My 94 Formula recently got a new opti, and a new water pump put in. Before the new opti and waterpump, it was running rough and had a slight miss in it, on top of its 14 mpg average. I had tried all the simple things first, like replacing the plugs, the oxygen sensors, the wires, and the coil, along with a 160 thermostat, and a PCM's for less tune, but it still ran like junk without throwing any codes. With 73,000 on what to my knowledge was the original opti, I thought I would solve the problem by changing it. Well since I have changed the opti, it is running much worse than it did before! The opti went on nice and smooth, so I believe it to be a good install. I checked and re-checked all the connections and wires and sensors, and all of them checked out good. I even replaced my EGR valve, and still nothing. I am thinking I may be a victom of a bad opti from the factory. Does anyone know how many opti's are actually bad from the factory? Or does anyone have any other suggestions?

 

How sure are you that you got the splined shaft aligned correctly? I've seen numerous people swear that there is only one way it goes together and swear that they put it together correctly, only to find out they screwed it up.

Also might be a good idea to get a bit more specific about how it starts and runs..... "ran like junk" and "running much worse" don't really give anyone an idea of what the symptoms are.

 

I can't say that I am 100% sure it was aligned perfectly. As soon as I get a day off, I am going to take it back off and put it back on to check it. As for the specifics of how it is running; it has a hard time starting most of the time, meaning it usually turns more than a few times before it starts, sometimes it even seems to make a "clunk" sound while it is trying to turn over, then right after it starts it stays okay for about 10 seconds and then slowly the RPM's start to fall until it gets to about 900 RPM, and it seems to go in a pattern of surging down were it almost (and in some cases it has) dies, and then picks itself back up to 1000 RPM or so. Regular acceleration is were it drives the best, which is fairly smooth with a slight miss here or there. Under WOT it seems to run slightly weak, and extremly rich. When I am holding about 2000 RPM driving about 25 MPH it surges really bad, and even shakes the car fairly violently where I sometimes put in the clutch and feed it a little gas to keep from shaking and or running so rough.

 

If I was considering pulling the opti back off, I'd replace the wires first and quadruple check the order.

 

Wires and their order have been triple checked, and all are fine. I just got done taking out the opti again, although now my starter has just died on me, so it'll be a few days before I can crank it up again. I am just replacing the opti again (its still under warranty anyways since it only has about 100 miles on it). I'll post again in about a week if it isn't corrected.

 

Did you ever get this issue resolved? I'm having the exact same problem right now. The engine misfires, does not run consistently at any RPM and has very bad throttle response. It's also hard to start (in that the starter can barely turn the motor over...yet if I disconnect the coil wire, the motor turns over freely). Seemed to me like a timing/optispark issue. However, everything is NEW. I even tried changing the optispark again. I've gone over all the connections numerous times.

I know it can't be anything TOO significant because the car has been running extremely well for the last month. I only took off the water pump and the distributor (and since have replaced the distributor again) to change a leaky water pump driveshaft seal. I also at the same time added a new y-pipe/catalytic converter (old one was gutted) and a new O2 sensor in that y-pipe. After doing the distributor twice, I'm certain it's indexed properly. How can such minor changes make my engine run terribly? What should I look for? Any insight would be greatly appreciated!

 

you can put the opti on wrong, happened to me

 

Got it resolved. I believe my original opti install was correct, I think I had a bad new opti from the factory. With the new one in, it finally runs like a champ!

 

when you say factory, i assume you bought one from the dealer. did they give you a bunch of flak when you swapped it? i don't know if these things can crap out slowly or not, but i think mine is on its way out.

 

Got it from a buddy that works for a GM parts store. No flak was given, but I didn't even put 30 miles on the thing when I suspected it was a faulty one from the factory.

 

CALL911 and RestoRoc89, both of your issues sound like an incorrectly installed opti. I done the EXACT same thiing a few weeks ago while installing mine. The car cranked so slow that my starter smoked. After that I knew I had a problem. I removed it and reinstalled it and it fired up but ran HORRABLY. No throttle responce, missed very erratically. I removed it once again and reinstalled it. And vouala! It ran great. My opti went out very slowly. It started with a few high RPM missfires. Then some low RPM ones. Then it got kinda slow to start, more high RPM misfires, more low RPMs then one day it missed EVERYWHERE.......but 2300-2500rpm. So i drove it for a bit while saving for an opti. Once it was installed right there was a night and day differance. The opti had been slowly dieing for who knows how long. It has alot more topend power now. Sorry for the long post. Good luck with your car RetsoRoc89. Glad you got yours taken care of CALL911.

Jeremy

 

Triple checked on the original install, and it was the opti. We tried taking it off and putting it back on and firing it up without the water pump on, and you could instantly tell because the idle was crap.

I know it doesn't happen often, but I did in fact have a bad opti from the factory on this one.

 

Well, I've made a little progress...It turns out that my grounding of the ICM wasn't the greatest. I sanded down all the contact points and ran a new, heavier braided ground strap. Now the engine has better throttle response in the mid-high RPM range and runs better overall. However, the idle is still quite stumbly and throttle response off idle isn't what it used to be. The engine will also stall out if I let it idle for awhile. Now I'm suspecting that the original, 170,000 km EGR valve may be leaking (the one part I re-used from the car...ack!). I think this is reasonable because its opening is back-pressure assisted and I just replaced a gutted cat with a new one. Anyone agree or have any other ideas? For the most part, the hard starting is gone, though it did occur on one occasion. I really don't want to dig into that optispark again if I don't have to.

 

Well, my EGR valve WAS shot, but it wasn't leaking...so that was a phenominal amount of work to no appreciable end. Here's where I'm at now: My car stumbles badly when running, has poor throttle response and (this I think is the most significant) is very difficult to start. With the coil disconnected, the motor turns over freely. With the coil connected, the starter strains to turn it over. I've already melted the innards of one starter. The engine only has to turn over once to fire, but achieving that one revolution is no easy feat.

I can only imagine that this hard starting is a timing issue. I'm certain that I indexed the distributor correctly having checked it twice now and replaced it once. When I lined the splines up on the distributor shaft, it dropped right in and sat flush against the timing cover. What could possibly cause my timing issue? I can see either the computer or the distributor (brand new X2). My question is, what could possibly cause my timing/hard start issue? Where should I start looking? This car build was going so well and now I'm about ready to quit. If I can't come up with anything, I'm going to try one more time with a new AC Delco optispark to eliminate the distributor concern (the ones I've been using were rebuilds...but the motor ran beautifully on them last month). If that doesn't work, I'll just get a bloody GMPP LS1 crate engine and use the 355 as an anchor for my boat. Any help is greatly appreciated. Thanks.

 

It sounds to me like its not indexed correctly on the shaft. Mine did the EXACT same thing. The opti sat flush against the timing cover and everything went on just fine. I removed and installed it 3 times befor it got it right. I had to make my drive sleeve with a paint marker to make sure it went on correctly. I say pull it apart again. But thats up to you.

Jeremy