Hi guys I have a 96 LT1 in my truck. My waterpump went out recently and It started to run like it was missing. I replaced the waterpump and took the opti off and cleaned it. It had some moisture in it. Now its not as bad but it surges at idle and when I accelarate.It will stall every now and then when I stop and my tach will cut out while im driving. I have an aftermarket tach and it keeps working just the one on the dash cuts out. While all this is happening my oil pressure and voltage gauge go crazy. If anyone can help or offer any suggestions I would appreciate it.

 

You need a new opti; try the partsladi on ebay for a good price gm unit.http://stores.ebay.com/Thepartsladi_...&submit=Search

 

Ok thanks I figured that was the problem just wanted a second opinion. Also another question. The engine will run great (besides the surging) for about 10 min. Then it just loses power and accelaration. If you turn it off for about a minute and restart it the problem stops for about another 3 or 4 min then happens again. It doesnt stop unless you turn it off. It had cold air and headers when I bought it. Is it possible that whoever modded the engine didnt have it tuned or didnt tune it right. If so will an open loop tune fix it and about how much does it cost to have a tune done.

 

Hey man thats usually the signs when an opti is going toward the end of its life. Usually it will run fine until the engine is warm and then it will die. At first mine started to die at stoplights at idle then it got worse and my rpms would jump around and then it would die, id let it rest for an hour and i could drive the car home it sucked but it was the opti in my case. I never had any surging problems besides when i had a fuel leak in one of my fuel lines.

 

You really do not need a tune for headers and a cold air intake; I ran mine with the cam and all my bolton's on a stock tune and it was not all that bad. Change out that opti with a GM or MSD unit and you should be good. If you want you could also do a mail order tune and pick up a couple hp and change the way your trans shifts if its a auto. But if you plan on more modifications later I would wait on the tune. Also with a new opti it is a good idea to make sure the rotor screws have high strength thread locker on them; this should be done already but I always take them apart and put red thread locker on the two rotor screws.

 

Have you checked your Opti harness connectors for corrosion or pin damage? Have you verified that all the engine grounds are intact. The Opti is not going to affect your oil pressure gauge and system voltage. Sound like a possible alternator problem, or missing engine grounds.

 

I had a opti go out once and my tack would jump all over the place can't remember if the other gauges were acting up ..

 

The tach acts up because its driven by the PCM, which reads the RPM from the Opti low res pulse signal.