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Chevy Suburban/Tahoe Rough Idle and Stalling

I have a 2001 Chevy Suburban 2500, 2WD w/ 6.0L engine. We purchased it from a Chevy dealership back in 2002. It was a GM buy-back, for the same reasons it's now having. NO DTC's, NO CEL.

Having a problem with stalling. It usually happens after backing out of parking areas when vehical returns to idle while shifting from reverse to drive. It then become difficult to restart. Also during this issue if vehical doesn't stall it starts exibiting erratic idle. The vehical also seems to idle low 550rpm down to 400 and lower on occasion.

I have attempted to locate the idle air valve but it doesn't seem to have one in the location in the manual (on throttle body by altinator). I can only find what I believe is the Throttle position sensor in that location.

Vehical doesn't do this all the time but nore times than not and seems to be more often during cool/cold weather.

Any help or idea would be gratly appreciated.

Curtis
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Comments

  • I have a "Late" 2001 Suburban LT 1500 2WD that stalls when you are slowly moving the vehicle. It most commonly occurs when pulling into a parking lot at idle speed. The vehicle runs great at speed and if you hold your foot lightly on the accelerator it will not die. It is simply that the Idle speed is too low. From what I had read I decided to replace the fuel pump module because it was whining but never quit pumping fuel. I ordered the pump to find that the 2001 module had different plugs than my vehicle had. It took many calls but I found a dealer that researched the problem to find a harness designed to rewire the module to fit my application. The pump did not fix the problem. The next step was to replace the Idle Air Control Valve. I ordered the part and when it came in I went to install it to find that the throttle body on my suburban did not have an IAC Valve on it (I have Pics). I climbed under the dash and put an adhesive spacer under the stop for the pedal and the problem is fixed for now. What is going with these vehicles? HELP!
  • After alot of research and calling the chevy dealership that did all the work prior to and after the GM buy back we figured out the problem.

    The Chevy 6.0L w/ electronic throttle (no cable) does not have a idle air control motor (valve). The electronic throttle motor and pcm control the idle. On models that have no idle air control motor there is a small machined opening on on the throttle body that prevents the throttle plate from completly closing. Ater what seems to be a realativly short period of time the back side of the throttle plate and intake will have a large amount of carbon and oil from the EGR and crank vent systems. I removed and cleand the throttle body and what I could of the intake where the TB mounts and it solved all my idle issues.

