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Vibration and shudder with lots of boost

J

jasonnovak

New member
I have a recently acquired 99 GTP. Supercharger sounds fine at idle - not rattles -though it does seem to get quieter at 30+. It's been fine driving at low speed and highway speeds. But on a certain trip with some hills at highway speeds when it downshifts to climb a hill and the boost jumps to 80-100% the car vibrates and there's a unhealthy rattle/vibration that sounds like it's coming from the motor. That's really the only time I've seen boost that high so I can't say if it would happen under other driving conditions.

I did change the supercharger oil, was low and pretty dark. Check a few plugs and looked ok. Scanner shows no codes. 206K on motor, 70K on rebuilt transmission. Any thoughts, hopefully it's not destroying itself
 


Try the zzp coupler. I have a 99 as well and my snout was shot. Do you know if your snout was rebuilt or not? Also if you dont mind post a video up of said sound
 
Is it only when accelerating? If under a hard load or wot it could be something loose in the steering, suspension, or CV axle. When I got my car I had what felt like what you are describing. Mine had bad hub's, lower ball joint's, outer tie rod's, and both CV axle's. I don't know what item in particular was causing mine but after I replaced all item's and aligned it the vibration is gone.

Check for somthing loose in the steering and try to shake the cv's from under the car and listen for clunking and feel for movement. Check to see if they have exploded grease all over.

Sent from my XT1080 using Tapatalk
 
ericspecullaas said:
Try the zzp coupler. I have a 99 as well and my snout was shot. Do you know if your snout was rebuilt or not? Also if you dont mind post a video up of said sound
Click to expand...

I wondered about the coupler, it seems like when that's the issue it's sound like gravel banging around in their at idle? I listened to some videos and mine seems ok at idle. I don't think it has been rebuilt, have the last 100K worth of receipts. Can get a recording of it at idle, may be a bit before I can get it somewhere I recreate the vibration. Was going to the last time it happened but by the time I got my phone out I was already over the hill
 
I've stepped on it a bit passing people and it's fine, it doesn't really get too much boost though. When it's happened I'm just going normal highway speeds with cruise set and get to decent sized hill, it downshifts, boost shoots way up, and then all the noise starts. That's what made me initially think it may be a supercharger issue

It's had a fair amount of work done by the previous own, I'd compiled it from the receipts:

[TABLE="width: 666"]
[TR]
[TD="align: right"]6/15/2012
[/TD]
[TD] 198,057[/TD]
[TD]Oil Change (inspection all passed) 5w30[/TD]
[/TR]
[TR]
[TD="align: right"]3/20/2012
[/TD]
[TD] 195,057[/TD]
[TD]Replace FR Wheel bearing, real brake bad/rotors
[/TD]
[/TR]
[TR]
[TD="align: right"]2/17/2012
[/TD]
[TD] 194,299[/TD]
[TD]Alternator (battery 2 yr old)[/TD]
[/TR]
[TR]
[TD="align: right"]7/15/2011
[/TD]
[TD] 186,444[/TD]
[TD]Traction Control C0035/C0036 Left Front Speed, sensor gooddamaged wire on left front wiring harness declined repair[/TD]
[/TR]
[TR]
[TD="align: right"]7/5/2011
[/TD]
[TD] 186,158[/TD]
[TD]Exhaust leak, installed 5in pipe 54-8518[/TD]
[/TR]
[TR]
[TD="align: right"]6/17/2011
[/TD]
[TD] 182,788[/TD]
[TD]New Radiator hose Replace front brake pads/rotors/RF Caliper
Installed exhaust flex pipe/MAF sensor?[/TD]
[/TR]
[TR]
[TD="align: right"]6/8/2011
[/TD]
[TD] 181,731[/TD]
[TD]Radiator (1890) Aftermarket, not perfect fit[/TD]
[/TR]
[TR]
[TD="align: right"]4/27/2011
[/TD]
[TD] 182,788[/TD]
[TD]Replaced front tires[/TD]
[/TR]
[TR]
[TD="align: right"]3/25/2011
[/TD]
[TD] 181,346[/TD]
[TD]Left outer tierod, rf lower ball joint, front sway bar, left rear trailing arm[/TD]
[/TR]
[TR]
[TD="align: right"]4/13/2010
[/TD]
[TD] 165,839[/TD]
[TD]repaired radiator fan wiring[/TD]
[/TR]
[TR]
[TD="align: right"]9/23/2009
[/TD]
[TD] 158,764[/TD]
[TD]Replace both belts 12588411/12574914[/TD]
[/TR]
[TR]
[TD="align: right"]6/2/2009
[/TD]
[TD] 154,043[/TD]
[TD]Overheats: Replaced lower intake manifold gaskets/related/thermostat[/TD]
[/TR]
[TR]
[TD="align: right"]6/21/2008
[/TD]
[TD] 136,878[/TD]
[TD]Recall/Left Valve cover gasket & wire retainer[/TD]
[/TR]
[TR]
[TD="align: right"]3/16/2008
[/TD]
[TD] ~136000 [/TD]
[TD]Tie Rod/Front Left Hub/Left CV Shaft/Fuel Filter/Exhaust Gasket[/TD]
[/TR]
[TR]
[TD="align: right"]2/23/2007
[/TD]
[TD] 130,845[/TD]
[TD]New Transmission[/TD]
[/TR]
[TR]
[TD="align: right"]11/9/2006
[/TD]
[TD] 126,000[/TD]
[TD]Replace both swaybar links[/TD]
[/TR]
[TR]
[TD="align: right"]7/13/2006
[/TD]
[TD] - [/TD]
[TD]Windshield[/TD]
[/TR]
[/TABLE]


