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Black, in the video the car would stall (or attempt to) when driving around at idle in slow speeds. A new Idle Air Control Valve solved that issue, although I did replace the EGR as well.

This one just happens on start of a warm engine.
OK, only the vid and your recent symptoms appear nearly identical. So, issue with warmed up. A smart guy might come in and know exactly what circuits are on with closed loop. And, EGR is already replaced so I'd be heading to spray the intake for leaks and eyeballing vacuum lines. Basically, anything that's opened up (and leaking more) when warm. You might pour over "warm off-idle stumble" for possibly the related inverse of what you got.

Again, I'm filling time until a real answer shows here. :D

I had reason to replace the TPS years ago at 150,XXX and recall it helped whatever problem I was having at the time.
 

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My fix

Been chasing the rough and rich condition on my 96 that was sitting for 7 years, went thru everything, fresh pump and sender, new filters, opti, plugs and wires, car finally started but still ran like crap and loaded up. New Spin-Tech exhaust was here anyway, so installed it with fresh O2's, removed the EGR, air pump was already gone.
Injectors pulled and sent to Cody motorsports in Ga, yes they were in aweful shape, Chuck cleaned and flowed them, sent back the next week, Sent the PCM to PCM for less, he spun it back to me the same week. Things much better then, car now starts and attempted to idle.
After running for maybe 1 minute the voltage light came on, I had suspected the alternator was weak, had a fresh one on the shelf, that was an easy fix and improved things a lot.
Car still running rich, would require, Flood clear start method to start consistently, and still hiccupped after starting, when it went into closed loop it got really rich and wanted to die, smoothed up at 2500 RPM.
Checked the ICM and yes it was weak, grease all dry, probably had overheated at some time.
An Autozone unit went in and things did get better. The odd issue was it kept running richer and richer. On a whim I checked the FP again, now it was 55 at idle, was 44 last week, pulled the vacuum line from the regulator, and fuel pissed out of it ! It had been dry last week, there it was, my Aeromotive regulator had failed in the midst of fixing everything else ! I think for the present I will install a stocker until I am employed again. Another fun issue was the starter nose breaking off (twice) during all the bad kick back starting attempts ! The original broke 3 months ago ( yes I have too busy to stay working on it, but have time now...) The new starter was an Autozone Gold, nice piece, of course they don't keep it in stock.
So there is tale, hope it helps someone else, I want to go back to head gasket replacement on my Turbo GN, less frustrating !
 

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How I finally got rid of the misfire

I tried to make this quick but I figured it could help somebody some day. I inherited my father's 95 Impala SS which he bought new. Now has 207k miles. She was running like garbage(misfiring/no power) and literally pissing coolant every where. I finally got a week to work on her and made some major gains. I felt like I was chasing a ghost through out most of the repair's but eventually I was able to get her purring like a very powerful kitten. The only reason I was able to figure it out was because of you guy's and this incredible forum. Thank you everyone, I'm sure this forum is helping a lot of people!

Issue's:
-Misfiring terribly in 4th gear at low RPM
-Coolant puddle's anywhere I parked it. (Cracked Radiator + worn out water pump after closer inspection)
-Zero power/ throttle response
-Strange ticking sound which I couldn't replicate unless motor was under load at low RPM
-Obvious vacuum leak somewhere

Solution's:
1st attempt:
-Checked all visible vacuum line's. Found multiple disintegrating tube's, especially to the throttle body.
-Replaced EGR valve and vacuum line's at the same time, working backward, forwards. No Gain's

2nd attempt:
-Pulled and replaced the radiator
-Ripped her down and replaced the water pump and the Opti. (First time pulling a harmonic balancer, SOB)

Once I started her back up she was running really smooth no issue's for about an hour of driving. Sound's like it's fixed right? Nope. Took a turn and kicked the rear end out a bit and then bam it started missing even worse then originally and now there is a strange new ticking coming from under the hood. And again I couldn't replicate it while the car was standing still at idle.

