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??? for a 82 vette owner

topless82vette

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Nov 1, 2001
Messages
910
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southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
hopefully one of you can answer this Ive got a coputer realted problem with my 82 but no codes in the computer so naturally its maechanical or bad electrical connection heres what the car does stumbles very bad at idle and jumps in and out of closed loop mode (technical for computer stops commanding fuel mixture) and has a extremly bad odor out the tail pipes and will use a 1/4 tank of fuel within two hours of idling however no fuel leaks anywhere and catalytic converter turn orange after say 15 minutes at 2000rpm car has plenty of power so Im sure the cat and exhaust aint plugged anyways heres a few possible problems Ive found

(1) ecm wires coming from motor go to fire wall and there is a black plastic cover that covers them problem here before the harness connector looks like wires have been cut since there is alot of electrical tape is yours like this ?

(2) prom chip number in mine is 9531 ecm service number unknown at this time do any of you know what it should have ?


(3) wire harness that goes directly to the starter motor has a connector mine is somewhat melted down .... could this be a problem ?

(4) ecm's coolant sensor at front of intake manifold wires were cut and a different sensor installed did this type of sensor on my trans am with no after effects its just a upgraded sensor ... but do wires have to be hooked up a certain way and could this cause my problem

(5) thermostat is some kind of a GM unit but no temperature data is on it here are some numbers of it has on the top it says ac delco then 54 after it, at the bottom under the spring it has the letters hrd inside where the spring is it says 2/3 Im hoping the thermostat is a low temp unit thus causing the car not to get to operating temp and causing this problem since it would be a easy fix
 

KANE

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Mar 2, 2002
Messages
3,244
Location
KY
Corvette
Dark Blue 1982 Trans Am(s): Polo Green 1995 MN6
Topless-

My dad has an 82. They are unique in the wiring to that year model alone. The best reference I can give you is to use a Mitchell systems wiring diagram availible from any public library. A voltmeter and schematics are the way to go because then you get to understand the harness.

Thermostat? I would just go to NAPA and buy a 195 and a 180 and try them both out and see what you think. Colder engines pack denser air, but warmer ones get better gas mileage.
 
C

c4ever

Guest
Topless,
I can't get into the possibilities here at work but I'll take a look at the items you brought up tonight. If you need any particular schematics just shoot me an e-mail.
Carlo
 

Twin_Turbo

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Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
You have a malfunctioning AIR valve, a leaking check valve or a leaking exhaust causing a false lean signal, the unburnt fuel will burn in the cat (O2 is introduced there thru the pipe)

Also, check TPS setting & balance TB's. CTS is a suspect too!

Marck
 

topless82vette

Well-known member
Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
ok ran a compression test on the car and all cylinders reached 175lbs after maybe 6 rotations of the distributor only two cylinders were low but they were only down to about 170lbs whether these numbers are good I have no idea the car has 132,000 miles on what I believe is the unrebuilt 350 so if 175 is considered good I guess Ive eliminated internal motor problems as being the problem
 

ggaagg57

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Joined
Feb 6, 2002
Messages
120
Location
alpharetta,ga,usa.
Corvette
68,502 convt. ,- &81,4speed ,80 4 speed, 70 454
??????

ck for corrosion in fuse panel. make sure timing is set right or ck it when car is running bad. do headers glow red also?
 

topless82vette

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Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
twinnie

excessive exhaust leaks were not found however the air injection system has been disconnected while the cat glows however all emmisions have been intact and car still jumped in and out of closed loop, coolant temp is the only other thing that has not been checked although cars temp gauge has been up to around 200 whether this gauge is 100% accurate I have no idea as for the tps idle setting key on engine off is .46, full throttle is either 5.4 or 4.5 cant remember map appears to be working coolant temp also maxes 85Celcius this is the ecms temp switch..
O2 sensor is always above 500minivolts which my book says is rich sometimes reaches 800, injectors are spraying nice and dont puddle after shutdown, condition of distributor is unknown also knock sensor retards when knock is present I have a nice snapon computer thing that reads all this info not just relying on codes fuel pressure is at a constant 12 psi which is just a bit low I know 14.5 is the proper psi, Im going to try the tuned port injection pump in it when I get around to it, hope this response helps more
 