osiris94ej said:
Is it only when accelerating? If under a hard load or wot it could be something loose in the steering, suspension, or CV axle. When I got my car I had what felt like what you are describing. Mine had bad hub's, lower ball joint's, outer tie rod's, and both CV axle's. I don't know what item in particular was causing mine but after I replaced all item's and aligned it the vibration is gone.

Sent from my XT1080 using Tapatalk
Click to expand...
 
Easy way to tell if the coupler is bad is to take the supercharger belt off and see if there is any play in the pulley (turn it back and forth by hand)

Does it just make noise and vibration, or can you feel the car bucking any? (like your losing power on and off)

There's a good chance it is driveline related, or could even be a misfire.(Though usually if it misfires a bunch the SES light will flash on and off for a few seconds)
 


Thanks, I'll check out the pull when it warming up a little in a few days, barely double digits today :)

I got a few video clips, at idle:

http://youtu.be/cbd9pkNAsGE

I actually noticed it got louder when it warmed up, though not really rattling, it's pretty loud at the air filter at start

I also noticed I could get the rattle at lower speeds just by really stepping on it, though to a lesser degree. Just been babying it a bit since there are a couple of things I'm worried about with the transmission. Can't really tell a whole lot from this clip, maybe it is suspension rattled since it does seem like it was a lot more pronounced at highway speeds

http://youtu.be/tSqkIFxyxuI
 
Yea that definitely doesn't seem like drivetrain like I thought at first.

Sounds like at least one cylinder down.

Sent from my XT1080 using Tapatalk
 
Thanks for the replies. My service light is actually out and I'm about to replace the bulb (that and the ABS, was diagnosed a bad wire on VSS I saw so I found the break, ordered a new connector). Used a scan tool a while ago didn't didn't see any codes other than the bad bulbs I believe, have to check again now that I've been pushing it.

Think it may be the plugs? I'd just checked one or two and they looked fairly clean and had good gaps, but didn't check them all. They looked like gm iridium plugs, was guessing they were changed about about 100K by original owner, the second owner never changed them. I have a copy of alex peper's obd2 software I could have recording live on my laptop when it occurs
 


its over due for a tune up so start there. the abs light wont make it run funny. unless it thinks the wheels are slipping, then it will do a similar shudder because its pulling timing to reduce power to the wheels. but most of the time when the abs light is off so is traction control. both inactive.
 
I just mentioned the ABS a side note as to why my check engine light has burned out because you mentioned the check engine light flashing as a sign, I didn't think it was related.

By tune up, you mean plugs and maybe wires? All of the other little things have pretty much been done, ie re-oiled air filter, changed fluids, etc
 


those oiled filters aint all that good. its best to spray lightly and let it sit over night. when i had one on my 97 truck i kept the stock filter so the k and n could sit all day after cleaning and re oiling it.

i had maf problems with that truck looking back it just may have been the air filter. even tho i never over oiled it. and let it dry over night or 24 hours at least.
 
I think the original owner put it in, I cleaned it because it was pretty dirty. My kit had a squeeze bottle for the oil.

So does the maf seem like a likely cause? Is there something I can check to see if it's the issue? If there's no code, a sensor value when reading obd-2 data?
 
pick up some maf cleaner. its a spray can. take the maf out spray the little metal wires in the housing there. let it dry, reinstall it.

do not touch or brush or any thing but spray the cleaner on the maf. or it may die on you.
 
Agree, the plugs looked good? How so? Did you check the gap on them? Plugs, wires, oil, new filters, check belts, fuel filter, injector cleaner, maybe sea foam, replace that oiled filter too. 8k on the oil... Really? Or has it been changed since 198k? I'd drop the tranny pan and change the oil and filter in it too. Get to look in the pan for debris and know maybe if it was ridden hard. After doing the basics, then I'd move on to the suspension if vibration was still there.
 
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