Injector Ohm question
Thread Starter
Heel & Toe
Joined: Apr 2006
Posts: 23
Likes: 0
Injector Ohm question
1992 coupe, 6 spd, 103k miles. I replaced a lot of parts last spring - new water pump, MSD opti, found two cracked vac hoses, new radiator, cleaned throttle body, replaced cruise cont vac hoses and adjusted throttle cable. It then wouldn't idle worth a s--t. I replaced the IAC. The idle got better but still stalled and/or ran rough. I then discovered the EGR would not hold vac - it was replaced. The idle is quite better - no stalling but rpm at idle rises and falls whether hot or cold.
I then checked the resistance on injectors. They read 11.3 to 11.7 ohms on all eight. I know this site says 16 ohms. Vette magazine says "low teens" and Corvette Fever Mag has said "they should all read the same + or - 2 or 3 ohms." The FSM - from all I can find - says to check the resistance but gives no resistance guidelines. HELP !!
Do I have good injectors or are they all failing together ?
I then checked the resistance on injectors. They read 11.3 to 11.7 ohms on all eight. I know this site says 16 ohms. Vette magazine says "low teens" and Corvette Fever Mag has said "they should all read the same + or - 2 or 3 ohms." The FSM - from all I can find - says to check the resistance but gives no resistance guidelines. HELP !!
Do I have good injectors or are they all failing together ?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
The coil resistance you posted is fine for the LT1 injectors.
http://forums.corvetteforum.com/show....php?t=1568928
EDIT: check the fuel pressure leak down for a leaky injector or two causing the idle problem. "The idle is quite better - no stalling but rpm at idle rises and falls whether hot or cold.".....sounds like a vacuum leak.
http://forums.corvetteforum.com/show....php?t=1568928
EDIT: check the fuel pressure leak down for a leaky injector or two causing the idle problem. "The idle is quite better - no stalling but rpm at idle rises and falls whether hot or cold.".....sounds like a vacuum leak.
Last edited by RRT vette; Dec 9, 2006 at 03:11 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Measuring the d.c. resistance of coils to determine their quality is almost worthless. Direct current is not supplied to your injector coils, pulsed current is and to determine if your coils are good, you need to measure the inductance and the Q. This is done with an impedance bridge. A really cheap instrument for measuring coil Q can be done with your computer if it has a sound card, you build a simple two op-amp circuit, and you install some free software. Info is available at www.arrl.org/qex/2005/Steber.pdf
I think they charge $3 to download the article on using your pc to measure impedance.
I think they charge $3 to download the article on using your pc to measure impedance.
Thread Starter
Heel & Toe
Joined: Apr 2006
Posts: 23
Likes: 0
Thanx Guys. I am worried about another vac leak The trouble I have with checking vac is the up-and-down idle causes the vac guage to go berzerk. The needle rapidly moves btw 15hg and 10hg at the bad idle but the moment I get it off idle the vac jumps to 20hg and stays there. I have seen the great post on reading a vac gauge. The best description is scenario 15 - but, obviously, I don't have a carb.
Other than injectors my last hope is checking the vapor canister lines for air leaks. I got the car a year ago and when I removed the gas cap there was a release (or intake) of air. Since the idle problem there is no air release when I remove gas cap.
Oh yeah - no codes. I also replaced both O2 sens.
Other than injectors my last hope is checking the vapor canister lines for air leaks. I got the car a year ago and when I removed the gas cap there was a release (or intake) of air. Since the idle problem there is no air release when I remove gas cap.
Oh yeah - no codes. I also replaced both O2 sens.
