Bad Opti symptoms/experience
Melting Slicks
Joined: May 2001
Posts: 2,143
Likes: 7
From: San Diego CA
Re: Bad Opti symptoms/experience (sumoboy)
I first noticed my idle would randomly jump 300-400 RPM. That turned out to be a miss that the IAC overcorrected for which resulted in the jump.
A little later I began noticing a slight miss at cruising speeds on the freeway.
Gradually, both symptoms got worse. This all happened over a 3 month time span.
Finally, I took it to the shop and paid them to hook up a TECH II (a really cool instrument). It allowed me to cut out the ignition on each cylinder 1 at a time then the injectors one at a time. We could not find a single cylinder that would cause a consistent miss.
A little later I began noticing a slight miss at cruising speeds on the freeway.
Gradually, both symptoms got worse. This all happened over a 3 month time span.
Finally, I took it to the shop and paid them to hook up a TECH II (a really cool instrument). It allowed me to cut out the ignition on each cylinder 1 at a time then the injectors one at a time. We could not find a single cylinder that would cause a consistent miss.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Re: Bad Opti symptoms/experience (sumoboy)
What are the actual symptoms of the Opti as it goes bad and what are your experiences. :confused:
Works fine all the way to 6800rpm now :D
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Bad Opti symptoms/experience (sumoboy)
:withstupid:
My experience was with hesitation, or jerking motion under load. For instance, if you floor it off idle and it hesitates and jerks forward, that's a symptom. Or if you're in 4, 5, or 6th gear and you give it about 1/2 to full throttle and it bogs or jerks, that's another symptom.
If you're interested I've made my own Opti replacement guide. IM me your email and I'll send it to you.
:cheers:
[Modified by vvv90, 8:56 PM 7/18/2003]
My experience was with hesitation, or jerking motion under load. For instance, if you floor it off idle and it hesitates and jerks forward, that's a symptom. Or if you're in 4, 5, or 6th gear and you give it about 1/2 to full throttle and it bogs or jerks, that's another symptom.
If you're interested I've made my own Opti replacement guide. IM me your email and I'll send it to you.
:cheers:
[Modified by vvv90, 8:56 PM 7/18/2003]
Advanced
Joined: May 2002
Posts: 59
Likes: 0
From: Clermont FL
Re: Bad Opti symptoms/experience (vvv90)
Matt, that guide really helped. I just finished the opti conversion. Hope to get it in tomorrow. BTW, does the water pump drive gear simply pull out so I can remove the seal? My opti did not give any indication of a problem until it started to miss and within 30 seconds died. Tonight when I opened it up it was a rust bucket, all from high humidity. The steel plate was totally covered with rust and there was rust powder in it. I had absolutely no water leaks or oil leaks. Thanks again, you guys have been very helpful. When I finish I'll email Matt with a few comments on his guide.
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Bad Opti symptoms/experience (Slick94)
Glad to hear it :cheers: Mine was covered in rust too.
I forgot, are you just replacing the seal and putting in a new mechanical water pump? If so, you don't have to remove the spindle, there's a notch at the top of the seal in the timing chain cover. Just pry the seal out with a small flat head screw driver. When you put the new seal on you have to be careful not to fold or wrap it. Put a little oil around the shaft and slide it on with a socket or something cylinderical to put even pressure around the circumference.
Make sure you put a little point grease on the shaft, and also the shaft on the water pump before you put the sleeve on in between the two. Make sure the O-rings seat on either side of the sleeve also to keep the grease in the sleeve, you should've gotten new ones with your new water pump.
O.k. now I'm being repetetive because I know I mentioned that in the guide :crazy:
I forgot, are you just replacing the seal and putting in a new mechanical water pump? If so, you don't have to remove the spindle, there's a notch at the top of the seal in the timing chain cover. Just pry the seal out with a small flat head screw driver. When you put the new seal on you have to be careful not to fold or wrap it. Put a little oil around the shaft and slide it on with a socket or something cylinderical to put even pressure around the circumference.
Make sure you put a little point grease on the shaft, and also the shaft on the water pump before you put the sleeve on in between the two. Make sure the O-rings seat on either side of the sleeve also to keep the grease in the sleeve, you should've gotten new ones with your new water pump.
