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Its an Invasion 4.9, 5spd Stick Fiero

6721 Views 16 Replies 5 Participants Last post by  cruella89deville
OK quick intro.

Pics and short video's can be found at

Car is an 85GT with a 5spd Stick, Centerforce Clutch, 4.9 from a 93 Elderodo dual O2 setup. Using a custom Chip with the "Fast Chips" fuel and timing maps.

Car setup is like I said an 85GT Fiero.:bouncy:

Mid Engine, transverse mount rear wheel drive, 4 wheel disk brakes, 4 wheel independent suspension, 245/50/16's in the back and 225/50/16's in the front.

I have got a bunch of rather unique issues that hopefully ya all can help me sort out.:confused:

First off The old stock O2 sensors were old so I bought a pair of brand new NTK O2 sensors with the correct plugs. Well as soon as I got them in I noticed that on the scan tool, the voltage on the O2's are pretty much flat at 444mv the cross counts are down to like 2-6. They are located about 5" from the manifolds so location should not be a problem. The exhaust on my car is rather short. It is approximately 36"s yes 3ft from the down pipe to the Tip where it exits. The car will drop back into open loop at idle which is strange but I am told it is not un-common. What do you guys recomend for good O2 sensors.:thumbsup:

I have had a hell of an issue with the idle down procedure. It does not want to drop to idle until I am below 5-10mph. Which is really annoying especially when I am out cruising along in 5th and the car wants to cruise along without me touching the gas. Anyone got any good tips.:D

It looks like many of you guys swap out the OEM injectors for the Mustang ones. Which I just happen to have because it is also a common swap in the Fiero's. I have a set of perfect 19# orange top injectors kicking around. Is there any real benefit to using them.:confused:

Oh I could go on for a while with other odd questions about swapping the Allante intake and the Delta Hot Cam for the 4.9 but I think I need to get the car running right before I hit up all the mods.:bouncy:

And before anyone asks, yep the car runs like a raped ape with a firecracker up his butt scaring all the Ricerized Hondas and other Imports every day of the week.:cloud9:
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That's actually pretty common. The car I was going to get before the Cadillac (probably should've from all the expenses so far), was my cousins 1986 Fiero GT. This thing was rediculous. 16k miles. Really. The original owner lived a few houses up from him, he drove it like 4 times, then sold it to him a year or so back. So I joined alot of Fiero forums becasue I was going to buy it. In the "engine swaps" area, there's actually "aluminum Cadillac engine" somewhere near the top of the swaps. Then I asked them about it becasue I'm a valet, and I drove a 4.9 Coupe DeVille that night. I liked it. But to make a long story short, those things get that relatively frequently. A guy around me (attends many local shows) has an '85 style (like pictured) with a 350 in the back.

??? lol.

Here's the Fiero I was gonna get...

Yeah...a little dirty...but you get the idea.
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The O2 sensor (my car has 1) for my 4.9 was a Bosch, and it was $20. Not a problem with it since.

I just did the Ford injector swap... I gotta say, definitly do it! far better idle, noticeable more power, seems to be better fuel mileage, it was more involved then I thought, but very much worth it.

The Allante intake manifold *does* flow better, I am not sure about the Fiero, but atleast on the Caddy's, it would be in the way of the master brake cylinder, that would have to be relocated... alot more trouble then it is worth.

My father has an '88 Fiero Formula, 2.8 V6 w/ 3spd auto, it was his daily driver for a really long time, it has 167k miles on it and runs great. It hasn't been on the road this season, but he had it out of the garage today.... I never used to like it, as I love huge cars.... but there is a certain thing to it that I do like, very neat little car, and with a nice powerful Caddy engine, and a 5spd, I could just imagine how good it must be.

It seems like over here, us Caddy guys have our own thoughts on what to do with the 4.9, and you Fiero guys have the same... we should combine and use all the knowladge to get both the Caddy's and the Fiero's that much better.

my '93 Coupe is my baby.... but I do have a complete pieces.... and my plan with that is to rebuild it, and if I want an easy swap, buy a '95 Eldorado ETC with a blown engine..... or if I want a much more difficult swap, buy a Fiero :)

Though my next vehicle is going to be a Jeep, I need the change :)
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Well some of the mods the Fiero guys use may not be workable for the Caddy.

I was able to remove the

Power Steering Pump
Air Conditioner
EGR System

I am going to add

The Delta Cam .480 lift works with stock heads and springs and lifters
Allante Intake (our brake master is in the front of the car so that is a non issue.
Mustang Injectors, I already have a set of 19# injectors here from my Fiero.

I already have
Custom Fast Chips Prom
Exhaust system that is 3.5 ft total length with no cat, just a short muffler and tip. Very low restriction.

