Hey guys,

I bought my Vette from C&V out of Phoenix and I love it, but.. they couldn't get it to idle smooth. They said they tried everything they could think of. What I have is a great car that runs great but idles rough. I spoke with one of the guys over at Boyd Cottingtons and he said just put a blower on it and get rid of the crossfire garbage. Good advice?

Thanks,
Old guy who doesn't know it

 

The throttle plate shafts are probably worn. If you wiggle them do you see the Throttle body plates move or does the idle change? Was the gasket on the throttle plate changed....it goes.

Jim

 

Most likely the upper plenum gasket has blown out at the rear of the intake.
Mike

 

On my '82 it began to do that and I just sprayed some throttle body cleaner into and on to the throttle bodies to get all the gunk off of them. It worked for me. I'm told there is an idle screw but you have to gain access to it with a drill. When the car saw the drill on the tool chest it began to run smooth.

 

ok.....here it is..check out the following link. print it, read it, read it again, get the proper tools, read it again then do it. It works. My car Idled really rough and high at about 1200 rpm.

http://www.corvettefever.com/techart...ing/index.html

I ran through this process. It took about an hour or so. My car now idles realtively smooth at about 650-700 rpm in gear and aroung 800 rpm in park or nuetral which is close but not perfect. My car has 120K on the original motor. I am sure if I rebuilt the TBI units it would idle perfect. Also I would change a few of the senors. IE: The coolant temperature sensor (CPS) and the O2 sensor. Check the EGR valve and make sure its working correctly as well. The crossfire cars are extremely sensitve to vaccum leaks aswell. Good luck and let us know how it turns out.

 

Keep the crossfire and fix it or sell the car and buy a differant year if you dont want crossfire. So many of these cars have been converted because the owners dont understand the system and get fed up with it. Also contrary to popular beleif these cars can be modified to put out well over 300 hp.

 

He is right about vacuum leaks. I found one little line that had came loose and once put back on it dropped a good 150 rpm.

 

these cars also have soft cam shafts , check for worn lobes that can cause a bad idle .vac leaks are the most common problem .check your plugs and see how they are burning.how many miles are on the car.

 

1980 L48 When I bought mine it idled rough. Traced each vacuum line down and found the leaker. Fixed and idle was corrected.

Darrel1

 

http://www.crossfire.homeip.net/cftest/try this.

 

Check or replace your EGR valve.

 

The throttle shafts wear badly generally at around 50k and become a vacuum leak. The only way to cure it is to have them bushed. Check the Crossfire Injection Vault forum on who offers that service.

This is only MO, but 800rpm at idle in park is way too high for a stock motor. I'm running a fairly high modded 383 CFI motor that only idles at about 750rpm with an XFI cam, so your motor is idling much higher than mine and being probably close to stock to boot.

My guess is that either you still have a vacuum leak somewhere else like the top plates or TB base, or your TB shafts are shot. The Crossfire Injection Forum is a much better place for info that caters to CFI only cars. If there are any CFI owners in the Phoenix AZ area that needs help with their CFI vette, contact me and I'll be glad to help you out and get your vette running the way it should.

 

Did you get your idle problem fixed?

 

Check the timing on the car: Remember to disconnect the computer connector before setting the timing. Suggested timing from GM is 6 degrees, but the car will perform better at 8 10 and 12 as long as it’s not pinging. Play with it and see what you get!

Many people try to set the timing on these cars and don’t know that its computer advanced! Check it to make sure, but also take a vacuum reading to check for other problems. We have a chart on our site called “the old fart vacuum chart”. It might help you isolate a problem if the vacuum is not within range.

You should also check the pressure on the fuel pump. This is done from the input side of the passenger side carb (I call them carbs since they are way far from what I would call fuel injection).

The fuel pressure should be around 12-14 lbs.

You can upgrade the fuel pump to the newer 85 and up style but then you will have to regulate the pressure to 14 lbs inbound. This will be an issue if you don’t have an adjustable fuel pressure regulator on the car.

The Throttle positioning sensor should be at 5.25 volts.

The other thing to check and as mentioned above would be the throttle shaft end play. These usually take a dump at 50 – 60 thousand miles. If you have play in them then you will need to have the units repaired.

There is also a site called. http://www.crossfireinjection.net/DCS%20Services.html which can rebuild your carbs.

Or there is another site to help with strictly cross fire cars called. http://www.crossfire.homeip.net/cftest/startdefault.asp which has many useful tips on these cars for you.

I hate to send anyone away form the forum, but this site has a ton of info on the 82 and 84 cars/

Willcox Inc.

 

CrossfireInjection.net (DCS) did a lot of work on my Crossfire and I couldn't be happier with them!!
I also had bad idle, throttle cut out at medium to high RPM - like is was running out of gas and just poor performance. DCS helped me install an 85-87 fuel pump, rebuilt, bushed and balanced both TB's and installed their Fuel Pressure Gauge assembly.
I have a C&V Vette also and they have no clue how to get these Crossfires running right - you would think C&V could get it right by now, especially with the number of 82-84 CFI they sell!!
Don't let anyone tell you the Crossfire is junk - You just need a little knowledge and time to learn about this unique system. If you are looking for more HP, it can be found with what you basically have; if you want Way more HP - then look for another vette.
Consider also, if you remove the CFI and install a carb(s), you will reduce the value of your Vette!
Be sure to check out the sites that Wilcox Corvette suggested, you can't go wrong!
Good Luck!