Strange vibration or normal?
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Strange vibration or normal?
I am in the end run of re doing about all I can think of on my engine 
Did the Valve gaskets and swapped the Injectors out yesterday. Went for an alignment and found out I got bad ball joints on the bottom ( no big suprise 155k on em) so I got an appointment with my mechanic to replace them decided to do an opti cap and rotor/water pump at the same time He is gonna charge me $200 labor for it all 
. Gotta love this guy. Anyway was sitting in the garage doing some engine revs and noticed something I did not really like.
When I hold the throttle at various RPMs I notice two spots at around 1200 and 1800-2000 rpm that I get a pretty noticable vibration. Can't really feel it that much on the road but unloaded it shudders pretty good at those areas and not at other RPMs.I am pretty sure it is not the tranny/TC. Is this something significant? Could the opti be the reason? Could the harmonic balance be causing this? I know someone in the past has been playin under my hood because I have been finding some bolts and fittings slightly boogered. I would assume someone also has changed an Opti in this car and mabey put the balancer on wrong. What are you thoughts?
Did the Valve gaskets and swapped the Injectors out yesterday. Went for an alignment and found out I got bad ball joints on the bottom ( no big suprise 155k on em) so I got an appointment with my mechanic to replace them decided to do an opti cap and rotor/water pump at the same time He is gonna charge me $200 labor for it all . Gotta love this guy. Anyway was sitting in the garage doing some engine revs and noticed something I did not really like.When I hold the throttle at various RPMs I notice two spots at around 1200 and 1800-2000 rpm that I get a pretty noticable vibration. Can't really feel it that much on the road but unloaded it shudders pretty good at those areas and not at other RPMs.I am pretty sure it is not the tranny/TC. Is this something significant? Could the opti be the reason? Could the harmonic balance be causing this? I know someone in the past has been playin under my hood because I have been finding some bolts and fittings slightly boogered. I would assume someone also has changed an Opti in this car and mabey put the balancer on wrong. What are you thoughts?
Melting Slicks
Joined: Dec 2000
Posts: 2,719
Likes: 60
From: Fremont Oh
I wouldn't think as a lot of vibration to be normal...
I had a simular situation, I changed out my throttle positioner and it seemed to resolve it.. since it seems to be in ares that the cars sruise and suchI would certainlycheck that out, mine had 130K on it and it was stock so it can't but help...
Mo
I had a simular situation, I changed out my throttle positioner and it seemed to resolve it.. since it seems to be in ares that the cars sruise and suchI would certainlycheck that out, mine had 130K on it and it was stock so it can't but help...
Mo
Advanced
Joined: Dec 2001
Posts: 51
Likes: 0
From: Nashville TN
Don't worry about it until after the opti. Bad or poor-shape optis have been known to cause wierd dead spots in the RPM range.
If it still does it afterward I'd look at the rest of your ignition system and the Throttle position sensor, as sometimes it can develop bad spots in it as you open the throttle.
Plugs & wires should be replaced if not new already and depending on mileage a new coil and ignition control module wouldn't hurt either.
I highly doubt it has anything to do with the harmonic balancer. Since the stock balancer isn't keyed it is possible for it to move on the end of the crank snout but I've not heard of that happening except in high belt load conditions like supercharger applications (which is why a keyed crank hub is a great idea).
If it still does it afterward I'd look at the rest of your ignition system and the Throttle position sensor, as sometimes it can develop bad spots in it as you open the throttle.
Plugs & wires should be replaced if not new already and depending on mileage a new coil and ignition control module wouldn't hurt either.
I highly doubt it has anything to do with the harmonic balancer. Since the stock balancer isn't keyed it is possible for it to move on the end of the crank snout but I've not heard of that happening except in high belt load conditions like supercharger applications (which is why a keyed crank hub is a great idea).
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Thanks guys I suspected the Opti might cause it possible acring in the cap but was not aware of the TPS being a possible cause also so I guess both are going to be changed. Since Mo's car had high miles too and his was the TPS I have no problem fixing it I want a totally reliable drive with this car. Anybody else seen this happen on thier cars?
