1982 vette idle issues

grumpyvette

Administrator
Staff member
TexasDan said:
guys I just got me a barn find in a 82. been in storage since 2010. I can get it to run but its real ruff. fuel pump, filters were changed, new plugs, wires etc... I can drive it down the road and it will just die. I can start it back up but I have to WOT to get it started.

Are there any good shops in Northwest Houston Texas I can take it too?

as usual your going to be well ahead doing some testing and having the correct FACTORY SHOP MANUAL, to refer to, and start by verifying the basics, of spark, compression,fuel pressure and volume plus, your obviously going to need to verify fuel delivery, ignition advance curve ,timing and throttle body adjustments , proper valve adjustment and proper sensor function, and without a shop manual to look up the values your supposed to be setting things for or values you need to verify and a few tools like a multi meter and vacuum gauge and timing light that will be far more difficult.
check all the fuses both in the pass side dash fuse box and under the hood near the battery , clean the battery connections, replace the fuel filter, and replace the oil pressure sensor near the distributor base as these frequently fail.
An hour spent reading links and sub links NOW can save you days of frustrating guess work
http://www.helminc.com/helm/Result.asp? ... ted_media=

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that twin tb systems not that difficult to work on, the first thing ID do if it was my car would be to, verify the fuel pressure at the TB inlets correct and set the ignition timing, and verify the voltage from the alternator, and battery.then I'd take off the TB's one at a time and use a full can of throttle body cleaner on each after partial dis-assembly to get them clean, next suggestion would be to add a can of injector cleaner to the fuel tank. then check all the fuses, look for loose electrical connections and vacuum lines and Id strongly suggest adjusting the valves and an oil and oil filter change, ID strongly suggest checking all the fuses, and looking for vacuum leaks. and ID replace the oil pressure switch as they have a well known track record for being intermittently defective, which can make you nuts tracking that issue down,ID also suggest replacing the distributor cap and rotor as older,components, with wear and internal deposits tend to cause ignition issues, and get out a multi meter and replace any ignition wire that reads over about 2000 ohms per foot. and ON BOTH THROTTLE BODYS, ID verify the TPS is set correctly, and ID clean and verify the IAC is also and if not replace it.
ID also verify exhaust back-pressure as an older partially clogged catalytic converter is a common issue , on those corvettes.
yes there are throttle body rebuilders and parts
you can easily fabricate a low cost yet very accurate,custom built MANOMETER
(fancy word for a tool that allows you to balance and equalize the flow rates of the two throttle bodys on the cross fire intake manifold
and just as important, LEARN HOW TO CORRECTLY USE IT!

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It took me awhile but I learned you need to put a couple cap fulls of the dark blue MARINE STA-BIL in the car generator or any other engine in storage, gas tank , or several ounces in a cars gas tank,before you store it, or in several weeks time the alcohol makes the engine hard or impossible to start.
be very sure,
as a general rule with any new automotive toy,
(1) you check the oil, trans fluid or coolant and brake fluid levels
,(2) the tire pressure is correct in all 4 tires,
(3) verify the fan belts are in decent shape,
(4) verify that you have the ownership documentation, the required licences
and you test the brake function, before driving.
(5) start it up and let it idle for 10 minutes and check the oil pressure
and coolant temps.
(6) try shifting it into all gears.
(7) check the signal blinkers and head lights

READ THRU THIS THREAD AND LINKS ALSO
viewtopic.php?f=87&t=7770&p=26552#p26552
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READING THE LINKS AND SUB LINKS WILL PROVIDE A TON OF ADDITIONAL RELATED INFO YOULL NEED!
http://www.throttlebodyinjection.com/?g ... 7AodMS8A8A

http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=g58drf76n90cbra6nih4detdi1

viewtopic.php?f=32&t=10096&p=39710&hilit=cross+fire+balance#p39710

http://www.corvettephotographs.com/c4vettes/codes.htm

http://www.ecklerscorvette.com/corvette-factory-shop-manual-perfect-bound-1984.html

viewtopic.php?f=32&t=640&p=25767&hilit=cross+fire+balance#p25767

http://garage.grumpysperformance.com/index.php?threads/1984-fuel-pressure.11776/#post-55675

viewtopic.php?f=56&t=495

viewtopic.php?f=44&t=882&p=45944&hilit=+propane+torch+leaks#p45944

viewtopic.php?f=70&t=875&p=39956&hilit=lights+timing#p39956

viewtopic.php?f=52&t=196&p=35392&hilit=adjusting+rocker#p35392

viewtopic.php?f=70&t=2798
 
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[URL='http://www.corvetteforum.com/forums/members/389576-emnash.html']EmNash[/URL] said:
This is the procedure to check codes on the 82:

You need to jump the two top right pins in the connector under the ash tray.

Turn the ignition switch to "On" but do not start the engine.

Depending on the model year, either the "Check Engine Light" or the "Service Engine Soon" will begin to flash.

As the code display sequence begins, you will see a flash followed by a pause and then two flashes. This is the indication for the number "12". The number 12 is a delimiter intended to show where the ECM code display starts and stops.

Code 12 will flash three times and then any stored codes will flash. When all codes have been displayed or if there are no stored codes, the number 12 will again flash three times.

