2004 silverado Z71 flashing check engine light

180

Asked by Mar 22, 2013 at 10:45 PM about the 2004 Chevrolet Silverado 1500 Z71 Crew Cab Short Bed 4WD

Question type: Maintenance & Repair

my check engine light has come on and had started blinking just lately. which means engine misfire. after replacing the plugs and wires the truck seems to have a rough idle and still seems to misfire sometimes. seems to only happen in town. have yet t figure out if its because it is cold or because the truck is running at a slower pace. also the gas mileage is very bad but only when the check engine  is flashing?

any help is appreciated. Thanks

49 Answers

good guess, the evap system is throwin up the red flag, probably your gas cap is missing, not tight, or you're overfilled the tank chokin' off the evap canister (guilty of this myself) it will recover with use, the light will go off if you've corrected with the proper fuel cap and not over-filling the gas tank....also you may need an oxygen sensor...all these and more can be found out if you go on by your parts store NAPA, O'reilly, kragen will do this for free, write down the information and relay it to the gurus here, we will tell you exactly how to correct the situation if none of these 'pinata' answers work!~

9 of 9 people found this helpful.
180

Sorry. Forgot to also say that I've had the truck scanned many times the 1 time it said multiple misfire so I changed the plugs and wires. 2 time I got him to clear all the old codes and drive it for the day and got it scanned again. Said that the #8 cylinder was the issue of the misfire. So swapped the coil with another on the truck to see if that was the problem. But then the 3rd time it says that all cylinders but #4&6 have misfired.

10 of 10 people found this helpful.
99,185

Have you changed the plugs? Air filter?

2 of 2 people found this helpful.
180

Yes. I've changed the plugs and the wires. Haven't checked the air filter. Would that make the truck misfire at any time? I'll still check it due to having no idea what the problem is.

5 of 5 people found this helpful.

change your bad coil pack and call it skippy!

3 of 3 people found this helpful.
180

I'm not sure if its the coil pack? It had only said that the one cylinder was bad once and it's back to 1,2,3,5,7&8 misfiring. And call it skippy?

2 of 2 people found this helpful.

well these are usually in pairs, that's why I assumed you had coil packs. by 2004 practically no one was using a distributor. but used pairs of coil packs...there are ways of testing these, take an ohm reading and compare that to the ones that work, and you'll know what to replace- skippy, yes like the peanut butter. seemed like a smooth exit~

2 of 2 people found this helpful.
1,205

I recently had a similar issue with my 03 avalanche. after checking coils replacing plugs and wires it turned out to be a fuel injector. Before you go swapping injectors though try a fuel filter especially if your getting up there in miles. I bought mine used and it still had the original fuel filter on at 100k miles. Once i changed my injector and filter its been running great no more multi cylinder misfires or cylinder 6 which is where the injector was clogged.

1 of 1 people found this helpful.
Best Answer
180

Been doing my research and only finding that the fuel filter on this generation of silverado is the same as the fuel sending unit. and it has been replace within the last 4-5 months.

1 of 1 people found this helpful.
1,205

I checked the chiltons book and it says 05 and up have only filters on the sending units and they are not replaceable. Since yours is an 04 its possible your in the same boat too. My 03 has an inline filter in the frame in the area below the drivers seat. According to the chilton's book yours should too. Wouldn't be the first time the book was wrong though. I would check your fuel pressure it sounds like your 4 and 6 cylinders are not mis firing and those are the closest to where the fuel line enters the fuel rails. There's a possibility that there is not enough pressure getting there and or not enough fuel coming through the lines

1 of 1 people found this helpful.
320

My 05 silverado is idling rough. CEL started flashing while parked. Soon after CED went off and truck was idling fine. Just happened an hour. Any thoughts.

18 of 18 people found this helpful.

Read and CLEAR THE CODES... with a small 15 dollar handheld OBD-II scanner~

3 of 3 people found this helpful.

that thing will come on if you did not fill the tank properly....stoppin' at the first click (which NO ONE can seem to do)~ the charcoal canister will get stifled but should recover~

3 of 3 people found this helpful.
320

Judge_roy, already on top of it. Ordered the code reader ten minutes ago. Are any steps I need to take in the mean time?

