well Ive already replaced my 02 sensors last year.. I dont know how often they need to be changed but they should still be fine. I also replaced my EGR valve last year which was a real pain in the *** because of the location of it. I replaced the radiator on friday, I did the fuel filter and oil change on saturday and just today did the tune up and as of now the car seems to be working just fine! I hope that it stays that way because the hesitation is gone as far as I can tell and I would really love to spare myself from having to go through the hassle of replacing the opti again! Im thinking Im going to do a service to my fuel injection system and transmission as well just for good measure within the next week or so. But will have to drive the car a few days to see if the problem is completely gone or just minimized. I'll keep you posted

 

Got car back from getting opti replaced
Runs great

They showed me the old one
It was rusted and coroded

If your car has been stored outside,you might have the same problem

The guy I got the car from changed the fuel pump thinking that was the problem,didn't fix it

So he told me there was nothing wrong with the car to sell it

He lied.

After two months and $1500 it's fixed

I hope he puts his head on the pillow every night and thinks about that

Remember
What comes around goes around goes around

 

You are beating yourself up with this?? when you replaced the plugs did you set the gap? The opti also has numbering on it for the cylinders so check that as well
change the fuel filter
FIX THE RIPPED INTAKE ELBOW!!
If I were you I would check the easy stuff first before you replace half the electronics...stumbles are fixed by wires and plugs 90% of the time

 

well i did the fuel filter it was the original, that was 2 weeks ago or so... didnt change anything, the intake elbow, i donno about this one, i first put it on there as tight as i could get it, and then i noticed i had an exhaust leak, so i thought maybe the intake leak was still there so i ripped off the first inch of the intake elbow and put it on there even tighter, well the exhaust leak was still there (i thought it was intake leak)

so yea i know someone else has had a problem w/ this car too cause its not the orgininal plugs they are bosch Supers... so i put ac delco in and i didnt notice a change in performace

and they look like they had been in there a few miles probably 15k or so, and that shouldnt really be done till 100k, and if im at 86, that means the other guy put them in about 70k...

so who knows man, i'll fix the EGR cause thats probably a gasket its leaking anyways... my gas mileage is shot 12 pretty much in all conditions(thinks it should be more like 15-16)... so i figure its either O2's or its clogged cat... and O2's are much cheaper.

i got a speedometer sensor to add an O-ring too aswell so i got a few hours of aimless screwing around... so i'll fix the problems i know and keep asking u guys about the ones i donno

 

sorry, change both o2's and get your mileage back

 

thats what my dad said could be one cause, but otherpeople on here said it could be one reason its hesitating after it warms up

 

but if the backfiring is related to the egr, why does it only happen when its in open cycle?

 

Well, day 3 and my car still seems to be working fine so far... so I think I took care of the problem.. . but just so your not guessing. Why dont you take your car in for a diagnostics at least? That should be able to tell you if your EGR is bad, and such, so your not changing parts that dont need to be changed, and it will let you know if the opti is malfunctioning and such. Because the EGR is a pain to swap. You have to do it completely blind due to its location and its also a very uncomfortable to do so also because of its location. But its up to you.

 

yea i donno a place that will do that, i know i have an exhaust leak its clear as day to that one... and egr is a known problem on these cars.

 

Any GM dealership can do it... also most autozones do free diagnostics on your cars too. And if you check in the phone book Im sure you will find others that have the equipment to diagnose your car

 

NewbieWar,

I once had the exact same symptoms you are having..

The way I cured it was simple. Classic arson... JK..

It started out with the engine just dieing at a stopped neutral idle at a red light once and a while, then it would stumble once and a while when I would step on it in low RPM's, then it went on to more stumbling at varying RPM's. Then one day, on my way to work, it got to about running temperature and just started to stumble at the steady speed of about 65 - 70MPH. So I got to work, and at lunch I called the dealer, and they said bring it in.

It was so bad getting it to the dealer that I was lucky it didn’t break a rod.. The opti-spark was firing (or not) whenever it wanted to.. It was having trouble just getting up to 20MPH or so.. On the way I had someone tell me it sounds like it needs a tune up. I laughed and said I'm on my way to do so.

I finally made it to the dealer (which was an expensive choice), and it in fact was the opti-spark...

They were mentioning that it had no vacuum tube attached. I believe the term’s might be "vented" and "non vented".. It's just a tube that 95-97 or so models have that goes from the bottom of the opti-spark to the bottom of the intake elbow to suck out any moisture.. Don't quote me on anything here..

Of course don’t just go out and buy a replacement opti-spark. Take your car to someone that can diagnose the problem…
If the opti-spark is your problem, before you go and get a new one, you should think about the alternatives. Yes there are alternatives to the opti-spark ignition.. I've done a bit of research on “opti” alternatives and there are a few to choose from.

1. A coil-pack system. It's got 4 coils that fire 2 plugs each, both at the same time. That's no problem since only one will have the oxygen/gas mixture in it to fire at any given point. I can’t remember the way it gets its timing..

2. A semi-direct coil firing system.. It's non optical alternative that uses the opti-spark housing (I believe) for it's timing method, and then uses an "external brain" for the real work.. It just replaces the innards with an electronic timing pickup..

3. A direct Opti-Spark replacement built from aluminum or something and then sealed..

Any way you go, a non factory/OEM unit is advised by me. I’m definitely going to find the coil pack system when my opti dies again..

I do apologize for not having any links to share, but I just spent the last hour looking and could not find any of the old sites I found previously..

Incase you are intent on just replacing the opti-spark yourself, here's a page that explains how to do so..
http://www.fierolt1.com/lt1_95_up_OptiReplace.htm

I hope I made some sense in here.

 

yea my repair bill is starting to add up... i got O2's EGR Opti Intake elbow... soon tires and for the moment i have no money really just enough for gas

 

im going to check see if my exhaust leak (i think) stops at 2100 rpms, cause thats i guess the point the egr doesnt work any more

 

well the leak didnt stop at 2100, it was consistent all the way thro the rpm range...

its getting worse tho, i got one backfire up at about 3500 rpms.

and the stumbling seems to increase to about 2500 almost... so im thinking i need to replace the opti soon, feels like somethings goin out

 

Well i found my problem, i just gotta fix it now

I replaced my wires on my passenger side... 2 of the wires had been missing some insulation i guess causing them to ground themselves or something...

anyhow it drove really well for 30 miles then it already chewed up another wire so my hesitations back so i gotta get some more wires and try again