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Chevy Silverado and GMC Sierra Stalling Problem

46 messages,  Last post on Aug 07, 2008 at 10:36 AM

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#35 of 46 1998 2500 GMC Sierra by jumlah Apr 09, 2008 (10:21 pm)
I have a 1998 2500 sierra that I bought used.. Automatic. 256,000K I had the rad changed and the original manifold gasket changed at the same time a few months ago. After the work was done, I noticed a hesitation in the "power band" almost like the engine was misfiring. It was very subtle and easy to miss. there is no hesitation while moving up through the gears until I hit about 90 km/hr (3rd gear), this usually corresponds to about 2000 to 2500 rpm. after that when I reach about 100 to 110 km/hr, and the RPM drops to about 2000 RPM to 2200 RPM (Overdrive) and there is another hesitation. It happens no other time. there are no Codes or check engine light. I also notice after the work was done the engine runs at a lower RPM while idling, and sometimes when I am in reverse and begin to give the engine a shot of gas it almost stall out. It did at least once.   I thought at first the mechanic may have messed up the timing so I brought it back. they double checked and everything was OK. They even checked injection ports and cleaned them. The problem continued, I took it to a transmission shop to see if it was a tranny problem, again no codes, the mechanic took it for a drive and was convinced that there was NOT a problem with the transmission or it's mechanical operation. The transmission was rebuilt about 76,000KM ago, and has only been on light duty. The transmission mechanic thought that it might be related to the ignition. Well, I don't know when the plugs were changed last and the truck has remote start that is no longer able to start the truck. The characteristic of the "hesitation" has not changed and continues to happen at the exact place and time while driving it.   I am at a loss as to what is happening. I would rather not spend ton of money trying to find the problem. Since there are no codes it is kinda hard to pinpoint. I appreciate any assistance I can get on this matter.   regards, John Replies to this message: mickeymouse2 (Apr 10, 2008 7:05 am)
#36 of 46 Re: 1998 2500 GMC Sierra [jumlah] by mickeymouse2 Apr 10, 2008 (7:05 am)
Replying to: jumlah (Apr 09, 2008 10:21 pm) A lot of miles on this truck. Here is what to look for. I understand mechanics have checked this, but maybe they over looked the obvious.   Low idle than normal may be the key to this. Check fuel pressure, and throttle body for carbon build up. IAC (idle air control) valve may be malfunctioning and not setting a code(pintal may be stuck in wrong position) I have run into this after manifold has been removed. Pintal position will not set codes for IAC, only electrical malfunctions of the IAC will. Pintal spring may be coked with sludge, impeeding correct relearn proceedure. Recommend cylinder balance test. Verify each cylinder is contributing on its power stroke. If this vehicle was brought to me, this is where I would start.   Keep in mind that my first rule to repair is to fix the obvious first, it might be related. I would focus on the low idle issue first. Even though timing has been checked, check it again by someone else. Timing cannot be accurately checked or set if your idle is below specs. Timing and idle are related. Your emission sticker under the hood will show the specs for timing at what idle rpm. Low idle retards timing, while a higher than normal idle advances timing.
#37 of 46 03 GMC SIERRA 4.8 STALLING by lrichy3 Apr 12, 2008 (10:59 am)
I have 03 sierra that i bought new, for the last year and a half it stalls when i come to a stop or turning. It runs fine when it is cold. After it warms up the rpm's drop down to about 550 and it has a miss. It's driving me crazy!! I put new plugs and wires on it,checked the fuel pressure. It's fine.Put new K&N air filter on,the throttlebody is clean. It does not have an IAC valve they only had them up to 02,it has one big electrical unit in the side of the throttlebody and nothing else!! ANY HELP WITH THIS I WOULD REALLY APPRECIATE IT!!!! Replies to this message: mickeymouse2 (Apr 12, 2008 6:08 pm)
#38 of 46 Re: 03 GMC SIERRA 4.8 STALLING [lrichy3] by mickeymouse2 Apr 12, 2008 (6:08 pm)
Replying to: lrichy3 (Apr 12, 2008 10:59 am) Hmmm, sounds like its starving for fuel only when warmed up. Check the output voltage signal from your upstream O2 sensors. They should be switching back and fourth between 600-900 mili volts within 1 second. If you don't know how to do this try a propane enritchment test. Take a propane torch(don't light it) and give your engine some extra fuel (propane) when it is warm and see if it smooths out. Just put the end of the torch into the air intake. If it runs worse, than your problem is too much fuel. Look for vacum leaks, and exhuast leaks, these will fool your O2's into sending a lean signal to the PCM wich inturn dumps extra fuel in there. Too much for the engine to burn up.
#39 of 46 03 Z71 5.3 Low idle problem!! by gixxerman1981 Jun 07, 2008 (5:30 am)
I was having the problems that some were having on here with the truck stalling at low rpm maneuvers. It wasn't the alt or battery, I put a new fuel filter on, still nothing, finally i got some cleaners and cleaned out the MAF sensors and the TB, by the way was loaded with carbon build up. I haven't have any luck with finding the IAC valve though, its not bolted on the TB like most, unless it is attached, meaning riveted on the TB, however since the cleaning it has ran fine, the test drive around the block was a success! If anyone knows where and how to get to the IAC valve shoot me an email, i really would like to clean that as well!
#41 of 46 engine stalling when using blinkers by neelaviat Jun 12, 2008 (6:19 am)
Hey, I have 2001 Chevy 2500HD Duramax w/ 200,000 plus miles. It's been a great truck, but... engine stalls when I use the turn signal to change lanes on the highway, or when coming out of a slow turn when the blinker arm returns. I can't duplicate this by wiggling the blinker arm. I have to put truck in N, and usually restarts first try. I can feel the truck hesitate or bump while changing lanes on the highway (70-80 MPH) if it doesn't stall completely. THANKS for any help. No codes being stored.
#42 of 46 Re: 94 silverado stalls on idle [adam11788] by 2doorhoe Jul 18, 2008 (12:14 pm)
Replying to: adam11788 (Apr 03, 2008 3:28 pm) had the same thing happen, replaced the harmonic balancer ran like new Replies to this message: neelaviat (Jul 19, 2008 4:48 am)
#43 of 46 Re: 94 silverado stalls on idle [2doorhoe] by neelaviat Jul 19, 2008 (4:48 am)
Replying to: 2doorhoe (Jul 18, 2008 12:14 pm) Did you experience this while using the blinkers? Or idle? Thanks.
#44 of 46 2003 Sierra 1500HD by loom Jul 29, 2008 (11:49 am)
I have a 2003 Sierra 1500HD, 2 Days ago I went to start it and the battery was dead. I jump started it, never had problems with the battery sense. Now it idles very low when I start it and when I come to a stop, sometimes it stalls. I was told that it could be the iac valve, and then I was told that the 2003 models doesn't have one. Any replies would Help Thanks. Replies to this message: jaysgmc03 (Jul 30, 2008 5:33 pm)

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