Spark Plugs and misfires

**kool-aide** · 10-31-2007, 08:57 AM

Ok, I never thought I would hear some one say a set of spark plugs were too cheap for an engine. I was discussing with a guy at the parts store about the LS1 and spark plugs regarding a little bump rattle and shake in the idling.

He told me a story about his 5.3L GMC truck and what was told to him as too cheap of a spark plug lead to his multiple misfires.

I'm a 99 completely stock z28.

Here is the question

Will the SES come on for misfires? Mine will come on for a day maybe two and then go off for several days or more. To me the book makes it out to be emissions related because it is a steady on.

Is there such a thing as too cheap of a plug for an engine or the LS1?

My car runs the same now as the day I bought it. I replaced the plugs and wires with Autolites. I've never bought high dollar plugs and wires for any engine i've owned. Granted most of my engines have been mopars from 4 bangers upto the 360.

I have an Actron 9180 on the way and hope it will help me figure this out.

The car runs strong and will leave plenty of rubber any where and way i want it. The only thing i know is a little shake or bump in the idle and the tail pipes smell a little rich with fuel.

BTW, don't hate me but I run 87 in my car all day every day, and i think the previous owner did too, not sure. I got the car with like 1/4 tank so naturally i had to fill it.

Like i said she is a strong beauty and i have no real complaints but can't sleep at night with this horror story called too cheap of a plug for an LS1.

thanks

kool-aide

**2001NBMZ28** · 10-31-2007, 09:25 AM

The SES will come on for misfires, and several other things - only way to tell what's going on is scan it for the code(s). I use NGK TR55 v-power plugs, they're cheap as opposed to what the car came with and no issues. I've never run 87 in my car since new - manual says run 91 or higher.

**kool-aide** · 10-31-2007, 02:19 PM

yeah i figured i would get a few bustin my chops about running 87

BTW i thought the ls1 wanted 93.

would the SES go off after awhile with misfires?

i pulled NGK PTR 5G - I3, can't tell if it is i3 or 13 at the end

Did you gap you NGKs? and to what if you did?

The Haynes says .060, i used a disc gapper and gapped so that the edge of the hook hit 60, think that gave me ~.059ish

Any idea what esle could cause a minor chop or shake in the idle? And nope it hasn't been cammed, i wish.

thanks

kool-aide

**Toes** · 10-31-2007, 03:19 PM

Have you checked for vacuum leaks? with your car running sometimes you can hear a hiss from the leak. check to make sure everything is plugged in and has a home

what did the spark plugs look like?

or could be a fuel issue my 00 silverado w/ 5.3L had a bad fuel regulator causing fuel to go down the vacuum hose to the intake

**kool-aide** · 10-31-2007, 04:15 PM

no hissy from under the hood.

To me the plugs look good considering i pulled them with unknown milage on them. My guess OEM and that would make them 95k miles.

I have a fresh fuel filter and PCV

The only thing I noticed after the fuel filter change is an increase in idle RPM, from about 400 to 600, but no other change. It idles the same at 600 as it did at 400.

here are pics, the only thing i find odd is two of the plugs have bad corrosion or rust on them

**kool-aide** · 10-31-2007, 04:20 PM

here is my attempt at posting pics

spark plugs pics on cardomain.com, kool-aide
http://www.cardomain.com/ride/2954870/1

**kool-aide** · 10-31-2007, 04:21 PM

the crapy ones on the left are driver side

again to me they look well used but not fowled or bad.

my Actron scanner should be here tomorrow, but i don't have my SES on. I have no idea if I have any stored codes in the PCM, or if that is possible.

**kool-aide** · 10-31-2007, 04:28 PM

i just thought of one key thing about my rough idle, the tach doesn't jump. You just feel the uneasiness of the chop and jump in the engine, no tach dancing.

i'm searching the threads now to compare stories. man i wish i would have bought that scanner awhile back, come on baby can't wait to you get here.

**kool-aide** · 11-01-2007, 04:49 AM

i was reading lots of other rough idle posts. I still have no idea if my engine is normal or a little off.

I did notice something this morning that has always bothered me and why i think my idle is not right.

every few seconds or minute or so the engine seems to miss a beat, kind of like a miss fire. It's like when you heart skips while going down that big drop on the roller coaster. It just kind of sudenly miss a beat and then gets right back into the groove.

The tach never jumps though. I don't think this kind of misstep in the idle is enough to make the tach dance or jump.

I swear it is almost like i'm explaining a cammed engine but i know its not.

I have a 99 Camaro A4 that seems to idle at 600 until after its warm and then sometimes likes to hang out at 500. Like I said prior to a new fuel filter it idled at 400.

thanks

**ls1blackbeauty98** · 11-01-2007, 11:40 AM

if ure misfiring the computer should throw an ses light and FLASH.
yes u will have stored codes if u threw a light before..
im sorry uve got so many posts with alotta detail/writing so im trying to read everything and tell u what i know..
dont run 87 seriously... i run 91 sometimes and i get a knocking. id run 92 or higher if u can..
rough idle could be alot of things, and since we cant hear the car... did u check ur MAF? i know when mine wasnt plugged in properly it seemed like i had a misfire.. and ses did come on for a day or two then went out with that problem.
you ordered a scanner? i would have taken it to autozone pulled codes there and came back to the forums to find out what codes u have haha but im broke with no money to buy a scanner, anyway its a good investment. good luck!

