Not a Fiero, but it is a 3.1 liter in 1995 Monte Carlo. I figured you guys have put one of these in a Fiero.

I am guessing a plugged exhaust, but did not have enough time to do all the troubleshooting. Here are the symptoms:

>Runs rough at idle and gets worst with higher RPM. Even some spitting while trying to accelerate
> Low power
> Blown head pipe gasket
> Can hold my hand across the end of the exhaust at idle
> Seems unrelated, but has NOISY rocker arm sound like they are way loose.
> Runs like it has a dead cylinder or two
> Good spark, sprak plugs and wires at all cylinders
> As you accelerate it groans like it is starving for air

My first guess is plugged cat
Second guess is contaminated fuel.

This is for my sister-in-law. She has already taken the car back home, but can you help me troubleshoot?

Does sound like it could be plugged exhaust. You could pull the O2 and see if it runs better and if there is a lot of exhaust blowing out.
If you have a vac gauge. You can put it on watch it at idle and then somewhat slowly raise the rpms. If the exhaust if plugged you will see it hold or dip a little as you raise the speed and then at some point the vac will drop off and the back pressure builds.

pull the 02 sensor,,then run engine .. the leak created by the missing 02 sensor will let you know if this is your problem..
dependining on location of the sensor ,,jack one side up so PB blaster can flow downward into threads of 02 sensor overnight then remove sensor .
if the exhaust is clogged.. the 02 sensor open hole will let gases out easier..engine runs better........
a bad coil will show these same symptoms,, the coil will spark but does not have the oooompph frankenstein spark of the other set of coils,
you can check the codes just like you can on a fiero..if this is a problem that has been steadily getting worse it could be a module
push the valve on the injector rail to see if there is a strong spurt of gas..
if clogged cat is chief suspect in lineup drill a hole in it untill she has lottery winning ticket to replace parts if not cat you can place metal patch over hole..
when cats first came on the market the scien tick fic way to check was to beat on it with a hammer to see if some of the crap would shaketh loose.. I supect impish demons !!

[This message has been edited by uhlanstan (edited 03-21-2009).]

Let me recap=

> Remove the O2 sensor- to open a hole to relieve pressure. If it runs better it could prove a plugged exhaust.
> No vacuum gauge- sorry
> Coil?- Nice thought. Slipped my mind. These are way different from a fiero. It looks like a bank of 6 coils. If this was bad would it show up in the codes?
> Ignition module- Same thing. Would this show up in the codes?
> I asked her to take the car by AutoZone to get them to read the codes.

I am out of town this week. I will check what she got when I get back.

Thanks for the help.

with 6 coils there is less chance she would have 2 bad coils..it would take at least 2 to create these symptoms..I had this problem on an 88 duke I was surprised how good the duke ran on 2 cylinders ,, Bad coils normally first show thier evil ways by hard starting.. this is on a DIS system.
some times an 02 sensor will remove easily since it is not a fiero I would just shoot some penetrant on it and let it sit for for 15 minutes then see if it removes easily ..
If you read the tech forum,,all who read it must suspect evil spirits or demons have chosen the Fiero as thier fave residence ..