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I bought a 1984 Corvette this past Saturday at an estate auction, The car really looks good and has 103,000 miles on the odometer. It acts like the timing is off or plug wires crossed. I haven't had time to look at it too close yet. Do the 84's still have a mechanical distributor/ I have a 2000 Ranger pickup that was running like this. My mechanic tried everything and finally found our the harmonic damper was loose. Tightened it up and it ran fine. An easy fix but one hard to find.
It's a standard HEI distributor with electronic advance. You set base timing by disconnecting the est wire by the brake booster and then proceed like a normal distributor. (Disconnect while the engine is off then reconnect.) Can't hurt checking the plug wires either.
I had a Cross fire and it was bullet proof. Since it is First Gen, you need to look at a few things. Please provide a better description of what the engine is doing. You say that it acts like timing is off or crossed wires, so check that first. If that does not solve it check:
Throttle Position sensor needs to be a .525
Check the spray on the fuel injectors. If needs to be a even, "cone"
MAP sensor is working and or has really good connections with no leaks.
Also, X Fires are super fuel pressure sensitive. Make sure you have 12-13 (others will debate this number) as low pressure or a clogged filter could make your engine run poor.
The 84's with the crossfire injection were very problematic.
BS. It's a simple system. Any car will have problems if there's something wrong with any of the components. A nice feature is being able to see the fuel injectors work! You can't do that with the later FI systems! Get that right, and the engine should run fine!
BS. It's a simple system. Any car will have problems if there's something wrong with any of the components. A nice feature is being able to see the fuel injectors work! You can't do that with the later FI systems! Get that right, and the engine should run fine!
Originally Posted by billschroeder5842
I had a Cross fire and it was bullet proof. Since it is First Gen, you need to look at a few things. Please provide a better description of what the engine is doing. You say that it acts like timing is off or crossed wires, so check that first. If that does not solve it check:
Throttle Position sensor needs to be a .525
Check the spray on the fuel injectors. If needs to be a even, "cone"
MAP sensor is working and or has really good connections with no leaks.
Also, X Fires are super fuel pressure sensitive. Make sure you have 12-13 (others will debate this number) as low pressure or a clogged filter could make your engine run poor.
I'd also agree with this. There are a hand full or two of sensors on the engine. Really isn't much to go wrong. Unless you're me. In which case when you try to make it better you have problems after. I also acknowledge that it is more than likely my own fault....
For the pressure it is a matter of what the car likes best. Drive it and look at the BLM numbers as you do if you have the option. The closer to 128 you get the better. Mine liked 14. If you can't look at data just play with it until it feels best. You'll be able to tell. The difference is noticeable while driving.
I have had two 84s. One was new in 1984 and I totally rebuilt another one in 2012 till the present. The new car ran great and this one I rebuilt runs better. I spent a lot of dollars on the latter and full well knowing I will never recoup the money. Call it a sentimental build.
Get yourself a factory service manual and the electrical supplement. They will show you the procedure that the members talked about above.
There are a hand full or two of sensors on the engine. Really isn't much to go wrong.
The CFI system is pretty simple . . . and reliable. Hardly a handfull of sensors: Coolant Temp Sensor (CTS, front of intake manifold), Manifold Absolute Pressure (MAP, above brake booster), Ignition Module (inside dist.), Throttle Position Sensor (TPS, rear throttle body), and Oxygen Sensor (O2, exhaust pipe). That's five, so I guess that's a handfull. The Knock Sensor (in front of starter) hardly counts, because a faulty KS won't make the engine run poorly.
The rest of the posters know their stuff. A more detailed description of the symptoms would help us, help you.
Agree a better description of the issue is needed.
I guess I must be very, very lucky. I don't find my cross fire to be problematic. Only a handful of sensors to go bad and pretty easy to work on......except for that freaking oil pressure sending unit.
I guess I must be very, very lucky. I don't find my cross fire to be problematic.
Nah....mine ran mint for 12 years that I owned it. It's not problematic. Typically (and unfortunately) the people who put it down don't have one and never have. Weird.
Agree a better description of the issue is needed.
I guess I must be very, very lucky. I don't find my cross fire to be problematic. Only a handful of sensors to go bad and pretty easy to work on......except for that freaking oil pressure sending unit.
The oil pressure sending unit on the 6.0l in my moms escalade was a pain to replace. This one isn't too bad by comparison lol. But yea, they are damn near bullet proof as far as problems go. It is essentially a carb but the fuel is metered by a computer. About as simple as fuel injection can get imo. And because of that we don't have to worry as much about those harder to find sensors like the tpi cars have. (I'm talking to you maf burn off relay... Friend has a problem with it on his tojan...)
Another 84 CFI owner here.
it's super simple to work on, and very little to go wrong.
On mine i never had any issues until i upgraded the fuel pump in preparation for mods i was about to do.
From there i found the fuel pump grounding appears to have been done through the tail lights...
Once i ran a fresh ground everything was much better.
Also, there is a coolant temperature sensor on the front of the intake manifold that is well known to go bad.
something with the old connector style i think...
That can cause some issues with the way it runs as the computer uses it to control fueling, and timing vs engine temperature...
I proactively replaced mine with the new style sensor right off the bat...
Check out ecklers, corvette central, and a handfull of other corvette specific retailers.
i found they often have the best prices, and if not, they are made super clear what's special about the part...
Also, there is a coolant temperature sensor on the front of the intake manifold that is well known to go bad.
something with the old connector style i think...
That can cause some issues with the way it runs as the computer uses it to control fueling, and timing vs engine temperature...
I proactively replaced mine with the new style sensor right off the bat...
Check out ecklers, corvette central, and a handfull of other corvette specific retailers.
i found they often have the best prices, and if not, they are made super clear what's special about the part...
This is a good point, the old style uses a knock sensor type connector and over time they get loose. You could try pushing on It with a screwdriver to see if it helps first, that'll tell you if it's the connector. (It should immediately run better if it's loose.)
84 Corvette running bad
