Will not run on all 8 cylinders
02-03-2011, 06:56 PM
#1
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Will not run on all 8 cylinders This is a brand new ls1 1999 c5 corvette install.
I have spark, I use a noid lite and see injectors pulsing even though pulsing lite is faint all injectors show faint lite strength. Even the ones that fire.
I chked the compression 150 lbs all across the board. I redid the valves to zero lash, I see 12 volt at coils
Basically 6, 3, 5 and 7 are the cylinders showing no fuel but some signs of spark on the plug. 1, 2 and 4 are pretty over rich but the 8th cylinder looks perfect.
Once started its like running half a motor with no codes either. Shows no missfires even though it may not be misfiring if getting spark and no fuel.
Does any one know if there is a way to tell the pcm to fire the coil and the injector manually from the pcm so I can test this?
I have the pcm open now testing for continuity but highly unlikely 4 cylinders would go out all at once. Will also be testing all grounds to pcm too.
One thing I did notice was the valve cover was pulling ground and it showed at the coil bolts also. Not sure if this needs to be insulated so the coils are not exposed to another ground or if this is ok because the ground to the ecu is separated from this?
I have spark, I use a noid lite and see injectors pulsing even though pulsing lite is faint all injectors show faint lite strength. Even the ones that fire.
I chked the compression 150 lbs all across the board. I redid the valves to zero lash, I see 12 volt at coils
Basically 6, 3, 5 and 7 are the cylinders showing no fuel but some signs of spark on the plug. 1, 2 and 4 are pretty over rich but the 8th cylinder looks perfect.
Once started its like running half a motor with no codes either. Shows no missfires even though it may not be misfiring if getting spark and no fuel.
Does any one know if there is a way to tell the pcm to fire the coil and the injector manually from the pcm so I can test this?
I have the pcm open now testing for continuity but highly unlikely 4 cylinders would go out all at once. Will also be testing all grounds to pcm too.
One thing I did notice was the valve cover was pulling ground and it showed at the coil bolts also. Not sure if this needs to be insulated so the coils are not exposed to another ground or if this is ok because the ground to the ecu is separated from this?
02-04-2011, 07:32 AM
#2
Coils are not isolated.
Used injs?
How long did the injs sit B4 you used them?
If used, and allowed to sit open for extended period of time, they may well be stuck shut. That could explain the random cyl problems.. Some stuck, some operating.
I see this frequently with injs I clean, that are in junk yard engines...
Used injs?
How long did the injs sit B4 you used them?
If used, and allowed to sit open for extended period of time, they may well be stuck shut. That could explain the random cyl problems.. Some stuck, some operating.
I see this frequently with injs I clean, that are in junk yard engines...
02-04-2011, 05:12 PM
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First thing I would verify is that you didn't miss any of the grounds or ground straps, since this is a new install. Is this a install into a similiar year? So there's no issue with reluctor wheel or cam sensor?
When the car runs do the gages stay stable or are the needles bouncing, etc? If you miss the ecu ground it creates all kinds of weird problems.
When the car runs do the gages stay stable or are the needles bouncing, etc? If you miss the ecu ground it creates all kinds of weird problems.
02-05-2011, 06:31 AM
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only 4 cylinders firing Hello All and thank you for your replies.
Old Geezer It is the same motor for the car just rebuilt. I had the injectors sitting for a year. That is what I will be doing today. Pulling the injectors and putting power to them to see if they click or not. My question is how do you clean the injectors?
Also what did you mean coils not isolated? Does that mean the coils definitely have to be isolated from the ground going thru the valve cover? I can do that easily but I ran this same setup for 6 years, never noticed if valve covers were grounded till now though so thats why I was trying to find out if the valve cover was designed to flow ground thru it or not.
Thank you ls2ttype but I am using 85lb rc engineering injectors.
Mike13 Thats the first thing I did was chk ground straps and splice packs but same issues even after going thru all the grounds. I can also assume the grounds to be good when one cylinder next to it is on the same ground works. I put in a new cam and crank sensor also. I am thinking it could also be the ecu but would like to know if there is a way I can test the cam and crank sensor at the ecu to make sure it is getting and passing the signal to the injectors to fire? Same thing for the injectors and coils. Can I test them also at the ecu to make sure the communication is complete?