2 of 2 people found this helpful.
320

BTW: I did NOT stop after the first click. Is it pretty likely this is my issue? This is my first Silverado. Never had to worry about that in my Lexus ES 300.

2 of 2 people found this helpful.

the OBD-II port is within three feet of the ignition switch...this is a dandy item because you can read EVERYONE's trouble codes now too~

yes....guessing the CEL came on after you gassed up...then yes...the heated 02 sensors DO need full power to operate the "HEATED" part correctly for correct readings....with any luck you haven't got an heated 02, but just a plain 02...which is very fussy, touchy technology~ the wire is more important than the platinum part~

1 of 1 people found this helpful.
320

What's steps should I take if it is a over fill issue?

3 of 3 people found this helpful.

,,,hey....lookin' back this is the first damn entry in this dialogue~

yes....the "black tape" solution will have to do until you run the tank down to say 3/4 fulll should go off and have sufficient vacuum to correct itself~ CLEAR the CODES with that 15 dollar scanner and it's off to the races~

320

I sprung for the $60.00 scanner. It did smell a little rich during this episode. Reading now about O2 sensors. I just freaking bought this truck (used). I love it, but really want it to last. Trying to stay on top of maintenance.

2 of 2 people found this helpful.

it's about vacuum at this point...you can keep your fingers crossed and hope that fuel ain't gettin into the vacuum supply...this might cause problems with the computer deciding what to do with it's air/fuel mixture~ .....as the substitution of fuel instead of air might cause it to cough a bit...maybe not...quite certain this HAS come up before and the Engineers think of everything....don't they~?

2 of 2 people found this helpful.

most troublesome is the "purge valve" which will NOT let you put fuel in...well, I oughta!! seen people having to fill with a funnel...all because the valve got damaged and will not allow liquid or gasses in....very helpful~

1 of 1 people found this helpful.

if you can sense that the timing chain and gears sound normal (not a can of folger's) you've got a real sweet ride....frankly am jealous...my wife makes me keep "bessie" the 93 toyota with 250,000 hard miles on it~

320

I traded up for my Lexus (Toyota) with 225,000 long and hard miles. It's was actually my wife's idea. Can you believe that. I was aiming for 300k. Oh well. Hope to put 300k on the bow tie now.

1 of 1 people found this helpful.

....well you cannot haul that old water heater to the dump with a Lexus...gotta keep the Toyota for "dump runs"....unsavory as that sounds...the MINI cooper is not happy with this NO pavement, but boulders that will smash up the undercarriage.....so mostly do not drive the mini which has only 36,000 miles on it~ in your case the BOWTIE (as you put it)~

10

ON THESE trucks it can also sometimes be a knock sensor or crank sensor that can cause a misfire or low fuel pressure or even intake gasket leaking. to check knock sensor shouold always throw a code. but on the crank not always needs to be put on a scanner and watch the info from the motor it can not send a single which would show up and cause a misfire but not always a crank shaft code. just possiabilitys

1 of 1 people found this helpful.
100

I also have a random misfire on my 04 silverado 5.3 with 135,000 miles. Dealership took motor apart ($1100) to no avail. They said it's my #2 and #7 cylinders. The number 2 is being caused by number 7 misfire. Parts I've replaced: Bank 1 sensor 1 (drivers side upstream o2) MAP sensor Plugs and wires Crank position sensor Throttle body which includes IACV and TCS Compression and fuel pressure checked by GM dealership.... Need serious help. My truck will not pass inspection with engine light on.

10 of 10 people found this helpful.
50

did u ever figure it out wgjones73? going thru the same thing with my 03 z71. missing on 6 outta 8 and throwing code for crank sensor and a bunch of evaps. runs rough as u step on gas tho, idles ok for the most part!

3 of 3 people found this helpful.
4,675

Read the codes to determine if sensor ! Go from cheapest to most difficult solution! Oreilly Autozone will let you use a OBD SCANNER for free!

