tune up/ mass air flow question

[stepside83]

i have a 2003 silverado z71 ls with 5.3 it has 93,000 miles on her, i have a air aide cold air intake, true dual exhaust, E3 spark plugs, and dura last wires which i just put the plugs and wires in a week ago, but heres my issue, bout 3 weeks ago my check engine light came on, so i took it to local parts store to have it scaned, it came up saying mass air flow sensor was dirty or bad, i dont know the excact code it said, the parts guy gave me stuff to clean the sensor, so i did, light went out for about a week, then came back on, went back to parts store and same thing came up along with, random mis fire, now i was told to change plugs and wires and that should fix problem, i havent had the money yet to get a new air flow sensor will this week, but im wondering changeing plugs and wires, would/does that fix random mis fire, or is there something else wrong like coil packs? or is it because the air flow sensor is messed up so its messing with the spark some how? or should i just re do my exhaust and have one muffler with 2 out lets again any help on this would be great, im 23 and dont know much about the newer stuff, thanks guys

[finch]

plugs and wires will not cause random misfire on their own. would be ignition related. have your coil packs tested but with only 93k it sounds a little premature. my truck is still running around on original coils and creepin up on 170k. take off your MAF sensor, soak it down with some Deep Creep and then clean it up with a rag. do not damage the sensor or do any monkeying with it, just wipe off the excess and maybe shoot with some electrical contact cleaner. have all codes cleared and then see what happens.

[clinebarger]

Originally Posted by stepside83

i have a 2003 silverado z71 ls with 5.3 it has 93,000 miles on her, i have a air aide cold air intake, true dual exhaust, E3 spark plugs, and dura last wires which i just put the plugs and wires in a week ago, but heres my issue, bout 3 weeks ago my check engine light came on, so i took it to local parts store to have it scaned, it came up saying mass air flow sensor was dirty or bad, i dont know the excact code it said, the parts guy gave me stuff to clean the sensor, so i did, light went out for about a week, then came back on, went back to parts store and same thing came up along with, random mis fire, now i was told to change plugs and wires and that should fix problem, i havent had the money yet to get a new air flow sensor will this week, but im wondering changeing plugs and wires, would/does that fix random mis fire, or is there something else wrong like coil packs? or is it because the air flow sensor is messed up so its messing with the spark some how? or should i just re do my exhaust and have one muffler with 2 out lets again any help on this would be great, im 23 and dont know much about the newer stuff, thanks guys

The coil packs on these truck are very durable. Take the "E3 spark plugs" out & throw them away. Put some NGK or AC delco plugs in it & see what happens.

[bwood]

Does your truck still have the cats? Have you noticed any loss of performance recently? The MAF code and misfire codes may be related. It might be worth some money to have a shop run a scanner on it capable of looking at live data and see which cylinders are misfiring. Misfires on just one side of the engine with the MAF codes may point to backpressure issues in the exhaust. Before buying a new MAF, talk to a shop about hooking it up on a scanner to look at the misfires, cat temps and MAF data.

Originally Posted by clinebarger

The coil packs on these truck are very durable. Take the "E3 spark plugs" out & throw them away. Put some NGK or AC delco plugs in it & see what happens.

I have the same opinion of the Bosch products, more gimik than quality. I have had poor performance from the Bosch and E3 products. I have found AC Delco plugs to be the best bet. I have read that NGK produces the AC Delco products. Duralast wires, not real high on my list either (Autozone). You may remove the plugs and see if you can see any fouling or signs of a misfire. If you have access to a multimeter, remove the wires one at a time and check resistance through the wires. They should all be very close to the same reading, especially since the wires are only a few inches long.

[truckdude239]

Originally Posted by clinebarger

The coil packs on these truck are very durable. Take the "E3 spark plugs" out & throw them away. Put some NGK or AC delco plugs in it & see what happens.

for the love of god take the e-3's out and put ina set of ac delo plugs i was reading about a colardo taht the owner installed e3's and and burne dup the coil packs

[bighaas79]

Originally Posted by finch

plugs and wires will not cause random misfire on their own. would be ignition related. have your coil packs tested but with only 93k it sounds a little premature. my truck is still running around on original coils and creepin up on 170k. take off your MAF sensor, soak it down with some Deep Creep and then clean it up with a rag. do not damage the sensor or do any monkeying with it, just wipe off the excess and maybe shoot with some electrical contact cleaner. have all codes cleared and then see what happens.