Guages are stable. rpm looks smooth and registering and the idle is solid on only 4 cylinders running.
Old Geezer It is the same motor for the car just rebuilt. I had the injectors sitting for a year. That is what I will be doing today. Pulling the injectors and putting power to them to see if they click or not. My question is how do you clean the injectors?
Also what did you mean coils not isolated? Does that mean the coils definitely have to be isolated from the ground going thru the valve cover? I can do that easily but I ran this same setup for 6 years, never noticed if valve covers were grounded till now though so thats why I was trying to find out if the valve cover was designed to flow ground thru it or not.
Thank you ls2ttype but I am using 85lb rc engineering injectors.
Mike13 Thats the first thing I did was chk ground straps and splice packs but same issues even after going thru all the grounds. I can also assume the grounds to be good when one cylinder next to it is on the same ground works. I put in a new cam and crank sensor also. I am thinking it could also be the ecu but would like to know if there is a way I can test the cam and crank sensor at the ecu to make sure it is getting and passing the signal to the injectors to fire? Same thing for the injectors and coils. Can I test them also at the ecu to make sure the communication is complete?
Guages are stable. rpm looks smooth and registering and the idle is solid on only 4 cylinders running.
02-05-2011, 07:46 AM
#6
What I meant was the coils are not grounded thru the mounts. They have a ground circuit to control pulsing by the PCM.
Cleaning is a process that requires equipment to do, and to verify the flow B4/after cleaning. [To do it right]. Given they sat for a yr, they well could be sticky..Being U R using that large inj, indicates U R making some serious HP. I'd have them flow tested/cleaned.
Cleaning is a process that requires equipment to do, and to verify the flow B4/after cleaning. [To do it right]. Given they sat for a yr, they well could be sticky..Being U R using that large inj, indicates U R making some serious HP. I'd have them flow tested/cleaned.
02-05-2011, 08:21 AM
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running on 4 cylinders Old Geezer
I agree. The injectors will be cleaned and reflowed next week. I am just trying to get an idle tune going. Nothing else if I can get them working over the weekend or buy new ones but I need to be sure thats the issue which seems is the last thing left to check also.
Will keep you posted within couple hrs will have all inj tested. As for the cleaning process you said soak them over nite. Even the electronics part of the injector or I elevate that part out of the solution?
I understand the grounding circuit thru the pcm and how the signals work for the coils and that was why my concern over seeing ground in the valve cover and how it may have affected anything electrical from the coil to the pcm. Obviously the head ground is flowing thru the valve cover by way of the valve cover bolts irregardless of the large rubber grommer in the center bolts
I agree. The injectors will be cleaned and reflowed next week. I am just trying to get an idle tune going. Nothing else if I can get them working over the weekend or buy new ones but I need to be sure thats the issue which seems is the last thing left to check also.
Will keep you posted within couple hrs will have all inj tested. As for the cleaning process you said soak them over nite. Even the electronics part of the injector or I elevate that part out of the solution?
I understand the grounding circuit thru the pcm and how the signals work for the coils and that was why my concern over seeing ground in the valve cover and how it may have affected anything electrical from the coil to the pcm. Obviously the head ground is flowing thru the valve cover by way of the valve cover bolts irregardless of the large rubber grommer in the center bolts
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03-02-2011, 07:53 PM
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Will not run on 8 cylinders Sorry it took so long for a reply. Fried my old hard drive and just getting back online.
It was the injectors. They sat for a year and when I had them cleaned and flow rated afterwards they turned out as good as new.
The next issue I found was one of the coil wires going to the coil bank main pack on drivers side were corroded. Just a white film over the contact area from sitting also Im sure. Once cleaned up everything fired up and purrs nicely now
It was the injectors. They sat for a year and when I had them cleaned and flow rated afterwards they turned out as good as new.
The next issue I found was one of the coil wires going to the coil bank main pack on drivers side were corroded. Just a white film over the contact area from sitting also Im sure. Once cleaned up everything fired up and purrs nicely now
