Going to do the first tuneup on my 85 GT. What are the best plugs for the V6? On my old bike I used NGK Iridium and they were pretty amazing. Do they make them for the 2.8L V6? Also, I've heard some stories about how hard it is to get at them. Is this true of overstated, as a lot of Fiero tales are?
Just simple one strap basic AC delco designed for your fiero the passenger side front is difficult to install if you have A/C A good idea to soak it in penetrant,overnight before removal there is a small performance gain to index 60o V6 spark plugs at least make sure the strap does not block the spark for best performance or at least point them all the same way,with in reason use a plug socket with the rubber still in it I install the spark plugs from the bottom it is easier if you remove engine lid & do it from top but Im to lazy to remove hood lid make sure the valve cover nuts are tight.good & snug
[This message has been edited by uhlanstan (edited 05-10-2012).]
Use any normal plugs. If they have a sale/rebate Most platinum can be used. Changing plugs every 3-4 year max or rust can, likely will, cause headaches for Fiero owners. (Faster in Rust Belt areas.)
DIS2, 87-88 Duke and some swap V6, Hates Bosch Platinum.
Use search for more.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Getting the front bank spark plugs changed is not very bad if you remove the air tube between the air cleaner housing and the throttle body, and then reach along the front side of the engine. You can easily reach all of the plugs and get a good grip on the boots.
All you need is a good sense of feel, a 3/8 ratchet and plug socket, and long arms. Do one cylinder at a time and make sure the plug wires don't touch the manifold.
It's a highly overrated job IMO. First time I did it, I was relieved it wasn't near the ordeal I had been led to believe. Some people lay on the engine and look at them, I'm not sure why, but whatever. I just find them with my hand, put the socket on them and remove them. The hardest part is sometimes the boots are hard to pull from the awkward angle. I get frustrated with the V6 alternator though, or working on the rear brakes. Everybody has a different nemesis I guess.
I might be wrong, but I've always been under the impression copper plugs are best in the short term, and the advantage of platinum and iridium is just longevity. Since corrosion can be a problem on the firewall side plugs, you don't want to leave them in for too long, so copper is the best choice. That's also the type of plug GM had in mind when they designed this ignition system, but I don't know how much that really matters. I haven't been through enough plugs to have an independent opinion on brand, but ACDelco R42TS and NGK V-Power are widely recommended. I used Autolite last time but don't have enough context to say if they're good or bad. My next set waiting to go in are the Delcos.
I always used Delco in my old 2.5 car, but it's been so long since I drove it that I can't give much opinion of them. But I was happy with them apparently.
[This message has been edited by armos (edited 05-11-2012).]
That's also the type of plug GM had in mind when they designed this ignition system, but I don't know how much that really matters.
From what I hear if you run a fancy one like an E3 or diamondfire it over works all the parts that lead up to the plug, parts in the distributor, and can shorten their life.
Getting to the front ones is not hard. I hit them with some PB blaster, let sit a day, then hit them again and let sit. I then get a 6" long extension on a spark plug socket. It reaches just onto the plug, while putting your ratchet right where it needs to be so it's not too high or too low in regards to what's around it.
Never broken a front plug and never had any other issues doing it this way. I typically remove the decklid too but you can do it without doing that if you have a flashlight and extra minutes of patience.
Stock AC Delco’s (make sure they are the stock one’s. AC Delco does make “high performance” plugs). Early GM fuel injected cars (early 80’s thru mid 90’s) have programming in the ECM that relies on several known factors including the heat and duration of the flame front which is dramatically affected by the heat and duration of the spark. While there might be some aftermarket plugs that have similar enough specs to match the stock plugs most do not and there isn’t any way to tell. Changing the plugs changes the performance of the flame front and the ECM doesn’t know it’s changed so it can’t react appropriately. I specialized in GM onboard computers during most of that time and I spend a lot of time replacing aftermarket plugs (in all kinds of GM’s) because of “it just doesn’t feel right” drivability complaints. The AC Delco plugs weren’t always the only problem but they did always make the car run better. Go with the AC Delco’s.
Originally posted by firejo24: Stock AC Delco’s (make sure they are the stock one’s. AC Delco does make “high performance” plugs). Early GM fuel injected cars (early 80’s thru mid 90’s) have programming in the ECM that relies on several known factors including the heat and duration of the flame front which is dramatically affected by the heat and duration of the spark. While there might be some aftermarket plugs that have similar enough specs to match the stock plugs most do not and there isn’t any way to tell.
