Hi to all and thanks ahead off time for any assistance you give. I recently bought a 93 Z28 w/ a little over 100K miles. The problem is the low RPM bucking that seems to be such a big topic. I have done some searching, but I'm still not sure what the problem is.
It has had plugs and wires all within the last 500 milles. The bucking only occurs at cruising RPMs. I have no lights but put a code reader on it and came up all clear. I guess my main question is does the EGR give a fault to the system or not. Should I start there. Also what about the optispark. I know a considerable amount about motors and ignition but the LT1 is new to me. Any help would be nice. Thanks

 

i could be wrong, but at 100k it could be a few things, did you make sure the wires are not being burnt on anything? my wires on my car were a PITA to put back on.

 

The wires were done one at a time by he best mechanic I know, he said he put them back to stock lacation. I forgot to mention the problem was there before the plugs were changed.
Thanks for the reply, and any other help would be greatly appreciated
Tyler

 

Also another add in the it only seems to studder after the car it warmed up for a while. If that helps any
Thanks again
Tyler

 

Yeah I'm experiencing your problem right now and it is the optispark. My water pump has a small leak which is causing the opti to missfire...
Not sure if that's your problem but might be.

 

I have had the same problem for over a year now. I have put new plugs and wires on as well as a new water pump that had sprung a leak. I am convinced it is either the ERG or the optispark. Mine also does it worse the warmer it gets, and it only does it when you load the engine( try to accelerate in too high of a gear). I runs great if you keep the revs up. One other thing I have found is it does it less after I replace the air filter? Strange animal this LT1. If you figure anything out, let me know!

 

btt for daytime
Thanks

 

Stick or Automatic.

 

was the coil wire replaced...if that's burned won't that cause problems?

i'd opt that it's the opti spark...they suck

 

I have the same problem and have seen several posts, some of them very long (300 plus posts). There really doesn't seem to be a definitive fix at this point. I've seen posts where everthing electrical has been replaced - from the opti on up. The only logical conclusion that I can make is that the low rpm stumble, studder whatever, is a common symptom for a number of different problems.

I just got some new heated 02s and am going to see if that helps. If it doesn't I'm going to yank the opti to see if there is something not quite right there. The opti is new, but installed by a shop in whom I've subsequently lost faith. If anyone actually comes up with a definitive answer for this problem - feel free to post it because it is literally driving me crazy.

How crazy you may ask? Well I was at the Ford dealer yesterday looking at an 03 Cobra for 35K and if the guy wasn't such a jerk I probably would have bought it - even though they were only offering 3000.00 for my car!

 

Opti's arent as hard as everyone makes out to change. It just takes a little time. I replaced mine without it even going out, it was just on the car for 75k and I thought it would be a good time to change it. The biggest problem I had with doing it was paying for a new one.

 

Might wana go ahead and throw on a new fuel filter as preventative maintenance. When clogged, they have been known to cause some of these symptoms. Not sure if this is the problem, but if you haven't yet a new filter would be a good idea plus they're cheap.

Jason

 

Opti... my car does the same thing... 93 z28 with 111k on it.. My Water pump leaks.. the hotter she gets.. the worse it gets.. this can make first gear a tad tricky.. wants to stall out when its hot enough,, makes me feel like gay, driving down the road like its my first time driving stick.. ick.. ill have my new opti and wp in befor the end of the month i think... i can let you know how that goes if you can wait that long

 

Thanks for all the help I guess I just need to start somewhere. And keep going untill I solve the problem.
Thanks again
Tyler

 

Wasssup dude,

Good maintenance is changing that EGR and fuel filter, I still had the original 93 one on my car. New EGR in mone as well. My Opti worked fine till the water pump kilt it.