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84 corvette Crossfire problems.

 
shanesmith52
I love my Chevy Chevette!
Posts: 1
Joined: 09/11
Posted: 09/23/11 05:25 PM

I have an 84 crossfire corvette. I'm having issues. When the motor is cold, it starts fine,though it has a rough idle until it warms up a bit. However, when the motor is hot(above 190) it idles roughly,sputters, and sometimes stalls. When this happens, it is almost impossible to start.(same when the car is turned off and attempted to start later) After the motor is bone cold, it starts right up.  I have checked and/or replaced all vacuume lines,sensors,gaskets, and am at a complete loss. I know next to nothing about these motors. Could it be fuel pressure, timing, or something with the distributor?


plz HELP?!  

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69GTOby
V-6 Camaros rule!
Posts: 29
Joined: 04/11
Posted: 09/23/11 06:33 PM

Well, I would look at everything...  Could just be in dire need of a tune up.  How old are your plugs, wires, cap, rotor, and filters?  When is the last time the timing was checked/set?  If those items need done anyway, go ahead and do them.  It may even fix your problem.  For the cold start rough idle, look at the choke if the tune up stuff is good.  Since it seems to be temp related, I am thinking maybe fuel is boiling, or there is an ignition issue.  When it gets rough while hot and stalls, listen for fuel boiling in the carb bowls and look for fuel spilling out of the overflow.  Use your nose, too.  A 180* t stat would be a good idea, regardless.  HEI distributor, right?  The HEI ignition modules and coils, too, tend to be heat sensitive.  
****
1969 GTO resto in progress. '76 350+.060, #13 heads, 9.2:1 CR, Lunati cam, Edelbrock Performer, 750 Holley, HEI, Ram Air manifolds, 2 1/2" exhaust. TH400 trans w/shift kit and 2400 stall.  235/60/15 front, 275/60/15 rear on Rally II 15X7s.  GM 12 bolt posi with 3.73's.

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waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 09/23/11 08:00 PM

first.... NO matter what anybody says...  unless you are going to put a custom chip in the computer...  these HAVE To have a 192F thermostat.   or they will run rich...

second...

on the front of the intake manifold sticking in with a black and yellow wire...  is the engine coolant temp sensor..  find an auto zone store.. or somebody who sells wells... Duralast/Engine Temperature Sensor Part Number: SU102  this costs under 20 bucks with the pig tail.. and yep it looks different...   the coaxial versions just don't work after 27 years...

you might want to look over at the corvette fever web site .. for my post on which Used scan tools work with the early C4 corvettes... this will make your life easier..

one warning..   the radiator cooling fans on these are ONLY controlled by the fan switch in the passenger side cylinder head... if the switch goes bad.. or the pig tail goes  bad..  or the relay which is near the master cylinder.. you won't have a radiator cooling fan that cycles on and off properly...

these are places to start..

i am very familiar with the cross fire system... you can use basic GM TBI trouble shooting as its a TBI.. same as what they used on millions of gm cars and truck up through 1994...   with only minor differences..

i totally agree on doing the basics first...   checking the cap .. checking the rotor...   removing and examining the coil for signs of high voltage leaks...   taking a close look at the pick up coil... if you see cracks in the dark grey /black layers... you will probably need a new pick up coil...

you might also want to pick up a new capacitor harness.. while they are still available..   the screw that holds it down HAS to be properly tightened..

if you have the coil out and you change the cap.. there is a ground strap... under the coil connects to the center wire of the 3 up from the module..  without it . the coil will blow out.. taking the module with it..



that car also has air injection...      i would really like you to examine the air injection system..  look for rotted out check valves..   rusted out tubes into the exhaust manifolds..  you might also want to for a test.. unplug the check valves.. block the check valve opening.. warm the engine to operating temp.. .  with the engine idling.. there should not be any airflow from the air injection system for the upstream exhaust..

why worry about the uncommanded upstream air.. . if the diverter valve leaks smog pump air when its NOT called for  into the tubes up stream from the oxygen sensors...  it fools the oxygen sensors into thinking the air fuel ratio is wrong...

currently i am not able to post pictures.... the locked has locked me out...  

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waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 09/23/11 08:01 PM

the server got me.. so i will edit and change the text to continue the answer...

if you need more info..  i have a LOT.... do you know how to pull codes????  

autozone.com covers the cross fire in 3 or 4 different sections of their repair section...

under 84 corvette

under 82 corvette

under 83 camaro..

under 83 firebird..

last time i looked the sections were slightly different..  

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waynep7122
I mow my lawn and find Chevys
Posts: 1130
Joined: 08/09
Posted: 09/23/11 08:17 PM

you will need this chart....

Scandatagm


post which craigs   list you use...

you can find scan tools like the monitor 2000.. with the proper cartridges and cables for usually under 100 bucks..

OTC2000

the monitors 2000s are good for up to 1987 models with the proper stuff...

the monitor 4000 versions.. 4000e  monitor extended.. monitor enhanced.. can be had for up to about 300 bucks with various amounts of cables.. and cartridges..  

be sure to contact me.. if you find one.. so i can tell you if it has the right stuff for your year of car...

there are these snap on MT 2500 versions..

Mt2500snapon

once in a while a genesys will pop up...

Otcgenisys

this is an actron CP9110.. some came with the GM cartridge and cable...  and are excellent units.. that will work up to 1994 models...

Cp9110actronobd1scantool

very few of the newest scan tools will actually do more than read codes.. these i have listed.. if they have the proper cartridges and cables will read live data streams... allowing you to see what the computer is seeing..  so you can compare it to the chart above..  

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