ok...judt drove my new rebuild (s4 TII) to school. at about 105 mi i hit 3500-4k rpm for maybe 10 seconds cause dad thought it would be a good idea to "blow it out every once in a while" anyway, not sure if thats what did it or not..started around then sometime...its vibrating and seems to run really rough at low (<1000) rpms. sometimes it runs smooth, others it shakes like hell...doesnt seem to be much of a pattern to it or anything....it was dark and i couldnt really check anything out...anyway it drives fine...has all the power it should...starts as well as it did before... did i blow a bearing? or an apex? doesnt seem like i did...it ran fine for another 50-100 miles after i noticed the shaking..... wtf? is there anything other than a blown bearing that might cause this?

thanks
pat

ps...oil pressure is fine, temp never went high, still runs stoich..just a tad on the rich side...

 

bumpity.

If the engine was just rebuilt a rought idle isn't too much to worry about as the compression hasn't reached it's maximum. If this keeps happening after breakin you should get the compression checked.

Did you tune up the car after installing the rebuilt engine? Are you using 10W30 or similar (non-synthetic) for breakin?

Did you change out the motor mounts & tranny mount to keep the engine vibration down ?

 

Perhaps you blew a hose off. Check for vaccum leaks. Those can make a car run very eratic.

 

thanks for the replies guys.

i did not change mounts..with exception of swapping a spare left mount rubber in for the right side...seems like the right ones always break... i used castrol 10-40 +MMO for the 0-10 mi, then changed oil +filter to castrol 20-50+MMO. i know the comp is low..its hard to start hot...i used the new rws apexes, so i expect a long break in... yeah i may have blown a hose...i accidently boosted a little right b4 i got here and i heard a bit of a hiss....not sure if that could do it tho...at 600 rpms it makes the exhaust sound funny and shakes the whole car...i am gonna put in new plugs and look for loose hoses this evening after my physics exam. (college blows)

pat

 

ok....just got back from the car....no vac hoses unhooked. engine sounds ok..no loose hoses either...

BUT turbo is rattling, either from the turbo or the exhaust manifold, cant tell which...which leads me to...i bought a used housing, and broke off an exhaust mani mounting stud. bottom front. so..i drilled it and force threaded another one in there...so it may have popped out..or there may be something wrong with the turbo. the question is, could either of these cause the vibration i described above? also exhaust kinda pulses/pops....

thanks,
pat

 

bump

 

anybody?

 

update again: the front pulley is spraying oil, so i think it may be that...im gonna replace it when i get home. also..i think the rough runningmay be due to the TPS.

i'll let y'all know when i find anything out

pat