The only problem I have with that is I don't know how much we can really assume any of today's ACDelco parts are the same as they were 25 years ago. After so many years they might just be another name on a box. But if experience shows their plugs run better, then that's the bottom line so I'll happily run them.
I'll admit I was partial to the NGK plugs, but after reading the responses there are some very good arguments for the AC Delco plugs. I will be going with them, thanks all!
[This message has been edited by NetCam (edited 05-25-2012).]
I'm using Bosch Iridium on the theory that I won't have to change them again, but I can't point to any improvement in mileage. I also added a higher performance coil and larger wires on the theory that the Iridium plugs need more power to function effectively. The ICM died within a month, but a new one has lasted over a year since then.
The idea that the ECM can't take advantage of such improvements seems a little weak - can't the ECM be tweaked to take advantage of the newer plugs, etc.?
If I had it to do over I wouldn't bother with the better plugs, wires, and coil simply because they don't seem to be necessary; Fieros seem to run great on old plugs.
I subscribe to the long arms, lie across the engine plug-changing strategy. Pull the boot, then put the socket on, then figure out what extensions and swivels you need to turn it. My front plugs were very loose. Fifteen foot-lbs seems to be the proper torque, but they work loose anyway.
I asked a similar question of Summit Racing before this project. I didn't take that advice, but it seems to have been good. Bosch has some good advice about spark plugs and heat ranges and not using silicone because it damages the O2 sensor. I think the site I bought them from is sparkplugs.com, in California. It also had some specific recommendations.
The statement I was making was referring to a stock ECM setup. If you have the ability to program the ECM (or prom to be more accurate) then there is a lot you can do (hotter plugs, multiple firing coil, etc…) but most people don’t go down that road and as you’ve pointed out “Fiero’s seem to run great on old plugs”. I must also admit that of all of the older GM’s I’ve worked on over the years Fiero’s (along with Vette’s) did always seem to run the best. Nice clean simple ignitions and fuel injection systems without trying to “over do it”.
The Fiero ECM is not that complicated. It really doesn't care what plugs you put in as long as you match the plug gap to the compression of your engine. From there it's all about the plug itself.
I have always put AC rapidfire in all my GM cars and change them every 50,000, the Fiero V6 you might be able to go longer? I never seem to keep mine long enough to find out, on my 19th one currently.
------------------ D A V E ' S ************* 87 FIERO GT
Old thread revive since I'm currently looking into plugs myself.
I have Champion RV15YC4 currently (also did cap/rotor/wires when I bought the car Jan. '12 and corrected a poor initial timing setting), but I'm getting close to the interval for copper plugs (current plugs are showing some wear), and I'm debating on a switch to platinum.
I'm curious if anyone has any back-to-back experience between copper and platinum. My '92 full size pickup averaged 24.5mpg (4.3, 3.08 gearing) on its drive from Michigan to Arizona, and I also found that with stock replacement Delco coppers, it failed emissions horribly (no testing in MI) compared to just a minor failure with the Bosch platinums that were already in it (turned out I needed a new cat beside the fact). I since built a 383 for the same truck, and it had a seemingly intermittent miss around 1900-2100rpm with replacement copper plugs (Vortec heads, not TBI heads), which was resolved with stock replacement platinum plugs (happened to be Bosch as well).
The total price difference between the copper and platinum plugs I'm looking at is only about $.50 per plug, so a grand price spread of about $3.
I use Bosch Platinum Plus plug in my 2.8 and have for years. There is one primary reason I use the Bosch Platinum plugs instead of Delco plugs. The Delco plugs have a carbon steel outer sleeve that is black in color (paint?, electro-coating?) My car is a hobby car and never sees rain. The Delco plugs always acquire a heavy coat of rust on the outer threaded sleeve. The Bosch Platinum plugs have an outer sleeve that appears to be nickel plated and they do not rust.
I noticed that about the Bosches as well. I never had a problem removing them in my truck, even after about 3 years of driving.