Combining the list of stuff I have done, and will do, is a proven combo to take the 4.9 up to around 260-270 crank horsepower. I am running it through a 5spd that has a lot less loss to the wheels, combined with the fact my car with motor in it is only 2700 lbs. I should end up deep in the 12's chasing Vipers and late model Corvette's around town. I have not taken it to the track yet as frankly the torque from the 4.9 keeps trying to rip the damn motor off the mounts. I am (damn I can't think of the word) resulting, Uhm, ah hell, I am just chaining the damn motor down. Yes 1700# chain and mounts should hold this damn thing in. The big tires on the back 245/50/16's don't want to spin, the clutch won't slip so mounts seem to be next.

I will look into the Bosch O2 sensor

and cruella89deville The car pictured is not an 85, it is either an 86 or 87. There were no fastbacks in 85, and the 88 fastback as monochrome paint scheme. My 85GT is what they call an Aero Body GT. Same nose and bumper as the fastback just does not have the fastback clip on it.
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Can I get more info on that Delta Cam? it is basically a stock replacement, and works well with the ECM? any benifit when used with the 4T60E?

So you got 70-80hp from removing power steering and AC, and EGR (which I heard only helps) the cam, the computer chip, and a free flowing exhuast?
Here is my fathers '88 Formula, from what I know, the Formula is basically a GT with the SE body, and in '88, it was the best year as they have the Lotus-tuned suspension and stuff. 2.8 V6 HO and TH125, it actually has a really nice sound to it... of course it idles rough... to me... bounces back in RPM, which my father said all Fiero's do that.

The car is not perfect though, 167k miles, it shows in some ways, but my father takes excelent care of his cars, and it is solid.

He wants to repaint it all in Cadillac Pearl White... no more two-tone, and I tell him to swap in a 4.9, but he says if he dosn't to a 2.8-3.4 conversion (then build up the 3.4) he would want a Northstar... even after I told him, he really dosn't understand just how hard it is to swap a N* into anything... all the computer stuff..... a 4.9 with a carburator, very easy, and very fast.

This is the car my father had all when I was growing up, my mother had a Chevette, a very neat little car for it's time, did what it was made to do.He has had this car since 1990 or 1991 and bought it with 70k miles or so for like $3,500.

Very cool little cars... just like the Lotus Elise at the track tonight... but I dunno..... little engines in little cars don't do much for me... even big engines in little cars.... I like huge engines in even bigger cars :) that is what makes me all happy inside :)
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The Delta cam is a kinda re-grind cam for the 4.9 works with stock heads, springs and such, it is a drop in cam. The OEM cam that came with the caddy was meant for Low End grunt, low rpm power for grandpa to roll away from a light without more than an idle and a super quite car. This was not just poor cam it was a bad cam for anyone that wanted to use the 4.9 to go fast with.

So it is not like going from a stock decent cam to a good cam, this is going from bad, skipping averag and right to good. (not race but good)

They say it is an aveage of 30hp and 30lbs of torque just by dropping it in with no other changes.

Delta Cams is in Washington state. Many Fiero guys are using these in there 4.9 Fieros.

I will try to dig up a link for you tomorrow.

As for hte 88 Lotus Tuned Suspension that is uttlerly false. Lotus had nothing to do with the 88 Suspension at all. It is a 100% myth propagated by people that just simply don't know any better. If you don't belive me, Hulki Aldaktike the designer of the Fiero spoke at the 20th Aniv. Celebration for the Fiero where they had the 4 seat Fiero and 90 Fiero's out to show off. He even stated the only Thing GM talked to Lotus about was how to keep the Fiberglass and Paint to stick well.

As to what makes the power go up

Intake, Allante
Exhaust High FLow Setup
Cam, Delta Cam
Remove Caddy Stuff not needed in Fiero

Performance Chip (GM De-Tuned these motors from the Factory to make them smooth. It just took a place like FastChips to offer a drop in chip to give the motor an extra 20hp and 20lbs of torque. Check there site they have dyno numbers using the Caddy still, as the chip was made for the Caddy not for the FIero. We just happen to (borrow) the fuel and timming maps from there chips in the Fiero Chips.

Other stuff I have that I forgot to Mention
Full MSD 6AL Ignitioin with Superconductor Wires and Blaster II Coil Hey it helps.
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Wow, learn something new... no Lotus suspension in '88.... the front and rear track is wider though, right?

So that Delta cam is a pretty nice choice? would that work with the shift points of the 4T60E? as it is now, the redline is 5,250, but under WOT it always shifts right at 4,900RPM.

I was going to get the Fast Chips computer chip for the Caddy, IIRC $160 and it removes the speed limiter, but then i heard all it does is advance the timing, which I already did physically, but I also heard that changes the fuel/air ratio? I saw the claim of 20hp/20tq. or so, but is it really what much?

