fuel knock up to the cold weather, the fact that my truck has alot of miles, and my sheer laziness to no go out and plug it in. Aside from this, it ran top notch. The PHP tune in my ficm made it run sweet. It was smoother, quieter, and had a noticeable increase in power as well as the extra cash left in my wallet after I hit the fuel station. Overall, totally impressed...until last week.
One morning last week I went out to start up the truck. It was like -10, not too bad. Always started great in worse temps before so i didn't plug it in the night before. Anyways, started, sounded great, ficm voltage 49, perfect, back in the house I go. 5 minutes later I heard it go into a big lope like it was going high idle, low idle, high idle, low idle. I went out and hit the brake pedal thinking my high idle was messed up and it returned to a normal smooth low idle so I didn't think too much of it and went about with my day. A few mornings later it did the same thing, only this time I hit the brake and nothing happened, it wouldn't stop. I rev'd it up and it rev smooth but when returned to idle it only came down to 1000 rpm. No lope now, but nothing I could do short of putting it in gear could get the rpm to drop below 1000, and slowly over time it was actually creeping up.
Now it is doing it virtually every morning. Starts with a roar, comes to a smooth low idle, then after like 2 minutes of sounding like the best idling powerstroke you have ever heard it goes into a crazy lope and idles at any rpm it feels like. Today it finally threw me a code. P0148. I did a little research into it and see that it's a fueling issue and could potentially be the pcm. I spoke with ed at ficm repair and he has been helpfull, I just wanted to see if anyone has run across a issue with PHP or other ficm tunes. The thing thats boggling me is that it idles normally at first, then goes nuts.
Other helpful information;
Stock PCM tune
Ficm PHP atlas 80
Ficm voltage always 48+ volts
no faults other then p0148
stock injectors ( no real performance mods other then intake/exhaust)
Only seems to happen first start of the morning when cold (ECT less then 50)
Plugging it in makes problem go away
new fuel filters
Fuel press 65 low idle 63 high idle
ICP/IPR both new in last 2500 km
ICP sensor not oily and connector is new/dry
Anyone ran into something like this before?