Thread: .120 Gap Spark Plugs, New Cone Filter install, New Wires and Road Trip. Worst Plugs.

So my wife daughter and I needed to take a short road trip, about 1000 miles round trip. I decided seeing as I did not personally know the history on the GTP I would give it the basics. Some plugs and wires. I went with the Autolite 606s for plugs and had some extra MSD 8.5mm Superconductors kicking around.

The plugs that I pulled out were so bad; I honestly don't know how the car ran on them. They had worn to a .120 gap. More than double what the spec was for them. (See pics below) Reaching the plugs was a cake walk, removing the plugs was easy, getting the boots off, was a freaking nightmare. The boots were burnt onto the plugs. It took 15 mins to re and re the plugs, 90mins to re and re the wires. Well, I changed the plugs and wires and took it for a spin, although I had more bottom end power, I had lost a fair bit of top end power. Which was rather frustrating? I went from a 14.9 1/4 down to a 15.2. I really did not have much time to fiddle with more stuff as we were due to leave in 2 days.
So we got on the road to Oregon from BC Canada. Car got great gas mileage, well maybe not great, but better than we had been getting. I chose to be the passanger so I could data log and watch sensor data, so even With my wife doing most of the driving, and she was averaging 80mph with a few spots in the 95ish range, and about an hour of stop and go traffic, she managed 26.4mpg on the trip down. Only 2 issues came to light on the trip. 1st was the ext. temp sensor failed, which disabled the A/C as the car thought it was 6 below zero outside. When it was really in the 80's and we really could have used the A/C. More on that later.
Lisa also noted that from a high speed stop, there was a bit of a shimmy in the front brakes. Which we suspect is an out of round rotor. So that will be on the list to do. Probably do all 4 corners with new pads and rotors just so we know they are done.

Me still feeling a bit frustrated that the car did not have the "SNAP" when you dropped the hammer at 40mph and it would downshift, I decided to take advantage of the cheap American auto parts suppliers. I was a bit worried that my old MSD wires were not up to snuff, so I grabbed a new set of Prebuilt BWG Wires, new fuel filter and new Cone Filter. One of Lisa's complaints was she could not hear the blower whine. So the first thing I did was replace the filter box with the cone filter and took it for a test drive, yep we have a noisy blower now. Power did increase a little bit too.

Next were the wires, so quickly popped off the MSD Wires and snapped the Borg wires on. Took it for another test drive, and some of the

"SNAP" was back. I think the Cone Filter and the Wires have actually increased the power a bit, enough so that even with the 225/60/16 Z rated tires the traction control is not able to keep them from spinning for at least a second or two from a dead stop. Looks like I'll need some bigger tires for the car. I HATE WHEELSPIN. You can never have too much traction, because if you do have too much traction, just means you don't have enough horsepower.

Well enough with the chit chat, here are the pics.

First up the plugs.


Honestly how did these even fire.


















If the plugs were not bad enough, rusty coil packs, YIKES. I Used a brass brush to clean them up like new.











Couple quick pics down the oil filler hole to show the clean roller rockers.







My box of spare MSD and MISC Wires from various V8 and V6 tune ups.




A few naked engine shots







My solution to getting to the back plugs, gave me the extra couple inches of clearance I needed. I am use to doing plugs on a V8 Fiero, so this

was really a piece of cake, except for 2 of the stock wires were burnt onto the plugs. I twisted the boot so hard that I twisted the top of the

boot off. I had to get in there with pliers and just about break the plug to get the boot off.




My solution to mounting the Cone Filter was to modify the stock intake tube so it would accept the filter that had a 4" opening on it. Turned out it worked really well. I left the back half of the air box in place as I did not want to disturb the ECM that was under it. When we get

back to Canada I'll take my Air Die grinder to it and tweak it a bit.






This is just a random shot to show the BOSE logo on the speakers as someone asked if the system was really a BOSE System being it has a tape deck instead of a CD Player. Kind of odd for a 2000 model year if you ask me.

I did remove both of the dogbone mounts, and then attached that ratchet strap to pull the motor back. I don't know about this hole you are talking about, but I'll take a look and see for next time.

