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2003 Silverado Lean Banks 1&2
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ttopformula89
Novice
Apr 30, 2014, 8:07 PM
Post #1 of 14
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2003 Silverado Lean Banks 1&2
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Hello, here are my issues with this truck.
2003 Silverado 5.3 Vin T
I get a check engine light every few days and it is always the same codes, engine lean bank 1 and bank 2. It just started doing it this winter.
I have replaced the oxygen sensors
I have replaced the fuel filter
I have replaced the Fuel Pressure Regulator
I have replaced the MAF Sensor
Also Replaced all of the normal tune up stuff, wires, plugs air filter, pcv, etc.
I have sprayed around the intake with starting fluid & also tried propane to see if any change in idle would occur and it holds true and does not change. (learned a lesson too, ALWAYS turn off your heater or your truck will smell like starting fluid inside for a week)
I tested the fuel pressure (with 3 different gauges) and here are my specs.
Gauge hooked up to fuel rail, engine off, when I turn the key on and the pump is running it reads 55 psi, when the pump stops running it drops to 51psi. If I let it sit for 10-15 min the pressure drops to 49 and holds there.
With the truck running and the pressure regulator connected it stays at 49 psi. When I disconnect the fuel pressure regulator it jumps to 58 psi.
It runs great driving down the highway, and 90% of the time its good at idle too. Sometimes when I pull up to a stop light it runs rough and seems like its going to die, a few times it has died, but starts right back up. It tends to do this more on very cold days, and when that happens I get a check engine light right away.
I think it is either weak fuel pressure (pump) or a very small intake manifold leak, so small that when I sprayed around it nothing seemed to happen. I do not have a live scanner to watch the O2 sensors when I did that so I am guessing here. I had problems with my Cats 2 years ago and I gutted them and re-welded them. I was getting a code for cats below efficiency but I cured that with O2 extenders for the rear O2 sensors.
I need the truck for a 2,000 mile road trip in 2 weeks and I am trying to figure this out quickly.
(This post was edited by ttopformula89 on Apr 30, 2014, 8:18 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
May 1, 2014, 12:10 AM
Post #2 of 14
(2090 views)
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Re: 2003 Silverado Lean Banks 1&2
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Your going to have a difficult time solving this without scan tool data. You should have your mechanic check it out. The amount of money you spent chasing the problem you could of had your mechanic diagnose the problem for a lot less.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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kev2
Veteran
May 1, 2014, 2:39 AM
Post #3 of 14
(2080 views)
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Re: 2003 Silverado Lean Banks 1&2
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I gotta mention - it is ILLEGAL to operate with the cats like that.... anything else changed, modified?
I agree that a scanner woould answer a string of our questions very quickly... FT would be one as well as the freeze frame data...
I was confused by the fuel pressure readings- likely I need to reread when I am not rushed and check the spec's.
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kev2
Veteran
May 1, 2014, 3:34 AM
Post #4 of 14
(2074 views)
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Re: 2003 Silverado Lean Banks 1&2
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fuel pressure spec 55-62- seams you are LOW - critical number and this does NOT take into account volume
knowing the fuel trims would be the key here-
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Hammer Time
Ultimate Carjunky
/ Moderator
May 1, 2014, 4:25 AM
Post #5 of 14
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Re: 2003 Silverado Lean Banks 1&2
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If this is a VIN "Z", the spec is 48-54
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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ttopformula89
Novice
May 1, 2014, 8:14 AM
Post #6 of 14
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Re: 2003 Silverado Lean Banks 1&2
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The truck is bone stock except for the cats, and a slightly larger cat back exhaust. I understand its Illegal to modify your cats, however at the time they were plugged to the point that the transmission didn't want to shift, and the transmission shop determined it was the cats. Low funds and super expensive fix ended in that modification. Sometimes you just have to do what you need to in order to get by, I'm sure you have been in situations like that before.
As for the fuel specs needing to be between 55-60psi, is that with the truck running or just ignition turned on, or with the pressure regulator vacuum hose connected or disconnected?
