misfiring?

[yodaddy4200]

So today I was sitting at the drive up window at the bank. My truck felt like it was misfiring? So a couple stop lights later I go to take off and it feels like I'm running out of gas or misfiring or something.

Once I got going it was fine. But still sputtering upon take off.

I cleaned the TB at the end of last summer. The truck has 72,Xxx. I got it with 56,Xxx almost two years ago.

I've also serviced the TC as well as the tranny a few thousand miles back. No CEL or anything weird on the gauges.

Ill hook my buddys scan gauge II up to it tonight nor tomorrow and see if that helps but from what I've read id say it needs plugs. And maybe a coil pack?


Any input is appreciated thanks!

 

[Texan]

My first thought. Moisture (water) in fuel. just a guess.

 

[The_Roadie]

Consider changing plugs. Check air filter. Swapping coils is premature.

 

[RayVoy]

If the CEL did not light, you probably do not have mis-firing. A mis-fire will set codes and light the CEL.

As someone suggested, maybe it's gas, how old is the fuel in the tank?

 

[yodaddy4200]

I filled her up last friday. Its got a little over a quarter of a tank still. Should be top tier.

So I had the serpentine belt changed yesterday at my mother in laws work. ( a subaru dealer ship). I just went out and pushed on the belt and it goes down about id say a little more than a half an inch. Could this be connected and should I tighten the belt?

I'll have to wait till my kid goes down for a nap to check the air filter. The air filter is a k&n and I cleaned it about 6 months ago. It stays fairly clean no dirt roads or anything.

Another thing to note. I've smelled the rotten egg smell a couple times. Could my CAT be clogged/bad?

 

[CaptainXL]

I've smelled the rotten egg smell a couple times. Could my CAT be clogged/bad?

Not likely unless you notice a lack of power when passing cars on the highway.

Have you changed your FPR yet? That could definitely be the cause. A rotten egg sulfer smell is usually the sign your too rich and the converter bed is having a hard time keeping up.

 

[KNBlazer]

the belt I doubt is your problem, you would've had problems leaving the shop... it could be a coincedince and you just have a bad coil....

I had a problem about a year ago, no SES light, but did have a bad coil.. unplugged every coil one at a time and found the culprit, after going back into the truck, SES light was on, got a PO300...but I had already diagnosed Cyl 1...

 

[Texan]

Speculation on my part. Smell like rotten eggs = to much sulfur in gasoline.
Assume that gas is E10, not E15. Add a bottle of Chevron Techron fuel treatment
to next fill up. Do use Top Tier fuel. If you change plugs use AC41-103.
The belt is not adjustable, it has a spring loader tensioner.

 

[The_Roadie]

...air filter is a k&n ...stays fairly clean ...

Sure does, because it lets all the small particles through to harm your engine. Recommend doing more research and getting back to quality paper ones even if you have to swap them 1-2 times a year. Not wasted money.

 

[IllogicTC]

Sure does, because it lets all the small particles through to harm your engine. Recommend doing more research and getting back to quality paper ones even if you have to swap them 1-2 times a year. Not wasted money.

This. A Google search will turn up some interesting studies on air filters. I can't recall the exact link at the moment, but they tested the default OEM paper filter, a K&N, and some others, through a battery of standard ASTM standards regarding air filters, on a Duramax diesel. The OEM had the most restriction (of course), but also allowed in less dirt overall and its wear characteristics were more predictable, being nearly linear throughout the length of the test cycle. Some of the other filters either clogged up immediately once dirt was introduced into the air, or kept restriction low for a while but then had sudden jumps, rather than a linear increase in restriction.

The question is: Do you want ~10HP? Or do you want to have a low-worry, long-maintenance-cycle part protecting your intake?

 

[yodaddy4200]

looks like I'm not going to hear the end of it until I get a green filter! Lol.

I would rather my truck last longer than have a couple extra ponies. In my defence that filter was one of the first few mods I did before I read about the green filter.

Fpr? Fuel pressure regulater? No I have not

Me and a buddy were supposed to put my girls stereo in tomorrow but I think instead im going to get under there and check the plugs.

As far as the egg smell. I've only smelt it twice, once driving so I payed it no mind. But then one day I was loading some stuff in the back and I smelt it.

I just mentioned the belt cause I know some cars required them to be tightened up a bit after they ware some. I wasn't sure on how this one worked!

 

[yodaddy4200]

I just priced the plugs and the fpr. While I was on the phone I described the situation. The guy at oriellys mentioned cleaning the idle control valve. And checking the MAF?

Just thought id see if that was worth looking into...

MAF lol thinking about it... we have a MAP right? Or am I confusing two different parts? Search button here I come...

 

[KNBlazer]

Might the shop that replaced the belt, disconnected the battery?

