cold starts chevy k2500hd

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#1
Hello, I am the original owner of my k2500 HD. I'm an auto body and frame tech, so I'm somewhat knowledgable mechanically, and maintain my own vehicles. Truck is as follows 6.0 engine, 4L80 e trans, 4.10 rr axle. Mods are a K&N fipk2 installed at 25,000 mi, throttle body spacer installed at 25,000 mi, and a flowmaster muffler installed at 15,000 mi. It also has oversized tires. I bought the Hypertech power programmer to correct the speedo and also changed the shift too firmer and have had no drivability problems. since new I've only put in 89 oct gas. Truck has 90,000 mi on it now. Then in Nov 2006 at cold starts (40* and lower) truck would start easy and idle up but about 5 sec later the idle would drop to 200 to 300 RPM and engine would lobe. It never stalled and would always respond to the gas pedal. After it warmed up to temp, all is O.K. Eventually it threw a check engine light so using my Hypertech I retrieved the following P0300- misfire P0171 fuel trim lean bank 1 P0174 fuel trim lean bank 2. I changed the fuel filter (2nd one, first was at 40,000 mi) and cleaned the MAF sensor with maf sensor cleaner, then cleared the codes. Problem persists and lately the idle has been too high at cold start 1200 to 1300 RPM and hanging there until operating temp is reached.
 
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#2
I do not see the model year....

First step is fuel pressure....

Till we know that the suspects are the problematic K&N as well as the chip ,

A suggestion ... Have you done the old simple spray trick for a vacuum leak?
 
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#4
typical typical problem with K&N .... fouling up mafs....Lets work the p0300 code after the leam problem.

that being said, double check for a vacuum leak, I mentioned the quick easy spray trick, just spray some carb or brake clean at suspected vac leak areas....the engine RPM will change if you spray a leaking area.... next would be a fuel pressure reading gauges are available as loaners anrd rental at parts stores
there are no other codes p0171 p0174 and a p0300....no EGR codes??
 

EricC

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#5
Adding to what Kev said, make sure when spraying it down pay special attention to the intake gasket sealing surfaces. Should you find the intake gaskets leaking, make sure to replace them with OEM teal colored gaskets, not the orange ones.
 
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#6
I did the spray test and no problem was noticed. Ialso cleaned the IAC valve which proved no difference either. do you s know how the PCV valve works on my engine in the Chiltons manual it is not as specific with the heavy duty series. There is a tube that runs from the driver side valve cover to the top of the intake but it does not seem to have anything in it, I took this off to inspect it. Since i'm almost at 100,000 mi im going to flush the cooling system and maybe change the cooling temp sensor. Could this be the TPS that is causing my prob or would that only matter when the gas pedal is touched. Thanks for the help if you think of anything else please post ill keep digging also.
 
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#8
:eek: fixed Well B4 I could get too check fuel pressure or change coolant temp sensor, she quit on me while on my way to work last week. Now being forced to find the problem, no fuel pressure, no problem at the regulator, all fuses good and no electrical issues the problem was.................. Fuel pump. retail $450. and 2 hours of actual R&I and were up and runnin' |:| Thanks guys.