its not fiero related but i had a customer with an 06 saab 9-3 which is a cobalt(sad? mabye?) anyways the customer complained of resonance and strange vibrations in the car and i was quickly able to confirm this. at 23,000 miles the engine was vibrating so badly that depending on rpm it would vibrate various sections of the car. the motor didnt shake like a misfire but more like it was slightly off balance. touching it would feel like you were being electrocuted but you werent. the crank pulley was damaged so we replaced it to no difference. the old dampner was obviously off center and damaging the belt so i replaced it and the belt but if you watched the teeth on the new crank pulley it was still shaking, the teeth looked fuzzy instead of solid which just tells me the crank is bent somehow. looking at how the crank is sunken into the oil pump i imagine the snout is right next to one of the mains so i cant see how it could have gotten bent and not damage the engine worse. it also had no runout but it was difficult to get a good reading on it.

from what ive read the ecotec uses two balance shafts and having them get out of synch would do this but the only reported time sthis happened in iatn and just searching google foudn that this only happens when someone tries to replace the timing chain or some other kind of internal work which nobody had done. i read some reports that the engine had bad harmonics and vibrated alot normally but i cant imagine this is normal and if it was then i cant believe anyone buys cars with ecotecs in them, ive driven rabbits with less vibrations than this thing. does this engine vibrate alot? i dont know since the new cars dont usually show up in the independant shops this early. did i miss something i could done to fix it?

well its not normal for an ecotec to vibrate like that. im not an expert but
it might be valvetrain related
or the flywheel losing a counterweight
the only ecotec ive driven is my old cavalier we beat the snot out of.
it just wouldnt die

[This message has been edited by BlackGT Codde (edited 11-08-2008).]

My daughter has a 06 Cobalt, and I was surprised at how smooth it is for a 4 banger.

That is not normal, I have 30,400 miles on my 07 and it runs smooth. If it is valvetrain related, it might be that one of the balance shafts went out prematurely.

23,000 miles? Isn't it sitll under warranty? Have GM deal with it then. That sounds like a warranty claim to me.

check out ecotecforum.com

A few guys on there might lead you in the right direction. My ecotec has alot of vibrations, but nothing like that.

i have around 45000 miles on mine and it does not shake at all .and with only 23000 why isnt he getting it fixed by the dealer ? sounds like the balance shafts are out of sync somehow .early ecotecs had a check valve on the chain oiler that stuck closed and caused the chain to break .this was fixed by late 03 but maybe the chain is going ,maybe this engine isnt as new as the owner thinks it is ?

I had an'04 Saab with the ecotec and I had no vibration whatsoever. Infact, The engine ran quite smooth.

With the two counter balance shafts the ECOTEC is the smoothest 4 banger out there.

if the timing chain was replaced then the counter balance shafts could be out of alignment

but with the amount vibration you are talking about sounds a balancing weight has been lost on the either the flywheel or the crank.

Why isn't the owner going to the dealer for warranty work? The car is well within the old standard of 30,000 or 3 years. Unless the owner has done some kind of mod that voided the warranty????

[This message has been edited by Tanlrat (edited 11-09-2008).]

thanks for the responses, i know that it wasnt under warranty i may have just mixed the date. he had just bought it used too and alot of customers dont trust the dealer even when facing needing a new trans and paying for it or getting it for free(such is the state of the image of the automechanic). the engine showed no signs that it was ever serviced on beyond oil changes and im pretty good at spotting that. had someone removed the timing cover id have given up there and told em the motor was done. it will probably run for a long time but will just never be smooth, o well. id done the same to a golf id owned but it was really obviously a bent crank and the offbalance was such to cause a misfire code to be set. i did it racing so i dont have an excuse.

poor guy, hope new 9-3s are cheap used