What's this shudder about???

[Ninety7PrixGT]

I have a 97 GPGT, 156K, been driving just fine til last night. Started driving home and all of a sudden I gave it the gas and it just start shuddering whenever power was put to the wheels. SES was flashing for about a min then went steady and still is. Stops doing it the second I take the power off the wheels. Doesn't do it coasting or anything. Does it in every gear, from the second the power is applied till I let up. Torque converter maybe? Please help. Too much money wrapped up in it to see it sit in my driveway

[bangbg]

My guess is that your car needs either 1 or both of the axle shaft/CV joints replaced.

My car was doing exactly what you described and after replacing both front axles the problem went away completely.

The cost for me to get them replaced at a local shop was about $350.00.

[Ninety7PrixGT]

If those were bad wouldn't it do it power to the wheels or not? I do know that there may be a bad hub. Check tire pressure, abs, and trac off light always come on at random, and once on they don't shut of till the car does. Another possible cause?

[BNaylor]

When the SES light flashes it is normally a misfire condition. Get it scanned and see what codes are stored. How old are the spark plugs and ignition wires?

For abs and trac problem get it scanned with an ABS capable scanner. Probably one of the hubs, electrical connector or wiring.

[Ninety7PrixGT]

Yeah that is what I thought, but I put it in neutral coasting and it is fine, revs up just fine, no problems. Soon as i put it into gear and give it gas it starts shuddering, sluggish, and just sounds like something isn't engaging. Plugs are iridium and are only 6000mi old, likewise with the wires. ACDelco wires. I plan on scanning it, if I dare drive it anymore. AutoZ is like 8 mi from my house. Had to drive it about 5 yesterday to get it home

[BNaylor]

I noticed you have a 97 model. What brand Iridium plugs? Sometimes the Iridium plugs don't work out and you may need to switch back to the OEM type AC Delco Double Platinums. Hopefully the scan shows misfire DTCs and you can go from there. Also, the coilpacks and ICM can cause misfire.

[Ninety7PrixGT]

acdelco iridium plugs

[Ninety7PrixGT]

So diagnoses...NOT GOOD. Haven't had it scanned yet, but located possible problem. Does it now just running. Definite misfire. Middle plug on front of engine has something bubbling a little bit around it when running. Can hear when it is misfiring. Also, what would be the cause of a pool of coolant in on the top of the back right of the engine, above the valve cover? Definitely leaking out above that. Everything is soaked, and she eats through coolant. I don't really want the answer because I know what it'll probably mean, but I'll take it anyways.

I should add when I bought the car the oil filler cap was all bright yellow gunk. Hasn't happend since because I run synthetic w/lucas and change it regularly.

[BNaylor]

Misfire is ignition related. With a scanner it will show a DTC(s) of P03XX.

That doesn't sound good. The coolant leak could be cooling system related or since you have a '97 GT it could be the upper intake manifold. Possible gaskets or plenum EGR stovepipe damage where you will get coolant consumption/loss. I'd pull the spark plugs and do a closer inspection.

Also check all coolant lines like like heater hoses, radiator hoses and the 90 degree elbow between the tensioner and lower intake manifold.

[Ninety7PrixGT]

well I know that the elbow between tensioner and manifold is a copper elbow. Had to replace tensioner and broke the plastice one. One end of the piece is still in the lines, fell off in the manifold side. well you dropped that dreaded word, plenum, I knew it was coming B. This week has just been awesome. I'm going to be checking plugs and other things this weekend. I'm more than positive the manifold gasket or plenum is done. She never runs hot, just eats up the coolant. Never white smoke, or any at all in fact. If I can get it to the AZ i'll have codes, but don't know how to yet. Maybe she'll run better after checking the plugs

[richtazz]

I agree with bnaylor that the coolant loss sounds like a bad UIM. They fail around the EGR stovepipe, and will leak externally around the throttle body mount as well as into the engine. I'ts a common issue on your year engine. The bubbling around the plug could be a loose plug or cracked ceramic insulator on the plug, leaking combustion chamber pressure. This would cause a misfire for sure.

[Ninety7PrixGT]

That's definitely where it's leaking. I guess we'll start with that, and messing with the plugs. Thanks guys

[DJ JEFF]

So what did you figure out on this situation? I have the same thing going with my 97GTP and I hoping you figured this out. It makes me nervous reading the last post. I was hoping my cat converter was clogged.