major Engine Stalling on an 03 Z-71

rgdepew · January 30, 2007

Truck in question is a 2003 Silverado Ext Cab Z-71...5.3L V-8, 67,160 miles...Fuel Filter has not been replaced...has an K&N air filter.

I was doing 70mph on the interstate last night when I noticed that the engine started to work harder than it should and the Check engine light began to flash off and on. Later on in the evening, I noticed more and more "stalling" and major hesitation the more I drove. It feels and acts like I had "bad gas"...aka water in the fuel. Today, I drove it to work and went to Autozone to get the trouble codes. I am getting a P0101-Mass Air flow Sensor Performance, and P0300-Engine Misfire detected...I am getting 2 of each code for a total of 4 trouble codes. At their advice I bought some Lucas Oil Fuel System treatment with injector cleaner and conditioner...I put 6 ounces in the tank (at the time the truck had 3/4ths of a tank of gas, so 6ozs treated 20 gallons...3ozs per 10 gallons.) Tonight I drained that fuel and filled it up with Marathon 93 octane (put another 6ozs of aforementioned fuel system cleaner in the tank.) I drove it and things got much worse...I think it actually put itself in limp mode. the truck will not go above 30-40mph; idles rough; major engine vibration at idle; no acceleration power at all...It acts like it is running on 4-5 cylinders at best...

Tomorrow I plan on getting a new fuel filter to see what that does.

Does anyone have any other suggestions? has this happened to anyone else? Any help is greatly appreciated! In the meantime I have to downgrade to a '97 Ford Ranger since the Chevy is not safe to drive until it runs again...

asepgrad98 · January 30, 2007

the oil from your k&n could have messed up your mass air flow sensor. try to clean it with a spray can of electronic cleaner.

asilverblazer · January 30, 2007

I'd try that too. Maybe you could use some alchol swabs.

rgdepew · January 30, 2007

I'll try that...Thanks. I think I still will try to brave the Indiana cold weather and replace the fuel filter...Can't hurt. Especially since I should have replaced it a while ago. Either way I'll let you know how it goes.

Thanks.

ken1mod · January 30, 2007

I have seen more problems caused by the maf sensor than any other.

Ken

lerbud · January 30, 2007

my buddy had an 02 that had the same symptoms and codes. his had a clatter also. he took it to the dealer and they worked on it for a few days and never did figure it out. he finally just traded it and bought a new one. they put it back together and sent it on to auction. he did get a good trade in despite the engine problem....

mrsilv04 · January 30, 2007

It seems to me that 67,000 miles on a fuel filter is too many. Assuming 15mpg, nearly 5,000 gallons of gas have passed through it.

I've got 38,000 miles on my '04, and it will be getting a new fuel filter when it goes in for the new steering shaft sometime here in the next couple of months.

Loomis462 · January 30, 2007

when the check engine light flashes you should stop asap!

rgdepew · January 31, 2007

Well...replaced the fuel filter and cleared the codes. The truck is not running any differently. I was going to try to clean the MAF but it got too cold for me to work outside (Temp was in the teens' when I got the fuel filter on...). I may try to clean the MAF tomorrow after work but if that doesn't work I think I will try to figure out a way to get it to a shop and let someone who knows more about this and who has the necessary tools to figure this out....Its too cold and its making me madder by the minute so I better not try myself.)

frdfandc · January 31, 2007

when the check engine light flashes you should stop asap!

Wrong. Unless something is acting up like a misfire or transmission slipping, and everything seems to be ok, you can continue to drive it. I know if my CEL came on because of a loose gas cap, I'm not going to stop driving it.

rgdepew · February 1, 2007

With the help of a ASE certified friend of mine, I think I have figured out what the problem is but I am not totally sure yet. He thinks it is a faulty MAF Sensor. I changed the fuel filter last night and cleaned the MAF today with no change. I am still getting the same Engine codes (at least it is still behaving in the same manor...steady light until 20mph then flashing.)

