02 Yukon Denali

Everything involved with getting to the track and working in the pits

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02 Yukon Denali

#1 Post by Ls7camaro » Tue Dec 04, 2012 8:22 pm

I have a question. What should an 02 Denali be idling at? Its a 6.0 and has been surging and stalling. My wife drives the yukon to and from work, since its not even 2 miles a day. The fuel pump went out about a month ago. I changed that and the fuel filter. I took all the engine covers off and replaced the PCV valve and the hoses connect the PCV to the plastic pipe and the pipe to the intake. Last year I put on taylor wires and NGK I think TR5N plugs. I just had the battery tested and put a Duralast gold from AZ in. I also put a cold air kit on. I just cleaned the Mass Air Sensor, but need to clean the throttle body yet.

There are no codes kicked off, it just stalls when she gets to a stop sign. Its idling about 500 now since I changed the PCV and hoses and cleaned the Mass air sensor.

If there are any other tips on getting the fuel mileage up, I sure would appreciate it. I am going to use this as the vehicle to tow my car to the track, I towed my dad's nova and my neighbors 74 chrysler and this truck had no problem pulling it.
I can't wait for race season, this has got to be the year.

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Re: 02 Yukon Denali

#2 Post by ytnova » Wed Dec 05, 2012 8:24 am

A couple of things. Was it having idling issues before you did anything? What brand pcv valve did you use? This is a calibrated vaccum leak, something other than a ac delco may cause issues. Next, you said you cleaned the maf sensor, with what? Anything left on the maf wire inside will lead to incorrect readings, this would include over oiling a k&n style filter. A scan tool watching the grams per second helps, stable at idle and should increase steadily with rpm, no dips if you can graph it. I would also recommend that you clean the throttle body, some throttle body cleaner and a old tooth brush works great. While you are at it, pull the IAC motor from the throttle body and clean the end of it and the seat it rest on, like a needle and seat, both usually are covered with carbon. If you are still having issues, IAC motors have a tendacy to stick or are slow to respond. IAC motors are used to control idle speed, basically a needle and seat air bypass around the throttle blades to control the idle, once you are driving(throttle blades open) they usually close on the seat. When the throttle blades close, the valve opens, allowing air into the engine to idle. I do not remember if that year has a feedback IAC so the PCM knows the IAC position, but if it does, using a scan tool to compare the position of the IAC with the commanded position will tell you if it is sticking. This is one of the reasons most manufacturers have gone with drive by wire, the PCM can now control the throttle do many functions from cruise control, idle speed, closing slightly for EGR flow, closing slightly for EVAP flow, etc. Hope this helps-ED
I am not really sure what the question is, but I am pretty sure the answer is Big Block.

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