1995 chevy 4.3 tbi bad misfire at idle help!! - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-13-2014, 03:26 PM   #11
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try the cap and rotor,,
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Old 05-13-2014, 07:05 PM   #12
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i just did a compression check and all all cylinders and one came up low, first I let it warm up and took a water bottle wit a small hole in the top and sprayed it on each exhaust manifold from each cylinder to see which one was running cooler (which cylinder evaporated quicker) and one of the cylinders ran really cool took about 10 seconds to evaporate where others were 1-2 seconds so that there told me something was up so then I ran the compression check 5 of the cylinders had good compression at 175psi then number two back on the drivers side came up with 90psi after cranking the engine over about 5 times, if I cranked it about 10 times I could get about 105-110psi still not optimal , does that sound like it could cause my miss at idle? thanks
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Old 05-13-2014, 09:08 PM   #13
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Id say you found the misfire. Check for a broken or weak valve spring on the bad cylinder. Burnt valve or worn seat is very probable as well
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Old 05-14-2014, 07:21 AM   #14
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put a spoon of oil in the cylinder and redo the compression test. if the number goes up its the rings or worn out lower end, if not its something in the upper end like he mentioned
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Old 05-14-2014, 01:49 PM   #15
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ok I will check the compression again, I drove it for a little while today and it started (dieseling) when Id shut it off, it would fire a few times after the key was off and spin backwards, what could be the cause of that, I know running rich can cause this, and also the cat was completely destroyed before I changed it which also can be caused by running rich, the exhaust has a terrible smell to it aswell, I know the compression was low on that cylinder but I know 100psi is still functional, im so lost of this thing!
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Old 05-14-2014, 04:03 PM   #16
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you dont have a bad battery do you? mine had done the same things with the miss fire and dieseling and found that the battery was bad. sonething inside the battery broke and was sending too much voltage to the computer and made it do all kinds of strange things. just a thought.
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Old 05-14-2014, 04:55 PM   #17
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the one under a hundred is not going to be completely burning the mix
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