Hey new guy here. I have a few questions. I recently bought my first Fiero Its a 86 fastback GT Its has already been under the knife, and I will post those topics later, But for now I have some questions for you. I started to do a regular tune up when I discovered a few things, for one it has a Holley throttle body. Is this stock? I would like to get more performance parts if they are available. The car has a K&N air filter, split fire plugs, 9mm wires 2 new ground straps 1 from the intake to the strut mount on left and 1 from the engine block to the strut mount right. it has a polyurethane engine mount and what sound like a after market muffler. The car is really fast. I have had 11 300zx turbos, and 3 twin turbos so comparitively speaking for a normally aspirated car it is damn fast. The only Noticable problem I have is a weird Idle, it jumps from 1100 to 1700 up and down ?what would this be? Also from about 20MPH on it has a roaring noise for the engine bay, Its not the engine It is associated with the car rolling thats is when it starts, and when I stop its not there. The CV axle boots are in real good condition, But what should I check first?maybe a few pointers in the right direction. here is the throttle body what do you think?
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04:17 AM
PFF
System Bot
MilleniumFiero Member
Posts: 1225 From: Pearl Harbor, Hawaii USA Registered: Dec 2002
yes I'm sure its stock because every fiero I've owned has had that.
I felt the same way when I first bought my old old 85GT with a 4speed and 2.8L. I definatly could throw you back into the seat but just wasn't fast enough... as you can tell from my sig...
Yes the holley trottle body is stock on V6 fieros. Welcome to the forum though, you're gonna enjoy spending time over here and of course driving your fiero. I agree, even a regular 2.8 fiero feels pretty fast. It's not a real muscle car but it sure gives most regular cars a hard time keeping up. Have fun !! later..
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05:09 AM
litespd Member
Posts: 8128 From: No where you want to be Registered: Aug 99
As others have said, the Holley Throttle Body is stock on the V6 Fiero. As far as your idle goes, it should sit about 900-1000. If yours is that fast, you probably have a vacuum leak. Many times, it's the EGR tube, which runs between the EGR valve on the crossover exhaust pipe, and the bottom of the intake plenum. While the engine is running, spray a little WD40 underneath the heat shield blanketing on the tube. If the idle drops momentarily, you've got a cracked or broken EGR tube. Other than that, check all the vacuum lines for cracks or leaks...they're made out of plastic and rubber, and as old as these cars are, they tend to get brittle with heat and age.
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08:05 AM
865spd Member
Posts: 805 From: Tri-Cities, Washington, USA Registered: Oct 2004
Just to tell you what ive heard, splitfires aren't the way to go. A real good mechanic buddy of mine said he has pulled more plitfires out of cars than any other type of plug. He told me that just the stock brand AC delcos are the best for the motor. According to him it only sparks on one of the prongs anyways because it just takes the path of least resisitance, which i beleive undering electricity. It it runs fine great and more power to ya, but i just though i would let you know what i've heard about em.
Oh and welcome to forum these guys are real helpful with just about anything having to do with a Fiero.
865spd
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10:31 AM
ditch Member
Posts: 3780 From: Brookston, IN Registered: Mar 2003
The car has a K&N air filter, split fire plugs, 9mm wires 2 new ground straps
Next time you tune it up, get rid of the splitfire plugs and put in some stock AC Delco plugs. They're just a gimmick.
As far as the idle problem. I would clean out the throttle body with spray cleaner as well as the IAC tube. Mine was gummed up and the idle was everywhere like yours. Cleaning out that helped greatly. The extra grounds are good to have as they help idle too.
welcome to the forum Dave
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10:39 AM
jigsaw Member
Posts: 52 From: Sand Springs, Ok 74063 Registered: Mar 2005
Hey guys thanks for the info. I will look at the EGR tube as well as clean out the Throttle body and IAC tube. You heard me wrong I had already bought AC delco plugs and wires, as well as numerous tune up stuff. When I went to change the plugs the split fires were in there So they are already gone. I put a new O2 sensor, water temp sensor ( My TEMP guage doesnt work)... ANd still dont...LOL ..But I could tell someone had put a little money in the motor. What can I do to gain any horsepower with this motor? or is it more logical to just build something different and put in ? Do any of you know what the roaring noise from the rear would be ? Its only there while the car is rolling, its more apparent from about 20 mph on . How do I check the wheel bearing and axles? the axle boots look good, but can they still be bad? Thanks you for your helpm and thewarm welcome.
