I just spent a lot of time to replace the optispark on my 96 Impala SS> I replaced with an AC Delco 1938351 unit from Rockauto. The engine fired right up, but had a misfire. I believe the engine code was P300 (general misfire) RPM was also high, so I suspected a vacuum leak. I smoked checked and got a ton of smoke coming from the new Optispark. For comparison I hooked smoke machine to the old Optispark and got no smoke. I think this tells me that the 96 impala Optispark should be vacuum tight and I have a bad unit. Can anyone confirm this? Thanks
Im gonna disconnect vacuum line to the optispark and plug them to see how the engine runs to confirm. Will let you know
It should seal up well enough to not let air smoke coolant or oil into or out of it.
The 'Opti-snorkel' Vent & Vacuum Harness is supposed to be the only way that fresh air gets in, specifically for the purpose of venting ozone out of the Opti-Spark.
Maybe disconnect both hoses from the engine side and plug? And way easy to inadvertently knock some other hose off with something as deep as an opti R&R. BTW and FTR I have done 4 opti pulls/installs, and every time but the last I initially got exactly 2 wires crossed.
One other fact is that vehicle has not been driven in 3+ years. When I first started it ran terribly. Since that time I replaced plugs, oil, Opti and water pump. Its running now but still high rpm and miss. With high rpm and miss, still seems like vacuum leak/lean. I rechecked all vacuum lines and also should have shown vacuum leak during smoke tests. Could I have and internal failure of some component like EGR, etc?
Looks like we're all alone on Sunday. I take it you've got bloody fingers from using the keywords of your symptoms on search here and the overall web. It could be simple vacuum. EGR is a good start, and easy to test to check if the gremlin. And I'd be checking all the initials associated with fuel & air - on and around the throttle body = IAC, MAF, MAP, TPS......
Questions:
Did you 'blueprint' the new opti before installing?
Did you have the car 3 years back to know if it ran right then?
3 years is a long time. Was the car parked in a place rodents could feast on wires and hoses?
Does the 'miss' and idle change as it warms up?
No "blueprint" (whats that?)
Car ran fine originally
No signs of rodents (that ive noticed), its in Sacramento CA area, warm and dry, so don't know how likely rodents are
Miss does not appear to change with warm up
"New" optis have been having a bad habit of being manufactured sloppy, wrong or with parts missing. So even with a lifetime warranty it turns out easier just to rebuild it anyway for longer/better service. There are two clear gaskets sealing the sections. I found one was completely missing. Many guys seal them with di-electric grease to answer the vacuum issue.
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