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1982 corvette cross fire

42K views 57 replies 10 participants last post by  KenD 
#1 ·
i have a 1982 crossfire that is all stock bought the car about a year ago, the car is a work in progress and runs pretty good for being as old as it is. the car has 62k miles i am working on getting it to run good and then i will turn my attention to the cosmetics i rebuilt the tranny replaced the plugs, wires, points and distributer, have put about 1500 miles on it since i bought it only premium fuel two oil changes and for the most part the car runs fair to good once warmed up however, the car is hard to start when it is cold it seems to not be going to a choke start up for the cold start, a couple of times on the cold weather start up the car starts up like a champ with a smooth high idle warm up but that has only happened a couple of times. i am ready to try to isolate my cold weather start up issues but i dont know were to start any suggestions corvette friends i need some help
 
#2 · (Edited)
Something Doesn't Make Sense Here




Huh? Your car only has 62,000 miles on it and you had to rebuild it's 4-speed TH700R4 automatic transmission? And '82's don't have points in their distributors because their distributors are computer controlled. Also the Crossfire Injection doesn't have a choke. The air fuel mixture is enriched by the computer that uses the sensor at the front of the intake manifold to detect coolant temperature. To start it just turn the key and crank it because all fuel injected cars are supposed to be started with a closed throttle. And '82's are designed to run on 87 octane gas. And '82's will go 7000 miles between oil changes so why on earth have you changed your oil twice in just 1500 miles? Are you really sure you have an '82?
 
#3 · (Edited)
1982

yes i am sure it is a 1982, the car sat for a time and the oil was black when i got it the reason for the two oil changes in the short period of time was to help the car clean out, sticky valves etc, probably not necessary, the car is not burning any oil but the car sure did run a lot smoother after the fresh change the second was just to let any crud in the engine help to clean out, what i ment was a new distributor cap only, and positive that it is a 1982 your information is helpful and i will see about that sensor you mentioned
 
#4 · (Edited)
700r4

and also yea the tranny was shot amco showed me the insides of it worn out for sure, after tracking down the second owner he told me the miles on the car are close to accurate except for a period of time when the speedo was down and from inspecting the car close i think it is right ,original shocks, original clamps, all original cross fire, clean sound of engine no knockin or lifter tap, no oil consumption, cant see any evidence that the engine has been out of the car, but maybe i am wrong i know that 700r4s dont die that soon but yea rebuilt tranny from amco and they did a good job. anyway i did learn a lesson to never buy a car from another state and trust someone with out going to see it for myself, anyway i paid 9k for the car ,it is what it is not to bad and i am comitted to it now, the color is gold and the finish is still nice only 648made in this color
 
#5 · (Edited)
choke

i know the car is not carburated and that the ECM calls all the shots .me using the term choke was just to get the message across that under cold start up the ecm is not getting the correct info to compensate for a cold wether start you follow me gold leader, plus let me humble myself in sayin i am not a professional mechanic but information is the key to making sure that i know were to look thanks
 
#6 · (Edited)
1982 CrossFire Injected Corvette

i know the car is not carburated and that the ECM calls all the shots .me using the term choke was just to get the message across that under cold start up the ecm is not getting the correct info to compensate for a cold wether start you follow me gold leader, plus let me humble myself in sayin i am not a professional mechanic but information is the key to making sure that i know were to look thanks

Okay pumper, I have owned my '82 for 23 years and I can tell you most anything you would ever want to know about the Crossfire Injected engine. For starters there is a temperature sensor that is screwed into the front of the intake manifold about 3" to the right of center. That sensor gives the computer the coolant temperature needed to adjust the air/fuel mixture for cold starts. Then on the firewall behind the power brake unit is your MAP sensor. The MAP sensor reads manifold vacuum and sends that information to the computer. Also there is a throttle position switch (TPS) mounted on the left side of the left throttle body. That TPS gives the computer the amount of throttle opening and should be adjusted to .525 volts. Then there is a O2 sensor just ahead of your catalytic converter and that tells the computer how rich or lean your fuel mixture is. As your engine is "fuel injected" you always start it with a closed throttle. The computer will automatically make your engine fast idle when the coolant temperature is low and will gradually slow the engine down as it warms up. There is a 25 micron fuel filter in the inlet line and it's mounted on the right side frame rail right under the passenger's feet. Your electric fuel pump is mounted inside the fuel tank and it will only run for 2 seconds when you turn your key on unless your oil pressure switch reads 5 psi or more pressure. If the pressure is there the fuel pump will continue to run.