    BTW I will have to give the Chevy parts manager a plug because he reviewed the work orders (from 2003) and found a mistake on the paper work. The mistake was fuel injectors where replaced which actually all that was done was that the throttle body was cleaned. Then he suggested what I did to remedy the problem. I would have changed uneeded parts with out his help.
  • i have a 93 suburban with the 7.4 ltr engine.it has a miss
    you can feel in gear stopped.i did a full tune up and changed the cat.i also replaced the fuel injectors.i think it might be a bad plug wire but at this point i give up,please help
  • My 1999 454 7.4 liter suburban LT turns over several times when cold before spluttering into life ( it then nees a bit of gas) and Idles roughly. i think it may have a slight missfire. is this a common problem. I have replaced the oxy sensors, fuel pump and plugs n leads but it is still rough and vibrates like a bus. no problems restarting from hot though. ANY IDEAS?
  • plaserplaser Posts: 1
    I've had this 1989 GMC Suburban for a couple of years. The engine was relplaced right after we bought the vehicle.The only parts that were not replaced by new parts were the distibuter,ignition modules or anything else on the throttle body. If I am not in gear I can lightly press on the accellerator(ACC) and it won't try to stall but if I put it in gear and try to do the same, like if I'm backing out of a stall or trying scootch foward a little it will try to die out. I have to throttle the accellerator peddle a little to keep it from dying. It started about a year ago and really hasn't gotten worse. Also if I was driving for like 40 minutes or so and I came to a stop on the freeway or something it would try to die out again and I would again throttle the ACC. After I did a really good tune up the stalling on the freeway deal went away but I'm still having issues. The truck doesn't give me any other issues, runs great otherwise and purrs like a kitten when idling. A couple mechanics couldn't find any codes and both said the timing was correct. Like I said it only does it when in gear. Any help would be greatly appreciated. At the very least a suggestion on where to start to replace something.I am also noticing when I try to start the truck it takes a little longer than it used to,it needs more turn over time then it starts up. Before I could just hit the ignition and it would fire right up, kinda like I lose fuel pressure in the line.
  • I have a 2001 Chevy Suburban. It sounds like the same problems I was having. I replaced my intake manifold gasket it had cracks. Have it checked out for vacuum leaks. They can smoke the engine for leaks. The gasket is made of rubber. So when it is cold it contracts to normal. Which creates a vacuum leak. When the truck is warmed or hot the gasket expands. Have it checked for vacuum leaks in the morning after the truck has sat. don't test for vacuum leaks when car is hot. hope this works
  • fryall4fryall4 Posts: 1
    I have a 93 Chevy Suburban 4X4. 5.7, AT, A/C, all power. Problem is after warm up and stopping at a light the truck will stall. It starts up quickly and runs perfectly off idle. I have replaced the fuel filter, Idle air control valve, plugs, cap nd rotor with no solution. I have been researching and think the problem may be the Torque Converter Clutch lock up solenoid (TCC). There is a way to test this, but I don't know how. I don't have the $ to take it in, I just dropped $1400 on a blown up rear end. Does anyone else know how to test this solenoid on a 4L60E? Or maybe what the problem might be? Fry-
  • I have an '02 Surburban that has a rough idle on cold start. Typically, the temps have to be 40 degrees or below for this to occur. It never happens during the warm spring, summer and fall months. I replaced the fuel filter last fall and was told at that time by the local dealer that my burb has a flex-fuel motor and that this was a bit rare for this year model. At times, the check engine light will activate during the rough idle. Sometimes the light flashes and goes off after a half hour or so, and sometimes it will come on and stay on for as much as a day or two. The burb always runs fine after warming up, even if the light stays on. I have attempted to have the code pulled when the check engine light comes on, but the last two times, nothing shows up. Anyone have advice for me? The truck runs great 85% of the time.
  • ksmockksmock Posts: 2
    I have a 1997 sub with a 7.4 liter and the check engine light is on. Every time I start the engine it shuts off unless I rev the engine. If I try to just rev the engine once after starting the engine will continue to miss or shut i off until it gets cleared out. Somtimes the engine will even sputter right after I start driving. I have hooked up a scanner and it gave me 3 differnt possibilties mass air flow, pcv valve, or leaking fuel injectors. I have replaced the PCV vale. But before I go any farther and buy parts I dont need does anyone have an idea what is wrong?
    PS
    After the engine clears out the thing runs great but my gas millage is horrible.
  • I have a 99 tahoe it is stalling when i come to a stop or at an idle, and sometimes when i am driving down the road it will not take any gas for a minute then it will go. The main confusion is it only does this when the temp outside is 85 degrees or higher. When it is cooler out it runs like a brand new truck!!! I have replaced the IAC valve, plugs and wires, cap and rotor button. none of these has made a bit of difference. ANY HELP would be greatly appreciated.
  • bc13bc13 Posts: 32
    I was having the same problem with my 2000 suburban. Had a tune-up but that did not correct the problem (needed the tune-up anyway, so no loss there). The solution (atleast for now) was reflashing (??? or reprograming?) the ECM (computer). It seems to have corrected the problem and its running pretty well now.
  • My 2002 Chev Suburban has a slight tremor or vibration when it is idle or at a red light. I have replaced the plugs, and added gas treatment, but it still vibrates. It noticed it right after a fillup with 87 octane gas, and wonder if it is a gasoline issue.It has 52k miles on it, and otherwise runs great.
  • I have a 95 Tahoe that we recently purchased with a 350 5.7 L, it has a rough idle when cold and worsens when warms up. I've changed all the plugs,wires, rotor and distributor cap and a new fuel filter and still nothing. Can anyone give advise on what this could be.
  • I am having the same exact issues with my '03 Suburban. I literally just cut and pasted your symptoms here to save me time in telling you exactly what mine is doing. Typically, the temps have to be 40 degrees or below for this to occur. It never happens during the warm spring, summer and fall months. I replaced the fuel filter last fall and was told at that time by the local dealer that my burb has a flex-fuel motor and that this was a bit rare for this year model. At times, the check engine light will activate during the rough idle. Sometimes the light flashes and goes off after a half hour or so, and sometimes it will come on and stay on for as much as a day or two. The burb always runs fine after warming up, even if the light stays on.

