timscott

Hey all, I'm new here, just so you know.
I just bought a 1984 corvette with the crossfire injection and it idles very ruff and is running extremely rich. I would really love to drive her.....any ideas?
Thanks, Tim

Grease Monkey

A good tune up couldn't hurt. Nice to see another '84 on here Also the air filter may be clogged and not letting air in.

xrcrx

Good tune up and troubleshoot. This is the link to the crossfire forum:http://www.crossfire.homeip.net/cftest/

Welcome aboard, nice to see another Crossfire!

timscott

Thanks guys. It's great to be here.

CFI-EFI

Running rich is most often caused by vacuum leaks. The number one suspect on a Crossfire is the manifold to lid bolts and/or gasket. Another cause of a rough idle, but without running rich, is unsynchronized throttle bodies. Step one is obtaining a factory service manual (FSM). They are published for GM by Helm Inc. You can order yours, new, from Helm, look for one to come up in the C4 Parts For Sale/Wanted section, or search on eBay. If you plan on working on your own car, you are going to need it.

RACE ON!!!

JoBy

A bad temp sensor (near thermostat) will often read as a cold in the ECM. Fuel will be added as a choke funktion and the engine will run too rich. If the engine runs 'ok' when cold and rich when in normal operating temp then this might be the problem.

( dash uses another temp sender)

elkabong

Also, see if your throttle shafts are worn by moving them up and down. If there is movement they are worn and should be rebushed otherwise you will have problems balancing them. What everyone has stated are common problems. I would look at the CTS sensor as JoBy mentions first. It is located on the front of the manifold by just below the air pump and above the water pump. You will need to remove the belt to get to it. The newer style connectors have two prongs. Only one wire is needed to be spliced into the harness. I don't remember if the other wire goes to ground. It has been a while but the instructions will let you know.

How many miles are on the ol 84?

CFI-EFI

All these suggestions are good possibilities . Be sure to TEST components before wasting money on replacing them.

RACE ON!!!

timscott

Thank you guys for all the info. I will take a look at these for sure. The first thing I'm going to do is plugs, wires ect.......
She has 143K. Needs some work, lots of little stuff but I already love it! My first Corvette and my life long dream to own one.

drewber

well its a shame to admit this, but i had the same problem last year, changed the temp switch, all the vaccume hoses etc, what the problem turned out to be is the pipe that comes off the air pump that T's to 2 larger hoses that connect to the check valves. The back side was corroded and rusted through. How ever I didnt notice this till I started yanking the whole motor out for a rebuild. Still looking for a replacement part my self. Its definalty worth a check though.

D

Sprint7677

The IAC's should be cleaned

timscott

Ok cool...I'll check that out. I just put new plugs wires ect on it and made no difference, but it sure needed it anyways!
Thanks.....Tim
P.S. What are IAC's?

elkabong

CFI has a good point. Just don't throw parts at it. Not only will you get frustrated but your wallet will be a tad lighter. If you don't have a Helms manual or FSM (factory shop manual) get one. It will help out quite a bit.

ps374

Are you getting a check engine light? If so find out what your codes are. You can do it with a paper clip.

CFI-EFI

Bad IACs won't cause it to run rich.

RACE ON!!!

timscott

hey thanks. Not getting a check engine light. But it is running EXTREMELY rich.........never had anything run that rich.........?

Sprint7677

No not run rich but they effect the idle. I remove mine and cleaned, and checked adjustment per the FSM and the engine idled much better and did not have the "rich" smell anymore. Just my experience, I am not an expert, that is why I purchase the FSM to help me along. It certainly does not hurt to remove them and clean them, AND it's easy too.

Sprint7677

Another neat little thing I found by accident. There is a small plastic vacuum valve that is mounted near the HEI with a vacuum line going to the manifold. Mine was broke and I was also sucking vacuum there. It's hard to see, I found it before I cleaned the IAC's. It made a nice difference in idle but did not completely cure the shaking until i cleaned the IAC's

CFI-EFI

There is no adjustment for the IACs.

RACE ON!!!

CFI-EFI

Idle air controls. You definitely need a FSM.

RACE ON!!!