Hello i have a 03 silverado 5.3 and for the past few months it has been idling rough. It is a V8 1500 Z71 with 280,000 miles. It has been very well maintained, engine oil & filter always changed earlier then recommended. Same with transmission fluid and filter. Always kept very clean. Any time the engine light came on or something didn’t seem right it was always properly diagnosed and fixed ASAP. This rough idle is really the only thing that’s given me a hard time, it started in the beginning of winter and since it started I have replaced, MAF sensor, spark plugs, fuel filter, fuel pressure regulator, Cadillac converters & the oil pressure sensor. And along with that I have also cleaned the throttle body & intake a few times and checked, O2 sensors, spark plug wires, I did a resistance test on the ignition coils but I don’t currently have a spark tester to do a spark test. But also check for vacuum leaks & checked vacuum & fuel pressure. Vacuum is good right at a steady 17 psi at idle. But the fuel pressure was a bit low while running and none when it wasn’t running. But this was before I replaced the regulator the other day & I haven’t checked it since but do plan to do so either today or tomorrow am. Also another thing about this truck, it doesn’t have a distributor or a EGR or a IAC. I’m sure there’s another thing or two I’ve checked that I can’t remember at the moment but, Anyone have any suggestions? This has been driving me nuts!
03 silverado 5.3 rough idle
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The only codes I have are two related to my EVAP vent valve. I know the valve itself is bad & have a new one I just haven’t had time to put it in. I just checked the fuel pressure again & at idle it was steady at 47. Shut the truck off, it stayed at 47 for a second then slowly rose to 55 and stayed there. I know pressure is supposed to be around 55 while idling to.. I’m thinking it could be having a hard time keeping pressure because the vent valve is stuck open?
The codes are P0449 - EVAP system vent valve solenoid circuit & P0445 - EVAP system leak detected (large leak) & or better yet could it be caused by a bad connection to the fuel pump? Or relay? Just curious because A few weeks after I had installed this new pump I had a little problem, the truck completely died after hitting a pothole from a wire to the pump coming apart. the new pumps for these trucks come with an updated wire harness that must be hardwired in place of the old one & that’s what it was one of the hardwired wires had came apart so I’m just curious if another one of those wires could have came loose and have a bad connection & if that could possibly be the problem.
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Anything like that is possible Keith. When I wire anything in a vehicle I always solder and then heat shrink wires. Automotive environments are usually somewhat contaminated especially under the hood or anywhere outside the body. The crimp connectors don't last as they tend to corrode and loosen over time but quite a few mechanics use them due to saving time.
Yeah that’s what was used, crimp connectors. Me personally I always like to solder and heat shrink everything too I like things neat, organized & protected but I got halfway thru installing the new pump and had to go to work & my neighbor who’s garage I was using had some down time & finished installing it for me while I was at work. But I think tomorrow morning when I get back from town I’m going to drop the tank remove all the crimp connectors and solder everything. It’d be a perfect time My tank should be just about empty by then and I have to drop it anyways to replace my EVAP vent valve so I figure why not right. Hopefully that’s all it turns out to be just a bad connection, I wouldn’t be surprised with those crimp connectors considering the problem I had two weeks after the pump was installed with one coming unconnected.
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I agree on the soldering. And a tip from one who's been there: Don't habitually run the tank below 1/4 full. The pump as designed is immersed in fuel to cool it. The pump sits high on the assembly so when the fuel gets really low it can overheat and over time can stress it to failure.
Ted
Ted
Oh okay thank you for the tip! I usually don’t let it get under 1/4 but I’m planning on dropping the tank today it’s my day off and just wanted to make it easy and quick as possible especially because I will be working outside & the high in my area today is 26 degrees lol.
So Instead of dropping the tank I decided to try the tilt bed method and well. That didn’t exactly work. I broke two bolts and the rest are stuck. And I mean stuck. I tried a 2ft breaker bar, then added a 2ft Cheater onto that & that’s how I broke the two bolts I broke. & the rest wouldn’t budge. Then I tried my regular 550 ft lbs air impact, no luck. So then I broke out my 1,000 ft lbs air impact, and still no luck. So I’m thinking I’m going to have to grind the bolts off so I looked all over the Internet for a new set of bolts but I can’t find any anywhere? Anyone know where to find some? Or what size they are so I can grab some from Home Depot or something?
I did accomplish something though I managed to replace the EVAP vent valve without lifting the bed or dropping the tank! but I would still like to get the bed up to re-wire my fuel pump I really do feel like there’s definitely a bad connection
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When they get that bad I usually cut them off with a 3 inch cutting wheel. I think Dorman makes a set of bolts and you may be able to get them at the auto parts store or at least order them.
I think that’s going to be the plan. But first i think I’m going to try once more later today with my breaker bar & torch just to try and save myself the work of getting studs out. I checked all of the parts stores I could think of, O’reilly, advance, NAPA, Sanel & no luck there. Rock auto doesn’t even have any witch is really surprising because they usually have pretty much every little part & piece you could think of. I did however just find some on wholesalegmpartsonline.com but they are almost $5 each. Witch I mean I don’t mind paying if I can’t find any for less but I think it’s worth a try to see if somewhere like Home Depot has the same size because on the site I just mentioned they have the size posted, they are M12 X 1.75 X 45. So I figure if I can find the same size somewhere like Home Depot or Ace it would just be a bit cheaper & i have a local Ace & Home Depot so I wouldn’t have to wait for shipping
smh hate waiting for things to come in the mail. I have a little wobble in the steering wheel due to worn sway bar link bushings that started about a month ago, Ordered a pair of heavy duty sway bar links at that time, were supposed to be here a little over two weeks ago & still haven’t arrived
smh hate waiting for things to come in the mail. I have a little wobble in the steering wheel due to worn sway bar link bushings that started about a month ago, Ordered a pair of heavy duty sway bar links at that time, were supposed to be here a little over two weeks ago & still haven’t arrived
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Sounds like you have a plan. I would make sure the bolts are at least grade 5 or better too because the big box stores buy Chinese bolts and screws and I've broken a few of those. There is a place called Fastenall that sells quality hardware if there is one near you..... Never had a problem with their stuff.
Well I haven’t had much time to get to getting the bed off I had a few other things that needed to be done, struts, parking brake shoes & cable, & abs sensor. But when I do have time for the bed I got some new bolts, exact size grade 8.8. But also theres something else I have been trying to figure out, lately i when I have the heat on, every 8 seconds or so there’s a realitively loud noise, sounds like a pump or something kicking on. Coming from sounds like the Passenger side of the engine bay. It only happens with the heat on though & it will go for about a second or so, stop for about 8 seconds, then happen again. & it will do this the whole time I have the heat on. Anyone know what this is?
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