**kool-aide** · 11-01-2007, 02:01 PM

i one of those that doesn't what to take advantage of others. I know Adv Auto will come out and read your car, but to me they are in the business of selling not free diagnosis. Besides, I don't mind having tools in my garage. I buy them when I need them one at a time.

Can the PCM hold codes after the battery has been disconnected? I have gone trough a couple of disconnected battery sessions since my last SES was on.

The SES has never flashed. If it comes on it is on solid until it goes off again.

My best description is the one before about skipping a heart beat. It's like the engine is fine and out of now where it just shutters or skips and then runs fine.

I've had a TB cleaning and have checked all the sensors. Like i said the car has run this way from purchase, 11 months ago. The only thing the TB clean did was given a few days of good throttle response.

I'm in the process of getting ready to do another oil change. I've been reading about Auto Rx. Maybe I'll give that a go. In my last oil change I ran STP oil add and fuel add. Call me crazy but I have always used STP products, generally the blue oil add and black fuel add about every couple oil changes. Mind you in my past I drove about 3300 miles a month, now i drive about 5-6k a year, big diff.

Is there a way to post a video?

BTW what's the worst 87 will do to an LS1?

**ls1blackbeauty98** · 11-01-2007, 02:12 PM

if u disconnected ur battery the codes arent stored
the worst 87 will do is make the car ping, thats good enough for me tho
if the ses isnt flashing i think u can rule out a misfire. fuel injectors???? come on people help me and this guy out!!

did u check the maf like i said before?

**jigger1166** · 11-01-2007, 03:03 PM

It sounds like your fuel injectors need to be cleaned. Where I work, we use a GM cleaner. It works way better than the stuff you put in the fuel tank. We connect a canister with the cleaner to the fuel rail, and close the fuel feed, and return lines. The shop air line supplies pressure to feed the injectors.

When I do a tune-up for customers, I put GM's Fuel System Treatment in the fuel tank. It's made by, and is the same stuff as, Chevron Techron fuel system cleaner. You can buy it at the parts stores.

I highly recommend getting a professional fuel injector cleaning service done.

As for the Service Engine Soon lamp, it may be a DTC for an O2 sensor, or Fuel Trim. A misfire caused by fuel related issues won't set a code for misfire.

Let me know what the DTC is.

**kool-aide** · 11-01-2007, 03:12 PM

np, i hope the codes are still in there.

i have been reading past posts on cleaners, fuels adds and oil adds. Like I said I have never heard bad things nor exp bad things using STP products, but i'm not chemist. I've been thinking about a maint program and the best off the self stuff.

I wouldn't mind AutoRx but i'm an instant results impulse goof. Just like i won't buy books online. The only reason i bought the scanner online cuz the SES went off and i nkew i had time before it would pop on again, plus i always try to save money on big ticket items.

I hope to hook up to the car tomorrow after work.

**kool-aide** · 11-01-2007, 06:13 PM

well no stored codes and no pending codes. I have a shinny new toy and no codes, bummer. There are a boat load of things to look at. I'm gunna be busy from now 'til Xmas, oh boy.

any one now how to use an Actron CP9180?

**kool-aide** · 11-01-2007, 06:14 PM

lemme rephrase that

any one willing to share a few short cuts and helpful secrets on one of these things?

**0rion** · 11-01-2007, 09:45 PM

I have that same scanner. Pretty good scanner for the money. I thought the instructions were pretty decent for it. What are you wanting to do? I've just messed with mine a little bit. Since buying it I really haven't had any issues with any of my vehicles (knock on wood)but I played with it a little bit. You should be able to monitor misfires and long term fuel trims for both banks (LTFT bank1 and LTFT bank 2). You do that by monitoring and/or recording live data. I would have to re-read my manual but I think then you can hook it up to your computer and export it as a .csv file or something. See if you can do that, just play with it. Can't hurt anything. If you get the .csv file let me know and I'll have you email it to me.
To your problem.
The first order of business is to wait until that code comes back and see what the code is. You really can't go any further until that happens. It's like guessing the problem until then unless your scanner shows something going on. Also, LS1's just don't idle rock steady. There shouldn't be a miss there but both of my LS1's have a somewhat rough idle ( especially the one with the cam

). You can't really guess what's going on. You need some data, a code or data from the scanner showing you something isn't right. "rich smelling" exhaust might not be rich at all but actually be lean. Are your tips sooted up?
The plugs if in the correct heat range and gapped right I don't have a problem with. Running cheap wires is asking for trouble in my opinion. I would personally stick with what most people here run. NGK plugs and MSD wires. There are some other good plugs and wires out there but that's a pretty tried and true combo.
Lastly, stop running the cheap gas in it. Premium is normally 20 cents a gallon more than 87 here. .20x16 gallons = $3.20 a tank extra. Unless you put a ton of miles on your car I would guess a tank will pretty much get you through the week so it's $3 a week extra. The car will love you more if you spend $3 a week on it.