Final solution
- Thanks to one of you guy's. I was pointed to the Ignition coil, my thought was its a cheap part and I might as well rule it out. I popped the coil wire off and the corrosion was nasty. I separated the coil from the ICM and swapped it out for the new one. EDIT: It turn's out that ticking sound, was from the fried Ignition coil

The car is running like a champion at all RPM range and under any type of load. When I have another minute or two I'll replace the 100k mile spark plugs for good measure. I hope this helps anyone experiencing similar issue's.

P.S. In retrospect I would highly advise checking the Ignition coil much earlier than I had.
 

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Dam Fine Contribution

All that on just your 3rd-ever post! This should go far in helping others there Ar-. Applaudable attention to detail, and it flows like buttuh. ;)

Here's one back for ya. From all the trauma and strife one guy's recently had (CapriceCarl up there from January), you'll want to keep an eye on the cats of your dad's old car. Between age, dirty EGRs and broke manifold bolts it seems those can be an issue once you've piled on enough miles.
 

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This is why this forum is TOP NOTCH

96 Black,

I appreciate that man! Not only is everyone here working to fix problem's, but you're pointing out future potential issue's to keep an eye out for. Well done!

In regards to my Impala. I have been watching the manifold bolts, especially closest to the firewall, very closely and now that you've brought it up I will continue to do so. Haven't even considered the Cat's though. I know the exhaust was replaced for some kind of Edelbrock at some point, but I have no clue if anything was done otherwise. Good tip's!

And CapriceCarl, I hope you've gained some traction (No pun intended) on getting everything worked out!
 

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Don"t wait!!!!

Get a set of collared Gr8 bolts and replace them all BEFORE they break. It's the difference between a 20-minute job and a 6-hour cursing fest. They may snap off when you go to wrenching on them anyway if not gentle. I found nice black collared pieces at ACE.

The rearmost 4 will be 1 1/2" But some reports are the heads bottom out so get a couple of 1 1/4" in case. The center 4 are 1". I've not heard much about the front 4 breaking. Aside from the headed studs for the alt brackets those will be 1 1/2" also.

Don't dare leave off the caststeel spacer/sliders!
 

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Act now or regret it. Got it!

Well it look's like I know what needs to be addressed next! I might as well knock those out when I put in the time to replace the plug's. I'm assuming this is a known issue that I've overlooked, 'cause you listed those length's off pretty damn quick lol. All I need now is a 6 pack of miller and an hour or so to wrench on her. Thank's again boss!

While we're on the point, now that she's running right again, I was planning to get her on jack's to track down an exhaust leak. I wasn't quite sure if I should be looking into the O2 sensor's at all. Any thoughts?

EDIT: Not trying to steal the thread BTW. Hopefully preventative recommendations can help other's like myself avoid a headache here or there
 

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I was planning to get her on jack's to track down an exhaust leak. I wasn't quite sure if I should be looking into the O2 sensor's at all. Any thoughts?

EDIT: Not trying to steal the thread BTW. Hopefully preventative recommendations can help other's like myself avoid a headache here or there
The original s.s. system likely won't be leaking. But, after 15 years the welds along my aluminized AERO catback system pipes were heat-eroding clear through at multiple spots. The O2s get old and lazy, and start affecting performance even before, and without, throwing a code. On my SS (about 60, XXX and no codes) I got new fronts. AC DELCO ONLY! That's yelling BTW. Urban Legend is Bosch sucks and jury is out for DENSO. Would love to hear different from the oldsters. Spend 3-4 minutes trying to remove them on the car, then if they don't fall out just take the cat off and attack removal on the bench. Buy a bung chaser too. Lots of PB Blaster and an impact on Low will save headaches replacing stripped/snapped exhaust studs coming off the header. That's all I got.

And the thread-jacking? F'em if they can't take a joke.
 

