Crossfire Guru Needed
Thread Starter
Heel & Toe
Joined: Nov 2006
Posts: 15
Likes: 0
Crossfire Guru Needed
Im having problems with my 84 crossfire. Upon a cold start it runs fine. Once warmed up the idle will surge at times. When coming to a stop the car will sometimes stall, unless i feather the gas pedal. Anyone have any ideas, any help would be greatly appreciated.
Instructor
Joined: Dec 2007
Posts: 156
Likes: 0
From: Powhatan Virginia
Mag Article
There is an article in the Sept. issue of Corvette Enthusiast magazine about idling & running problems in 82 & 84 crossfires---seems many problems begin and end with vacuum leak problems--even mentions the vacuum operated headlamp doors---it's an interesting read for anyone --most especially if you own a crossfire.
Burning Brakes
Joined: Feb 2006
Posts: 1,098
Likes: 1
From: Webster Texas
The headlights in the 84 are not vacuum operated. The Throttle obdies may need re-bushing. IAC motors are possible culprits, though I havn't seen one fail. TPS may be the prob, and it may have a leak at the manifold/head or around the lid/top of the intake. Possibilities-check for leaks first. then go to the electronics.
Pro
Joined: Apr 2008
Posts: 694
Likes: 1
From: Spokane WA
Your coolant temperature sensor is probably going. Not a big deal to change and your car will run perfect again. But first check your computer for codes.
If it is surging and wanting to stall the computer thinks it is really cold out and puts more fuel in to keep it running but in actual fact it is just flooding the engine causing it to sputter when at a stop. It will run better when cruising because the car needs more fuel at speed.
It could be something else though.
If it is surging and wanting to stall the computer thinks it is really cold out and puts more fuel in to keep it running but in actual fact it is just flooding the engine causing it to sputter when at a stop. It will run better when cruising because the car needs more fuel at speed.
It could be something else though.
Intermediate
Joined: May 2008
Posts: 29
Likes: 0
From: Lively ON
Throttle body bushings...
I think these two ideas are pretty accurate. Take a look at your throttle bodies. Not very hard to do. Check if the bushings are shot. If they are, that's pretty much the problem, and even if it isn't you should fix it.
If those are tight, find someone with a comp to check the signal from your coolant sensor or just change it.
If those are tight, find someone with a comp to check the signal from your coolant sensor or just change it.
Team Owner
Joined: Mar 2001
Posts: 30,858
Likes: 293
From: Boston, Dallas, Detroit, SoCal, back to Boston MA
There used to be some really good cross-fire websites out there.
This is where getting the FSM(Factory Service Manual) can really pay off. All sorts of good dianostics.
I've only got the one for my 95, otherwise I could look your problem up.
This is where getting the FSM(Factory Service Manual) can really pay off. All sorts of good dianostics.
I've only got the one for my 95, otherwise I could look your problem up.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by 85vette-84vette
Your coolant temperature sensor is probably going. Not a big deal to change and your car will run perfect again. But first check your computer for codes.
If it is surging and wanting to stall the computer thinks it is really cold out and puts more fuel in to keep it running but in actual fact it is just flooding the engine causing it to sputter when at a stop. It will run better when cruising because the car needs more fuel at speed.
It could be something else though.
If it is surging and wanting to stall the computer thinks it is really cold out and puts more fuel in to keep it running but in actual fact it is just flooding the engine causing it to sputter when at a stop. It will run better when cruising because the car needs more fuel at speed.
It could be something else though.
Sloppy throttle shaft to housing clearance can cause a vacuum leak, but usually it prevents the throttle plates from closing properly and causes a high idle that can often be "kicked down" by blipping the throttle.
Usually a vacuum leak results in a faster than normal idle, but if it isn't a consistent leak, the ECM and IACs may be "chasing" varying conditions. I would look for vacuum leaks, first.
Have the TBs ever been removed from lid? If so, were the TBs properly synchronized? That can cause all sorts of idle and low speed drive-ability problems.
RACE ON!!!
Advanced
Joined: Jul 2008
Posts: 51
Likes: 0
Before spending money, torque down all the bolts around the perimeter of your intake top plate. Its worth a try. Also, maybe block off the EGR valve with a plate cut from a coke can (pepsi is for stupid mustang owners) as it creates a vacuum leak if it doesn't close all the way.
DO NOT spray carb cleaner around the intake looking for a vacuum leak and ESPECIALLY dont spray carb cleaner around the intake looking for a vacuum leak when the engine is hot if you have crappy plug wires that arc. That is a bad thing to do, but I'm not going to tell you how I know. ;-)
DO NOT spray carb cleaner around the intake looking for a vacuum leak and ESPECIALLY dont spray carb cleaner around the intake looking for a vacuum leak when the engine is hot if you have crappy plug wires that arc. That is a bad thing to do, but I'm not going to tell you how I know. ;-)
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Safety Car
Joined: Oct 2007
Posts: 3,816
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From: :45 minutes from everywhere / E-I-E-I-O
There is an article in the Sept. issue of Corvette Enthusiast magazine about idling & running problems in 82 & 84 crossfires---seems many problems begin and end with vacuum leak problems--even mentions the vacuum operated headlamp doors---it's an interesting read for anyone --most especially if you own a crossfire.