I understand that throwing parts at it is like tossing money away, and all of you are by the book it seems and I respect that. When you don't live in a city or large town, it can be rather difficult to follow the by the book rules. The only thing I have purchased outside the realm of a normal tune up is a MAF, and the front O2's. I had problems with the MAF in the past due to the last owner installing an over oiled K&N filter, even after cleaning it, I would get MAF codes from time to time, so it wasn't to bad of an idea to install a fresh MAF, and paper filter.
The O2 sensors were what every code reader said was the problem, so after "tossing" a set of them at this and realizing that didn't cure anything, I have stepped back and decided to track the problem further before "tossing" parts at it anymore. Thats why I am here, to ask you fine gentlemen your opinions and to "pick" your fine tuned brains a bit.
The only shop in a 50 mile area here has a very bad rep, and has tried to pull some dirty stuff with me before, so thats why I have not taken it in, and I won't until its a last resort.
I will probably need a live scan tool to check the O2 senors while I check for leaks around the manifold right? Also, do you think having it smoke tested would be a benefit or waste of time?
I also feel that the fuel pressure is a bit low, but after trying to find exact specs online, I have found very conflicting numbers. I would like to add that the truck has no power issues, it accelerates great never misses a beat even when I put the hammer down, and the rough idle is intermitant, sometimes it acts up, sometimes it doesn't. Which has to make me think that if its low pressure causing this, wouldn't it happen more consistanly, and wouldn't I notice some power loss when Im getting on it?
This "problem" happens more frequently when its very cold outside. More so when the temps fall below 20. With a plastic intake I have been thinking that the cold could cause some "shrinkage" in rubber gaskets and plactic intake, maybe just enough to cause a manifold air leak? Ehh its just a thought.
Thanks for your replys so far and if you have anymore questions from me I will try my best to give you accurate answers.
(This post was edited by ttopformula89 on May 1, 2014, 8:16 AM)
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ttopformula89
Novice
May 1, 2014, 8:15 AM
Post #7 of 14
(2058 views)
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Re: 2003 Silverado Lean Banks 1&2
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Its a Vin T
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kev2
Veteran
May 1, 2014, 8:51 AM
Post #8 of 14
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Re: 2003 Silverado Lean Banks 1&2
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I mentioned the cat issue as a note for others.... My feeling is that emissions testing is unnecessary, a feel good money maker - a burden that belongs only to NEW vehicles that are under warranty. As the newer cleaner vehicles become the norm the air will show cleaner JUST as fast in places without testing as in those that test. Sorry for the rant.
The scanner would be a easy way of looking at lots of data... My thoughts after you mention its worse when temps drop.. are to concentrate on fuel pressure - for a test lets try- remove the vacuum line to the fuel pressure regulator. plug the vacuum leak, replace the fuel filter (if not done) - see if that little extra PSI prevents the lean code.
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ttopformula89
Novice
May 1, 2014, 9:13 AM
Post #10 of 14
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Re: 2003 Silverado Lean Banks 1&2
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Minnesota does not do emission testing, so there will be no fine, and this is my garage not a shop. I understand that shops will not do this none the less. I'm glad to hear you have a reputable shop, and you stand by your guidelines. And when I said "I'm sure you have been in a situation like that before" I was not implying that situation was in a fully set up shop, but more out in the sticks without a whole lot of directions to chose from, and a vehicle that needs help to get home. I was pretty sure everyone who knows a bit about cars would have at one time had to do what was needed to get home, but maybe not.
As for the fuel pressure... when I disconnect the vacuum line and plug the line, the pressure does rise to 58 psi. Is it safe to drive like that for awhile to see if the problem comes back? I don't want to harm anything, so I am just covering my bases. OH and yes the fuel filter is less than 2 months old, and it is installed correctly.
I will ask around and see if I can get my hands on a live scan tool.
Thanks again for your helpful responses.
