lt1 swap starts and dies. power to control side of injector
12-24-2012, 10:56 AM
#1
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
lt1 swap starts and dies. power to control side of injector here is a rundown of everything i have checked. i did not wire the car up, im just trying to hunt down the problem for them.
i found that there is a little bit of voltage coming from the control side of the injector, .021 volts where the other has 12v. i swapped out the computer with another computer reflashed it with the same tune and it does the same thing.
they have replaced coil, ignition module, opti, map, tps, iacc
i have checked the power and grounds and all seem to be right.
this is a 94/95 caprice 4.3 l99 engine.
it does not have a maf on it but is tuned for it( shouldnt cause it not to stay running when i give it gas)
sometimes when it does stay running it missfires until it finally smooths out and runs fine... im lost with it
i found that there is a little bit of voltage coming from the control side of the injector, .021 volts where the other has 12v. i swapped out the computer with another computer reflashed it with the same tune and it does the same thing.
they have replaced coil, ignition module, opti, map, tps, iacc
i have checked the power and grounds and all seem to be right.
this is a 94/95 caprice 4.3 l99 engine.
it does not have a maf on it but is tuned for it( shouldnt cause it not to stay running when i give it gas)
sometimes when it does stay running it missfires until it finally smooths out and runs fine... im lost with it
12-24-2012, 10:59 AM
#2
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
doesnt seem to have vats, but could something with the nuetral safety cause this. what would cause injectors to not always fire? and have voltage to the control side
12-24-2012, 03:44 PM
#4
Weird if it runs from time to time....
There should be two power feeds in the harness for even and odd bank injectors. Is it one bank that is having issues? In the past when I do swap harnesses I tie the injector powers into one line and fuse it. Maybe there is abad connection in the power feeds?
There should be two power feeds in the harness for even and odd bank injectors. Is it one bank that is having issues? In the past when I do swap harnesses I tie the injector powers into one line and fuse it. Maybe there is abad connection in the power feeds?
12-24-2012, 09:48 PM
#5
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
Weird if it runs from time to time....
There should be two power feeds in the harness for even and odd bank injectors. Is it one bank that is having issues? In the past when I do swap harnesses I tie the injector powers into one line and fuse it. Maybe there is abad connection in the power feeds?
There should be two power feeds in the harness for even and odd bank injectors. Is it one bank that is having issues? In the past when I do swap harnesses I tie the injector powers into one line and fuse it. Maybe there is abad connection in the power feeds?
12-25-2012, 02:27 AM
#7
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
this is a swap into a 55 chevy so there isnt any of the factory fuses. but giving it throttle wont make it stay running. the injectors just arnt firing, whatever is causin them not to pulse is the problem. seems like a ground problem to me but they are all good at the computer.
Trending Topics
12-25-2012, 07:09 AM
#8
Teching In
Join Date: Oct 2012
Location: Va. Beach, VA
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Injectors get power the following method:
Black wire is battery power and controlled by a relay, under normal application, yours may be different, hopefully an inline fuse.
The other injector wire goes to the ECM and is pulsed by the ECM placing a LOW onto it - this wire is not placed to ground and generally a 0.5 volts. You have to use a noid light or a high impedance test light - no filament test lights to check the pulsing.
Another item to check is injector resistance, make sure the injector coils read the ohmic value. If one is higher/lower, it upsets the apple cart.
Black wire is battery power and controlled by a relay, under normal application, yours may be different, hopefully an inline fuse.
The other injector wire goes to the ECM and is pulsed by the ECM placing a LOW onto it - this wire is not placed to ground and generally a 0.5 volts. You have to use a noid light or a high impedance test light - no filament test lights to check the pulsing.
Another item to check is injector resistance, make sure the injector coils read the ohmic value. If one is higher/lower, it upsets the apple cart.
12-27-2012, 07:37 AM
#10
Launching!
Join Date: Oct 2011
Location: Dixon, IL
Posts: 284
Likes: 0
Received 0 Likes
on
0 Posts
+1. Might want to go to orileys and rent a NOID light set.
ohms measures resistance to the ground, so id say anything over 0.2 is too high. But check to make sure they are all similar in resistance.
ohms measures resistance to the ground, so id say anything over 0.2 is too high. But check to make sure they are all similar in resistance.
01-02-2013, 11:57 PM
#11
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
i have noid lights, they will light them up when they are working right, but when they are not working properly they stop lighting up. they are showing me anywere from 11.7 to 11.0 ohms. this is by putting one test lead on each of the injector prongs.
thanks for all of your help guys. please let me know if this is normal
thanks for all of your help guys. please let me know if this is normal
01-06-2013, 11:16 PM
#12
Most likely not your problem, but you may want to verify VATS is completely tuned out. Apparently there is "Normal VATS" and "Corvette VATS"
When I swapped a different year LT1 engine, harness, and PCM into my Trans Am I had a problem where the car would fire up, run for about 3 seconds then die due to the injector pulse stopping.
Turned out for some reason simply deactivating "Normal VATS" did not eliminate the VATS, and in my application both Normal and Corvetter VATS needed turned off for my injector pulse to not get cut off about 3 seconds after startup.
The injectors never pulsed for longer than 3 seconds until I had the mail order tuner tune out the corvette VATS though. Since in your scenario it is running intermittently this might now be your problem, but it wouldn't hurt to check.
When I swapped a different year LT1 engine, harness, and PCM into my Trans Am I had a problem where the car would fire up, run for about 3 seconds then die due to the injector pulse stopping.
Turned out for some reason simply deactivating "Normal VATS" did not eliminate the VATS, and in my application both Normal and Corvetter VATS needed turned off for my injector pulse to not get cut off about 3 seconds after startup.
The injectors never pulsed for longer than 3 seconds until I had the mail order tuner tune out the corvette VATS though. Since in your scenario it is running intermittently this might now be your problem, but it wouldn't hurt to check.
01-08-2013, 01:32 AM
#13
Restricted User
Thread Starter
iTrader: (2)
Join Date: Feb 2009
Posts: 707
Likes: 0
Received 0 Likes
on
0 Posts
ill check again sense i havnt messed with it for awhile. i have ion soltan of mad tuner look over the tune for me and he said there wasnt any vats turned on and i looked thru it and also didnt see anything that looked odd. all i seen for vats was the checked boxs in tunercats.