topless82vette

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Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
no none of the other exhaust parts glow, twinnie also how do I balance the tbi's, ive heard of this and know it requies a special tool
 

topless82vette

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Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
one other question ... to time the car according to my emmisions decal it refers to bypass the est system by disconnecting a tan wire with a black strip where is this wire located thanks
 

ggaagg57

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Joined
Feb 6, 2002
Messages
120
Location
alpharetta,ga,usa.
Corvette
68,502 convt. ,- &81,4speed ,80 4 speed, 70 454
est bypass

trace the four wires from the distributor housing which join at a common multi-connector,close to the distributor. follow the tan wire with a black stripe(est bypass wire) from the multiconnector. past multiconnector , the est wire has its own,single connector separate this connector.
 

Twin_Turbo

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Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
topless82vette said:
no none of the other exhaust parts glow, twinnie also how do I balance the tbi's, ive heard of this and know it requies a special tool

Nope you won't need special tools. A water manometer IS usefull tho but it can be done by hand w/ a feeler gauge and some tweeking. I always did it on looks and feel and it never failed!

Look on http://www.crossfire.webhop.net for the instructions.

As for the stupid kidney shaped IAC plugs. Don't use them!

You can set the IAC's to #0 by grounding thre ALDL, Watch for the IAC's to cycle (they cycle in/out at a constant rate) remove the ground when you think they're ready to cycle back, then wait to when you think it'll go out again and reconnect ground. W/ a little exercise you can seat the pintles!

Marck
 

Twin_Turbo

Well-known member
Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
topless82vette said:
one other question ... to time the car according to my emmisions decal it refers to bypass the est system by disconnecting a tan wire with a black strip where is this wire located thanks

Some early 82's don't have the connector. Clip the wire and install connector. The General found out later it would be handy to be able to disconnect that wire!

Oh and another thing, what kind of CTS do you have?

The ol style round connector? If so REPLACE it. They're prone to malfunctioning (water seeping in connector) and replace w/ 85+ unit:

cts.jpg


Marck
 

topless82vette

Well-known member
Joined
Nov 1, 2001
Messages
910
Location
southern california
Corvette
1982 convertible (not factory) stock 350cfi auto
Twinnie

ok did a few things to the vette yesterday, (spark plugs, 195 thermostat, and did the timing thing) timing was at around 4-5 degrees with bypass wire connected, with bypass wire unconnected timing was about 1 1/2 inches below the zero degree mark ( that was probably ones of the horrible stumbling problems) anyways bumped the base timing to 6degrees, after the bypass wire is connected timing jumps past the timing tab with all the numbers ( is this sounding like the ecm is functioning right) the car idles really nice now at around 800-850 idling and around 600-625 drive, car still has a fuel odor though but can a disconnected air injection system cause this problem, I set the tps at .50 (key on engine off) and with motor running and my snap on scanner connect to alcl connector it showing car is in closed loop but its constantly switching from lean to rich whether this is normal I have no idea, all other sensor also appear to be functioning correctly according to the scanner, Im hoping within 2 weeks if it can pass a smog test, it will be drivable cant wait to take it out on the freeway with the top off only have driven one other convertible and that was a mustang and we both know a mustang convertible could never compare to a convertible vette so Im at least 99% sure I will have a blast

thanks for your help
 

Twin_Turbo

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Joined
Jan 11, 2001
Messages
618
Location
Enschede, The Netherlands
Corvette
1982 Twin Turbocharged Red/Black
Lean to rich cycling (and back) is normal. This IS closed loop, ECM reads off O2 and corrects A/F micture. The ECM always enriches, unless there's a rich O2 signal, then the ECM leans out till signal is gone and then starts enriching again. This way it always stays closest to ideal. Remember, (non wideband) O2 sensor only gives signal rich or lean. The O2 sensor sees no difference between no O2 in exhaust due to perfect burn or overly rich condition!

Marck
 

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