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random miss fire 1996 impala

replaced opti with new 7/2013 . reason is the water pump rear seal blew out. my opti I inspected had a slight rotor wobble. so I figured do it all opti/waterpump/coolant/hoses.

job worked perfectly saved old OEM original ac delco opti. which still worked.


no problems till now.
today wife says car has a bad idle . I get out the fuel pressure / vacuum /gauge and the timing light . timing light shows a miss on the coil wire . vac gauge on the opti vent harness , vacuum to opti , but NO vacuum at the intake hose. I thought the hoses where blocked . no !!! it was the opti cap seals are crap ! thing leaks bad so its getting contaminated with moisture being sucked in . I put a small hand air pump pressure into the opti vent hoses air was blowing out the opti seals ..

got out the 21 yr old opti no seal leaks ! tested it the same way .
the 3yr old opti has a warranty so if I can get one I will use a new free replacement . If I cannot get a replacement I will get my $250 back and put in the 21 yr old opti .

the vent harness has a filter/orifice and a check valve. I took out the filter/orifice so it had max vacuum to the opti . I then got a slight suck at the intake hose connection . ran vehicle idle is now perfect so it looks like I got it down pretty good on what is my next fun project.

scan tool took a while to show the p0300 code .. timing light was immediate .
 

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Misfire Passenger side from idle-Wide open

Trying not to hijack thread but, Recently my 95 SS has been giving me lots of issues. I had E3 spark plugs in there (Big mistake) took those out and #8 was COVERED in black soot or oil, almost all of them had the white casing on them cracked. I put Bosch platinums in (they've worked for me for years) It got a little better. then the injector stopped firing for #8. Replaced that. it stopped again. Ran a Darkblue/White wire from the 22 pin on the red connector on the pcm to that injector, it fires now but its still misfiring, I Pulled out all the plugs and did a compression test. all the cylinders were either 180 or 179 except for #5 was 175 and #8 on the 4th rev was at 150 then at the 7th rev it got up to 160 and no more. and i noticed that the Bosch plug i put in #8 was covered in the same black stuff not even a day after changing it. The 02 sensors have been replaced a year ago, the fuel pump and filter last year as well. the opti is a little over a year old. and the ignition coil isnt even a year old. Also the plug wires have been replaced last year. Im looking for help from anyone on this, could the rings on #8 be bad? Right now its the only car I got for school and work so as much as I dont want to drive it I kind of have too.
 

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the plug wires could be bad. they should read 1000 ohms on #8 approx...

replacing these wires is a PITA.. so if it was not routed properly sure could be the problem.

also put dielectric grease in the boot ends.

the OHMS of these wires ac delco GM spec is 1500-600 ohms. #7 is the one that usually goes bad since that is exposed to the manifold heat .. my #7 had slightly higher OHMS than the new ac delco wire for #7...

black would indicate a bad spark ..
 

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the plug wires could be bad. they should read 1000 ohms on #8 approx...

replacing these wires is a PITA.. so if it was not routed properly sure could be the problem.

also put dielectric grease in the boot ends.

the OHMS of these wires ac delco GM spec is 1500-600 ohms. #7 is the one that usually goes bad since that is exposed to the manifold heat .. my #7 had slightly higher OHMS than the new ac delco wire for #7...

black would indicate a bad spark ..
Thanks I will check that tonight when I get off work and I will report back with results the plug wires on the outside look fine. none of them look like they are burned or have insulation missing but I will check and get back soon
 

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Thanks I will check that tonight when I get off work and I will report back with results the plug wires on the outside look fine. none of them look like they are burned or have insulation missing but I will check and get back soon
I have used Bocsh +2 in the past but I now use the ac delco plat plugs . new ac plug # appears to work very good.

since the injector had a wiring problem and did not feed fuel into that cyl #8 could be the exhaust valve got burned up. fuel does cool down the combustion chamber so if you ran it too much it could melt it .
 

