03 burb won't idle

[cliffdavis1]

My 03 suburban starts fine but then the idle speed starts to bounce up and down erratically. It is not a gradual drop, it is a very fast drop like it is being shut off then it rebounds before it stalls. It is an itermittant problem and does it when cold and at temp. Occassionally stalls while sitting at stoplights. Anybody have any ideas?

[JMoney02]

Any changes made to the vehicle before this happended? Was it all of the sudden? Conditions change
in your location? Did you just get Fuel recently? CEL on? What engine type does it have?
Jeff

[ct9a]

If it was a Honda I'd tell you to look at the Intake Air Control Valve, but I don't know if GM uses those. Vacuum leak maybe?

[JMoney02]

Actually they do use the IAC/IAT.......

Jeff

[wesleytravis]

my 03 sierra was acting the same way recently, i got a spry can of B-12 and cleaned the throttle body real good. i unbolted mine and got it good inside and out. runs like a champ now

[cliffdavis1]

I have a 5.3 flex fuel. I've cleaned the maf with maf spray cleaner. Ran a can of lucas fuel cleaner in the gas tank. Scanned the codes and I have codes: 101, 171, 174, and 446. It's been doing this for over 6 months but just recently got bad enough to bother me. It does this weather it's warm or cold, wet or dry. I think I might try the throttle body cleaning. It did get worse recently after I ran a tank of flex fuel through it. This is only the 2nd tank of flex fuel that I have used. First one was over a year ago. Same gas station. Runs like **** on flex, no power, bad milage. Engine light did come on after tank of flex was burned. Changed the air filter yesterday. Put a stp paper filter back in. Was running one of the expensive orange oily paper one's. It was still clean but I've read bad things about the oiled ones. This wasn't a K&N but it was oiled paper heavy duty. The guy at Auto Zone turned the engine light off for me and it ran great immediatly after that, more power and no rough idle. Only lasted a day before it started acting up again and light came back on. Filled up on regular fuel and put another can of cleaner in the gas tank. Different brand this time, I think it was STP. I'm going to try seafoam next, heard good things about that brand. Only drove it about 50 miles so far on this tank. Like I said before, there is no pattern to when it acts up and it only does it when idling. No misfires while driving. I also have headlights and guage lights that flicker for no reason. Bad speedometer, Tranny tends to slip occasionally between 1st and 2nd then bangs hard into 2nd. I love this truck but for this price I didn't expect all of these factory defects. I need to keep a log, more than this has happened but my mind is slipping also.

[Kamd91GMC]

i know this is going to sounds awfully off the wall, but it's something to think of. My Dad's 03 had the FlexFuel in it...our ECM wen't bad. We took it back to the dealer and traded is straight across for his 98' Chevrolet K-1500 LWB 4x4 w/ the 5.7 Vortec backed by the 4L80e Auto and a 4:11 Detriot Posi'd Rear end. only had 91k on it

[JMoney02]

You are more than one store I've encounter about the FLEX FUEL dilemma. Appears to cause several
different problems that you've mentioned with yours, others. Yes keep a log so you know what you have done,that way your not stepping on yourself. Keep with the regular gas for now if you can. Oil filters are good, if you oil only from the bottom, let dry to the pleats(just can't oil and put back) and don't staturate, not necessary. Use the seafoam if you haven't yet, it'll clean up the inside(fuel, vaccuum) areas. The electrical with the dash, have you had it apart? Someone before you? If you can,
see if move any harness under the dash and see if it flickers the lights, have a Bro help, I know can't see and wiggle at the same time. Seems that there may be a connection problem to the back of the cluster, or with the dimmer switch... Let us know......

Jeff

[cliffdavis1]

I had a can of spray cleaner and I started to spray the throttle body. The red tube on the end of the spray nozzle wanted to see what was inside of the throttle body so it shot off of the end of the can and went down inside. I had to take the throttle body off to get it out. At least I cleaned it really well. Runs a little better but still stalls. I bought a cheap code reader and 101 MAF keeps coming up. I ordered a MAF off of ebay and will post if that was actually the problem. Oh, bye the way, the vacume line on the throttle body has antifreeze in it.(I thought it was a vacuum line but it wasn't) LOL. Next time I'll make sure that the cooling system doesn't have any pressure in it before I remove it.

[JMoney02]

I had a can of spray cleaner and I started to spray the throttle body. The red tube on the end of the spray nozzle wanted to see what was inside of the throttle body so it shot off of the end of the can and went down inside. I had to take the throttle body off to get it out. At least I cleaned it really well. Runs a little better but still stalls. I bought a cheap code reader and 101 MAF keeps coming up. I ordered a MAF off of ebay and will post if that was actually the problem. Oh, bye the way, the vacume line on the throttle body has antifreeze in it. LOL. Next time I'll make sure that the cooling system doesn't have any pressure in it before I remove it.

Good you got the code, check thw wiring back from the sensor also, make sure no problems with it also... And now WD-40 has the attached tubes and new head, that sucks Dude.....


Jeff

[mudpuppy]

this is the same problem im having with my 94 atm. ive been battling this problem for 2 years. all new sensors( i mean every freaking sensor on the damm thing) new tbi. all new ignition. at first it pop'd the maf code then the o2 code now no codes but still have bad idle problems. only thing left is the injectors and/or start to look into the tranny(4l60e)

[cliffdavis1]

I replaced the MAF and the 101 code doesn't show up anymore but I still gat 171 and 174. I'm starting to think that it is the intake manafold gaskets.

