I just got my zc fired up today and I drove it with the si computer it ran good then I changed it to the 89 teg computer and it started to idle fast and fluctuate up and down do I have to reset the timming again because I changed the computer. Also how can I tell if the computer that i purchased is a 5 speed ecu. Any info would be appreciated

 

I don't know about the 5 speed thing but you can find that out on the Zydne.com site.

The ECU could just be adjusting it self to your altitude, and atmospheric conditions. I did a ZC swap with a ZC ecu. At first it ran like crap. The idle would go up to 1500 and drop back down. IT seemed like the computer and engine were fighting themselves. After driving around awile( a couple days) it started to learn the conditions and idled at a stock 750. Ever since (a year) it has ran great!!

Now start thinking about a turbo!

 

I had a similar problem. Mine would only do it on the teg ECU. It would also just hold the rpm at 3000 sometimes. It went away one day, and it hasn't done it since. It drove me crazy. I can't stand driving with the Si ECU either because the car feels like a dog. Sometimes now if the batter goes dead (I don't drive the car often) it will do it again.