...and just a heads up, the spark plugs that our trucks call for, SHOULD NOT be gapped the way of the old days, you run the risk of damaging the tip... youtube has a good vid on gapping iridiums...

 

[CaptainXL]

youtube has a good vid on gapping iridiums...

I myself would never gap iridium plugs. Too risky. Any flex in the ground electrode will chip the iridium layer.

Just check them with a feeler guage as they should be very close to spec. If they are not then return them.

Denso does have some tips I copied below from their website if you want to test your luck....

Should you decide to re-gap your Iridium Power plug, use extreme caution as improper gapping may damage or destroy the Iridium center electrode or porcelain center.

To increase the gap size:

Step 1: Use needle nose pliers or spark plug gapping tool to bend the ground strap up to the desired height. DO NOT LET THE PLIERS OR GAPPING TOOL TOUCH THE IRIDIUM CENTER ELECTRODE OR PORCELAIN.

Step 2: Re-check the gap with a calibrated gapping tool.

To decrease the gap size:

Step 1:Use the same method as above, however bend the ground strap down to the desired height. DO NOT LET THE PLIERS OR GAPPING TOOL TOUCH THE IRIDIUM CENTER ELECTRODE OR PORCELAIN.

Step 2: Re-check the gap with a calibrated gapping tool. WARNING: Failure to follow these directions may permanently damage the spark plug. Note: Never use a round gapping tool to check the gap or to increase or decrease the gap setting.

WARNING: Failure to follow these directions may permanently damage the spark plug. Note: Never use a round gapping tool to check the gap or to increase or decrease the gap setting.

 

[yodaddy4200]

Might the shop that replaced the belt, disconnected the battery?

...and just a heads up, the spark plugs that our trucks call for, SHOULD NOT be gapped the way of the old days, you run the risk of damaging the tip... youtube has a good vid on gapping iridiums...

That's a good idea about the battery. But call me crazy... I've never noticed my truck run like shit after a batt disconnect?

As far as gapping. If its that much of a pain then yes I will measure them and if they aren't right I'll ask them to swap them out!

 

[KNBlazer]

I used the pliers method, then used compressed air to make sure plug was clean... my plugs have always been off...

borrowed this pic from a google search..

That's a good idea about the battery. But call me crazy... I've never noticed my truck run like shit after a batt disconnect?

As far as gapping. If its that much of a pain then yes I will measure them and if they aren't right I'll ask them to swap them out!

I would also check camshaft position sensor for any damage caused by the belt tensioner tool hitting it...unlikely, but just a thought...

 

[CaptainXL]

my plugs have always been off...

Are you sure about that? Are you being overcritical?

Your experience would be the exception and not the norm. All of the ACDelco Iridium plugs I have installed have been close enough. If they are off just a little it is not necessary to re-gap them. Repeat it is not necessary. According to Denso the technology of Iridium allows for minor variations in the gap because they are so efficient.

 

[KNBlazer]

Are you sure about that? Are you being overcritical?
Your experience would be the exception and not the norm. All of the ACDelco Iridium plugs I have installed have been close enough. If they are off just a little it is not necessary to re-gap them. Repeat it is not necessary. According to Denso the technology of Iridium allows for minor variations in the gap because they are so efficient.

I've replaced the plugs on this truck twice, this last time, I got anywhere from .040 to .043....only one plug was at .044...

how many thousandths are acceptable...btw, this last set, I bought from RA, the first from Kragen/Oreilly...

where do you buy your plugs at?

 

[CaptainXL]

I got anywhere from .040 to .043....only one plug was at .044...

Perfectly acceptable depending on what brand of plugs you are using. The .040 plug (If Iridium) seems a bit narrowed. Possibly dropped.

Some brands/models of Iridium plugs are NOT adjustable. Just thought I would lay that out as well. Check this website and you will see what I mean.

DENSO SPARK PLUGS - Basic Knowledge

It's a gray area and confusing. So I have come to the conclusion that if the plugs aren't relatively close across the board as a set then I return them. So in a sense all I am doing is just trying to discourage the practice of regapping. Some old timers on here might be unaware of the new technology. Just acting as an advisor. But do what you want. It's your vehicle.

Denso plugs are .045. ACDelco Platinum are .0425

ACDelco Iridium are .043


View attachment 33973

Be aware the 41-103 Iridium spark plug is the recommended spark plug for
your vehicle. This spark plug should not be deviated from preset gap.
We are sorry that we cannot be of more assistance with this inquiry. If
further assistance is required please call our representatives at
1-800-ACDelco (1-800-223-3526). They are available from Monday through
Friday, from 8 a.m. until 8 p.m. Eastern Time, for your convenience.
Thank you for your interest in ACDelco.
ACDelco Customer Assistance
---

So in other words if GM says I can't deviate from the preset gap but when I check and the gap is wildly out of the ballpark ( I would say less than .040 or greater than .045) then I will be returning them. The reason I chose these numbers is because .0425 is in between and sounds like a good range. And another thing is how are you checking the gap. I have chipped a few by sliding my feeler gauges in between the electrodes and accidentally tweaking it up. It takes a steady hand. Or better yet just hold up a known good plug and eyeball it across from one to the other.

