I had it diagnosed and was told that the Dist Cap had corrosion in it so I changed the Opti and the water pump. Had the plugs checked out and they are fine. Changed the MAF and switched to a K&N filter. In low RPM it runs ok but it sounds really hollow like there is a hole in the muffler or it's missing or something. At high RPM, it sounds worst and there is no increased power. If i step on the gas to hard to fast then all of the above happens right away. SOMEONE PLEASE HELP A FELLOW Z28 comrad!

 

So was it doing all this before the diagnosis----and all that you did didn't help? What are your mods? Is the plenum to othe TB secure all the way around, especially on the bottom side that you can't see? Need more information. How about the guy who did the original diagnosis? Does he/she have any ideas?

When did you first experience the problem (s)?

 

Thanks for the reply. The only mod that i made was a cold air intake which i removed because i didn't like the response that it gave off of the line. After I removed it I started having these problems. I changed the MAF and the throttle position sensor before the diag. After the mechanic told me that the opti had corrosion then I changed that. I don't know what the plenum is?

 

The plenum is the tube linking the MAF to the Throttle Body. Just about everyone, sooner or later, will forget to make sure it is secured all the way around. The result being terrible running. Just a thought.

 

i just checked it and it looked fine, speaking of mass air flow, there are two sensors on it...one on the MAF itself and another on the elbow. When I unhooked the larger one attached to the MAF the car died. Cranked it back up and unplugged the other one and there was no difference in idle or anything. Do you think that sensor might have something to do with anything...like it's just not working or something?

 

The sensor on the elbow is probably the air intake sensor. Wouldn't make that much difference. The larger MAF plug tranmits the measured air flow which in turn assists in telling the computer how much air is entering the intake and adjusts the fuel to get the right mixture. Might affect it adversly, however I believe you have something else going on. Again, no matter how it "looks" feel the bottom of the air duct/plenum on the bottom side of the throttle body to make sure it is on all the way. Looks can be deceiving.

BTW a CAI with K&N should improve throttle response, not the opposite. JMHO

 

I checked the plenum and it was fine. I appreciate you helping me to figure this out.

 

sounds like you have a vacuum leak, I'd suggest checking that first.

 

I too was having a problem with my engine missing at high rpm. I took it to gm and it was showing codes for the MAF and EGR. Also replaced my opti. I replaced them and now it runs fine. Don't know if this helps you at all but it helped me.