TBI Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

Ive got a CFI problem

Thread Tools
 
Search this Thread
 
Old 11-23-2013, 10:37 AM
  #1  
Senior Member
Thread Starter
iTrader: (1)
 
Chevy8588's Avatar
 
Join Date: Feb 2009
Location: La Grange Park, IL
Posts: 972
Likes: 0
Received 1 Like on 1 Post
Car: 1987 Iroc Z28/ 1982 Z28
Engine: 355 TPI IP/ 305 CFI
Transmission: T-56/ 300C
Axle/Gears: 3.42 Open/ 3.73 Posi
Ive got a CFI problem

Ok I've got a 1982 Z28 with the crossfire system on it. It seems like it has weak spark because fuel delivery seems to be on point, ive got 10 PSI pressure at the filter up front, and the injectors deliver a nice conical spray. but the motor runs like ****. He's what Ive tried so far. I have a code for EST trouble. I replaced the entire dizzy with a known good one form a cfi car that ran. I also tried two coils. two syptoms that bother me is the tach bounces all over the place, it missfires like a son of a bitch, and ive noticed that as soon as i turn the car off, the fuel pressure bleeds off almost instantly. what do you guys think?
Old 11-23-2013, 12:37 PM
  #2  
Senior Member
Thread Starter
iTrader: (1)
 
Chevy8588's Avatar
 
Join Date: Feb 2009
Location: La Grange Park, IL
Posts: 972
Likes: 0
Received 1 Like on 1 Post
Car: 1987 Iroc Z28/ 1982 Z28
Engine: 355 TPI IP/ 305 CFI
Transmission: T-56/ 300C
Axle/Gears: 3.42 Open/ 3.73 Posi
Re: Ive got a CFI problem

no one?
Old 11-23-2013, 01:00 PM
  #3  
Supreme Member

 
Schurkey's Avatar
 
Join Date: Feb 2011
Posts: 1,523
Received 77 Likes on 61 Posts
Re: Ive got a CFI problem

Originally Posted by Chevy8588
It seems like it has weak spark
So test the spark. Buy a less-than-twelve-dollar spark tester, see what happens.
KD Tools 2756 Ignition Tester Calibrated For HEI Ignitions - Amazon.com KD Tools 2756 Ignition Tester Calibrated For HEI Ignitions - Amazon.com




Originally Posted by Chevy8588
two syptoms that bother me is the tach bounces all over the place, it missfires like a son of a bitch
If the ignition is interrupted, the tach will drop. When the ignition comes on-line again, the tach works again. First three things that come to mind:
  • Loose wires/poor connections on the power supply to coil
  • Loose wires/poor connections on power supply between coil and distributor
  • Defective pick-up coil (but you've already replaced the distributor)

Originally Posted by Chevy8588
and ive noticed that as soon as i turn the car off, the fuel pressure bleeds off almost instantly.
Is the cross-fire system supposed to retain pressure? The other GM TBI systems don't.
Old 11-23-2013, 03:52 PM
  #4  
Senior Member
Thread Starter
iTrader: (1)
 
Chevy8588's Avatar
 
Join Date: Feb 2009
Location: La Grange Park, IL
Posts: 972
Likes: 0
Received 1 Like on 1 Post
Car: 1987 Iroc Z28/ 1982 Z28
Engine: 355 TPI IP/ 305 CFI
Transmission: T-56/ 300C
Axle/Gears: 3.42 Open/ 3.73 Posi
Re: Ive got a CFI problem

i was unsure on the fuel pressure, as for the bouncing tach, i mean this things bouncing FAST, as if it were on a rubber band and someone flicked it
Old 11-29-2013, 07:13 PM
  #5  
Member

iTrader: (8)
 
tartagliaz28's Avatar
 
Join Date: Oct 2011
Location: upstate NY
Posts: 101
Likes: 0
Received 1 Like on 1 Post
Car: 2013 ZL1 convertible
Engine: 6.2 supercharged
Transmission: 6l90e
Re: Ive got a CFI problem

10 psi seem a bit to low, every thing I read It says to have at least 13 psi. my crossfire liked 14-15 psi. also check to see if your throttle bodies are sync together. google search that, plenty of articles on it.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
88rscamar0
Transmissions and Drivetrain
5
09-23-2015 09:08 PM
pjsparts
Tech / General Engine
6
09-17-2015 01:28 PM
Ranbo108
Tech / General Engine
14
09-09-2015 12:20 PM
383cam
Electronics
5
09-09-2015 06:01 AM
andy74
Electronics
2
09-03-2015 08:41 AM



Quick Reply: Ive got a CFI problem



All times are GMT -5. The time now is 12:40 AM.