So my engine shakes when i shut off the ignition. What I did was open the hood and peek through the crack into the engine bay and shut it off. Seems to me like it shakes waay to much, shakes my butt in the seat. When i first bought it, it never made any movement like that, im sure i woulda noticed.........
I didnt hit anything prior to that problem, I just want to get it fixed

 

alright so ive heard of a thing that sounds simular to your problem
im pretty sure its called detonation, and its when the gasses in the engine spontaneously combust during and after the car is shut off, which in your case, it doesnt fire for very long after u turn it off so id say it sounds minor but id still get it checked out. sorry i dont know more about it, but i think thats wat it is, so maybe you can search it up on google to find some info. good luck!

 

hmmm, intresting, thanks mojo!!!!!
does anyone have any info on detonation???? I have recently replaced my fuel pump, was it installed incorrectly? like maybe cutting off the fuel too late of something??? im lost on that one......wheres hanr when you need em j/k bro

 

bump! c'mon guys!!! this problem is making me mad [>:] I dont think its as serious as to the detonation idea.......but it does shake more than it should when my ignition is cut........kyle?, tim? [8D]

 

The technical term is not detonation, but rather engine run-on or dieseling.

Most of the time, in modern fuel injected engines, this is caused by a few different things happening at the same time. In your case, I would attribute this to carbon buildup in the combustion chamber creating hot spots and quite possibly a few leaky poppet nozzles on the SCFI injection spyder. These poppet nozzles are supposed to only open when ~50psi of fuel pressure is acting on them. When they get gummed up, they have a tendancy to stick open. In the SCFI injection setup, the electronic fuel injectors are mounted in a centralized pack. From the injectors, fuel lines run down to the poppet nozzle. These lines are supposed to continuously have fuel at a pressure just below the opening pressure of the poppet valves. When the electronic injector opens, the pressure in the lines rises until the poppet nozzle opens spraying fuel into the intake runner right before the intake valve. If these injectors are leaking, they may continue to spray, then dribble fuel into the intake runner and, given a hot spot in the cylinder, can cause run-on.

One quick thing to do would be to run a can or two of seafoam through the TB to clean out the carbon in the cylinders. Once you have done this, I would recommend at the very least pulling out the spark plugs and checking them for contamination as well as recheck the gaps. Also, an oil change should always follow an top end cleaning no matter what product you use to do it so if you plan accordingly, you can get an oil change done on schedule directly after doing the top end cleaning.

Now, that was the easy part... A sticking poppet nozzle is not as easy to verify. Only way that I know how to do it is to have a fuel pressure gauge hooked up and cycle the injector (without the fuel pump on, but at full fuel pressure). For my vehicles, this requires my scan tool to be plugged in to tell the individual electronic injectors to open. Once an injector opens, you should see the fuel pressure drop until the poppet nozzle closes. If the pressure continues to drop, then you have a stuck poppet nozzle. Prime the fuel system back up again and cycle through all of the 6 injectors/poppets.

By running a fuel injector cleaner through a few tanks of fuel, you may unstick a nozzle, but it is highly unlikely. After you have determined that the poppet nozzles are sticking, I would have to recommend having a professional fuel injector cleaning done. That would give you a much better chance of having them stay unstuck for the longest amount of time.

Other than that, your options are pretty much limited to either replacing the SCFI spyder with a new one that may down the road do the exact same thing again... Or upgrading to the new MPFI spyder which is a direct replacement and removes the fault prone poppet nozzles and puts electronic injectors in their place. The costs for the injection spyders are about the same IIRC and both require the same amount of work to do. If the fuel injection cleaning was going to cost you $100, I'd save the money on a new spyder. But again, this is only after verifying that your poppet nozzles are the culprit.

 

Hi there !

I seems to have similar problem, but when i'm on idle. It's a little shaking. Does some one have any idea ?

Thanks

 

I thought dieseling was when it kept running after you shut it off

 

From the first post:
It could be considered dieseling when after he shuts off the engine, it shakes... Detonation would be while it's running and if you have detonation at idle, you've got problems.