JDMricist_03

Hey guys. Bad news
Yesterday I was cruising on my way home from the first day of school for the semester at about 65mph. I notice the check engine light start to flash then noticed I started loosing power so I pull into the closest parking lot that I could see. The engine then died. I tried turning it back on and this is what happened:


The only 2 codes that it's throwing are the following.
P0106: Manifold Absolute Pressure (MAP) sensor signal not within predicted range for 2 seconds.
P0300: Multiple Cylinder Misfire

If anyone has any idea of what this could possibly be and what to check for I would greatly appreciate your input.
Thanks!

runner140*

If those (2) codes are the only ones, try an old "shade tree mech." first thought. Start up the engine is a DARK garage and look for a spark gap, as in a bad plug wire etc. Or look for a vacuum leak. Guess its a place to start.
Others will chime in.

neutron82

hopefully not a broken valve spring... engine sounds kinda noisy

73Corvette

https://www.corvetteforum.com/forums...-failures.html

ssrallyred

Sure sounds like a valve spring issue.

JDMricist_03

Sure enough...


Any recommendations on what valve springs and retainers I should order?

neutron82

dang that sucks but on the bright side you are pretty dang lucky that the valve didn't drop and take out the whole motor... after you get the springs swapped out I would do a compression and leak down check on at least that one cylinder to rule out any damage to the valve seat, just to be safe... the blue oem replacement springs should be fine on a stock setup... while you're there it would be a good idea to replace the seals as well and if you have the spare cash do a trunion upgrade... you can probably reuse your retainers and locks as long as there isn't any damage to them

JDMricist_03

Alright, cool! Here is what I just ordered.

Spark Plugs and Wires (red): $75.99
https://sdparts.com/details/msd-ignition/32819

OEM Valve Spring Set (blue): $60.80
https://sdparts.com/details/gm-perfo...parts/12499224

Total: $136.79

What seals are you talking about? I'm fairly new to doing engine work. Usually I get that stuff done by my mechanic but since these engines are so easy to work on, I'm doing all the work on my Corvette myself.

neutron82

valve seals, they are under the springs and seal oil from leaking past the valve stem into the combustion chamber... they are cheap and might as well replace them while you are in there

JDMricist_03

Do I need to pull the heads to install them? Also, which ones do I need? I can't really find "oem valve seals".

neutron82

nope, they pop off the valve stem after you remove the spring... you can use a pair of pliers to pull the old ones off but be careful installing the new ones so you don't booger them up... you can buy an install tool for pretty cheap or use a socket to push them on, just be careful... oem intake valve seals part # 12482063 and exhaust is 12482062... also when you install the springs make sure to heat cycle them a few times before you drive the car... basically just start the car up and let it idle for 30 mins or so until it is at full operating temp, shut it off and let it cool down for a few hours, and repeat the process... some people don't think this is necessary but I have always done it and something I do as a habit, I just don't agree with immediately going out and beating on brand new cold springs

JDMricist_03

Thanks for the helpful info! I wasn't aware of that break-in procedure. I went ahead and ordered the valve seals, retainers, and valve cover gasket.

73Corvette

Nice job Neutron82

vettelover8306

JDMricist_03

I dropped one of the valves replacing one of the valve springs... How do I get it out without taking out the head?

tblu92

I would also inspect the rocker arm for that valve as well-- all of them actually---Make sure they move freely and don't feel or sound gravely---A bad rocker could have caused the spring to break in the 1st place---

JDMricist_03

Here's the valve almost dropping into the engine... how do I get that out? The only thing I could think of is hand crank it to where the piston comes up slowly on the valve so I could bring it up high enough to pinch out. Problem is, I don't know if it's on the up stroke or the down stroke.. If I go any lower the valve will drop..





Can anyone tell me if the piston in question is on the upstroke or downstroke off that last picture?? The two valves without the rockers are supposed to be all the way up.

neutron82

use a pen magnet to pull it back out, I would not try to turn the motor over... usually the seals will hold the valves in place long enough to swap the springs but since you are replacing those as well I would get a spark plug adapter hose that you hook up to an air compressor and it fills the cylinder with air and will hold the valves up so you can work

JDMricist_03

Pen magnet was too weak. Even the strongest one out of 3. We thought it was top dead center but it wasn't..

neutron82

you need something like this, http://www.jegs.com/p/Moroso/Moroso-...64238/10002/-1 ... or get creative and try to rig something up that will allow you to pull a vacuum on the valve tip and suck it back up through the guide