At his suggestion; while the truck was running, I unplugged the MAF Sensor. He said that if it is functioning properly, you should definately hear a difference and should die after 5 seconds or so. The first time I unplugged it i left the plug off for 10 seconds with no change in engine performance...kept running/missing, etc. Plugged it in....then unplugged it again...this time for 20 seconds...and I still didn;t notice any change in engine performance...it sounded no different with it unplugged versus plugged in...SO I think this is the problem...

what do ya'll think??? How long should the truck stay running if the MAF Sensor is unplugged? Should it stay running for 20+ seconds???

Ape0r · February 1, 2007

when the check engine light flashes you should stop asap!

Wrong. Unless something is acting up like a misfire or transmission slipping, and everything seems to be ok, you can continue to drive it. I know if my CEL came on because of a loose gas cap, I'm not going to stop driving it.

Check your owner's manual. Engine light ON is a-ok. Engine light BLINKING = misfire.

As far as the problem is concerned, I agree with everyone else that its probably the airflow sensor.

Gooberlog · February 6, 2007

As a ASE certified mechanic i can tell you that the computer only causes the Check Engine Light to FLASH/BLINK in one condition, where there is missfire seveere enough to damage the catylitic converter. Now considering that cats cost close to $1000 you can bet that i would pull over. There reasoning is that with converter damage emmisions will shoot through the roof, that's not my concern, i would just not like to prematurely replace a cat.

In this gentlemans case though the combination of Mass airflow malfunction and the P0300 random cylinder missfire i would say that the problem lies with in the mass air flow sensor also. Modern mass air flow sensors use a couple of thin wires exposed to intake air flow, and these wires are heated up to Hundreds of degrees and if they get dirty from age or say K&N filter charger oil soaked, they can not measure the intake air temperature and propper air flow readings acurately and send the computer this false information for IAT and air flow values. Then the computer inputs this false information to its air/fuel ratio chart and based on the "Garbage in...Garbage out" theory, the computer sees the wrong input information and outputs a wrong fuel mixture based on the input and this Rich or Lean conditon causes a random missfire evenly accross all cylinders as opposed to a single cylinder misfire ie: P0301 cyl #1 misfire due to a damaged spark plug wire.

I'm not saying this is what is exactly going in with your truck, but from previous experiences. I would recomend cleaning or replacing the Mass airflow sensor and clearing codes and or reseting the ecm memory.

mikbor1 · February 6, 2007

I had similiar problems with my 03' Suburban z71 (5.3)--If MAF doesn't check out, try pulling the the 2 O2 sensors closest to the manifolds--Run truck and see if it gets better--My problem was a clogged Catalytic Converter--I believe they are under warranty until 80,000 miles

Skip Talker · February 8, 2007

Same exact problem here. '04 Z-71 with 127,000 plus on it. K&N filter, cat back and a tune.

I bought it new and average about 1,000 miles a week. Started acting up with light on (and flashing sometimes). Rented the Autozone reader and got P0101 and P0300. The guy behind the counter asked when I last changed the spark plugs, I said huh? So I bought a new set of plugs. That smoothed up the idles a little but the codes did not go away.

Next I entered "P0101" in the search box of this forum and read all the results. So I ran back to the auto parts store and sure enough there was a can of CRC MAF cleaner. It was all ready dark but held the MAF up to the light it didn't appear to be dirty but what the heck. After I sprayed it a bit I could start to see the difference. I used the whole can on it and noticed the screen was still dirty. You could see where the spray had cleaned it up. I used a can of Gumout on the screen pointing away from the wires.

Put it back to gether and cleared the codes. Went for a 20 minute joy ride, highway, up hills, burnout and no light came on. Before when I would clear the codes the light would come back on with in a mile.

So for a little reading, a $6 can of MAF cleaner, and bearing with the bitter cold of a San Diego night (52 degrees) I think I solved my problem. I'll check back in a few days with an update.

Thanks for every ones input on the forum.

Skip