I have a 1984 Corvette that has 80,000 miles on it. I am the fifth owner of the car but the car is mostly original. The car runs but it is starting to show signs of age, and with that being said I have replaced the following items that have failed. The master brake cylinder, antenna, bulbs and basic tune-up parts, air filter, oil and filter, fuel filter, cap and rotor, platinum dual tip plugs and 8mm wires. When I first bought the car it had problems starting, but always started after 3 or 4 tries. I replaced the fuel pump with one from a 1985 and that made the difference. I also replaced the temp sensor for the heck of it. Just recently the car has been running rough and making a tapping noise under passenger’s rocker. I checked the compression and all eight are within lps. of each other. Leak down test was good as well, most likely a loose rocker or dirty lifter. The car idles at 700 rpm’s with the car in drive and brake on, when you accelerate it hesitates but once the rpm’s are over 1000 it runs great. When you come to a light and stop the tach drops to 5,4,3 and then stalls. It starts right back up again but still wants to stall. To fix this I have run fresh gas with an additive in it, cleaned the throttle bodies with carb cleaner. Removed and replaced the T.P.S, set to .54 volts. I replaced both I.A.C valves, cleaning the orifices and setting the pindles to 1 1/8”. Water balanced the throttle bodies and replaced all hoses (no leaks). No matter what I adjust the idle to the ECM resets it to 700 rpms, which is what it should do. Also on an occasion will the car misfire/cough or “flames out” on hard acceleration. What am I missing? Again the car runs great at 1000+rpms and incredible over 2000+rpms. It starts first turn of the key and runs in neutral but once it has a load until over 1000 rpms it hesitates and stalls at lights.
dannyfierce
Have you pulled the codes yet? I suggest your doing that first and see what pops up. And there is a fuel filter mounted to the right frame rail right under the passenger's feet so it would be a good idea to replace that to ensure a good fuel flow to your injectors. Also the '84's have two large injectors and two IAC valves that are powered by the computer. I've had to replace my computer 4 times in 23 years as my computer failed to power the IAC motors at times. My engine acted just like yours as my idle would often fluctuate and then my engine would die. And when the computer's IAC drivers go bad it won't set any code. Most any parts store will stock an '84 computer. And how many miles are on your O2 sensor? They should be replaced every 30,000 miles so yours might be in need of replacement. And make sure your 1/4" hose going to your MAP sensor is in good condition and fits tight.
stalling
Check the codes here the are right on. Just did mine. MAP sensor linewas not on tight
Check the codes here the are right on. Just did mine. MAP sensor linewas not on tight
Ok, still stalling and rough idle. I checked the timing and it is set to 6 BTC at idle. If I disconnect the EST the timing drops to 6 ATC. I think that is wrong. I can reset the timing but do I set the timing with the EST unplugged and the car in Neutral or in park. i hope this does it. The IAC are working with the throttle so I assume the ECM is good. Any other tips.
Base (initial) timing should be set with the EST disconnected. If you leave it connected the computer will intervene and adjust accordingly. You may have found your problem (timing is off by 12°):thumbsup3: Set timing in park.
Resetting A CrossFire Idle
I suggest your reading my explanation on how to reset your idle in the other CrossFire idle problem posting.
I suggest your reading my explanation on how to reset your idle in the other CrossFire idle problem posting.
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