NGK TR55IX plug problems?
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,202
Likes: 117
From: San Antonio Texas
NGK TR55IX plug problems?
I'm having a high RMP breakup about 5200 rpm in my LT4.
I've changed the Opti, Wires, Coil, Ign. module, Injectors, Fuel filter.....damn near the works.
The car starts & runs just fine, gets good gas mileage and will tear your head off as long as you don't take it much above 5200. No codes, heat or any other problems other than not wanting to rev much past 5000 (and 5000 comes up real quick when I get down on it). I've had some people say that the stock type plugs work best for the full rpm range and some of the "fancy pants" plugs are good only for longevity and not so good for higher RPM. Have any of you had any high rpm problems with the iridium plugs?
I've changed the Opti, Wires, Coil, Ign. module, Injectors, Fuel filter.....damn near the works.
The car starts & runs just fine, gets good gas mileage and will tear your head off as long as you don't take it much above 5200. No codes, heat or any other problems other than not wanting to rev much past 5000 (and 5000 comes up real quick when I get down on it). I've had some people say that the stock type plugs work best for the full rpm range and some of the "fancy pants" plugs are good only for longevity and not so good for higher RPM. Have any of you had any high rpm problems with the iridium plugs?
Safety Car
Joined: May 2002
Posts: 4,659
Likes: 82
From: Toronto ontario
i tried the +4s and iridiums and there was no issue at all when my car had the stock lt1. If you have headers its just a 15 min job switch em back and find out? Could be injectors, o2 sensor... list goes on..
Tech Contributor
Joined: Aug 2006
Posts: 9,933
Likes: 103
From: Peoria Arizona.. Resident Gold Cylon
Theres some truth to that statement. Id throw a fresh set of ACs and see if your getting the same result. No platniums, No Spilt Fires just plain ole ACs. The Irdiums are great plugs for longevity but when you look at the resistors towards the gapping set point they are incrediably mirco small resistor tips. You maybe seeing high arc abridgement or carbon based overarcing not effectively burning the fuel in the chambers causing a high rpm missfire in one or more cylinders. For less than $20 you make have hit on the answer. Sometimes I think engineers try to overthink the problem. Which really is not a problem just change your plugs interval more often. Give it a shot let me know I had a set of the same plugs in my ZR-1, the damn car was powering through the high end missing because its a beast and I really could not feel it but when you pulled the plugs it was obvious what the hell was going on, there is no way two cylinders were firing correctly. I put in a set of plain jane ACs and guess what? Runs great. GC
Last edited by Goldcylon; Mar 24, 2009 at 08:52 AM.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,202
Likes: 117
From: San Antonio Texas
Theres some truth to that statement. Id throw a fresh set of ACs and see if your getting the same result. No platniums, No Spilt Fires just plain ole ACs. The Irdiums are great plugs for longevity but when you look at the resistors towards the gapping set point they are incrediably mirco small resistor tips. You maybe seeing high arc abridgement or carbon based overarcing not effectively burning the fuel in the chambers causing a high rpm missfire in one or more cylinders. For less than $20 you make have hit on the answer. Sometimes I think engineers try to overthink the problem. Which really is not a problem just change your plugs interval more often. Give it a shot let me know I had a set of the same plugs in my ZR-1, the damn car was powering through the high end missing because its a beast and I really could not feel it but when you pulled the plugs it was obvious what the hell was going on, there is no way two cylinders were firing correctly. I put in a set of plain jane ACs and guess what? Runs great. GC
Someone mentioned O2's; forgot to add them to the list of things I changed. Got 4 brand new ones. Made a big difference in smoothness and mileage but still wouldn't "rev up".
Race Director
Joined: May 2006
Posts: 10,691
Likes: 71
From: Phoenix Arizona
The newer plugs are designed to run on lean burn engines. When you start getting some miles on the engine (increased oil consumption,richer mixtures), you can have problems. Especially if you drive, er....agressively.
Last edited by zr1fred; Mar 24, 2009 at 11:48 AM.
Tech Contributor
Joined: Aug 2006
Posts: 9,933
Likes: 103
From: Peoria Arizona.. Resident Gold Cylon
We only take Spirtited rides, yeah... Thats the ticket.
