Rough idle/low power untill the engine warms up

1169 Views 7 Replies 4 Participants Last post by klhansen, Feb 14, 2009

jas504on

Discussion Starter · Feb 13, 2009

My truck will start and run rough untill the engine is completely warm. I can start the truck in the morning and take off and floor it and only get 1000 rpm's and I have to baby it to warm it up or it will die. I have to sit in park and rev the engine up and hold it just below 1k but do not let off because it will die for sure. This started about a month or two ago when the weather kind of changed where I live. But we just had a good 3 or so days of 70 degree weather and it still did the same thing. I had one person tell me it was normal due to the cold ambient pkg(CAP) and the exhaust back pressure valve (EBPV) being that when the engine oil is cold the valve will close in the exhaust the build up pressure in the engine to warm up faster. If this is the case then why did it do it when I had my truck sit in 70 degree weather for 4 days or why woudl it do it after the truck was running for awhile then I let it sit for 6 hours and it does it again? Does anyone know how to fix this problem? I am at the point where I have to let my truck warm up for like 30 mins and I can not let it warm up on its own or it will die. I have to sit in it and baby it for the first 10 mins or so and then I can let it idle to warm up. Anyone?????

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klhansen

· #2 · Feb 13, 2009

Sounds like you may have an injector or two that don't like being cold. If one hangs open, the HPOP may not be able to keep up with the HP oil demand to run the rest of the injectors, causing the rough running.

First thing to try is an oil change. These things are sensitive to oil condition.

If that doesn't help, get someone to pull codes, and you might also consider taking it to someone who could check the cylinder contribution when cold, using a scan tool that can display the PERDEL for each cylinder. Or you could pull the valve covers, and take a look at the oil coming out of the injector spouts when it runs cold. If one dumps more than the others, or doesn't dump any at all, that would be your suspect injector.

Good luck

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klhansen

· #8 · Feb 14, 2009

Yep, Low oil would definitely do that.

The thicker cold oil would take longer to run back down and refill the pan, causing the LPOP to suck air, which doesn't make a hydraulic system do very well. Glad you found the problem. But you either need to find what's causing your oil consumption (turbo seal leak - either intake or exhaust side?, excessive blowby?) or check the oil level more frequently.

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