 

[KNBlazer]

AcDelco is all I've used...Internet is also split on this practice... both times, I've stayed away from the tip, and haven't had trouble...thanks for your input...

 

[sLAsh]

Thought I would add onto this thread rather than make a new one. Wife's truck was misfiring on cylinder 1(shows up on torque). Plugs only have about 30,000 km so i changed plugs on cylinder 1&2 and swapped the coil s between them. Now a misfire on cylinder 2.
Gotta go pick up a new coil now. And try that Not impressed that they are twice as much here as in the US

 

[CaptainXL]

Not impressed that they are twice as much here as in the US

Don't buy from a Dealer. Get this one from Amazon. It's the exact same thing. Delphi printed on top.

But be aware that many issues thought to be a result of the coil are actually corrosion in the spring, split boot, or bad spark plug.

http://www.amazon.com/dp/B000CGM5T6/?tag=gmtnation-20

 

[sLAsh]

^
Nice idea but by the time it ships to Canada it will be close to $100 with customs and duties.
Plug should be good since i just replaced it and the missfire changed cylinders when i moved the coils. Thanks for mentioning the boot and spring though. I thought it was all part of the coil pack. Now that I see they are available separately I will give that a try before replacing the coil.

 

[RayVoy]

^
Nice idea but by the time it ships to Canada it will be close to $100 with customs and duties.

Did you try Part Source? Corner of Brant and Fairview, or Brant and Plains (don't remember which).

 

[yodaddy4200]

I've decided I'm not gonna start throwing $$ at until I have a better idea what it is. I've driven it several times and it hasn't done it again so.

 

[yodaddy4200]

So I got a P0300 code today guys? Also on my Torque App it says catalist Incomplete?

What is the first step? Plugs? Coil packs? Any help is appriciated!

 

[signalnc]

from my experience with the misfire codes the p0300 is a misfire, but, it didn't misfire long enough for the computer to figure out which cylinder was misfiring. That's what happened to me last year. It took another drive to get the cyclinder number to register.

 

[MAY03LT]

My first step would be finding the offending cylinder(s). I've read some posts where peeps were able to get misfire counters off of torque.

The catalyst incomplete taint nothing to worry about. Just like EVAP, it takes a lot of drive cycles to complete.

 

[yodaddy4200]

Ok time to learn some more stuff. Thanks!

Well it just gave me a p0304 cylinder 4 misfire detected. So should I swap coil pack 4 out with one of the others and see if that's the problem before I mess with the plugs? Thanks again everyone!

 

[MAY03LT]

Yuppers. You sound like a vet now.

 

[yodaddy4200]

I'll have to tackle this tomorrow. I'll post what I find...

 

[sLAsh]

FYI I tried just changing the boot and spring first but the misfire was still there.
Replacing the coil pack fixed it for me

 

[The_Roadie]

You might also find the plug well filled with water that gets in from flowing through the cowl. Blow it out with compressed air before pulling the plug if you want to inspect the plugs.

 

[yodaddy4200]

Only because of your youtube vids!

It the video it looks like just the TB and the intake silencer have to come off. I think I can handle it. I'll watch it again before I try and attempt tomorrow!

 

[yodaddy4200]

Swapped coils #3 & #4. Its doing the same thing. It hasn't given me a code yet. When it does and hopefully its p0303. Then I'll grab a coil pack and see if that does it!

 

[yodaddy4200]

p0303 code today. The misfire followed the coil pack id say its on its way out.

Napa wants $110 for one. Oreillys wants like $80.

I want a quality product and don't want to spend an arm and a leg. I've seen six packs of these things on line for $140. So I'm confused?

Where should I buy one? I only want one now... I'll replace the rest in about another 20,000. I'm at 75,000 now. Figured at 100,000 I'll do the plugs too. And of coarse the TC.

 

[MAY03LT]

Yeah they average $80 around here. I've had to use duralast a few times, no complaints here.

Some guys buy used ones from ebay and after verifying that they work (important lol), keep them in the truck as spares. For times like these.

 

[yodaddy4200]

Ok I'll hit up Orielly's! Thanks!

 

[yodaddy4200]

I found a prozone coil pack for a 02. $28 shipped NEW. On ebay! 18 month warranty

 

[MAY03LT]

77 sold, eh? I wonder how well they hold up.