Let's start with the code and some good gas and work from there.

**jigger1166** · 11-02-2007, 01:50 AM

Originally Posted by 0rion

I have that same scanner. Pretty good scanner for the money. I thought the instructions were pretty decent for it. What are you wanting to do? I've just messed with mine a little bit. Since buying it I really haven't had any issues with any of my vehicles (knock on wood)but I played with it a little bit. You should be able to monitor misfires and long term fuel trims for both banks (LTFT bank1 and LTFT bank 2). You do that by monitoring and/or recording live data. I would have to re-read my manual but I think then you can hook it up to your computer and export it as a .csv file or something. See if you can do that, just play with it. Can't hurt anything. If you get the .csv file let me know and I'll have you email it to me.
To your problem.
The first order of business is to wait until that code comes back and see what the code is. You really can't go any further until that happens. It's like guessing the problem until then unless your scanner shows something going on. Also, LS1's just don't idle rock steady. There shouldn't be a miss there but both of my LS1's have a somewhat rough idle ( especially the one with the cam

). You can't really guess what's going on. You need some data, a code or data from the scanner showing you something isn't right. "rich smelling" exhaust might not be rich at all but actually be lean. Are your tips sooted up?
The plugs if in the correct heat range and gapped right I don't have a problem with. Running cheap wires is asking for trouble in my opinion. I would personally stick with what most people here run. NGK plugs and MSD wires. There are some other good plugs and wires out there but that's a pretty tried and true combo.
Lastly, stop running the cheap gas in it. Premium is normally 20 cents a gallon more than 87 here. .20x16 gallons = $3.20 a tank extra. Unless you put a ton of miles on your car I would guess a tank will pretty much get you through the week so it's $3 a week extra. The car will love you more if you spend $3 a week on it.

Let's start with the code and some good gas and work from there.

x2, I agree with Orion, run Premium unleaded, it's not that much more money, and you'll feel a difference

**ls1blackbeauty98** · 11-02-2007, 06:54 AM

Originally Posted by 0rion

I have that same scanner. Pretty good scanner for the money. I thought the instructions were pretty decent for it. What are you wanting to do? I've just messed with mine a little bit. Since buying it I really haven't had any issues with any of my vehicles (knock on wood)but I played with it a little bit. You should be able to monitor misfires and long term fuel trims for both banks (LTFT bank1 and LTFT bank 2). You do that by monitoring and/or recording live data. I would have to re-read my manual but I think then you can hook it up to your computer and export it as a .csv file or something. See if you can do that, just play with it. Can't hurt anything. If you get the .csv file let me know and I'll have you email it to me.
To your problem.
The first order of business is to wait until that code comes back and see what the code is. You really can't go any further until that happens. It's like guessing the problem until then unless your scanner shows something going on. Also, LS1's just don't idle rock steady. There shouldn't be a miss there but both of my LS1's have a somewhat rough idle ( especially the one with the cam

). You can't really guess what's going on. You need some data, a code or data from the scanner showing you something isn't right. "rich smelling" exhaust might not be rich at all but actually be lean. Are your tips sooted up?
The plugs if in the correct heat range and gapped right I don't have a problem with. Running cheap wires is asking for trouble in my opinion. I would personally stick with what most people here run. NGK plugs and MSD wires. There are some other good plugs and wires out there but that's a pretty tried and true combo.
Lastly, stop running the cheap gas in it. Premium is normally 20 cents a gallon more than 87 here. .20x16 gallons = $3.20 a tank extra. Unless you put a ton of miles on your car I would guess a tank will pretty much get you through the week so it's $3 a week extra. The car will love you more if you spend $3 a week on it.

Let's start with the code and some good gas and work from there.

agree!
nicely put

**kool-aide** · 11-02-2007, 01:56 PM

hah, i fill up once every two weeks. I put any where from 13 to 14 gallons in, just depends on how often i get on it. The only time i go above this when i go to the beach. More than half the time my car sits parked in the drive way all weekend. I get a combined 19-20 MPGs. I drive about 24 miles a day and most of the time none on the weekend, wow.

I understand the wait and see on the code. I was just hoping maybe someone could shed light on what this tool can really do. I don't have a clue when it comes to PCMs. I haven't read the manual, just got it last night. I wasn't sure how "good" the manual is. I would just like to learn a few important uses for the tool in case i need it down the road. With 96k+ miles things will start to go south sooner or later. I bought it cuz i don't want to fork out the cash to someone esle every time something is wrong.

Well, I spent good money on an Autolite setup, and plenty of hours on those stuborn plugs. I'm not really in the mood to drop more money and time on plugs. If the tool can help me learn what's going on and it points to problems in the plug/wire area, then i would be more than happy to swap parts and donate more blood. I'm pretty sure every thing is in the right heat range. I've never had a problem with part look ups at Advance Auto before.

Thanks for the info.