Keep me up-to-date and let me know if you have any other problems. I'll be glad to walk you through them.
 
#9 ·
Can I step into this discussion? I too have an 82. I have done all of the standard plug, oil change, dizzy cap / rotor / coil things to it since I have purchased it last week. I have been spending most of my time reading about the xfire. I have a very rough idle. I am going to check the TPS for the correct voltage thanks to your post above. I also suspect that I may have a vac leak. How can I measure that? I read somewhere that if I pull one of the vac leads off, put a *T* in the line and then a gauge, I should be seeing 15-18 PSI of vac. Any thoughts on that, or the rough idle?

Thanks again!

Rick
 
#10 ·
welcome to SV.. and you can jump in anytime you like..rough idle can have numerous causes..if you connect a vac gauge to manifold, it can tell you a lot by its action. Thats what we old guys used before the age of computer diagnostics..this may help, http://www.secondchancegarage.com/public/186.cfm compare your gauge reading with the various scenarios , see what you match.. Toobroke has extensive knowledge of that damn crossfire system..if the trouble is in it, he can help.. he can also tell you about a better option if you want more upper rpm power.
 
#11 ·
Great! I just purchased a vac gauge today so I am going to go home and check it out. I have soooo much to do with this car, but it is my 5th restoration ... 2 Triumphs, 1 Lotus, and a Porsche. This one, however, is a keeper! I will let you all know what I see. :woowoo:

Rick
 
#16 ·
previous owner did away with stock converter, looks like two cherry bombs there now, thin pipe that runs parallel to exhaust is sealed by weld i hope to re establish connection when i replace exhaust back to stock, would that affect cold start, no sample going back to ecm for air fuel mix right? the exhaust is rich in smell except after warm up other then cold start up problems the car runs like a top
 
#17 ·
Sensors Are Necessary




When your engine first starts the coolant and O2 sensors will tell the ECM to make the fuel mixture rich (open loop) until the coolant and O2 sensors tell the computer to go to a leaner condition (closed loop). If a hot exhaust temperature isn't maintained the computer will go back to an open loop and enrichen the mixture again. So it's very necessary to have both of the sensors functioning all the time. The computer used in the '82's and '84's make fuel and timing adjustments at 80 times per second but the later cars had computers that made several hundred adjustments per second.
 
#19 ·
thats what i thought i was looking at the exhaust systems on corvette central and did notice the inlet on the catalatic converter not sure were the 02 sensor is i just need to re establish the connection how does the 02 sensor connect to the converter and were is the electrical connection for the ecm
 
#20 ·
i see that the line from the converter goes into the engine compartment, and you said sensors i see in the engine compartment what looks like two of them brass looking one direct from the converter line and one off the exhaust manifold am i looking at the o2 sensors
 
#21 ·
ok i see the connection for the o2 sensor above the heat shield, the female end is still there and looks intact i assume a good exhaust shop can mount a new o2 sensor and reconnect the catalatic converter air line which is sealed by weld i think i get the picture now of how it all was original
 
#22 ·
1982 Corvette Tune-Up




If you still have the original stainless steel "hedders" on it you'll see where the pipe attaches that goes back to the side of the catalytic converter. Your air valve on the engine will send air one of two ways.........either into the exhaust manifolds or into the catalytic converter. And the O2 sensor is supposed to screw into the pipe just ahead of the catalytic converter. Did you find the EST wire yet? It's behind the distributor and I believe it's an 18-gauge brown wire that has a connection in it's middle. You disconnect that wire when you adjust your initial timing so your ECM isn't controlling the timing. Then be sure to plug it back together again.
 
#25 ·
The EST wire is behind the distributor and about 6" toward the driver's side. It is a small wire and has a brown "locking" connector on it. If you unplug it and your engine slows down then you've found the right one. And the TPS switch doesn't come pre-adjusted. Once installed it must be set to .525 volts (slightly more than 1/2 volt).
 