1 of 1 people found this helpful.
30

If on my 04 Silverado the injector is clogged will it still make a clicking noise

2 of 2 people found this helpful.
1,205

It could jayZ71 mine did.

1 of 1 people found this helpful.
30

Now my oil has gas smell to it cause its missing I gotta see witch coil pack has went out

30

If my catalytic converter is stopped up wouldn't the engine run hotter than usual

1 of 1 people found this helpful.
4,675

Yes catalytic would kill the engine! Have you cleaned inspected sensors crankshaft etc? But evacuate the vapor system if gas entered into it! These are closed systems designed to keep emissions low!!

30

I got my codes read and the first thing that popes up is running Lean then multiple miss fire do u think its my fuel pump it doesn't miss at high rpm also no fuel filter

4,675

No filter yikes! If any contiminants get into to fuel injector it is going to get clogged and cause it to run sporadic! Yes if fuel pump is old replace it! But get a filter on it!!

10

i hope this is still somewhat active. i just got a used 96 chevy silverado 1500. it knocks pretty loud when idling and knocks when driving. when im driving it doesnt want to shift out of 1st gear unless i let off the gas at about 25-30mph otherwise rpm's just keep rising. i took it to get the codes read because my check engine light is on and flashes, he said o2 sensor bank 1 sensor 1 and bank 1 sensor 3, its missing, running rich, and something about a cylinder. can ANYONE help me?

1 of 1 people found this helpful.
20

I bought a 2003 silverado went to Texas to get it he said it was missing and cel was flashing I put fuel pump filters all the major sensors cleaned fuel rail injectors intake gasket was about to leave it there and already paid for it my dad told me to drill a couple holes in the driver side converter and beat it with a hammer and it runs great

2 of 2 people found this helpful.
20

If I ever have that problem again I'm drilling holes first it's free

10

Hey yall my 2004 Silverado had a misfire in the 6th cylinder and I replaced both 02 sensors on the passenger side and It ran fine then I started my truck soon after I fixed it and it would idle fine for about 25 seconds then start to misfire again then after about a minute and a half of misfiring it would stop and then it would idle justfine. It only misfires on startup and I need some help!!!

1 of 1 people found this helpful.
10

Craig if your truck only misfires on start up and it has a fuel pressure regulator that is controlled by a vacuum hose on the driverside of the engine it could be leaking into the #4 cylinder after sitting. If the regulator leaks profusely you could have a misfire most of the time. especially during idle.

10

my 2000 silverado 4wd 5.3, cel is on. In the mornings it flashes and seems to have power loss, poor acceleration. After work cel just stays on, no flashing runs fine. any ideas?

1 of 1 people found this helpful.
10

If when cold it misfires and runs poorly, the most likely cause could be leaking intake gaskets. They would be leaking vacuum. When the engine warms up the seals swell and the misfires go away. One way to test for this is to do the following. Have a spray bottle full of water read on a cold start up. Once the engine is running spray the water at the intake near the cylinder head over the valve covers. Do Not soak the intake! You could cause other issues. If the engine runs worse and you sometimes hear a sucking noise, then the intake gaskets should be removed. I hope this helps.

10

On my last post I stated that the intake gaskets should be removed. actually they need to be "replaced".

10

well it actually seems to be moisture issue. The other morning was cold but no moisture on windshield at all. Truck ran great. Rained and ran poor. Have changed plugs, wires and all coil packs, cleaned MAF and throttle body, Fuel pressure is around 48 at idle up to maybe 55 driving. No obvious broken or exposed wires

5

wow thank goodness my 1500 Silverado 94 and 1988 2500 doesn't have that problem either with a check engine light. But I do find this site useful I'm definitely will be looking up my cylinders this month

Did anyone figure out a solution to these problem I been having a misfire problem for months and need help on my 2004 avalanche

My 2000 z71 was doing the same exact thing and I put a 6in rough country lift on and it just went away lol there might have been a loose wire or something I don't know but that's what fixed mine

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