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Pickups Chevrolet Silverado & GMC Sierra Chevy Silverado and GMC Sierra Gasoline Engine Problems
258 messages, Last post on Nov 26, 2009 at 1:55 PM
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Replying to: buzzat (Nov 23, 2008 6:08 pm) |
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Greetings! Have a 1999 Sierra Z71 with 5.3L engine, last winter service engine light would come on when engine was started when very cold only. Check of codes showed P0171 and P0174 fuel system lean bank 1 & 2, after posting determined fuel pump pressure low, replace MAF, EGR valve, fuel pump, fuel filter, & fuel pressure regulator over course of several weeks attempting to fix . This improved problem but didn't completely go away. By time all of this had been done it warmed back up and no problems since. Since it has turned cold again recently, had service engine light come on when engine was cold and sometimes after this happens it will idle fine but surges in 15-40 mph range. At highway speeds it runs fine. Rechecked codes and found P0405 EGR sensor A circuit low. Truck has factory engine heater and when it is plugged in overnight problem doesn't occur, but when parked at work for entire day and then started cold it will trip. Suggestions on possible places to look to solve problem? Any help would be appreciated! Thanks!
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Replying to: treedog (Aug 27, 2008 6:59 pm) I just read your thread on the overheating and airlock issue with your truck. Although it's been several months since you resolved the issue I'm hoping that I can get some details on how you resolved the problem...my truck is having the exact same problem after changing a leaky water pump and old thermostat. Thanks, Jose
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Replying to: dmbaero (Dec 04, 2008 6:31 pm) Thanks, vettenjet |
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| I have a 1993 GMC Sierra. I parked in my driveway, shut it off, came back out in about 5 minutes and will not start. I changed the fuel pump relay. I have no voltage to the fuel pump fuse located on the firewall, and no voltage out of the relay. I don't think that I have the fuel pump/oil pressure switch on this model, but I do have the oil pressure sending unit. It doesn't have the wires that my schematic says it shold have, just the one output line. All fuses in the cab are good. Any ideas???? | |
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Replying to: Silverado_2003 (Jan 30, 2009 7:07 am) |
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Greetings All! 5.3L 1999 GMC Sierra Z71 with 233,000 miles I have posted here a couple of times in the last year regarding ongoing problems with P0171 & P0174 bank 1 lean and bank 2 lean codes. After continually chasing the problem, recently while driving at 65 mph on interstate the vehicle lost power. The cruise control was on at the time and the light still showed it as engaged, engine was still running, but vehicle just was losing power, when accelerator was pressed down, nothing seemed to happen, if pressed to the floor, it would cough and act like it was backfiring. Pulled over and shut off, called someone to come pick me up which was going to take about 30 minutes. After the vehicle had set about 15 minutes, decided to retry, found it started up fine and ran fine at highway speeds for about 20-25 miles then problem reoccurred, no SES light and no codes. Shut down and let cool for 10-15 minutes and able to continue on for another 20-25 miles. It took about three legs like this to make it home, on last leg I had noticed while using monitor mode on scantool that when problem occurred a couple of the oxygen sensors went to 0.0, also found couple of oxygen sensor codes pending. Long story short, ended up replacing oxygen sensors after removal for troubleshooting due to threads galling on removal. Also replaced catalytic converter Y pipe for same reason. Seemed to fix problem, vehicle ran fine for 2 1/2 to 3 weeks. All of a sudden on way home from work, had same problem occur. Noticed this time on scantool monitor mode that when problem was happening that the fuel loop 1 and fuel loop 2 were showing open, so computer was not using oxygen sensors to adjust fuel. Presently going through all grounds on vehicle and cleaning, then going to check connections at PCM. My questions is if there is any procedure to test PCM other than having GM dealer go through troubleshooting chart with Tech II?
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I have an 04 Sierra with a really bad idle problem. Let me start out by explaining the first day of problems. I was heading out to school one morning and I had a bad misfire. I went to the local garage and they said it could be the ethonol in the gas and to treat the gas with Stabil Marine cause everyone is using it right now to cure their problems. That sunday I started to notice that the RPMs would drop down to around 500 where it never used to drop to. I decided to go to the dealer and see what they would fine after a a week cause the truck was still running rough and now low idle. The dealer found a bad O2 sensor on bank 1. They replaced that and it still didn't cure the low idle but stopped the hitching. They said replace the spark plugs if it dont clear up and so I did with the originals in the truck. Still no fix. I went down this past week and they said that my throttle body unit would have to be replaced. So I replaced that and still no fix. I also had the intake gasket checked thats good. They said the injectors were firing good. Both garages I have been to virtually cant find anything. I know personally it's not running normally. I am going broke and going nuts trying to figure out the problem. When I come to a stop the RPM goes way down to 400 then will go back up to around 500-550. I used to idle normal at 750-850. I am hoping someone out there can help me out or may have had that same problem. It also seems to take a while to shift in the hills and to make it shift I have to give the pedal more gas. I know eventually its gonna start stalling and what not.
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Replying to: nmgmguy22 (Mar 21, 2009 4:15 pm)
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Replying to: obyone (Mar 25, 2009 12:03 am) |
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