The Allante intake should be good for 15hp, after all, it brought the 4.5 PFI (normally 180hp) up to 200hp, well that engine also had a few other things going on, but yeah... I can see how that number is pretty accurate.

the MSD ignition helped? I figured the stock HEI was plenty fine... then again I am talking about some stuff to boost performance in the Caddy, not turbo Fiero etc...

If only I was here in NY for longer, would I seriosuly want to swap that cam, but moving to FL next week.... not going to happen.

So since i installed the 19.4lbs Ford injectors, if I got the Fast Chip, should I tell them about the higher flowing injectors to alter the chip anymore, or should I just use it as it is?

Actually, then again, with that engine, to swap the cam, the engine has to be out of the car.... no fun... maybe I'll wait for the day I need to remove the transmission or something.
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I am not feeling very good at the moment so bear/bare with me.

The 88 does have a totally unique suspension. It is a factory 4 link style similar to many exotic cars. This is where the rumor has been told from.

The 88 is the best handling car of all Fiero's and out did the 88 Corvette in both handling and braking. The main issue with owning an 88 Fiero is that it is "both great and Unique" the later being the problem. At one point if you had a front wheel bearing go bad, you had to park the car. There were simply no new replacement bearings. Not from the dealer, not from the Aftermarket. You would see them on ebay for $300 used. Recently a company has agreed to produce a limited quantity of them. However they are no where near as good as OEM.

The rear suspension pieces are also unique so if you curb the car and bend or brake a part, be ready a several thousand dollar bill. I think the rear link arms are around 3-400$ each.

I chose the 85GT as it has factory the GM's WS6 suspension, and I prefer the notch-back over the fastback, as the notch-back is both lighter and in my opinion looks more like a real race car than is slightly more plump big brother. (86-88GT) The early suspension can be tweaked with upgrade parts to not only compete with the 88 cars but far surpass there handling limits. Being bad turned out to be good for early suspension as the aftermarket for the 84-87 suspension is astounding, from coil overs to tubular control arms.

This also holds true for the Caddy motors. As more and more hot rodders realize that the Caddy 4.9 is a rather simple designed push rod V8 that has the awesome attribute of being an aluminum block and so lightweight they will be snatching up the motors faster than Grandma or Grandpa Joe can retire the car due to old age or rising gas prices. (in a Fiero the 4.9 with a 5spd can get close to 30mpg)
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Interesting thread!! I too have that "idle down" problem with my '90 4.5 and it really irks me. MPG and brake life will surely improve if this could be solved. It makes driving on ice a nightmare!!
Well I am going to try and read the stickies on here and play with the scan tool to see if I can find a fix for mine and my problem running really really rich.
Capt Fiero said:
and cruella89deville The car pictured is not an 85, it is either an 86 or 87. There were no fastbacks in 85, and the 88 fastback as monochrome paint scheme. My 85GT is what they call an Aero Body GT. Same nose and bumper as the fastback just does not have the fastback clip on it.
I'm sorry if you thought I meant that was an '85. I meant that another one around me had a 350 in it. That one was an '85. The silver one pictured is an '86 GT with 16k on the clock.


BTW: The yellow one I mentioned... I was in traffic the other day. When I was pulling in to get gas, I see the yellow 350'd Fiero. It looked so funny to see a sorta 80's technology car that sounded like a Chevelle. lol.

Fiero that sounds like a

some things, honestly... just don't go together.... and a heavy rumbling muscle car V8 coming from a small 2 seater, mid engine "exoitc" type car is one of them.

It would be like putting a ricer fart cannon on a Chevelle (maybe that would sound good?)

Which is why when it comes Caddy 500 time, yeah, it'll have a little gurgle at idle from the cam, and the exhaust will be more agressive then stock... but for the most part, it'll be somewhat mellow, and help retain the Cadillac image.
LOL, ever see my short video of my Fiero running a 4.9 open headers.

Heck even my current exhaust is rather unique, it is a side exit system exiting just behind the passenger door. Exhaust is a bottle muffler and an oval Camaro tip.

Total exhaust length is 3.5 feet.
I know when we replaced the cat on the '93 Coupe, I fired her up....damn, did it sound pretty nice.... had a gurgle at idle, and when I raced it up... it was just crazy.

I always thought on the '93 Coupe, a sweet exhaust would be a dual setup (not true obviosuly) with side pipes exiting behind the rear wheels, under the quarter panel... I just think that is cool :)
Since everyone is talking about exhausts right now...

My '89 4.5 has a Dyonmax Super-Turbo exactly where the stock one was (end of trunk), then piping bent like OEM wit hthe 90 degree bend, and a chrome pipe. It's a funny exhaust. The first time I turned it on, I was underwhelmed. It was VERY OEM. But after awhile, it's better. When driving, it's just like OEM. There isn't even much (if any) more interior noise. The idle is sick though. I didn't want some loud thing going on becasue it IS still a Cadillac and if it was TOO loud...that would seem kinda dumb.

*shrugs *
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