stuck valve? Broken spring?

[stangeater]

I was on the interstate on my way home today when I noticed that my car seemed to have a major loss of power. I turned the radio, and AC off, and my car had a horrible miss! I was able to limp it home, but can't seem to figure it out. There are NO CODES, or at least it's not blinking any codes. All plug wires are fine, coil seems okay, DIS seems okay. My car is a 92 btw.

The car sounds like it's running on 4 cylinders, and has a top-engine tick sound comming from the back passengers side of the engine. It's hard to start also. I have to press the gas pedal to the floor to make it start. Could this be a stuck valve? If I pull the valve cover off, would I be able to tell just by looking?

Any ideas would be greatly appreciated. I need the great sho minds to chime in!
Thanks,
Jeff

 

[HotRodKid]

start it up and start pulling coil wires one at a time and find out which cylinders arent making power. then make sure the "dead" cylinders both have FULL spark.

a v6 that seams to be "running on 4 cylinders" AND is a vehical that has a waste spark ignition just SCREAMS "one of my 3 coils is dead"

 

[Eric VerValin]

When is the last time you did your RB's? Smells funny to me.. Hopefully its something simple.

 

[stangeater]

When is the last time you did your RB's? Smells funny to me.. Hopefully its something simple.

Rb's were done approx 40k miles ago. The sound is a tick from the valve cover area, doesn't sound like a rod bearing knock to me.....I guess if a cylinder isn't firing, it could make some top end noise?? I'll pull the coil wires tomorrow, and see if I can narrow it down that way. It's weird to me that I don't have any codes blinking.

 

[yamahaSHO]

Hmmmm, not trying to make a joke, but have you checked for crank cancer?

 

[HotRodKid]

if you had a stuck exhuast valve it SHOULD be making an odd huffing noise via the exhaust as that cylinder goes through the intake stroke

if you had a stuck intake valve, it would probably do a random backfire out the intake as it ran.

 

[stangeater]

Hmmmm, not trying to make a joke, but have you checked for crank cancer?

No, but I replaced the crank sensor about a year ago, and all looked good then. I'm wondering if I did lose a coil.....it just did it like the flip of a switch.

 

[stangeater]

if you had a stuck exhuast valve it SHOULD be making an odd huffing noise via the exhaust as that cylinder goes through the intake stroke

if you had a stuck intake valve, it would probably do a random backfire out the intake as it ran.

I'll admit, I'm not a valve guy! It's not backfiring at all thru the intake, but of course it does sound horrible at the exhaust end, but then again if it's only running on 4 or 5 cylinders, it's going to sound like that.

 

[stangeater]

if you had a stuck exhuast valve it SHOULD be making an odd huffing noise via the exhaust as that cylinder goes through the intake stroke

if you had a stuck intake valve, it would probably do a random backfire out the intake as it ran.

Would I be able to see if the exhaust valve was bad just by pulling the valve cover?

 

[HotRodKid]

yea, there would be a space between the shim and the cam lobe while the lobe is pointing away from the valve.

edit, example:

4th from the left, obviously this is a rocker arm setup, but the 4th valve from the right is down while the rocker is up

http://www.boicey.com/midget/pics/midget_broken_valve_spring.jpg

 

[Eric VerValin]

I just said RB's..as I was certian when mine went the sound was up top. But I had that sudden loss of power, all at once.. just reminded me of it.. plus it wasn't easy to get it started afterwards.

I'll be crossin my fingers for ya. Pull the valve covers and take a look see if anything is loose.

 

[yamahaSHO]

Any smoke from your oil fill when the car is running?

 

[Phoenix]

I call bad DIS.

 

[SHO_ROLLER_2]

How old is all the ignition parts? You know, plugs, wires, coil pack, DIS, ect.

I thought my wires were fine one time when my car was running bad. I popped the hood one night to find that the wires were lighting up my engine bay like a christmas tree!!

Oh, and my friends SHO (CWHalenSHO) was doing the same thing when the DIS crapped out.

 

[frosho]

You say the coil and DIS "seem okay"... What makes you think that?

I also think it's the DIS. I've had two go bad, and the symptoms were exactly like your description.

 

[stangeater]

You say the coil and DIS "seem okay"... What makes you think that?

I also think it's the DIS. I've had two go bad, and the symptoms were exactly like your description.

Well I said they seemed okay because while the car was running, I pulled each plug wire off of the coil pack and they were all sparking as I pulled them off. Also I unplugged the DIS while the car was running, and the car died. I guess the DIS could be partially going bad or something.

I just pulled the back valve cover to take a look. Ill get back to you guys after I take a peek there.

I also have a spare DIS sitting around here somewhere, I'll give that a try after I reassemble the top end.
Thanks for all the good input so far!!
Jeff

 

[stangeater]

I just said RB's..as I was certian when mine went the sound was up top. But I had that sudden loss of power, all at once.. just reminded me of it.. plus it wasn't easy to get it started afterwards.

I'll be crossin my fingers for ya. Pull the valve covers and take a look see if anything is loose.

Okay, now you've officially got me worried!

 

[stangeater]

Well, the valves all seem to look good to me. The center cylinder in the back of the engine seems to be the culprit, at least it looked that way by looking at the plug. I wonder if the plug just died? I have NGK plugs in it now. I'm going to go get some more, and new plug wires also. Hopefully I can get this narrowed down.

 

[frosho]

Did you swap the DIS yet? R&Ring the 4 screws is a lot easier than pulling valve covers or changing plugs/wires.

EDIT - Nvm, I see you had already pulled the rear VC. Still, I'd try the DIS before messing with the plugs and wires.

 

[93rev2sev]

Here's a stuck valve...with shim on the floor of the head