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02:55 PM
ditch Member
Posts: 3780 From: Brookston, IN Registered: Mar 2003
What can I do to gain any horsepower with this motor? or is it more logical to just build something different and put in .
Logical and not very expensive: The easiest swap out there is the 3.4 pushrod out of a 93-95 camaro/firebird. I have one in my 87. I didn't build the motor, just installed it. It was a breeze. All you have to do is relocate the starter and they sell a jig for that. It uses all the electrical components from your 2.8 as well as the intake, heads, and exhaust manifolds. It's basically a block change. Stock, you'll go from ~140HP to 160HP, and torque will go up as well. You can increase those numbers quite a bit by putting in a bigger cam, porting the heads, porting the exhaust manifolds, and having the throttle body/plenum bored. I would also match all intake sections.
If you want to spend about $600 on a good intake and toss the very restrictive fiero intake, someone on here (FrancisT) sells an intake which improves flow over the stock intake. It's worth the money if you look at the numbers they have. I believe the intake comes with a computer chip as well. They also have dyno slips showing HP increases with the new intake.
You could also upgrade your 2.8 if it's not too high in mileage. Basically, all the mods above. K&N filter is always good. I would go with an aftermarket ignition coil as well like the MSD.
Dave
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03:17 PM
Black-Azz-GT Member
Posts: 2326 From: Florida Keys Registered: Oct 2003
Logical and not very expensive: The easiest swap out there is the 3.4 pushrod out of a 93-95 camaro/firebird. I have one in my 87. I didn't build the motor, just installed it. It was a breeze. All you have to do is relocate the starter and they sell a jig for that. It uses all the electrical components from your 2.8 as well as the intake, heads, and exhaust manifolds. It's basically a block change. Dave
You dont actualy have to change the heads. Just the intake system
You dont actualy have to change the heads. Just the intake system
Yea, I was just pointing out the interchangability (is that a word? ) in parts should he get a 3.4 block.
Side note: aren't the fiero heads a "HO" version with bigger ports or something like that? I know they were better in some way compared to the 2.8 V6 heads in the mid 80's chevy pick-ups. I don't know if that is also true for the 93-95 firebird/camaro 3.4.
[This message has been edited by ditch (edited 03-18-2005).]
Yea, I was just pointing out the interchangability (is that a word? ) in parts should he get a 3.4 block.
Side note: aren't the fiero heads a "HO" version with bigger ports or something like that? I know they were better in some way compared to the 2.8 V6 heads in the mid 80's chevy pick-ups. I don't know if that is also true for the 93-95 firebird/camaro 3.4.
The iron heads for the 60° V6 came in two varieties, the small valve and the big valve. The big valve is also referred to as the HO head. It was used on the Fiero 2.8 and the Citation X11 2.8, and it's also used on the 3.4. I don't know if it was used on the 3.1, but chances are that it was.
I had simillar issues with a high idle and wandering tach. The surging idle was a dirty IAC. Cleaned that with some Gumout spray. As for the high idle(1700-2300) Turns out, the thermostat was missing! Once replaced the car warms up and behaves great!
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08:16 PM
Mar 19th, 2005
fierogt28 Member
Posts: 2962 From: New-Brunswick, Canada. Registered: Feb 2005
For the Holley TB, as far as I know, GM hired Holley to specially make a TB for the Fiero V6. Also you can get them bored out from the Fiero Store 3mm bigger. The TB from Darrell Morse are 57mm in diameter. Stock size is 52mm. It's also better to get the plenum bored to match the TB. All V6 fieros have this Holley TB.
as you can tell from my sig...
) in parts should he get a 3.4 block. 
