Missfire from ported heads/headers??!

[DiMedici]

<--- Alero owner with a problem here:

I got the car back from the shop like 4 days ago, and have put just about 200 miles on it, with great performance from ported heads (possible culprit?), headers, and u-drive pulleys - these are in bold because they're important - was driving fine previously and all night; no noticable problems at all. However, when I start it up to come home tonight, it starts shaking noticably right after ignition, loss of power, exhaust sounds strange - slightly gargle-ey, also flashes Serv. Eng. Soon light; it's blinking, indicating a missfire condition (so says the manual). Limped it home. Felt awful. I'm taking it back to the shop who did the install Thurs., but I'd dearly like some imput as to what could be the trouble. PLEASE and THANK YOU!

[Mike Jung]

(i'm just guessing)

Maybe it is electrical problem ?

I would NOT use the under-drive pulleys.
You might not be producing enough voltage/amps with your alternator because of the under-drive pulleys; before (after the install & getting it out of the garage)it was maybe running partly off of the battery, supplementing the power needed. Now the battery is low, it is just getting the power from the alternator & not charging the car's battery properly.

You need a good level of voltage/amps in your car's electrical system to produce a good spark.
My dad's car a few years back was miss firing (everything was running ****ty) when his alternator went & the battery ran-down until the car would not run anymore (just in-time into the driveway).

Try fully charging the car's battery before driving back to the garage...see if that temporary helps.
Have the garage run a electrical A.V.R. test, if you think it is electrical related.