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View Full Version : 2003 Yukon engine idles too low and dies


Monsolo
07-09-2011, 08:51 PM
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.

Any ideas what the heck is going on? I need help please! Thanks! :(

Monsolo
07-10-2011, 12:44 AM
Anybody want to take a crack at the problem? I could really use some help!

Thanks!:D

Monsolo
07-10-2011, 09:17 AM
By the way, thought I'd add that 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.

Thought I'd throw that in...

Monsolo
07-10-2011, 05:10 PM
Well, since nobody wants to comment, I'll keep on plugging away at it. :) I'm going to try and clean the MAF sensor and see if that's contributing to the low idle. It has been quite a while since the air filter has been replaced and the MAF is right next to the filter... so maybe that's some of the problem. Anybody ever experience a low idle/stall issue and had a dirty MAF sensor?

happy 2011
07-10-2011, 08:26 PM
Well try removing the battery cable or the pcm fuse. This will reset the pcm and quit pos it will fix your problem. If not then you may want to remove and clean your IAC motor (idle air control). Let me know what happens

Monsolo
07-10-2011, 10:15 PM
Happy, thanks for the response. However, I think my problem is worse than I thought! While driving the Yukon home tonight, it started refusing to shift to third from second. Right before it should shift to third it would shudder a bit and then the engine would race to 4500rpm as there was suddenly no load. Is it possible that a failing transmission could cause an engine to idle erratically and stall? Looks like my problem is not the engine but the transmission... I just don't get how suddenly all this trouble has popped up! I think I'm just going to take her to the dealership and bite the bullet. Can transmission and engine problems be caused by a confused ECM that needs to be reset???

Monsolo
07-10-2011, 11:52 PM
Update: Just went out and checked the transmission fluid... was a quart and a half low. Still no change in the shifting issue. It's now refusing to shift into third altogether... the engine just revs very high. Bummer...:confused:

Monsolo
07-12-2011, 09:28 AM
Well, getting the transmission rebuilt. Should have it back by Friday. We'll see if the original idling problem goes away... :rolleyes:

happy 2011
07-12-2011, 05:06 PM
most likly it will fix your idling problem too. Sounds like the trans was staying in look up and that would stall the motor every time.

good luck

Monsolo
07-21-2011, 05:23 AM
Ok, everyone, I'm back! :D Got the tranny rebuilt... she shifts smoothly now! Anyway, still same idle problem... :mad: Here's what the tech over at the tranny shop told me... see if any of you guys have heard this: he said that the 2003's (and maybe other years) were notorious for the ECM's "losing" the idle speed settings when the battery was disconnected for a lengthy period of time, usually over an hour or two. Apparently, it can take up to fifty or so restarts during normal driving for the ECM to "re-learn" the correct idle position. He also said the dealership can fix the problem quickly, if I didn't mind paying them an arm and a leg, or I could just let it sort itself out. Now, in his defense, you'll notice in my previous posts that my idle problem didn't show up until after I had left the battery disconnected for about an hour to try to change my fuel pump. So that much rings true... has anyone ever heard of this explanation or is he full of hooey?

Molson02536
07-21-2011, 05:51 AM
Ok, everyone, I'm back! :D Got the tranny rebuilt... she shifts smoothly now! Anyway, still same idle problem... :mad: Here's what the tech over at the tranny shop told me... see if any of you guys have heard this: he said that the 2003's (and maybe other years) were notorious for the ECM's "losing" the idle speed settings when the battery was disconnected for a lengthy period of time, usually over an hour or two. Apparently, it can take up to fifty or so restarts during normal driving for the ECM to "re-learn" the correct idle position. He also said the dealership can fix the problem quickly, if I didn't mind paying them an arm and a leg, or I could just let it sort itself out. Now, in his defense, you'll notice in my previous posts that my idle problem didn't show up until after I had left the battery disconnected for about an hour to try to change my fuel pump. So that much rings true... has anyone ever heard of this explanation or is he full of hooey?