I don't know how the Cone could burn or rub through a wire to the PCM, but I will keep an eye on it. The filter is not touching the PCM harness at all. I am more worried about the filter coming off the end of the rubber intake tube. There is no metal or plastic joint pipe. I just trimmed the intake tube seams off and slide the filter over it.

Yep. Original. The engine I slapped in my SE was 100% stock down to the wires, all AC Delco and untouched. The plugs were NGK though. I have no doubt that's what it had from the factory.

Originally Posted by matt5112

On the passengers dog bone mount on the engine side, there are three holes.

I'll take a closer look, sounds like a neat trick.

Originally Posted by chrisatpsu

i just changed my plugs today and they seem to be about as bad as in your pictures... i wonder if they are original... LOL

I am used to changing my plugs every 10,000 miles or 3rd oil change, so seeing these this bad, really shocked me. I hate people that neglect their cars. How did your car run before the plug change, ours seem to run pretty decent, except for the odd misfire code that came up. So far so good, new plugs and no more misfire codes.

Originally Posted by RooK

Yep. Original. The engine I slapped in my SE was 100% stock down to the wires, all AC Delco and untouched. The plugs were NGK though. I have no doubt that's what it had from the factory.

I don't know if these were factory original or not, but they must have been in there for at least 60-80,000 miles to get that worn. The car has 130,000 miles on it.

Originally Posted by bps02gtp

my cone wasn't touching either. but with the engine rocking and stuff it must've done it. idk how but it did. it took a long time tho. almost a year.

I'll keep a close eye on it. I am usually under the hood checking one thing or another at least once a week. My wife and I make the trip from Surrey, BC down to Bellingham Washington every couple weeks, and I usually do a quick check of all the fluids and tires before we hit the road. Seeing as we are traveling with a 2 year old and she is now 4 months pregnant, the last thing we need is a break down.


Two side notes, I went to change the fuel filter and the damn thing is seized on. I am used to this style of filter on the Fiero's even in the same location. Just behind the drivers door under the car. However even with a line wrench that damn nut going into the filter was stuck solid. There is a place down here doing cheap oil changes so I am going to take it to them and let them get it up on the hoist for better leverage to pop the filter out, doing an extra oil change won't hurt anything.

I am also a bit worried about something. Today while checking the belts, I put some tension on the supercharger belt, enough that it moved the blower pulley a quarter inch, (which would be fine) except for the sound it made. Sounded like an alternator with bearings starting to go, not metal on metal exactly sound, but not smooth either. If I understand correctly, I can pop the drain plug out of the top of the blower and check the fluid level. It should be right up to the top? I don't have any GM Supercharger oil here, and the shop I spoke to does not have it either. I'll try a few parts stores, but if I can't find anything, what is a good substitute?

No... the debate is from an old GM Bulletin that I have and that I brought to forums attention. My boss has it from back in the day, it states that for US cars if no Supercharger Oil is available, you can drain and replace with Mobil1 Syn 5-30 (Full Syn, not regular), I forget Canada's specs tho. If you're worried about it, go to Intense-racing.com or ZZPerformance.com and order some fluid from them.
http://i93.photobucket.com/albums/l7...erOilPage1.jpg
http://i93.photobucket.com/albums/l7...erOilPage2.jpg
I know it states for use in the M62 superchargers, and for the older GPs/Bonnies/etc... but considering the use the same fluid, and considering I called into GM Parts support and asked about it, I was told it still stands as a replacement option for M90s as well. Your call. You would need to change the fluid about every 10k tho, unlike the GM Supercharger Fluid that lasts to 30k.


As to the PCM, don't hack the stock box, find a local JY and locate a S10 blazer/pickup and pull the PCM tray. It bolts directly to our cars and housesthe pcm properly... or do like most of us and get some padding to keep it from rattling and zip tie the pcm in place. I went to a local shop and bought some single sticky sided foam tape, lined the bottom of the area where the pcm sits, and just rested it there, it hold in place and no problems in 3 yrs.
http://www.grandprixforums.net/custo...res-50765.html

Well by the Owners Manual and GM Maintenance Schedule, you are suppose to Check and Add to if low every 30,000 miles... if you go "by the book" it never does say to drain and replace, just add to. So technically it has no rating and its good forever!!!