Thread Starter
Heel & Toe
Joined: Nov 2006
Posts: 15
Likes: 0
When the computer thinks the engine is cold, it opens the IAC to allow MORE air in for a FAST cold idle. A cold idle does call for a rich (choke) mixture, but with the higher idle speed it shouldn't cause the idle to surge like that and stall.
Sloppy throttle shaft to housing clearance can cause a vacuum leak, but usually it prevents the throttle plates from closing properly and causes a high idle that can often be "kicked down" by blipping the throttle.
Usually a vacuum leak results in a faster than normal idle, but if it isn't a consistent leak, the ECM and IACs may be "chasing" varying conditions. I would look for vacuum leaks, first.
Have the TBs ever been removed from lid? If so, were the TBs properly synchronized? That can cause all sorts of idle and low speed drive-ability problems.
RACE ON!!!
Sloppy throttle shaft to housing clearance can cause a vacuum leak, but usually it prevents the throttle plates from closing properly and causes a high idle that can often be "kicked down" by blipping the throttle.
Usually a vacuum leak results in a faster than normal idle, but if it isn't a consistent leak, the ECM and IACs may be "chasing" varying conditions. I would look for vacuum leaks, first.
Have the TBs ever been removed from lid? If so, were the TBs properly synchronized? That can cause all sorts of idle and low speed drive-ability problems.
RACE ON!!!
Melting Slicks
Joined: Jan 2005
Posts: 2,658
Likes: 4
From: Clifton Park NY
Crossfire fuel pressure should be between 9-13 psi.
Before assuming that your fp is bad have you checked your fuel filter? Its along side the passengers side frame rail just behind the front tire.
Last edited by qws; Aug 5, 2008 at 09:30 AM.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by Robs84c5
The TBs were removed a while back, and as far as I know they were just bolted back on. How do you synchronize them?
Originally Posted by Robs84c5
I have also found that my fuel pressure drops to about 10psi when I put a load on the engine. Anyone know how hard it is to change the fuel pump
RACE ON!!!
Thread Starter
Heel & Toe
Joined: Nov 2006
Posts: 15
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Fuel pressure / Fuel pump
The fuel pressure is about 13psi at idle, with a load it drops to about 10psi. I have already replaced the fuel filter.
The car has been siting for almost 3 years now, Ive owned it for the last 2years. The previous owner told me that during the winter the car was outside uncovered. The draing tube by the fuel filler/gas cap got plugged up and the gas tank filled up with water, due to melting snow. We siphoned the tank until it was empty, filled it with fresh gas and she fired up. This is why I have been suspecting the fuel pump.
The car has been siting for almost 3 years now, Ive owned it for the last 2years. The previous owner told me that during the winter the car was outside uncovered. The draing tube by the fuel filler/gas cap got plugged up and the gas tank filled up with water, due to melting snow. We siphoned the tank until it was empty, filled it with fresh gas and she fired up. This is why I have been suspecting the fuel pump.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
It sounds like you need a pump. It should hold pressure. As you rev it higher and put it under more load, does the pressure continue to drop? If so the pump isn't keeping up with the demand. However, even 10 psi (within specs) is more than enough to maintain a good idle, hot or cold. The first thing is to synchronize the TBs. That should be done, regardless. If that doesn't clear up the idle problem, go vacuum leak hunting. I think as already suggested, I would give all the cover bolts a tweak, to be sure none are loose.
RACE ON!!!
RACE ON!!!
1st Gear
Joined: Jun 2007
Posts: 1
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84 crossfire, floods out usually after a drive and re-start. do the clear flood start procedure. and even worse I can be at highway speed and it will do it. have to put in neutral and work the gas pedal till I rev the hell out of it to clear. I have FSM and just enough skill to get me in trouble. Have checked the temp sensor and it is tracking as the chart indicates. I've read the blogs and will look for related issues such as vac leaks. any other thoughts are welcome.
Burning Brakes
Joined: Feb 2013
Posts: 1,173
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From: norway
http://www.thecubestudio.com/Crossfi...estoration.htm http://www.corvettefever.com/techart...system_tuning/ http://forums.corvetteforum.com/c3-t...solutions.htmlhttp://crossfireinj.fr.yuku.com/ 
Last edited by corvettenorway; Mar 17, 2014 at 02:44 PM.
Racer
Joined: Sep 2007
Posts: 493
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From: Eden Utah
Man I started reading this post when I saw CFI-EFI sign in, almost freaked me out. Then I read that it was a older post. Jim has been dead for several years and was a real crossfire guru. You may also want to give a shout out to Tom400CFI as he is very knowledgeable. It is sad as a lot of the crossfire guys are gone and their knowledge has gone with them.