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

1986 vette surging when warm

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Old Mar 22, 2010 | 02:06 AM
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Default 1986 vette surging when warm

hi every body

was looking on yahoo and found this site. just got back from a trade and got this 1986 vette with the 4 + 3 tranny.

5.7 tpi all factory except the mufflers were removed and straits from cat back.

like a few other vettes on the forums it runs good while cold but when it starts getting warmer it surges and sputters. tomorrow im gonna get the cats tested and try ohm the injectors 16 is the right ohms right?

car has 78000 miles on it dont appears anybody has been in the motor at all has a valve cover leak on the driver side.

had a Lincoln ls that kinda did the same thing couldnt solve it so i got raid of it since is a sbc i think can figure this one out.

any tips would be great gonna try spraying carb clean on the motor to see if its a vacuum leak.
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Old Mar 22, 2010 | 08:44 AM
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Yes, about 16 ohms.

Here is 86 vacuum schematic, you can check to see if they are all there and in the right place.



You might want to check if there are any stored trouble codes in the ECM.
When sitting in the drivers seat, there is an electrical port, just above your right knee/shin.




Jumping terminals "A" and "B" on the connector and then turning the ignition to "run", will cause the "Service Engine Soon" light to flash.
Counting the flashes will tell you if there are any codes.
Read this>http://members.shaw.ca/corvette86/No...it%20Check.pdf
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Old Mar 22, 2010 | 04:55 PM
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the cars check engine light is off. i have to put valve cover gaskets on it today that will be easy.

i got a late start today so havnt been able to do much to it yet. but its not bad enough i cant drive it.

thanks for taking the time to post the diagrams and pictures that will really help me out.

will keep updates

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Old Mar 22, 2010 | 05:34 PM
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Try torquing the valve cover bolts at 8 ft. lbs and see if that solves your leak problem before you tackle replacing the gaskets.
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Old Apr 17, 2015 | 01:44 PM
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hi guys: 1986 E with 62,000mil I have had it out 4 times so far. first time ran great, that I know , then 2nd time out started surging back an forth up around 50 60MPH , 3rd an 4th time started even in low speeds driving through town an higher speeds. when setting idling runs smooth .. Can anyone tell me where to start looking,. yes the engine service light is on.. I / we put the meter on it , didn't show anything , code, Thanks Guys an Gals
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Old Apr 17, 2015 | 04:04 PM
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If the SES light is on and you aren't getting any codes it could be a bad ECM. Or bad communication due to a wiring issue. Are you certain you took the right steps in checking for stored codes?
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