Cam position sensor keeps going bad?
10-12-2010, 06:44 PM
#1
Cam position sensor keeps going bad? Ok. put together a new motor.. Used my old harness. I dont remember pins off top of my head, but i have the 12v, ground, and signal wire. All wires work, no pinch's and no burns. They all ohm out between ecu side and sensor side.
So I started with a brand new sensor. Worked fine, never saw a code. Went to dyno, after the first pull i was getting a code and it was not reading. tuner had some used ones laying around. Put one in, and it worked. Finished tuning, Went to the track ran the car was fine for several runs. End of the night, cel comes on, and it says cam position sensor again. I reset it and it stayed off for a little while. What could be causeing this? i tried to search, didn't see anything.
Thanks in advance, Chris
So I started with a brand new sensor. Worked fine, never saw a code. Went to dyno, after the first pull i was getting a code and it was not reading. tuner had some used ones laying around. Put one in, and it worked. Finished tuning, Went to the track ran the car was fine for several runs. End of the night, cel comes on, and it says cam position sensor again. I reset it and it stayed off for a little while. What could be causeing this? i tried to search, didn't see anything.
Thanks in advance, Chris
10-12-2010, 09:18 PM
#2
11 Second Club
iTrader: (13)
Join Date: Dec 2001
Location: Escondido, CA
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
I had similar problems though I did not replace the cam sensor. I reset the CEL a couple of times. Cam gear bolts had come loose and the cam gear was moving around. Cam walked back and took out the lifters and the entire shortblock.
BEWARE: the cam bolts torque specs from GM are wrong. If you torque the cam bolts down to 18 ft lbs per the GM spec you're cam gear will come loose.
I even used red loctite.
Not to scare you but I would check and see if the cam gear is loose. Do not drive it until you check it. I took out a LS3 Crate motor in less than 500 miles.
My .02.
DJ
BEWARE: the cam bolts torque specs from GM are wrong. If you torque the cam bolts down to 18 ft lbs per the GM spec you're cam gear will come loose.
I even used red loctite.
Not to scare you but I would check and see if the cam gear is loose. Do not drive it until you check it. I took out a LS3 Crate motor in less than 500 miles.
My .02.
DJ
10-12-2010, 09:21 PM
#3
I had similar problems though I did not replace the cam sensor. I reset the CEL a couple of times. Cam gear bolts had come loose and the cam gear was moving around. Cam walked back and took out the lifters and the entire shortblock.
BEWARE: the cam bolts torque specs from GM are wrong. If you torque the cam bolts down to 18 ft lbs per the GM spec you're cam gear will come loose.
I even used red loctite.
Not to scare you but I would check and see if the cam gear is loose. Do not drive it until you check it. I took out a LS3 Crate motor in less than 500 miles.
My .02.
DJ
BEWARE: the cam bolts torque specs from GM are wrong. If you torque the cam bolts down to 18 ft lbs per the GM spec you're cam gear will come loose.
I even used red loctite.
Not to scare you but I would check and see if the cam gear is loose. Do not drive it until you check it. I took out a LS3 Crate motor in less than 500 miles.
My .02.
DJ
You just scared the crap out of me.
Thank you though, Chris
10-12-2010, 09:38 PM
#5
I hope/ dont think this is the problem. but now i have to check it. I was going to pull the trans and send the converter in to get it restalled, its a little to loose, so i guess i can pull the turbo,crank pulley, and front cover.
Thanks, Chris
Thanks, Chris
10-12-2010, 11:18 PM
#6
11 Second Club
iTrader: (13)
Join Date: Dec 2001
Location: Escondido, CA
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
Re-read your post: This would apply to a LS2 or LS3 with cam sensor in the front cover. If its a LS1 sensor, you should be OK.
I guess I have LS3 on the brain.
DJ
I guess I have LS3 on the brain.
DJ
10-14-2010, 06:37 AM
#11
TECH Regular
iTrader: (12)
Join Date: Mar 2003
Location: Hershey, PA
Posts: 453
Likes: 0
Received 0 Likes
on
0 Posts
It still could be a loose cam.
My buddy in his 04 vette randomly had a cam position sensor code. I did some research on corvetteforum and turns out it was loose cam bolts. This was a bone stock car, just CAI and TB swap.
When we got the cover off you could see there was about 1/16" gap between the heads of the bolts and the cam sprocket. He was CRAZY lucky they didn't back out any further and trash the motor.
One sign that he noticed before the code started was the car seemed to crank longer than normal. He tought maybe his battery was goin bad, until the cam sensor code popped up.
My buddy in his 04 vette randomly had a cam position sensor code. I did some research on corvetteforum and turns out it was loose cam bolts. This was a bone stock car, just CAI and TB swap.
When we got the cover off you could see there was about 1/16" gap between the heads of the bolts and the cam sprocket. He was CRAZY lucky they didn't back out any further and trash the motor.
One sign that he noticed before the code started was the car seemed to crank longer than normal. He tought maybe his battery was goin bad, until the cam sensor code popped up.
10-14-2010, 03:23 PM
#13
TECH Senior Member
You may need to find someone with an oscilloscope (who knows how to use it) to look at the CMP waveform, this will give a clue as to what is happening (cam walking vs intermittent wiring).
02-15-2011, 07:58 PM
#16
We finally got around to checking the cam and it was all good. What else can it be, and what should we look at? Like I said my boss is a car guy who happens to be an electrical engineer that has a few oscilloscope's and knows how to use them. Is that the next step?
Sean
Sean
02-15-2011, 08:57 PM
#19
TECH Senior Member
We finally got around to checking the cam and it was all good. What else can it be, and what should we look at? Like I said my boss is a car guy who happens to be an electrical engineer that has a few oscilloscope's and knows how to use them. Is that the next step?
Sean
Sean
02-15-2011, 09:04 PM
#20
TECH Senior Member
Warning:
to protect your boss's oscilloscope, always measure each waveform wrt to ground (i.e. connect all the probe grounds to chassis/battery ground and not to the sensor);
this is critical on multiple channel scopes that have each probe's ground connected to a common point.
to protect your boss's oscilloscope, always measure each waveform wrt to ground (i.e. connect all the probe grounds to chassis/battery ground and not to the sensor);
this is critical on multiple channel scopes that have each probe's ground connected to a common point.