#24 ·
also friend you stated tps switch is to be set at 525, the car has the original if i buy new will it be set or will i have to set, slso from time to time i have the classic idle surge symtoms but it stops pretty soon after driveing a whole other set of challenges
 
#27 ·
Checking/Setting The TPS Voltage




Of the three wires going to it the center wire is the hot and the bottom wire is the ground. Many years ago I stripped a 1/2" section off the insulation of each of those two wires then soldered the strands so they would be rigid and not fray. Makes it real easy to hook up my digital voltmeter. But don't strip them one directly above the other. Stagger them at least 1/2" so they can't make contact with each other. Then with the throttle closed set the voltage to .525 volts (plus or minus .025).
 
#28 ·
ok then re seal them with black tape, did you read my post about the idle surge from time to time, my first order of business will be to replace exhaust back to stock with o2 sensor, timing,and coolant temp ecm sensor i should see an improvement dont you think
 
#29 ·
Idle And The IAC Motors




As the throttle bodies don't have any replaceable bushings for the shafts the bodies slowly wear out and then air can be sucked in thru the sides of the shaft. The bodies can be bored and re-bushed by DCS in Arizona. Also there is an IAC motor in each of the throttle bodies (the Tuned Port engines only use one) and both of them must be working for the idle to be smooth and not wander. Quite often simply removing the IAC's and spraying carburetor cleaner in the bore will clean off the built-up oil/carbon deposits that form around where the pintle seats (the tapered-point stem of the IAC). Those IAC's are what controls the idle speed as they will open and close to regulate the amount of air flow into the engine. Looking down from the top you can see the tips of those IAC's and when you "blip" the throttle you'll see them move.
 
#30 ·
ok IAC motors? what does IAC stand for are they a seperate part in the throttle body i would like to see a picture, spraying the cleaner remove them or spray in place. have no idea were IAC motors are will have to study throttle bodies, and yes had heard about the issue with the worn out bushings and have seen new rebuilt ones on line, your car must be tiptop what color is it i should track down a original twin throttle body service manual on ebay
 
#32 ·
ok to broke to retire,{ idle air control} there is one on ebay unplug and unscrew right? then clean up with cleaner tappered end that seats, also found service manual bought it it should have some pictures and info, also see rebuilt throttle bodies for about 200 bucks i can see that this system is complicated but simple if you know what to look for can i ship the car to you?
 
#35 ·
IAC Motors




You can buy new IAC's from every parts house in the country.

When you go to screw an IAC in make absolutely sure it's pintle is retracted enough to allow it to be tightened. As the IAC is a "stepper" motor the motor can run both directions. To retract the pintle hook the wires to it and ground the housing (or screw it in part way). Then when you turn the key on it'll fully retract. Just don't force it or you'll damage it. You can see if it's fully retracted by looking down into the 3-sided hole above it and see the pintle tip.
 
#36 ·
ok i was looking at it today down the three sided hole i just see a hole down there the car is not on not seeing anything what position is that retracted? also my car has a electric cooling fan close to radiator in addition to the belt drive fan is that stock or added on
 
#38 · (Edited)
More On IAC Motors And Electric Fan




When you look down into the "three sided hole" in the top of each throttle body you'll see a hole at the bottom/front that is about 3/8" diameter. If you don't see anything stuck into that hole from the front side then the pintles are retracted. With the IAC's removed you can stick your finger into the throttle body and see your fingertip from the three sided hole.

Now on to the electric fan. The fan should only run when the temperature exceeds 230 degrees and it's kicked on by a two-terminal switch that is screwed into the right cylinder head just above the #8 and #6 spark plugs. One of the wires going to that switch should be hot and the other will be hot ONLY when the temperature exceeds 230 degrees. It's impossible to see that switch from the top so you'll have to jack it up and crawl under it to see it. And even then it's hard to see because of the heat shield that covers the #8 and #6 plugs. Take that heat shield off and it's easy to get to.

In the 23 years I've driven my '82 I have only heard my electric fan kick on one time and that was when I was in Death Valley where summer daytime temperatures often exceed 120 degrees.
 
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