[JMoney02]

I replaced the MAF and the 101 code doesn't show up anymore but I still gat 171 and 174. I'm starting to think that it is the intake manafold gaskets.

Do you hear any vaccuum leak around the intake? Anywhre else? What about the fuel pressure after the truck is running, does it drop rapidily then pick back up? What leads you to the intake gaskets, something you have had other experienced? I don't have the codes in front of me, what were the 171/174/446, you still have the 446 code? Have you replaced the fuel filter also? Yes keep a log so you know what you have replaced,what you've corrected and what is still giving you issues. I have heard of the 4l60e giving people problems but not with the performance of the truck itself....Check the running fuel pressure and see if it drops and rises instead of staying at 50-55lbs....

Jeff

[cliffdavis1]

I don't hear any leaks but I have read about a service bullitin from chevy regarding replacing the gaskets to stop this problem. 446 and 101 codes have not returned. 171 and 174 return almost daily. I keep code reader in the truck so that I can read codes and reset them as soon as light comes on. Cliff

[JMoney02]

I don't hear any leaks but I have read about a service bullitin from chevy regarding replacing the gaskets to stop this problem. 446 and 101 codes have not returned. 171 and 174 return almost daily. I keep code reader in the truck so that I can read codes and reset them as soon as light comes on. Cliff

So it appears that 171 and 174 are refering to your O2 sensors on both sides before the Cat.Conv, did these get replaced? Have you checked wiring on these? They may be casuing your issue now???? Both state they are lean on left and right Cyl Banks, so both sensors...

Jeff

[91Sub4x4]

I'm having the same problem with my 91. Everything was fine until last monday when I went too deep in the mud and sucked up water. I drained the water from the engine and it ran perfectly for a few days before starting the idling problem. I haven't had the chance to check for codes but simple discussion with friends gets me suggestions about the fuel filter/pump and throttle body.

[cliffdavis1]

I haven't checked any sensors. It just seems odd that the left and the right can go bad at the same time. I ran a can of sea foam through the gas tank and it hasn't stalled for over a week now. the rough idling seems to be clearing up but the codes keep showing up. When I cleaned the throttle body it was really filthy. I got the torsion keys but haven't put them on yet, also got 1.5 inch spacers for the rear springs. The new 305/70/16 tires rub a little. Already put 2 inch spacers on the hubs to get the tires away from the inner wheel wells. I wish I could put lower gears in it. It has no low end power now with the bigger tires. I have a limited budget so I can only do one thing at a time.

[cliffdavis1]

I'll post new picture as soon as I take one. Also added OEM fender flares, Lund in channel vent visers, Lund lunar viser, EGR "U.S. AIR FORCE" bug shield. Plasma glow led fire storm light bar, remote start. Tires are Goodyear Wrangler Silent Armor's, I really like them, good ride and great traction. And lots more to come, little by little.

[vncj96]

Wasnt there a problem with some of the early flex vehicles in the that the gaskets were not strong enough for the E85 vehicles and were failing, could this be leading to something, also have you changed out the plugs and pcv valve. Your truck seems to not like the E85 for some reason so maybe the plugs are bad.

[JMoney02]

Wasnt there a problem with some of the early flex vehicles in the that the gaskets were not strong enough for the E85 vehicles and were failing, could this be leading to something, also have you changed out the plugs and pcv valve. Your truck seems to not like the E85 for some reason so maybe the plugs are bad.

Yes they did and it has caused several issues, bad gaskets with the vaccuum leak, O2 sensors to become irratic from one fuel to another(Hence 171/172/173/174 codes for lean/rich) depending on what the truck wants to do. It really does suck because with the O2 you can clean but it doesn't really work....Same with the gaskets, your F'd cause if you have no warranty then it's an out of pocket expense.....

[cliffdavis1]

I bought new plugs but they will have to wait to be put in. It is 12 below 0 here in northwest Indiana today. I think I'll stay INSIDE the truck where it is nice and warm. Starts right up and hasn't been misfiring at all lately. Throttle response is a little too sluggish for my liking though, I want more POWER!

[91Sub4x4]

-12 is way too cold for me and definitely not fun weather for working on a truck. I don't know anything about the E85 fuel since I haven't owned a vehicle that uses it. In my previous post I stated having the same idling problems you were having. Turns out it was the throttle position sensor. I changed it out ($23, 20 min job) and all of the problems went away. Just returned from a 400 mile trip and everything is still fine. Hope this helps and good luck fixing your truck.

[cliffdavis1]

Still running great. No sputtering or stalling. I'm thinking maybe it was just dirty injectors and the seafoam did the trick. With this cold weather, the bulldog remote starter that I put in last fall is wonderfull. Remote start is the way to go. I park it outside at night, the garage is full of other cars. It used to stall out in the driveway but hasn't stalled while warming up since the seafoam fuel system cleaner. Great stuff.

[JMoney02]

Excellent! Glad to hear that your back active again, thanks for the follow up! I did hear about the Seafoam stuff until I landed here and from what I see it appears to be a worker.....

Jeff