IAC should have been reset by now, Try this, turn the ignition on (engine not running) for 15 Seconds and then off for 5 seconds and then turn the ignition on again for 15 sec and then try to start the engine. This should reset the IAC.

Keep me posted and we can move on to plan B if this does not work LOL:D

Monsolo
07-21-2011, 11:22 AM
Thanks for the tip, Molson! I just got on here after lunch so I didn't see this post until after I tried another suggestion someone else gave me before lunch. I went out and disconnected the battery, waited 3-minutes, reconnected the battery, turned off all accessories that would create any kind of load (AC, radio, etc.), and then started the engine and let it idle for 10-minutes. Well, that did absolutely nothing... :cool:

So, I'll try your suggestion when I get home... :o

Monsolo
07-21-2011, 01:10 PM
Molson, thanks for the tip! I didn't read this forum until after lunch here at work today but I'll share what I did at lunch to try and fix the problem. Another tech said to disconnect the battery, let it sit for 3-minutes, reconnect the battery, turn off all accessories that create a load (AC, radio, etc.), start the engine, let it idle for 10-minutes, shut it down for a few minutes, then fire it back up again and run her around town for a bit. Well.... did all that and it was a big dud! :confused:

So, Molson, I'll try your advice tonight. I'm also going to take the advice of another forum member by taking both cables off the battery and connecting them together (off the battery, of course) in an attempt to "short" the computer... sort of like what's done on a PC motherboard to reset the EPROM back to factory defaults and get rid of any bad settings. At this point, I'll try anything! I'm hauling a camper next weekend and I do not need this headache! :mad:

Monsolo
07-21-2011, 01:18 PM
Happy, just went back and re-read your post and it looks like what the other forum guy is telling me is similar to what you're saying to do. I'll go one step further and remove the PCM fuse like you suggested and see if the combination of everything helps to reset the computer. :D

Molson02536
07-22-2011, 05:08 AM
So, Molson, I'll try your advice tonight. I'm also going to take the advice of another forum member by taking both cables off the battery and connecting them together (off the battery, of course) in an attempt to "short" the computer... sort of like what's done on a PC motherboard to reset the EPROM back to factory defaults and get rid of any bad settings. At this point, I'll try anything! I'm hauling a camper next weekend and I do not need this headache! :mad:

This should help you get your 5.3 running 100% again soon i hope.
Good luck and keep us posted. ;)

If you have a throttle cable actuated throttle body, the following bulletin applies.
If you have a "drive by wire" TB then just remove the air duct and clean the TB and blade with a quality choke cleaner and a soft tooth brush.
Removing the IAC is not necessary.
The condition is caused by dirt build up on the TB bore and blade


Increased Accelerator Pedal Effort, Idle Instability (Clean Throttle Body and Adjust Blade) #02-06-04-054B - (03/17/2003)
Table 1: TPS Voltage Chart
Increased Accelerator Pedal Effort, Idle Instability (Clean Throttle Body and Adjust Blade)
1999-2002 Chevrolet Silverado

2000-2002 Chevrolet Suburban, Tahoe

2002 Chevrolet Avalanche

1999-2002 GMC Sierra

2000-2002 GMC Yukon, Yukon XL

with 4.8L or 5.3L V8 Engine (VINs V, T, Z -- RPOs LR4, LM7, L59)

This bulletin is being revised to add condition information. Please discard Corporate Bulletin Number 02-06-04-054A (Section 06-Engine).

Condition
Some customers may comment on an idle instability and/or a higher than expected accelerator pedal effort from the idle position.

Cause
Condition may be caused by deposits in the throttle body bore and on the throttle plate.

Correction

Important
This procedure only applies to cable actuated throttle bodies on the models listed above. This procedure should not be performed on electronically controlled throttle bodies or on any vehicle or engine that is not listed above in the Models section.


