So I was driving in walmart parking lot, not racing or anything, and my car starts running funny. The exhaust was popping whenever one cylinder hit. The engine runs smooth, then whenever the bad cylinder hits, the engine shakes very hard. So I'm going to tow it back to the house and do a compression test. So do you think that I'm headded the right direction?

 

No. Miss fires are rarely from valves. Most likely ignition. Plug, wire etc..

 

I hope you are right. I'll check the plugs and wires first. Thanks.

 

Dunno: which direction is your house?

Yes, a compression check should tell which cyl. A burnt valve will cause backfiring. Let us know what you find.

 

i checked the wires and they dont seem loose. when it misses it sounds more violent than just a miss from not getting fire. ill check for fire next.

 

ok i bought a spark tester and when i pulled off the #3 plug the spark seemed weak. but the wierd thing was the hard knocking went away. What would that mean?

 

I guess you need to be more specific. You first said it was "popping" then "missing" , "knocking". You mentioned it was "more violent" then a "miss".

If it is "popping" it may be backfiring, especially if it is an exhaust valve. If it stops when you pull the wire, obviously it won't fire and if it doesn't fire then it will "miss" or it will not backfire since their is no ignition.

At least you know which cyl. so you can narrow down the cause. You can check your plugs and wires without removing the covers, but you will need to pull the head if it is a burned valve or valve seat. And if it is a burned valve you might consider doing all the valves or seats, etc. I don't know if deleting the EGR would cause burned valves, however if you are not recirculating your hot exhaust gasses and your valves/seats get too hot one never knows.

On the other hand, I might be full of sh..

 

I doubt the valve is broken, the worst case scenario is abent valve, if the valve were broken aluminum and steel are very incompatable. You would be either replacing the motor now or have a little oil consumption problem.

I'll vote for an ign miss.

 

Ok, I've replaced spark plugs and the #3 wire (got a taylor repair wire). It still detonates. Doesn't seem to detonate as bad as before. What should I check next? Thanks!

 

Remove the driver's side valve cover and check for problems with a rocker arm or pushrod on #3.

 

Ok, this made no sense to me. I unplugged my fuel injector and with the spark plug wire plugged up it still knocked. Which doesn't make any sense to me. I am clueless on this one. Haven't taken the valve cover off yet though.

 

Generally knocking at any speed, particularly in the driveway is not good.

Didn't get into any deep water lately did ya?

Give us a little more detail on this "knocking" please.

 

Does this knocking sound trace with rpms?

 

I reved the engine and held it at about 4k and the voilent engine shake that I experienced at idle, didn't seem present. It obvously didn't sound right though. I did the same thing with the fuel injector plugged in and when I backed off the throttle I experenced several back fires.

 

Maybe a bent pushrod. Pop the valve covers off and check your valve train out.