    However, I just dumped $1600 in it over a 4 week time. I replaced fuel filter, fuel pump, had my fuel injectors cleaned, 2 O2 sensors, MAF Sensor and today a throttle body. The light came on 45 minutes after leaving the service dept.

    Anyone had any advice for the first one that might work with this one?
  • The battery in my 03 Tahoe went bad so I bought a replacement and installed. Now it wont idle correctly,wants to die and frequently does. Car was working great before dead battery.What am I missing? Help!!! Bob
  • kiawahkiawah Posts: 3,666
    Not a whole lot to go on here, but I would go have the battery and alternator checked under load testing. Since you've had a power problem, I'd start with ensuring that the power was good. Most autoparts chains will do a free load test to make sure your alternator is putting out the power that is needed, and your battery is good.

    In your case, I would also make sure your battery connectors are clean of corrosion, fit snugly on the battery, and the cable isn't deteriorated at the connectors.
  • I am having EXACT same problem and have spent a lot of money to no avail. Have you ever figured out the problem?
  • I highly recommend any one who is having idle stalling problems to remove and clean your Throttle Body. GM in my mind made a serious design flaw when engineering there system by eliminating a Idle Air Control Valve. Instead they machined a small opening (on one half the dia. of the TB bore) in the throttle body the prevented the throttle plate from closing completly. Well as soon as carbon builds up on the back side of the throttle body from the EGR then the machined opening starts to get restricted. Once the electronic throttle servo/motor can't compensate then you start having stalling that will only get worse until the Throttle Body is removed and cleaned as well as the inlet to the intake manifold. This info was passed on to me by a GM dealer Parts and Service manager who owned one as well. I followed his advice and have had NO issues for over a year. Keep in mind that this will be requied service evrey couple of years as needed to prevent or eliminate the issue as it will return due to the design.
  • kiawahkiawah Posts: 3,666
    Being very mechanically inclined and doing all the work on my vehicles (but never had to do that particular task before), how difficult is it and/or how long does it take/or what are the major steps involved?

    I assume they make some throttle body spray cleaner, like the old gumout of carb days.....
  • I own a 85 El cameo with a 350 Chevy in it many Tahoe's have a like engine
    if yours dose. heres how I cured mine I first tried to replace the solenoid. That
    made the car run smother but it would still stall a red lights some times. so I
    called my friend who works on older cheviots.He said replace the starter and that
    fixed everything I had this problem for a year and no mechanic would touch it
    for under 300.00 estimate . That was a month ago and it runs better than new now.
  • Sorry, but I fail to see how a "starter" can effect the way an engine runs. After the engine starts, the "starter" has no further function. The starter gear slides back into its shell and waits for the next engine crank. Do some starters perform an additional function that I am not aware of? Thanks.
  • woodyjwoodyj Posts: 6
    My wife and I purchased a 2003 Chevy Suburban. At first, we had no problems until we had the vehicle for a few months. We ran the ODB II diagnostics and found several cylinders misfiring, and injector circut malfunctioning. We then took it in to dealer to have it further diagnosed and fixed. They did their thing and replaced one injector wire at first, but that did not fixed the issue. Problem reoccurred after we brought the vehicle home. So we took the Suburban in again and they said they had to replace 3 more injector wires. They did that, and everything was fine until another week passed. Same problem again. I got tired of the run around and didn't have the patience with the dealer, or the money we were throwing away. I did simple check of sparkplug, sparkplug wires, fuel injector wires, and to my surprise it was the main ignition coil connector wires. I ended up splicing up the wires together. I did more checks inside the wire jacket that leads back to the main computer in the engine. Found more wires that were worn down to the copper. Seems like either prior owner or dealer tried to fix the problem and couldn't find the main issue.
    So now, my Suburban runs fine.
  • pear69pear69 Posts: 20
    Don't know if you solved this problem, but YES 87 octane gas will cause this problem. Octane is an additive that is put into gasoline to reduce the spontanious combustion that happens when gasoline is compressed inside of the combustion chamber. The lower the octane the higher the chance of spontanious combustion. This is bad because if gasoline combusts (fires) before the spark plug ignites the piston will be on the way up in the cylinder. This is what is known as a "ping" or "detonation". A "ping" will eventualy destroy a motor.
  • I have a 99 Suburban with a 5.7. I had a leak on my intake gasket and got that replaced. After a week, engine runs rough and showing P0300. Replaced cap/rotors, plug, wires, MAP sensor, Cam Sensor, and Crankshaft sensor. Then I replaced the ecm. Still doing the same thing. Mechanic advised me that it can be the head gasket that will run be about $1200 to $1500. I don't think thats the problem. I did not let them fix the head gasket. After I replaced all the things that I replaced, now its showing p0304 cylinder misfire on 4. Please help if anyone solved the problem. Can it be my EGR valve, fuel injector? I checked the plug on cylinder 4 and it is firing fine.

