2003 Yukon engine idles too low and dies

[Monsolo]

Had no problems except for the engine running a bit rough on my 2003 Yukon XL so I decided to tune her up (123k miles). Bought plugs, wires, PCV valve, air filter, and fuel filter. Changed all but the fuel filter the first day. Took it out and ran her around the neighborhood... holy cow, she was smooth as silk!

Here's where it gets interesting... the second day I de-pressurized the fuel system according to the Haynes manual and got up underneath her to change the fuel filter. Found out that the fuel filter I bought was the wrong kind... wife had to use the Yukon that night so I popped the relay back in, connected the battery, and off the wife went. She calls me later to tell me the Yukon is stalling every time she makes a turn after decelerating. So, the third day I got the right fuel filter, de-pressurized the fuel system again, and changed it. Got into the Yukon and took her around the neighborhood only to have it stall the same way as the day before! Took it to Autozone to have the codes checked but there weren't any. When I decelerate, the engine idles down to around 200rpm and then, when I put an additional load on the engine by turning the wheel, it finally stalls out. It stalls even more frequently, like when I just come to a stop, when I have the climate control system on and the compressor is active.

Also, when you give the engine gas, it goes like a bat out of heck. There's no problem accelerating or, once the idle smooths out, sitting still and idling. It's only during the deceleration that the engine falls to the low rpm and hesitates. Then, if given a little time, it goes right back up to normal idle and everything is fine.

I really need help asap, please! Thanks!

 

[adamabt]

i had this recently happen to my 2003 Tahoe. My mechanic could find nothing when he plugged in a code scanner. I Googled the issue and was directed to a youtube video of a guy using throttle body cleaner to flush out his throttle body to curer a similar issue on his Silverado. For less than 5 bucks and less than an hour i gave it a shot. My idle is now stable, i don't stall and the acceleration is remarkably better....worth a shot!

 

[Oger]

I know this is old, but I have had the same issue, and I am sure you found out by now. These older vehichles seem to take forever to remember how to idle smoothly after removal of the battery.

 

[blackdiamond]

battery disconnect shouldnt cause that problem unless you had it disconnected for a long time or accidentally grounded the pos wire and the af miixture is on a closed loop system when its cold so the idle should not be affected. I would start by seeing if it has any codes.. it probably wont... Then look for a ruptured Fuel pressure regulator. pull the vac line off immediately after shutting the vehicle off and look / smell for any signs of fuel in the vac line or in the regulator port itself. it shouldnt smell like fuel. if it does replace it.

 

[blackdiamond]

Then ck fuel pressure.

 

[04TahoeJeff]

Sounds exactly like throttle body cleaning is needed. Go buy a can of the liquid Sea Foam and a can of spray Sea Foam. I like introducing the liquid through the vacuum liine off the brake booster. The spray can usually comes with an adapter to make it easy to introduce the sea foam in through the throttle body intake. I do both and routinely pour a can in the gas tank. No joke, I bet this fixes your problem. Poor and rough idle are number one signs throttle body needs cleaning. Mine wouild idle very low and if you turned the sterring wheel it would kill the motor. If the throttle body cleaning doesn't help with the idle I say its your IAC. Idle Air Control sensor. You can clean it too but be delicate with it. Use only electrical contact cleaner on it. The throttle body cleaning should smooth it out and make it responsive just like new.