I have an ammendment to make to this... do not SOAK down the maf sensor use the cleaner, but vary sparingly, and only on the hot wires, be very gentle with them and wipe any residue off. Soaking down just about any sensor can lead to cleaning solution creeping into the sensor and cause premature failure.

[stepside83]

to answer your questions yes ive notice a loss in power, and it dosent seem to run the best anymore, ive been told already to get rid of the e 3 plugs, which is my plan i didnt know theyd cause this much problem or i wouldnt of bought them,, i was thinking that maybe my cats were clogged, to be honest id like to get rid of them, but not sure if i can, i dont have emissions testing so i could that way but not sure if it hurt the truck if i did, but they have never been replaced none the less at least for the 2 years ive owned the truck, im gonna have a buddy of mine plug it into his computer at work (he works at a gm dealer just started there out of school but has access to the comp) to see what the issue is

[truckdude239]

if you think your cats are stoepd up remove the pre cat o2 sensoras and take it for a drive and see how it drives then

[stepside83]

well i got my truck pluged into a computer the othe day, it said the left side of the motor is mis fireing, my dads buddy has the computer and he said to change the plugs back to what was in there, and that should fix the problem, if not then the coil packs are bad, so i hope just changeing the plugs will fix the problem i really hope

[truckdude239]

http://shop.advanceautoparts.com/web..._1286346866___

that is the oem plug(yess i know they are 7.00 a plug ) for that truck and the best one for it i hope that the e-3's didn;t burn out your coils, i would go ahead and replace the wires too

[bwood]

Originally Posted by stepside83

well i got my truck pluged into a computer the othe day, it said the left side of the motor is mis fireing, my dads buddy has the computer and he said to change the plugs back to what was in there, and that should fix the problem, if not then the coil packs are bad, so i hope just changeing the plugs will fix the problem i really hope

I hate to disagree with your mechanic, but if the plugs really were the only cause of the issue, it would be misfiring on all cylinders. The coil packs don't go out in groups either, maybe one at a time, but not 4 at a time.

Here is some reading on similar issues:

http://67-72chevytrucks.com/vboard/s...&highlight=MAF

http://67-72chevytrucks.com/vboard/s...&highlight=avy

[stepside83]

the coil packs did not go out, i was told to change the plugs first and if that didnt fix my mis fire then the coil pack or packs are bad not once did i say all 4 coil packs on the left side of the motor are bad

[Black 95 TSI]

I would start with putting factory plugs back in it first.

You may even try new O2 sensors. We had couple trucks come in with bad O2s causing misfires.

[stepside83]

well i changed the plugs back to the factory plugs, and still runs like crap still misfires, any other ideas as to what would cause this still? is there a way yo test to see if one or any of the coil packs are bad? would bad co2 sensors make check engine light come on, and or flash, yes when i really get it on the truck around 4000 rpm the light comes on not all the time and flashes and then goes out, any idea what would cause that? thanks guys for all the info so far please keep it coming

[clinebarger]

Originally Posted by stepside83

well i changed the plugs back to the factory plugs, and still runs like crap still misfires, any other ideas as to what would cause this still? is there a way yo test to see if one or any of the coil packs are bad? would bad co2 sensors make check engine light come on, and or flash, yes when i really get it on the truck around 4000 rpm the light comes on not all the time and flashes and then goes out, any idea what would cause that? thanks guys for all the info so far please keep it coming

Your coil packs are good, Period. The check engine light will flash when the PCM detects misfires that are bad enough to damage the catalytic converter.

Its hard to dianose things over the internet, & it make it even harder when you dont have all the tools to do the tests that are required to dianose it proporly.

Take it to a exhaust shop & have them cut the converter off on the side thats misfiring & see if its melted/clogged.

[spudz]

I work at a Chevy dealership... I see this all the time... its usually with people that has a k&n air filter. They over oil it and the oil contaminates the MAF. Nothing you can do but replace it. BUT!!!!!!!!, does the truck seem like it has less power? I have seen MAF codes throw because of a clogged catalytic convertor and that will definatly cause a random missfire. Your coils and wires are fine. Delco plugs are the only ones to ever run. They are good for 100k plus.

