Well I removed my MSD Box to sell and the next day the car started "Bucking" When in 4th gear crusing at 45 and then giving it a little gas but not enough to make it down shift. At that poing if I put it in 3rd gear the rpms would come up and it would feel fine. Well yesterday it started bucking worse then ever and making a tapping sound. If you let it idle, it fine, no tapping , no miss firing, no bucking. But if you put a load on it from a low rpm it starts to buck and tap. I just installed some expensive *** AC Delco Dbbl Platinum Plugs. The plugs I pulled out were rapid fire plugs Gapped at 64-65. I think stock it like 50. So now here I am with new plugs and still its bucking and tapping when enough of a load is put on it. If I bring up the RPM's slowly I've got no problem, no noise. So the tapping isn't a bearing problem. It only does it when the engine starts bucking. It almost sounds like a nasty rocker arm tap. But even a loose rocker arm would make noise through all the rpms including idle. So what do you all think, I'm up for any suggestions. Why would it start doing this After removing the MSD???? Should I try to reinstall the MSD To see If It runs right with the newer plugs??? Is the coil a piece of crap, is the opti spark a piece of crap???PLEASE HELP!!!!!!!!!!

 

The only thing the MSD might have been doing is cloaking some marginal plugs or plug wires. It would not have caused any mechanical noises (on or off). Are you sure the noise you hear is not a secondary ignition arc?

 

cmbob67:

This it basically the 3rd thread on the same subject.... I know I answered your original question about taking off the MSD, then you asked about the plugs, now your back with the same problem with the MSD.

Point is, if you keep all the posts in a single thread, it helps people know what the original problem was (as I recall you decided to run a hotter than stock plug), why you were looking for new plugs, and the fact that even these attempts have not solved the problem. And they would know what everyone else has already suggested, and not start all over telling you the same things people have already told you.

Just trying to help you solve your problem in the most efficient way.......

 

Ok, well sorry about that. Anyway, The point is I got new plugs that are Gapped correctly and I'm still getting the bucking and tapping when a load is put on the engine. Could it be that the coil was effected by the MSD Box and now doesn't have the power to give enough spark under a load. Could it be that Opti spark is the problem? Did I F-up a lifter or a valve because I'm running cheap gas? And why would it sputer and tap only under a load and only when the temp is about 160ish. Idle's like a champ and will run and drive great for about 5 min's and then start to fail? Sorry about all the threads but this is quite the strange problem. It's probably somthing simple(I hope), but it's just not adding up.

Thanks to everyone thats givin some info!!!
Cmbob67

 

Just how "cheap" is the gas? If its a poor enough quality, the knock sensor is going to be telling the PCM to retard timing = lost power. And, if its so poor that the PCM can't pull enough timing, its going to start detonating, and that sound could possbily be the "tapping" you are hearing. If it is, the life of the pistons may be somewhat limited.

 

I've been puttin in 87 octane for a little less than a year. Never had any issues untill I pulled the msd off and now "kaput." Should I try dumping some octane booster, resetting the pcm. Like I said before, it gets worse as the car comes to temp. When I put the new plugs in this afternoon and started it, I could rev the crap out of it and it sounded GREAT. Then I took it down the road and it started acting up again after about 2 min's. How could I test to see if the knock sensor is crappin out? I'm not getting a lite in the dash so I'm assuming I'm not pullin a code. What you said about it detonating makes sense cause the tapping noise only happends when is spudering, and the worse it spuders the louder the noise is. hmmmmmmm