Need some help- LSX carb conversion not getting spark with supplied ignition box
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Registered User
Joined: Mar 2001
Posts: 2,521
From: Costa Mesa, CA
Need some help- LSX carb conversion not getting spark with supplied ignition box
I'm posting this for a friend who's not on here. He's running out of ideas for troubleshooting a project that's been in the making for a while now. This information has been filtered through a few people to me so I could post this thread, so I'll do the best I can to keep it accurate-
The project is an LS2 swap into a fox body mustang. For simplicity sake, the owner decided to convert to a carburetor, and run a manual transmission. The LS2 shortblock came from Scoggin-Dickey, it has patriot stage III heads, a really healthy cam with somewhere near .630 lift (can't remember exactly) and the usual complement of bolt ons. From what I understand he bought the LS1 carb conversion deal, that comes with some MSD electronics intended to control the factory coil packs. I was told that this system uses a crank position sensor and a cam position sensor as inputs. Apparently, the ignition checks the crank position sensor first, and if that's ok it then checks the cam position sensor, and after these things check out it will spark.
The guy has already pulled the motor back out of the car since someone said the crank reluctor ring might be backwards, and it checked out fine. He has also replaced the crank sensor twice, to no avail. He has come to the conclusion that for some reason the ignition is not recognizing the crank position sensor, even though on a test it showed 24 pulses (the guy said waves, but I think he meant pulses). Apparently there are 24 teeth on this reluctor ring, so it should get 24 pulses per revolution??
There is no spark at any of the plugs, the motor just turns over. The guy has dropped $1300 on some prototype ignition system and had it overnighted to see if it would work, still nothing. If you guys have any input, not matter how minute it may seem I would appreciate it so I can pass it on to this guy. I figure that not many on here have converted to a carb, but any knowledge about how the reluctor rings, crank/cam position sensors work would be helpful. Thanks!
The project is an LS2 swap into a fox body mustang. For simplicity sake, the owner decided to convert to a carburetor, and run a manual transmission. The LS2 shortblock came from Scoggin-Dickey, it has patriot stage III heads, a really healthy cam with somewhere near .630 lift (can't remember exactly) and the usual complement of bolt ons. From what I understand he bought the LS1 carb conversion deal, that comes with some MSD electronics intended to control the factory coil packs. I was told that this system uses a crank position sensor and a cam position sensor as inputs. Apparently, the ignition checks the crank position sensor first, and if that's ok it then checks the cam position sensor, and after these things check out it will spark.
The guy has already pulled the motor back out of the car since someone said the crank reluctor ring might be backwards, and it checked out fine. He has also replaced the crank sensor twice, to no avail. He has come to the conclusion that for some reason the ignition is not recognizing the crank position sensor, even though on a test it showed 24 pulses (the guy said waves, but I think he meant pulses). Apparently there are 24 teeth on this reluctor ring, so it should get 24 pulses per revolution??
There is no spark at any of the plugs, the motor just turns over. The guy has dropped $1300 on some prototype ignition system and had it overnighted to see if it would work, still nothing. If you guys have any input, not matter how minute it may seem I would appreciate it so I can pass it on to this guy. I figure that not many on here have converted to a carb, but any knowledge about how the reluctor rings, crank/cam position sensors work would be helpful. Thanks!
Registered User
Joined: Oct 2000
Posts: 1,665
From: Livonia, Mi
Re: Need some help- LSX carb conversion not getting spark with supplied ignition box
Yeah the reluctor ring on the LS2 crank isn't compatible with the LS1 CPS. It's not the teeth on the edge its the holes in the side. Look on CorvetteForum in the C5 tech section.
Thread Starter
Registered User
Joined: Mar 2001
Posts: 2,521
From: Costa Mesa, CA
Re: Need some help- LSX carb conversion not getting spark with supplied ignition box
I looked on corvetteforum, but didn't find anywhere I can search. Maybe I have to be registered to search? If you run across that thread again, and could link me that would be great!
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