A few years ago, I picked up a 1986 Corvette couple with the Z52 package (suspension?). It was a bargain at the price but has over the years puzzled me with a lot of quirky problems. Initially, it would die if you got into the gas too hard after first starting up...so I would let it warm up before I got on it...then it would periodically die when turning a corner...then about two weeks ago after filling it with gas from Mobil, I got on the freeway and almost immediately it had a tremendous amount of surge and stall (bucking like a bronco!)...it finally settled down and I traveled about 40 miles down the road. After a break, I got back into my car and it started the routine all over again...with tremendous surge and stall...I got to thinking it might be bad gas. Anyway, I figured I was a danger to myself and the public so I left the car at a shopping center and got a ride to work from a friend. That afternoon, I picked up some "Heet" to dry up any crud that might be in the gas...the car did not run any better...as I nursed it home for the first 20 miles or so, the car would surge and stall and I could barely stay at 30 miles an hour...then all of a sudden, it settled down and I drove the rest of the way home at 55mph with little fanfare. Since that time, I have tried to scan the codes but the "Service Engine Soon" light does not flash (it does light up when the turn is turned to "ON"...the car will alternately crank and run okay one time and then the next be surging and stalling...and apparently flooding out (smells like gas)...I plan to swap out the fuel filter and, perhaps, the fuel pump. I also picked up an ECM on a whim in the event troubleshooting takes me that way...but first things first...I need to be able to scan the codes with the scanner I purchased (it is an OBD-1 type scanner)...any thoughts on why the "Service Engine Soon" light does not flash when the scanner is plugged in?

 

My guess would be a bad ECM.

 

As I had suspected and as you commented, it did turn out to be a bad ECM. After futzing around with the Mass Air Flow and doing a few of the other procedural steps, I was left with the ECM. I pulled it...popped off the cover, discovered a Hypertech EPROM, pulled it and installed it in the new ECM, installed the cover and reinstalled it in the car. I crawled behind the wheel and fired it up...all the wierdness was gone. The tester confirmed with 12s. I took it out for a ride and it was sweet!! I assume that the ECM starts out in a default position and then will adjust to the Hypertech EPROM...we will see. In short, though, I am very happy to have my Vette running smoothly again...

 

Good to see you found the problem

That hypertech prom doesnt really do much. It turns on the fans sooner and slightly adjusts the timing. If you want a performance tune its best to have someone custom make you a chip.