[stsalvage]

Here is a Book you need to buy on line to work on anything with your tbi

[bighaas79]

Originally Posted by stsalvage

Here is a Book you need to buy on line to work on anything with your tbi

This would work awesome if he had TBI. Im gonna guess that very little from the TBI book will be useful on newer multiport injection. Whole different dog we're talkin about here.

Starting to sound like cats to me wouldn't be hard to check that all plugs and injectors were working properly. Need some data streams. Would make diagnosis way easier.

[spudz]

I skipped over alot of this thread, i just read where it said you HAVE lost power.. I am here to tell you.... its your cats...... to prove it, take your pre cat o2 sensor out on the affected bank or both banks if you like, and drive it.. It will be loud but you will notice a power increase..... but...I bet 50 buxs its the cats.

[stepside83]

well thanks spudz for all the info, my truck has almost 94,000 miles on it its a 2003 with a 5.3 in it, i do have an air aide intake on it, but all of this started to happen before i cleaned it, the maf made check light come on, i cleaned it with what the parts store said to use since i didnt have money to buy new one at time, it worked for about a week, then light came back on, got it checked again said maf sensor bad/dirty something like that, and a random misfire, so i bought new plugs (E3 which didnt know they were bad to have till later on) and wires, which i was gonna do anyways before winter put them in still ran with a mis, went got it checked again this time only came up left side motor mis fire, no maf sensor problem this time on the scanner, the only time the light comes on now is if i romp on it a little bit to around 4,000 rpm's then it flashes and goes out, still not at 100% power still misses with new ac delco plugs i just put in a few days ago, also my truck has true dual exhaust 2 mufflers 1 for each manifold, thats how it was when i bought it a couple years ago never changed it cuz it ss pipeing, not sure if that matters how the exhaust is or not just thought id share thanks again guys youve been a huge help , and spudz i hope this is enough info to better understand my problem and enough to confirm the cats are the problem, im gonna try th o2 sensors this weekend thanks

[spudz]

your truck has 4 o2 sensors, 2 before the cats, and 2 after. you said the left bank was misfiring. Most likely the cat on that side is clogged. And if you remove the cats, the truck will run fine but you will have a check engine light on unless you get the rear 02 sensors programmed out by a tuner. I dont think anything was ever wrong with the MAF. Put it this way, it can only suck in as much air as it can put out. So if the exit is clogged, it wont be able to get as much air in the front. The computer sees that its not flowing the right amount of air and throws a MAF code.

[bwood]

Something to add, cats don't just clog up all of the sudden and generally start to fail due to working harder than they're suppose to. Burning oil, running rich/lean, burning coolant all decrease the life of a converter. I can go right now to at least five of these trucks with 150k+ and still running fine on stock cats. Now that I have a circled the bush, here's my point, even if you remove the cats and program the rear O2s out, you may still have an underlying issue that did the cats in originally.

Here is some reading on catalytic converter operation:

http://www.aa1car.com/library/converter.htm

[spudz]

Originally Posted by bwood

Something to add, cats don't just clog up all of the sudden and generally start to fail due to working harder than they're suppose to. Burning oil, running rich/lean, burning coolant all decrease the life of a converter. I can go right now to at least five of these trucks with 150k+ and still running fine on stock cats. Now that I have a circled the bush, here's my point, even if you remove the cats and program the rear O2s out, you may still have an underlying issue that did the cats in originally.

Here is some reading on catalytic converter operation:

http://www.aa1car.com/library/converter.htm

True but not always. These trucks cats seem to come apart and clog themselves up sometimes. And the hwy patrol tahoe dog trucks I work on get cats all the time and the only explaination we can come up with is they idle them all day. But your right. If they are melted or clogged it is from an underlying issure.

[Rudy67chevy]

Originally Posted by spudz

I work at a Chevy dealership... I see this all the time... its usually with people that has a k&n air filter. They over oil it and the oil contaminates the MAF. Nothing you can do but replace it. BUT!!!!!!!!, does the truck seem like it has less power? I have seen MAF codes throw because of a clogged catalytic convertor and that will definatly cause a random missfire. Your coils and wires are fine. Delco plugs are the only ones to ever run. They are good for 100k plus.

I had a k&n in my o2.. Change back to stock, and the check engine light hasn't been on since.

[clinebarger]

Originally Posted by Rudy67chevy

I had a k&n in my o2.. Change back to stock, and the check engine light hasn't been on since.

Running a K&N filter is not a problem, Over oiling them is.