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Discretesignals
Ultimate Carjunky
/ Moderator
May 1, 2014, 12:42 PM
Post #11 of 14
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Re: 2003 Silverado Lean Banks 1&2
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The trick is to find out what the engine is doing when the lean codes set. If you had a scan tool or code reader that had the capability of looking at freeze frame data you could see what was going on with the engine when the computer flagged the codes.
With that information you figure out if you have a vacuum leak or fuel delivery issue. Those engines are hard to figure out vacuum leaks on unless you are using propane and watching short term fuel trims. Spraying carb cleaner may not cause a change if the leak is small because the computer will compensate for the idle change if you listening for a leak. Smoke machine would be ideal if you had access.
If the problem is a fuel delivery issue, it gets more complex in that you have to figure out what part of the fuel system has the issue. Is the problem a old tired pump, restriction, clogged injectors, computer input or output problem? When you get into computer inputs and outputs, that is a whole new ball game.
We spend years and lots of money learning how to diagnose these problems that your chasing. We really can't help you solve the problem unless you provide the data.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 1, 2014, 12:46 PM)
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ttopformula89
Novice
May 3, 2014, 7:11 PM
Post #12 of 14
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Re: 2003 Silverado Lean Banks 1&2
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Ok so I got a live data scan tool now. I hooked it up and started the engine, I watched the live ft data after letting the system go to closed loop. I sprayed some starting fluid around the intake gasket on bank one side and the graph dropped off the charts, I did the same to bank 2 and when I sprayed about 1/2 way back on the gasket it too dropped off the charts. That would indicate a leaky gasket right? So I replaced the intake gasket and after hooking up the scanner and repeating the test, it no longer spikes, and it stays in range. That problem should be cured, or at least part of the problem should be. The truck runs good, but I still notice a slight shudder every now and then at idle, so I tested and re-tested the fuel pressure probably 10 times just to make darn sure I got the same numbers on every test and they stayed true. I do believe I have low fuel pressure. Here are the numbers once again. It is a vin code T.
Ignition turned on while fuel pump running, engine is not started (3 or 4 seconds, then it shuts down) Fuel pressure reads 55 psi
Ignition On Engine off, after fuel pump stops pumping it reads 53psi
After sitting for 10 minutes not running, ignition on, fuel pressure bleeds down to 43 psi
With engine running, and fuel pressure regulator vacuum line still hooked up it reads 49 psi.
With the engine running and the fuel pressure regulator vacuum line disconnected and plugged it reads 57 psi.
I hooked up the live data scanner and while it was running and at operating temp, I took a photo of every screen for reference. I tried to upload them here but it wouldn't allow me, so I posted them in a photobucket account. here is the address to the photos.
http://s1362.photobucket.com/user/ttopformula89/slideshow/
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ttopformula89
Novice
May 3, 2014, 11:08 PM
Post #13 of 14
(1986 views)
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Re: 2003 Silverado Lean Banks 1&2
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UPDATE!
Took it for a nice long drive tonight and it seems to be running great.
No check engine light, can barely tell its running when at idle. However I am still concerned about the fuel pressure, and I hope one of you guys will know by my last post if its not in spec. Also any input on the live data photos I posted would be wonderful if you have a minute to look it all over. Im new to the live data scanner and am still learning what everything means, so if you notice anything wrong with the data please explain it to me. Thanks in advance!
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Discretesignals
Ultimate Carjunky
/ Moderator
May 4, 2014, 7:27 AM
Post #14 of 14
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Re: 2003 Silverado Lean Banks 1&2
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Checked out your data. At the time you took it the long term fuel trim on both banks was negative, so it appears you corrected the lean condition if it had one at or around idle speed. The long term is borderline for fuel correction, but it isn't too bad and might have changed since you been driving it.
One easy way to see if you have enough fuel pressure is to do a wide open throttle test while watching the bank 1 sensor 1 and bank 2 sensor 1 O2 sensors' voltages. Find an open road and nail it. The O2s' voltages should peg out around .8-1.0 volts. If it does the entire time you have it wide open, you have enough fuel getting to the engine.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on May 4, 2014, 7:34 AM)
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