No compression in cylinder

[ILTTG]

A couple of months ago I posted about an issue with my car throwing a ton of codes after being driven on the highway after a jump start. For reference, here are the codes:

P0304 - Cylinder #4 Misfire
P0562 - System Voltage Low
P0652 - Sensor Reference Voltage “B” Circuit Low
P1628 - Module Ignition Supply Input Malfunction
P2104 - Throttle Actuator Ctrl Sys-Forced Idle
P2106 - Throttle Actuator Ctrl Sys-Forced Limited Power
P2100 - Throttle Actuator Ctrl Motor Circ/Open
P2127 Throttle/Pedal Pos Sensor/Switch E Circ Low Input
P2282 Air Leak Between Throttle Body and Intake Valves
P0316 Misfire Detected On Startup (First 1000 Revolutions)
P2282 Air Leak Between Throttle Body and Intake Valves

I finally took it to the local dealership (I think they're the only ones with a viper tech in my city) and after 2 days with it, they told me that cylinder 4 is showing "no compression". They are suggesting taking the engine apart to figure out the cause (5 hours at $105 an hour), but I've been researching and seen suggestions that a leak test should be performed before the engine is taken apart (they only did a compression test). Can anyone give me any suggestions on what the issue might be and whether taking the engine apart seems logical at this point? The engine is making a subtle "pinging" noise when it runs, now, along with all the misfiring/electronic throttle issues. I really have no trust in my local dealership; a family member also has a Viper and it took them 5 tries and 3 months to nail down an electrical issue that was causing the battery to drain overnight, so your thoughts would be appreciated.

Thanks.

Joe

 

[Dan Cragin]

If a cylinder has no compression then a leak test will only determine if you have a broken piston or bad valve. With no compression its gonna be one or the other. Either way the engine will need to come apart. Sorry to hear about your issue.

 

[ILTTG]

Thanks for the response, Dan. What kinds of scenarios am I looking at, here? The pinging sound is pretty concerning, as I'm reading that might mean a dropped valve seat.

 

[dester243]

No compression to me (from other engines) is from valve issues. Burnt/chipped valve. Or I have even seen something fall into the motor and keep a valve stuck open. Sounds like a bad deal. I bought a video inspection scope and can go down the spark tube holes to look at the tops of the pistons and they have an attachment to look up at the valves.

Either way like dan said. The head most likely needs to come off. I see a good sized repair bill either way. Sorry man

 

[AZTVR]

PM sent .

 

[ILTTG]

Hello all, I wanted to update this thread for anyone who might have similar issues in the future. The issue was caused by a bad exhaust valve spring - apparently that was what was causing the intermittent pinging sound. The car is being put back together today and, barring any problems, should be ready to go by this afternoon. Thanks for the suggestions, and I apologize for not responding to the *** I received. I don't get email notifications so I missed some.

Joe