Something else I noticed that's irked me the past few days. I had what I thought was an exhaust leak that's gotten worse as I was driving the car, turned out not one but 3 plugs had loosened up slightly (maybe 1 full turn tops, the plug wires kept them from coming out too far)... 1 on the rear bank and 2 on the front bank. I only discovered it because I removed the plugs to see what kinda shape they were in. Has anyone else had this happen? The plugs don't feel like there is any 'stretch' like you feel when torquing a bolt down, I don't know if the threads have just hardened that much or what, but with the torque I'm applying, they don't feel normal compared to past spark plugs I've changed.
I installed some NGK UR55IX Iridiums in my 84 Indy 2.5 and noticed that it ran smoother ( better idle was very noticeable). Someone posed the question regarding the differences between the stock AC plugs from 1984 vs. the 2013 AC version. There must have been changes ( improvements?) along the way to the point where the new one is much different that the original plug.
How about the E3 plugs. We run them in our 1996 4.3 Vortec Blazer and there was a noted power and economy improvements.
My Fiero does not have a stock ignition, I have an MSD Coil, MSD Digital 6AL Box, MSD Wires, MSD Cap and Rotor plus a rebuilt distributor with the heat sink mod on the bottom under the module.
The one benefit I can see to the E3 is that the plug electrode is actually so big, that it decreased head chamber volume slightly, giving a small boost in compression ratio. Plus having multiple strike points for the plug it might help with fouling out.
When the Fiero programing in the ECM was written they had no idea we would all be running 10% or more Ethanol in our fuel, and frankly the cars are not designed to use it. I am running about 15 degree's timing to compensate for it. So far between 13 and 15 is the sweet spot. (13 in the summer, 15 in the winter)
So E3 Plugs, what do you think about them. Anyone got any comments. I normally just run NGK UR5's and they last about a year (10,000 miles) on my MSD Ignition.
------------------ 857GT Part 85GT Part 87GT Part Caddy, 93 Eldorado 4.9, 5spd Dual O2 Custom Chip, Custom Exhaust. MSD Everything Now with Nitrous. Capt Fiero --- My Over View Cadero Pics For Sale $4000, Yellow 88GT 5spd Full Poly Suspension, Lowered 1/2" in front, Corner Carver.
I just bought Bosch platinum plugs for my 85GT 2.8 v6. The electrode doesn't even protrude form the porcelain insulation. There is just a small pinhole, and one strap of course. My car does burn oil a bit. Should I just get delcos and not even bother with these boschs? Especially that the spark plug job seems to be a PITA. My car hasn't had service in a long while I can see. Those plugs must be on pretty bad, but they have been well oiled.The valve covers are leaking all over everything and the rear main leaks too. At .89 cents a plug it isn't worth return shipping to return them to rock auto i guess.
------------------ Louis Duet Baldwin, Long Island, NY ~~~~~~~~~~~~~~~~~~~~~ "Blue" <= '85 Fiero GT Stock V6---Stock everything. Trying to keep it 'mostly' that way. ~~~~~~~~~~~~~~~~~~~~~ "Boo" <= '81 Delorean DMC-12 VIN #5835 Stock PRV engine Robertson Equipped Neiland/Delman Engineered Carbed and loving it! (Peugot 604 manifold) ---"Sorry purists"
A couple weeks ago I did my plugs... was considering platinum, but it happened that we had the correct size copper AC plugs in stock, so I used those.
I also discovered the exhaust leak I mentioned is from the manifold, the rear passenger side was missing a bolt - or so I thought... the 'missing' bolt is broken in the head, far enough in that I'll have to drill it to remove it.
Used ngk u-groove and a v nothed plug in the past. I am running RapidFires right now with MSD coil in stock location, guided by a Summit sourced distributor with MSD brass red cap, and Taylor 8.8 wires. Runs real strong, fires right up and is very responsive. IIRC, thry are copper plugs.
it's a GM car stick with AC deco, Ford stick with FORMOCO Stick with the brand made for the car and you will never regret it. Get the proper heat range and numbers tell you the right plug to use. I have owned GM, Ford, Dodge over the decades and that has never been wrong. A little bit of neverseze doesn't hurt as well. just enough, never glob it on there and you will never have any problems removing them, and I have lived most of my life in New England.
Steve
------------------ Technology is great when it works, and one big pain in the ass when it doesn't
Wow...! Old Lar, I am amazed that vinny did not get banned. Was that before the rating system and The Trash Can catagory? I kept reading as disturbing as it was, just becuase i wondered how it would end.
I just find them with my hand, put the socket on them and remove them. The hardest part is sometimes the boots are hard to pull from the awkward angle.