O.k. now I'm being repetetive because I know I mentioned that in the guide :crazy:
Advanced
Joined: May 2002
Posts: 59
Likes: 0
From: Clermont FL
Re: Bad Opti symptoms/experience (vvv90)
Thanks again, Matt. I'll be careful with the seals and o-rings. I think I can pop the opti seal out with a screwdriver. I had a hard time with the balancer but got it off this afternoon. New plugs, wires, water pump and opti....ready to cruise.
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Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
Re: Bad Opti symptoms/experience (sumoboy)
Personally, I think many people misdiagnose ignition problems and blame it on the OPTI. Before swapping the OPTI get yourself an ST-125 spark tester and check your plugs, wires, coil, ignition module, etc. The OPTI swap is a big job compared to replacing spark plugs.
Another test you can look at to determine if the OPTI is bad is watch the RPM and Reference Pulse timing on a scan tool. It should be stable at a contant RPM, if it jumps wildly they it's the OPTI's optical pickups, and more than likely you'll have a code set.
I had a problem with my Vette once that matched the symptom someone mentioned above. On the highway in 5th or 6th it would breakdown and stumble. At WOT it wouldn't rev over 4,000, etc. Turned out to be worn out plugs. Replaced the plugs with NGKs and now it's perfect. Someday I should replace the wires too, but it's working fine now.
My point, make sure you do a proper diagnosis of your problem before taking on an OPTI swap.
:cheers:
Another test you can look at to determine if the OPTI is bad is watch the RPM and Reference Pulse timing on a scan tool. It should be stable at a contant RPM, if it jumps wildly they it's the OPTI's optical pickups, and more than likely you'll have a code set.
I had a problem with my Vette once that matched the symptom someone mentioned above. On the highway in 5th or 6th it would breakdown and stumble. At WOT it wouldn't rev over 4,000, etc. Turned out to be worn out plugs. Replaced the plugs with NGKs and now it's perfect. Someday I should replace the wires too, but it's working fine now.
My point, make sure you do a proper diagnosis of your problem before taking on an OPTI swap.
:cheers:
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Bad Opti symptoms/experience (Atok)
:iagree: :iagree: :iagree:
I definitely agree, however, if you have an old LT-1 with low miles, or any LT-1 with high miles and you're going to be replacing the water pump, or coil, plugs wires, and especially ifyou notice sludge all over the front of the motor, I would recommend a new vented one as standard maintenance. I know it's expensive but it's better than being stranded. Also make sure that the sludge you may have, is not from oil leaking from the intake manifold gasket. This is another common problem area.
Newer stock vented Opti's should be better to take Atok's advice, as these devices are "Supposed" to last longer and there are more 95-96's with less complaints.
:cheers:
[Modified by vvv90, 10:59 AM 7/21/2003]
I definitely agree, however, if you have an old LT-1 with low miles, or any LT-1 with high miles and you're going to be replacing the water pump, or coil, plugs wires, and especially ifyou notice sludge all over the front of the motor, I would recommend a new vented one as standard maintenance. I know it's expensive but it's better than being stranded. Also make sure that the sludge you may have, is not from oil leaking from the intake manifold gasket. This is another common problem area.
Newer stock vented Opti's should be better to take Atok's advice, as these devices are "Supposed" to last longer and there are more 95-96's with less complaints.
:cheers:
[Modified by vvv90, 10:59 AM 7/21/2003]
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Bad Opti symptoms/experience (Gonzo)
There are various things it will do, but throwing codes, check engine light, SYS, won't happen OFTEN with an Opti, at least mine didn't anyway.
Do what Atok suggested before concentrating on the Opti.
How many miles by the way and what year?
[Modified by vvv90, 1:14 PM 7/21/2003]
Do what Atok suggested before concentrating on the Opti.
How many miles by the way and what year?
[Modified by vvv90, 1:14 PM 7/21/2003]
Race Director
Joined: Feb 2002
Posts: 11,268
Likes: 14
From: Honolulu, HI
Re: Bad Opti symptoms/experience (Gonzo)
Not sure, but check this out.
http://forums.corvetteforum.com/zerothread?id=499412
http://forums.corvetteforum.com/zerothread?id=499412
Melting Slicks
Joined: Apr 2003
Posts: 2,150
Likes: 6
From: NS
Re: Bad Opti symptoms/experience (Gonzo)
Code 16 is "Low Resolution Pulse Failure" set by the OPTI. Check the wiring and connectors first. There is a test procedure in the GM Service Manual for this code.