I still say it should be changed every 30k, but "preventative maintenance" is so over-rated these days. Do what you will, I'm not gonna twist your arm, just sayin.

For the record in case you didn't know. We have access to GM Service Info thru http://www.gpona.com/forums/

Create an account with them and then along the main top bar on the right is the GM Service Manual.
http://sm.gpona.com:9001/si/home.do - <--- takes you to here. Can be very helpful with your GM vehicles.
Just FYI.

WOW Thanks for all the replies guys. I am not sure how I missed them all. Ok I pulled the drain all plug out, and could not visibly see any oil, I dipped my allen key in and there was about 2" on the length of the key. I topped it up with 10w30 full synthetic oil, took about 2-3 ounces. When I pulled the allen key out, before adding the fresh oil, I wiped it off on the palm of my hand and smeared it around with my finger, it had a gray look to it and a few silver specs, but nothing severe so it looks like just normal wear.

Now for the funny part. When I initially got worried about this it was from pressing on the belt seeing the blower pulley move a bit and hearing/feeling an odd noise. I was doing this while standing in front and slight to the drivers side of the car. After I filled the oil, I did the same test again, only this time I was more to the passenger side of the car looking down at the front of the engine. Then realized what I had actually been feeling hearing. It was the tensioner moving in and out. DOH. Oh well it was not for nothing as the blower did need a bit of oil.

Well moving to new stuff.


Yesterday we took a short freeway drive, 60 miles round trip, to visit my father in law here in Oregon. Which gave me a chance to see how the fuel economy was doing with all these tweaks down here in Oregon. On the long drive we average 26.4mpg and we are at 80mph cruise sitting at 28.1mpg now. I won't be happy until we get to a 30mpg cruise, but I do feel better that we are making progress. I have an appointment this morning with a local shop to do an oil change. Which is just an excuse for me, to have them put it up on a hoist so I can inspect the underside of the car. I want to check all the exhaust stuff. We are also getting what sounds like a wheel bearing noise. The problem is that the bearing noise seems to be coming from everywhere. Lisa said it seems be coming from the rear and I thought it was the left front. Hopefully on a 4 post hoist, I'll be able to give all the wheels a good shake and see if anything is not right. Its not severe, or else I would not have done what I am about to say I did.

I had a couple friends one with a Dodge Stealth Twin Turbo AWD and the other with a newer Mustang 4.6. The Mustang is faster than the GP so that was no contest, but the Stealth has some major issues, however the owner has never been or owned a FAST car so they honestly believe its 310hp with their mods. LOL. I took them for a run in the GP. I lifted at 123mph, was actually kinda surprised that it let me get their. I thought these cars were limited to 118mph. Do these cars have a Speed governor? If they don't what should I expect from a good running mostly stock GTP. 125-130mph to me seems like it should be about the max.

127mph... stock limited

get a set of headers installed and tune it and it will go faster (not condoning the speeding at all, it gets you big tickets... or worse :P)

Transmissions hate high speeds like that.

Unless built to handle it.

Originally Posted by TLSheff

127mph... stock limited

get a set of headers installed and tune it and it will go faster (not condoning the speeding at all, it gets you big tickets... or worse :P)

Hmm so I was right on the edge of the limiter. I guess I'll need to get a "tune" as you guys call it. I'll probably wait and do it all at once. Headers, Down Pipe, 3.5 Pulley and Tune at the same time. I really need to do some more research on how you guys tune these cars. I am used to pulling the chip from the ECM, erasing it, flashing a new program on it and putting it back in the car with a new fuel / timing curve and disabling the entire EGR system. Fiero's don't have a speed governor, just a rev limiter.

To tune yourself, you need a powrtuner with software (it's been discontinued but you can buy them 2nd hand) or HPtuner and software. Both require a laptop and a lot of reading and effort on your part. Otherwise you can order a canned tune from several companies. You basically buy the PCM and swap it with yours. Lastly, take it to a dyno who has the software to tune it for you.

Naturally the best is a dyno with a good operator. However, if you get a wideband to scan while scanning your car, you can do some awesome street tunes yourself.