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I have used Bocsh +2 in the past but I now use the ac delco plat plugs . new ac plug # appears to work very good.

since the injector had a wiring problem and did not feed fuel into that cyl #8 could be the exhaust valve got burned up. fuel does cool down the combustion chamber so if you ran it too much it could melt it .
Not what I was hoping but if I gotta rebuild it then guess i will build something stronger. I checked the plug wire for #8 and it was about 1000ohms
 

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New AC Delco Wires from Rock Auto that I only put about 10k miles on started arcing near the coil and other places too. I varified this with the spray bottle in the dark. Especially verifyable if you have somebody sit in the car with it in drive and have them hold the brake and push the accelerator a bit to bring the arcs brighter in the dark. They all still felt new, looked new, felt soft and bendy after removal. Nothing was touching anything hot. I put new wires and plugs. I was running great again. They dont last as long as people may think. "my 2 cents"
 

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The way those wires are routed and all the convoluted manner they snake around and so close to the block and manifolds always struck me as a failure waiting to happen. I spent WAY more hours than expected doing a set on a FWB. Mindful of all the issues by reviewing other's replacements I made sure to reuse all the heat collars, isolators keeper points EXACTLY as original. Then there's the "check for proper working IC and ICM" and "double click the Opti boots". It just keeps going.

You make a good case for never presuming NOT to include any prior work during diagnosis.
 

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the plug wires could be bad. they should read 1000 ohms on #8 approx...

replacing these wires is a PITA.. so if it was not routed properly sure could be the problem.

also put dielectric grease in the boot ends.

the OHMS of these wires ac delco GM spec is 1500-600 ohms. #7 is the one that usually goes bad since that is exposed to the manifold heat .. my #7 had slightly higher OHMS than the new ac delco wire for #7...

black would indicate a bad spark ..
The resistance of brand-new ACDelco wires differed significantly from your description. Here are the numbers in kOhms (1000x Ohms) . Left column for old wires, the right one for new ones.
... OLD ... NEW
Coil 2.50 ... 4.50
#1 4.41 ... 6.15
#3 4.60... 7.40
#5 4.58... 7.52
#7 6.60... 11.40
#2 4.55... 4.65
#4 5.40 ... 5.94
#6 5.88 ..... 8.16
#8 5.30 .... 9.86
 

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A month ago I rebuilt the Opti and did new plugs/wires on the FWB I bought a year ago (currently 62,XXX). Gloating afterward that it actually ran I quickly went through checking things for wear and saw the valve cover vent hose was spongy at the throttle body. Quick snip the end and stick it back on, and the only I had to replace was the purge solenoid Z-hose. Now a week ago I just bought gas when about bone dry and immediately got a succession over a couple miles on the interstate of repeat faltering and tiny misses. I say, "Bad Gas", and it never did anything else the rest of the week.

Installing new shocks this morning over coffee I spy this:


Well now, maybe not bad gas after all. When I had cut off the end it fit so nice I didn't need a clamp. Maybe it wouldn't have split if I had used one though eh. I take the hose off and it's bone-dry. They usually have some oil from the valve cover so now I wonder why's that?

Removing the PCV I see this:


I'm wondering if the computer had done some quick on-the-fly adjusting things as that split occurred. At very best I may get a bit better than my current 20.2mpg.

Cliffs: Keep up with the simple maint. and you won't feel like a dumshtI overlooking the obvious. And if at all possible keep a garage queen at the ready to pilfer parts off of while you order replacements.
 

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Don't underestimate loose header bolts

Mine were 1/8 to 1/4 turn loose and wreaked havoc with very light throttle load or steady cruise under 60 mph.

Todd
 

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1996 Caprice B4U. Would start and drive sometimes. Sometimes, try to start then stall. All posts on the web pointed to the Opti.

I immediately went to NAPA an bought a replacement.... Not Opti.. I bought a new fuel pump. Problem solved by simple diagnosis.

Scott Odenton, MD
 
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