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Discussion Starter #1
Can someone explain to me if your Opti is having problems, is that likely to cause damage to the engine? There's a slight miss most of the time, and I was wondering does that cause the engine to sort of have an imbalance when the cylinder's are firing and put strain on the crank, cam, lifters, or rods? I want to get it fixed up as soon as I can, but it's mostly sitting right now as a backup car, and money is sadly pretty tight...
 

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First answers, then questions. A simple "miss" will not cause "engine damage" as the strain you describe, any more than any other normal maint. item like needing plugs or wires - or any of the other "non-electric" causes of getting a miss for that matter. A bonafide "knock" connotes internal parts worn or broke and that does cause problems, but don't sound close to what you describe.

So much for the miss, Now,
how many miles on this car? Waht maint. have you done?
what makes you think you need opti repair or maint.?
what fault codes do you have?
have you done any testing on other (much more frequent and common and easier to access periodic maint. items, like those plugs and wires, numerous solenoids, IC, ICM, EGR .....?
how about all the (seeming hundreds of locations on our car) vacuum leakers like hoses and the intake?
does it kick right over in 1 second, or, drag on sometimes to start? how about fuel issues? Getting good pressure at the FPR? No leakdown?

Have you done any sort of search on (again all the hundreds of causes of) miss and off-idle stumble and hard start? Opti is not usually first on any list.

The miss damage thing is meh. The cause of the miss is interesting.
 

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miss fires at idle should be the Ignition coil and ICM if its 20 plus years old. rivet install means it is the factory coil.

miss fires do cause the converters to get damaged . also the engine oil does get messed up .

the P0300 code can be many other causes .. fuel/ignition/wiring/injectors / PCM...

so not gonna get much help here unless your doing the diagnosis and have the tools .Need more vehicle info who worked on it how long you owned it and maintenance done.

THERE IS NO ONE ANSWER !
 

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Discussion Starter #5
Interesting! Tools?

I've had this 9C1 forever, like at least 11 years. In the past when it was my primary car the maintenance was pretty good. It's been running like this and on backup use only for a long time, at least 4-5 years believe it or not. It's very hard in this part of PA to find a good old school mechanic who will look at the little possible causes. Most I talk to want the big hit, oh it's got to be the Opti, $1400 please!

How many miles on this car? 101k
What maint. have you done? I believe plugs and wires were looked at before, and the fuel pump pressure was probably tested.
what makes you think you need opti repair or maint.? Because it's missing slightly.
what fault codes do you have? Can I do this with the flashing check engine light or do I need some kind of scan tool?
have you done any testing on other (much more frequent and common and easier to access periodic maint. items, like those plugs and wires, numerous solenoids, IC, ICM, EGR .....? This probably needs to be investigated. Can you tell me what IC and ICM are please?
how about all the (seeming hundreds of locations on our car) vacuum leakers like hoses and the intake? Have not explored this yet!
does it kick right over in 1 second, or, drag on sometimes to start? how about fuel issues? Getting good pressure at the FPR? No leakdown? I can tell you it starts right up every time.

Have you done any sort of search on (again all the hundreds of causes of) miss and off-idle stumble and hard start? Opti is not usually first on any list. VERY Interesting, will have to explore this!

Thank you.
 

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Discussion Starter #6
PCM Codes

the P0300 code can be many other causes .. fuel/ignition/wiring/injectors / PCM...

so not gonna get much help here unless your doing the diagnosis and have the tools .
Have a little experience with codes and GM ECM's/PCM's.

What tools would be a good start? Not sure how much I can do myself with my back the way it is...:frown2:
 

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what is the year of this ?

is the opti white/light brown ? 101K miles is probably not any major repairs .
the ICM is the ignition control module. the ignition coil is on the front of engine mounted on driver side with ICM on the same metal component . these being electrical fail due to age . so the coil arcs internally .. if you have engine running in the dark and see the coil have small flashes then replace the coil and the ICM. you will need a conductive tooth paste like material to place on the aluminum mounting surface . this protects this electronic ICM from over heating .

very possible @100K miles the #7 plug wire is bad . you have to measure the ohms should be 1500 ohms . this wire gets heat damaged as you will see how it passes next to exhaust manifold. plugs if 50K miles on them then they require replacing.

the EGR is a time component failure so if its 10 yrs old its bad. materials of the EGR break down , time is the killer.

fuel pressure test procedure is required . engine off key on pressure should be 41-47 psi..also pressure should hold .if it drops down to zero can be a bad fuel regulator or bad injectors .possible the fuel pump internal check valve...fuel filter should be replaced 30-50K miles but that depends on the quality of fuel .
 

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Have a little experience with codes and GM ECM's/PCM's.

What tools would be a good start? Not sure how much I can do myself with my back the way it is...:frown2:
IDK what year car you have but being able to scan for codes REALLY helps narrow down diagnostics

96 you can buy a scan/code reader tool for around $100-$200. Just a code reader is around $40
94-95 there is free software called scan9495 you download and use a ADL cable to a laptop to read codes and view data stream

Fuel Pressure gauge is always good to have to determine if fuel is a problem. Does not sound like that is in you case but good to have one in the toolbox

you should put the car up on ramps and in the dark with a water spray bottle lightly mist the plug boots and look carefully from up top, and under the car, for any plug arc with engine running. Plug arc can certainly cause a "miss"

Scan ability can show data stream which is very helpful to monitor 02 function, STFT (short term fuel trims) and dozens of other sensor data

If you don't have the ability to do this kind of stuff...it gets expensive paying a shop. 20+ year old cars most shops have very little experience with
 

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Discussion Starter #9
95 Caprice

Wow! You guys really have a lot of experience and good ideas, it's why I asked.

You're also SO right about the issue with finding someone with the right experience - that can be VERY hard.

I may have to poke around with it and see what I can figure out, starting with the easier and less expensive things.

It's annoying because it's sort of like an intermittent. It's running, just not well like I wish it would be...
 

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Quote: "....It's running, just not well like I wish it would be...". I'll take "Intake leaks and sparkie parts for about $3-400 and 2-3 weekends, Alex". lol

Your next B-Day you should treat yourself to a used FSM. Factory Service Manual. Odds are you got that 23-year old paid off so not a stretch to make a real good business case for investing in all the 'expected' maint. parts on any car that old to save from having to start payments on a younger replacement.

Even if uncomfortable with diagnostics tools and testing you can throw a boatload of new wear parts under the hood for the price of that installed Opti. You MIGHT get lucky with that approach while the odds are not so good jumping to the opti without solid reason.

You've gotten good leads here. Why not spend a couple weeks combing through the Stickies and doing some searches. There's gotta be like $30,000,000 worth experience hiding in here. And all free for the industrious. Good luck. Keep us posted.
 

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.....
how about all the (seeming hundreds of locations on our car) vacuum leakers like hoses and the intake?


.......The cause of the miss is interesting.
Here's just ONE of those hundreds. Who knows how many years this little booger was causing problems?

Did you find the miss?

 

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I have absolutely positively over-used these pics. I'll lay 70-30 it's in the OP's potentials to some degree. This was on my first FWB when 10 years old. It's got to be easy to check for this type leak just spraying Gumout along the seam.



 

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J-
Good point. But FTR that one was most assuredly oem and came off the Cady I bought 2 years ago. Funny it had only 55,XXX then. Parts wear out just sitting there regardless of mileage eh. I've been having luck still finding AC Delco replacements for most fittings under the hood. I always get 2 of anything and replace on both cars when doing either.

'ol k3000- has not checked back in for the past 1 1/2 months. Curious what he finds.
 
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