C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

87 runs rough

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Old Dec 22, 2004 | 08:40 PM
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Default 87 runs rough

My buddy has my old 87 that i sold to buy a zr1. The car has about 70 k miles and i owned it for 10 years before i sold it to him. Its been well taken care of but he is telling me at idle it runs rough and the check engine light is on. Once driving its fine. Anyone have any ideas why its running rough??
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Old Dec 22, 2004 | 08:42 PM
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1st step is to check the codes
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Old Dec 22, 2004 | 08:44 PM
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Originally Posted by Pete K
1st step is to check the codes
just jump the 2 pins under the dash does anyone have the codes.
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Old Dec 23, 2004 | 02:47 AM
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I'll Bet it's a code 34 EGR VALVE!
Take a paper clip and on the right end of the diag moduel install paper clip between the last two pins and turn on the key and count the flasher.
First will be one then two flashes or 12 and it will do it 3 times for each code just wait, this means the computer is working,then it will flash the next code and it will be 3 times and jot down the flashes .
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Old Dec 23, 2004 | 08:31 AM
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To many things it could be. Once you get the code let us know and we'll try to help. And don't rush out to buy parts-even if it is the EGR-because usually it's just the switch.
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Old Dec 23, 2004 | 08:41 AM
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He needs to pull the codes as step one.

If it is the dreaded EGR code 32, there is a diagnostic method on my site to isolate the faulty system component.
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Old Dec 27, 2004 | 11:31 AM
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Default code 34

my buddy jumped out the computer and he has a code 34. Should he change the egr and switch or troubleshoot some more.
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Old Dec 27, 2004 | 03:03 PM
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the Egr switch cured mine, and I've hears it said on the forum that it's likley the switch 95% of the time. It's also very cheap and easy to install-I ended up splicing mine simply because it plugs in down and behind the distributor.
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Old Dec 27, 2004 | 03:22 PM
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Originally Posted by ovhd
my buddy jumped out the computer and he has a code 34. Should he change the egr and switch or troubleshoot some more.
If I am not mistaken code 34 is maf issues.
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Old Dec 27, 2004 | 05:32 PM
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Originally Posted by MR.KIDD
If I am not mistaken code 34 is maf issues.

34, MAF low air flow. Since it has a rough idle, check IAC & TPS
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Old Dec 28, 2004 | 01:04 AM
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Simply time for a tune-up? Cap/rotor/plugs/wires??
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