BAD engine shaking!!
 

The last time I started my 96 z28, the engine began shaking so hard I thought it would break the motor mounts. The drivers side exhaust manifold smoked a little but that was the only visible problem, besides the lt1 violently moving inches in all directions.

Soo, any ideas?? It has a 5" underdrive pulley kit from the first owner, and has always leaked oil out of everywhere, mainly the rear main. This car was my daily driver until this happened, over a year ago. Anything would help, I'm out of ideas.. Thank you so much, I would love to have this car back on the road!

Re: BAD engine shaking!!
 

Wow. Doesn't sound like a misfire to me. Sounds like something much worse. You have a 96 with OBDII, use it! lol, any codes?

Re: BAD engine shaking!!
 

Take a look at the spark plug wires and the plugs. Bad wired will cause the shake......

Re: BAD engine shaking!!
 

Could it really cause something that bad, though? My misfire involved at LEAST three cylinders and it was just a mild shake. Could you get us a vid of the shake?

EDIT: Oh, you're talking about crosses wired. HA! Nvm.

Re: BAD engine shaking!!
 

I've had misfires codes and a mild vibration with this car since I got it. I fixed the misfires with new plugs and wires, but this is way worse. I am seriously afraid to drive it like this, can I rent a diagnostic tool? And what do you mean crossed? It was fine the day before. Then hopped in the next morning and it was like one of those pay-a-quarter hotel beds. I will get a vid, once I get the battery and valve covers back on.

Re: BAD engine shaking!!
 

You could wait until it's very dark outside, open the hood and start it, and see if there's a light show anywhere around the engine.

I've never seen a code reader or scan tool for rent. I realized a long time ago that if you're going to try any work on these that you need a scan tool. I guess you could call Autozone or some other places and see if they rent them.

Re: BAD engine shaking!!
 

Does the frequency or magnitude of the shake increase with RPM? Is it violent at stock idle RPM?

Re: BAD engine shaking!!
 

I will try that, but what failure would cause it? I would like to be one step ahead of the problem, maybe I could fix it before startup.

As for RPM's, it was so bad at idle I didnt want to fool with it too much, but it did get progressively worse up until about 2500rpms, I didn't want to take it much higher.

There was an obd2 scanner on powerblock tv this morning for $70, so I will have to order it.. http://www.summitracing.com/search/P.../?autoview=SKU

I checked and I haven't dropped any valves, but it seems far worse than that.. Do you think it's like a bad rod-end, or a broken main cap or what?

Re: BAD engine shaking!!
 

If there is a Harbor Freight near you, they have an OBDII code reader for around $50.

Re: BAD engine shaking!!
 

Yeah, after my last post I found scanners online from about $30 up.

Will it throw a code if I can't drive it anywhere?

Re: BAD engine shaking!!
 

Some codes set at idle, others require it to go into closed loop, and others will not set unless certain speed, rpm, time or temperature criteria are set.

Re: BAD engine shaking!!
 

Have you checked the harmonic balancer? Its worth a look.

Re: BAD engine shaking!!
 

Have you touched your transmission mount lately? Mine was binding or under tension or something when I bolted it down; it caused one hell of a vibration even stopped in park.

Re: BAD engine shaking!!
 

Bad A/C Compressor or Compressor Clutch?
Flywheel weight? (if aftermarket)

When I had a McLeod Street Twin I installed it without the balance weight. That will cause a severe shake/vibration. Luckily You can install it through the inspection plate. So I didn't have to pull the Tranny.

Re: BAD engine shaking!!
 

Some Autozone's offer them with their loan a tool program. Pay a deposit, get it refunded when you bring it back.