i took my car to a mechanic today because i had severe misfires in cylinder 5 and 6. prior to this i tried to change my plugs on my own for the first time. when i went to auto zone to get the materials i was given spark plugs that, i was told, were pre-gapped specifically for my car, but they weren't, and anti-sieze compound that was supposed to be for spark plugs, but it actually had insulating properties. since, as we all know, changing spark plugs in these cars is a pain, i didn't bother to verify the gap with the plugs currently in my car so i just change them out. since the gap was wrong my car ran like crap so i took my car to the first mechanic to get them re-gapped. i would have done it myself i just don't have that much time to spare working on my car and it takes a while to pull the plugs. so i take it to the mechanic and that's when i'm told the anti sieze used wasn't the right one. so they supposedly cleaned the plugs and the threads in the engine casing and re-gapped the plugs, breaking one of the plugs in the process. so they say it still has a slight "feathery" feeling when you accelerate but they didn't see any missfires on the computer. i take it home and on the way there it was bogging like hell, that must be one big, heavy *** feather! i check for missfires and 5 and 6 are severly missfiring. i swap the coil from 6 to 2 w/o change in cylinder missfire, then the wire from 6 to 2 w/o change in missfire location. i check the injector resistance and checks out good at 15 ohms. my wife starts getting upset because i don't spend enough time with her and my kid so i take it into a second mechanic. they are now saying that they swapped the plug from 6 to 2 and the missfire moved to 2, don't ask me why i didn't do that myself in the first place. not only this, they said that iridium plugs are recommended for my car and i used bosch platinum plus plugs and that could be causing the other cylinders to get a slight missfire. by the way, i did have very slight misfires in a few other cylinders. this doesn't seem right and i think the first mechanic just broke more plugs than they thought and just put them back in thinking they were ok. so now, because i don't know whether what the mechanic is saying about the iridium plugs is true or not and i haven't gotten to drive my car in forever i'm just taking the bill for an obscene amount to get my car running even though i doubt i have to do what they are saying i should do. my car is a '00 t/a. does anyone know if bosch platinum plugs have a tendancy to cause slight missfires as this mechanic claims they do? also, i researched iridium and i found out that it is a member of the platinum group of metals and has extremely high resistance to corrosion up to temps of 2000 degrees or some crap and i was wondering if these plugs should have the same maintenance replacement cycle as platinum plugs or what? thanks.

 

i'm not saying that the bosch plugs are the problem, but they could be. i've heard of several people having problems with them in GM cars, and the problems clearing up with a change of plugs. get yourself some NGK platinum plugs and be done with it.

 

Bosch spark plugs and Bosch 02 sensors WILL NOT work in my car, don't ask me why. It will not run. The 02's will hardly let it accelerate enoguh to get into second gear, it shakes and sputters violently.

NGK all the way. Gap them to .055.

 

I will never use bosch plugs again in ANYTHING ive had so many problems w them it isnt even funny pull them out and run ngk man

 

First mistake: Going to Auto Zone. I work for a parts store and I wouldn't recommend anything other than NGK for an LS1. Or atleast go with the OEM AC Delco plugs. I have had TONS of customers that have bought the Bosch crap and returned them because they are CRAP! Especially the Platinum +2 or +4. They will only fire on one side at a time. All it does is help incase one fouls out it has 1 or 3 others to fire from.

 

Iridium vs Platnium is not a real issue. I would try a different brand of plugs. As far as the anti-sieze goes there is no problems with one brand over the other. You slap some on the thread and place the plugs in. As for plug gaps always recheck everything. As mentioned before I would recommend a good NGK plug. I personally run the regular NGK plugs and change them more frequently. The only reason to run one of the platnium or iridium plugs is because you want 100k mile plug changing intervals. If you swap them every 20k a nice copper plug will work the best.

 

Get the NGK TR55's in there. No problems every with them.

I have had problems in the past with the Bosch plugs in various vechicles. Some cars just don't like them.

 

I use pre-gapped AC DELCO IRIDIUMS, and 13111 Bosch O2's....for over 2 years, same O2's...no problemo...

 

hey boost, what vendor are you working for(if you don't mind me asking). i agree on the bosch issues....the zone down the street from my store is great advertising for us. every customer they **** off ends up in our store. only problem i have is that louisville is a ford city.

 

If your mis is always in the same cylinders then you are probably fouling plugs. so u checked your injectors electronic coil, but it may be leaking causing overfueling. injector balance test my friend. do it. i have a 01 z28 with 130k miles. am a tech at a dealership, i put bosch platinum plugs in my ls1, did not gap them, just bought em and stuck em in without using antisieze. ive driven about 6k miles without a single mis. lets face it plugs are expensive. i will say tho after reading everyone elses response i dont think i will go bosch next time. maybe its just the anti sieze causing too much resistance through the arc ground path?

 

You should fill out your sig man so we know what else is on your car to help you determine other potential causes.

I use NGK-TR55s for my LS1 gapped to .055". I may switch to NGK-TR6 gapped to .035" (colder plug).

For my bolt on only LT1 i used NGK Iridium IXs because they are a PITA to swap. They've been fine for 20k so far.

I've never broken a spark plug even in some of the engine ive had that have say for 20 years. I've never used the anti-seize on the spark plugs either but i dont use a breaker bar to tighten them... I always use dielectric grease on the boots though, thats very important.

 

you are very lucky. heat and aluminum just dont go together very well. aluminum is a tricky metal and i have seen threads gall up on it very easily, therefor i always recommend anti-sieze for every bolt in an aluminum motor/head car. it takes longer to do but its the right way

OP i run the tr-55s w zero issues.

 

I run the cheap $2 a peice autolite 103's gapped @.030 and spray 150 on them with zero problems

 

I work for O'Reilly. I agree on AutoBone being good advertising. They sell the same brands as we do but offer less warranty and don't stand behind it anyway!

 

What about Pulstar's?

 

If your comfortable with paying 25$ a plug for them go for it. I think you would be the first person on ls1tech with them. Then you could do a product review

 

Ac delco or NGK nothing else!! ALWAYS use anti-seize on spark plugs in aluminum heads or you just might pull out a plug that has the threads from the head and that will really **** you off!!!

 

I have started searching for a fix which starts out as engine hesitation and through changing the typical things (plugs, wires, fuel filters, several visit to dealership, several visits to other shops). The top entry talked about swapping coils to determine if the misfire was related to coils or fuel. I am at that point as well: misfire on 2,4, and 6. 6 seemed to be misfiring regularly. Swapping-the-coil pointed to a fuel injector on 6. The car is still at the shop trying to be debugged.

Problem: I drive the car until it warms up. After stopping for at lease 20 minutes, driving the car after 50 yards, the engine hesitates for about 40 sec.

I do not believe the plug replacement on the original post will correct the problem. Have you had a chance to perform the Injector balance test?

 

autolight racing 103 if not spraying,,,as stated by a 7 year tuner and ar94 if spraying he compared them to a tr6 and there is a big diffrence...look for yourself

 

i have the autolite ar103`s in mine right now and my throtle response went trought the roof