    Thanks,

    Elorenzo39
  • kiawahkiawah Posts: 3,666
    You could have a bad head gasket around cylinder#4, right?

    Have any compression tests done??
  • pear69pear69 Posts: 20
    It is very important that A/C delco spark plugs, and spark plug wires are used on these engines.  A p0300 is a general misfire and a p0304 is cylinder 4 misfiring. They both may or may not be related. Your engine has a problem that many people overlook, the distributer gear wears out--especialy after it is removed and put back in--as it was when you had the intake gaskets done. If the distributer gear wears too much it will misfire the engine. Also, the timing on your engine must be set with a computer scan tool, NOT a timing light--like in the old days. When the distributer was removed on your engine, it is almost impossible to put back in exactly perfect. This is a commonly overlooked problem also. A dealer is the only one who can properly time your engine. When the intake is removed from the engine, the injector electrical connector must be unplugged. This plug is very sensitive to damage. It is easy to bend the little pin that plugs into the injector. This could be the cause of cylinder 4 missing.Also make sure that all the ground wires are put back on the engine. The ECM fires the injectors by controlling the ground (not the hot or power wire). If a ground is off it could overload the ground system by putting strain on other grounds to pick up the slack. Grounds work just like power wires when it comes to overloading.  This also could be an intake leak. Start the engine and let it run for a while. Now, get a spray can of electrical cleaner ( CRC ) or brake cleaner and spray it around the upper and lower intake while the engine is running. If the engine boggs down or starts to run bad-and -- then clears up when you stop spraying---you have an intake leak. If this is the case the intake gasket was changed wrong...  The best way to determine if the head gasket is bad is to do a compression and leak down test on all cylinders.    If the plug looks fine then it is probably NOT the head gasket---do a compression test to be sure though....
    Your problem sounds like a leaking intake somewhere or most likely electrical.
  • I Thank you all for helping me out. It really helped me alot. I think I got it figured out. The engine has no Vacuum leak. The problem is my #4 fuel injector. I pulled the spark plug that I have installed 2 weeks ago and it looks like the injector is bad. I will be replacing my fuel injector assembly this weekend and I will let you all know the outcome. Cross my finger that the problem is solve. I finally had another mechanic take a look at it last night. He checked the vacuum leak, compression and he came up with a bad injector on cylinder number 4.

    Keep you all posted after this weekend.

    Thank you again.
  • pear69pear69 Posts: 20
    If you are changing the entire assembly I suggest installing the upgraded injector assembly. Your stock injector assembly is called a cpfi system--the upgrade is called mpfi. The only difference is that the injector itself is moved from the center of the assembly (stock location) to the port of the intake runner (upgraded location). The reason this is better is that it elliminates the (problem proan) poppet. If the 4 injector is the problem, then it is the poppet sticking --causing a "burp" in the fuel flow. I bet the 4 spark plug is all covered with black soot---carbon--isn't it?
  • Thanks for the information. I heard about the upgrade version and that is what I will be looking for tomorrow and I get the new injector assembly. I really appreciate all your help. I will keep you all posted by this weekend if I solve the mystery.

    You are very right. The plugs are only about 2 1/2 weeks old and I have pulled number 2 and 4 plug to compare and you are right on. The number 4 plug was black and the number 2 was perfect. I have also pulled the plug next to 4 and it was fine looking too.

    Anyway, I will keep you all posted and thank you so much.

    Erwin
  • pear69pear69 Posts: 20
    Go on Ebay type in sefi update and you will see the updated version of your injector assembly in DR. INJECTORS Ebay store...
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