Question about 1999 Chevrolet Silverado 1500

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Silverado 1500HD 6.0 idles rough ONLY when temperature outside is cold,around 40 and below. warmer outside temp no problems at all. replaced mass air flow after scanning computer. no codes are flashing. replaced whole fuel pump assembly 3 weeks ago including new pigtail,pump went bad. this idle problem has been going on long before pump went bad.

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Clean throttle body and air by-pass valve

Posted on Feb 04, 2010

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1500 tdci fusion 2007 very rough idle when cold runs sweet when warm temp sensor 23 degrees from cold and goes up normally to working temp had misfire on cylinder 2 injector replaced no change

problem hydraulic lifters will maintain a problem regardless if temperature
Most likely an injector problem caused by wiring to the injector , or connection at the ECM
may be moisture around the plug or in the distributor cap or indepentent coil

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2002 chevy silverado 1500 5.3 engine codes po 171 and 174 system to lean

Check the idle air control on the throttle body and the etc sw. by the thermostat outlet, it looks like a temp sw but sends a signal to the cpu on outside temp and how to mix fuel.

Jul 20, 2012 | 2002 Chevrolet Silverado 1500HD

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2003chevy pu dies at stop lights, low idle whats wrong?

yea id definately try cleaning ur throttle body 1st. My 03 1500hd had the exact same bad idle after my battery went bad it would die at lights unless i kept foot on gas i cleaned throttle body runs perfect now took 30min cost 8$ for cleaner at autozone and theres how to videos on you tube

Aug 13, 2011 | 2003 Chevrolet Silverado 1500

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2003 1500hd chevy silverado 6.0 liter. I had a

DTC Number
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Feb 17, 2010 | 2003 Chevrolet Silverado 1500

1 Answer

99 silverado wont start when below 35 outside when it hit 40 outside it starts and runs fine ????

First place I'd look is at the coolant temp sensor. If it's out of range the computer will not know it's cold out and therefore will not demand the amount of fuel necessary for a cold start.

Jan 21, 2010 | 1999 Chevrolet Silverado 1500

2 Answers

Engine idles rough for 90 seconds after restart when hot

sounds like the mass air flow sensor it is located on the air inlet try unplugging it and see if it runs better when it is running rough

Apr 09, 2009 | 1993 Ford Thunderbird

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In cold weather I get no oil pressure from the gauge,

You can Purchase a Built in Block Warmer for your Truck.

Jan 15, 2009 | 2005 Chevrolet Silverado 1500HD

4 Answers

2002 Silverado code PO174

After fighting with mine (2003 GMC 5.3 liter), I believe I have it solved. Mine was throwing P0171 and P0174. Also, there was an occasional p0101. I had a rough idle sometimes right when I started it, but usually after 5 minutes when the fuel system went in to closed loop mode (about 200 RPM swings at idle that slowly went away). Days below 10 degrees were much worse.

I cleaned the MAF sensor, checked fuel pressue, changed spark plugs, and cleaned the throttle body. The code basically means that more fuel is being dumped in by opening the fuel injectors longer. The code is set by the long term trim on the injectors be over 23% (opened 23% longer than they should be based on sensor readings). The extra fuel allows the engine to run with the right air to fuel ratio (not necessarily lean as the code suggests). Causes could be low fuel pressure (from pump, fuel regulator, clogged injectors, and such). Running a scanner on it for several days, everything looked normal.

That is all background. The other cause is that air is being introduced into the intake after the MAF sensor. Extra fuel has to be added for the air that the MAF does not see. I did some digging and found out that the gaskets between the plastic intake manifold and cylinder heads are prone to leaking. I tried to spray throttle body injector around where it might leak to monitor the engine speed, but the air leak seems to be less on warmer days and leaks can occur on the inside edge of the gasket where it is hard to reach with the spray (there are foam ends that open the inside edges to atmosphere). I replaced the gaskets and my long term trim dropped to about 6% from 10% on warmer days to pegged out at 25% on cold days with a cold engine. The work isn't too bad as long as you are patient enough to get the plugs off of the ignitors. I have yet to test it out in cold weather, but I am pretty confident.

Jan 06, 2009 | 1999 Chevrolet Silverado 1500

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