For example, a problem with the EGR system (code 32) will be shown as 12, 12, 12, 32, 32, 32, 12, 12, 12.

This would be displayed on the Check Engine/Service Engine Soon light like this:

12: flash (pause), flash, flash, (long pause)
12: flash (pause), flash, flash, (long pause)
12: flash (pause), flash, flash, (long pause)
32: flash, flash, flash (pause) flash, flash (long pause)
32: flash, flash, flash (pause), flash, flash (long pause)
32: flash, flash, flash (pause), flash, flash (long pause)
12: flash (pause), flash, flash, (long pause)
12: flash (pause), flash, flash, (long pause)
12: flash (pause), flash, flash (long pause)

The ECM code display will repeat until you turn off the ignition switch and remove the short.


"SSROADSTER" said:
my suggestions....

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here is what I would check next.....
1-fuel pressure, you should have at least 13 psi fuel pressure in the system. best place to check is between the TB's. but you can also check at the fuel filter.
2-recheck spray pattern of both injectors, making sure that both have umbrella spray pattern, and not a drip pattern at anytime.
3-you replaced the fuel pump, did you also replace the hoses along with the pump? and if you did, the small rubber hose that actually sits in the fuel, needs to be fuel resistant hose, otherwise it will rot in a matter of days.....and can cause your surge condition.....
4-check 20 amp fuse near battery, take fuse out, make sure there is no corrosion in the connection, also check ECM connections for any type of corrosion, etc..
5-if the above checks out and you still have a problem, change fuel filter again, you may have build-up of "junk" in the fuel line from the pump to the fuel filter, that has not worked it self out. get a container and with the filter removed,run the pump, making sure the fuel coming out is clean and clear.

on my friend's 82, he skipped #1, but did #2,3,4 and that solved his problem of a no-start condition, and rough idle. he then developed almost same condition a week later and did #5 and his engine is running just fine.
on my 82, my idle is getting better with each little item I do. although I don't have a surge condition like yours, my idle does fluctuate slightly, but runs great. the dash and gauges are still out of the car, thus the speed sensor is disconnected, which contributes to the idle as it tells the ECM if the car is idling or in motion to make the necessary adjustments.
before you would attempt to balance the TB's, I would check and make sure that the TB plates both open and close exactly the same time. If they do, I would say that the TB's are probably balanced and would not attempt doing this at this time. I would concentrate on the above to eliminate every possible item that may be causing your condition.
all-in-all, the CFI is a great motor, I get great mileage with mine as my "dd". You just have to understand how it works, (which I am learning myself) and it will run forever when set-up properly.
hope this helps................................... ........Tom


on my friend's 82, he skipped #1, but did #2,3,4 and that solved his problem of a no-start condition, and rough idle. he then developed almost same condition a week later and did #5 and his engine is running just fine.
on my 82, my idle is getting better with each little item I do. although I don't have a surge condition like yours, my idle does fluctuate slightly, but runs great. the dash and guages are still out of the car, thus the speed sensor is disconnected, which contributes to the idle as it tells the ECM if the car is idling or in motion to make the necessary adjustments.
before you would attempt to balance the TB's, I would check and make sure that the TB plates both open and close exactly the same time. If they do, I would say that the TB's are probably balanced and would not attempt doing this at this time. I would concentrate on the above to eliminate every possible item that may be causing your condition.
all-in-all, the CFI is a great motor, I get great mileage with mine as my "dd". You just have to understand how it works, (which I am learning myself) and it will run forever when set-up properly.
hope this helps................................... ........Tom


although this may seem irrelevant, make sure your battery and alternator are in top shape and putting out the charge they need to be......also make sure your grounds are secure....

[URL='http://www.corvetteforum.com/forums/members/397120-corvetteherb.html']Corvetteherb[/URL] said:
I agree with everyone above, but I had a similar problem with my 84. It turned out that the 2 to 3 second run time is the time that the ecm turns the fuel pump (in the tank) to charge the fuel pressure for startup. confirming this I could hear the fuel pump run for a few seconds when I listened at the rear of the car while someone else turned the key on. Now the way I understand it is that after initial start when the oil pressure switch senses 5 psi it then provides power to the fuel pump. The oil pressure sensor is next to the distributor on the top of the engine. The plug is on top and has 3 contacts in the plug. When this sensor fails your car will only run for a few seconds, I can attest to this problem.

To confirm my suspicions about the pressure switch I simply used a trickle charger, found the electrical plug near the gas fill cap, there are 3 wires in the plug; one for the gage, one for the fuel pump (brown), and a ground (black). I pulled the plug apart and attached the red lead on the trickle charger to the brown wire going into the tank, and the black lead on the charger to the black wire going into the tank. The pump began running instantly! I turned the starter and the engine fired right up and idled nicely. My conclusion was either the oil pressure switch (or wire to it) was bad, or the ground wire was bad. The ground turned out to be my real problem.
check for water in the fuel. today's fuel is prone to attracting water because of the ethanol and condensation becomes an issue when a vehicle sits. it can happen in the cars tank or where the gas is purchased. water is heavier than gasoline and will lay in the bottom of the tank.
 
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