Verify that the cause for this condition is not a damaged or binding throttle cable.
Remove the air intake duct. Refer to Air Cleaner Duct Replacement.
Inspect the vehicle for installation of a fixed orifice PCV valve, refer to Corporate Bulletin Number 01-06-01-029B for PCV valve identification. Vehicles undergoing this throttle body procedure MUST use a Fixed Orifice PCV Valve, P/N 12572717.
Clean throttle body bore and throttle valve plate of carbon using a shop rag and an appropriate cleaner. Refer to Engine Controls Repair Procedures - Throttle Body Cleaning Procedure.
Select the correct plug for the size of the air bypass hole in the throttle body being serviced. Use a 1/8-inch (.125") drill bit to determine which plug to use.
Vehicles built before introduction of the Fixed Orifice PCV Valve will have a 3.75 mm (.150") air bypass hole in the throttle plate. The 1/8-inch drill bit is smaller than the air bypass hole in these throttle bodies and can be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the yellow plug, P/N 12580749.
Vehicles built after introduction of the Fixed Orifice PCV Valve will have a 2.6 mm (.104") air bypass hole in the throttle plate. The 1/8-inch drill bit is larger than the air bypass hole in these throttle bodies and cannot be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the red plug, P/N 12581011.




Insert the appropriate plug (1) into the air bypass hole in the throttle plate. Insert the "tail" end of the plug through the throttle plate air bypass hole.



Open the throttle plate to allow access to the tail end of the plug. Pull the tail section to securely position the plug into the air bypass hole and trim excess material (1) from plug.
Turn ignition key to the on position, with engine off.
Use the Tech 2 Scan tool to read initial TPS voltage.

Important
TPS voltage cannot exceed .69 V. If the vehicle has an initial TPS voltage greater than .61 V, replace the Throttle Body Assembly. This part is currently on parts restriction. Contact the General Motors Powertrain Quality Center at 866-654-7654 for assistance.


Using the Tech 2 Scan tool and a T15 driver to rotate the Minimum Air Rate screw, increase TPS voltage by .08 Volts (Refer to TPS Voltage Chart below).
Turn ignition key to the off position. Verify that the accelerator pedal moves freely - Depress the accelerator pedal to the floor and release.
Install the air intake duct. Refer to Air Cleaner Duct Replacement.
Start engine.
Using the Tech 2 scan tool, monitor TPS voltage and verify the TPS voltage is no greater than 0.69V.
Road Test Vehicle.

Important
If an increased accelerator pedal effort condition still exists after performing this bulletin, throttle body replacement may be required. Please contact the General Motors Powertrain Quality Center at 866-654-7654 for assistance, as the throttle body is currently on a parts restriction program.


TPS Voltage Chart Initial TPS Voltage
TPS Voltage After .08 Volt Increase

0.45 V
0.53 V

0.47 V
0.55 V

0.49 V
0.57 V

0.51V
0.59 V

0.53 V
0.61 V

0.55 V
0.63 V

0.57 V
0.65 V

0.59 V
0.67 V

0.61 V
0.69 V


If initial TPS voltage is greater than .61 V Replace Throttle Body Assembly

Parts Information
Part Number
Description
Qty

12580749
Plug, Throttle Plate - Yellow
1

12581011
Plug, Throttle Plate - Red
1


Parts are currently available from GMSPO.

Monsolo
07-22-2011, 08:37 AM
Molson, great stuff! I'll definately use it. Here's what stumps me... apparently, the 2003 5.3L doesn't have an idle air control valve or motor... I've tried to find one and have failed. I guess everything is electronically controlled within the throttle body hence the reason so many of us 2003 Yukon owners have had to drop $$$ on complete throttle body replacements! :mad: Well, I'm going to try cleaning the TB tonight and see if that helps. :cool:

Monsolo
07-22-2011, 06:57 PM
:D:D:D

Cleaned the throttle body, the MAF sensor, and the interconnecting plastic plenum and she's fixed!!! Idles perfectly! :)

Well, thanks for all the advice guys and I'll certainly be back on if anything else goes wrong.