When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So, back again. I've read every single troubleshooting thread on CMP for 01 ws6. Car ran like a raped ape for years. Broke the crank last year, new stroker kit over the winter. Same cam, small bump in compression, also got rid of the underdrive pulley for stock style ls1. Iron 408 stroker, big custom cam. Ls3 heads, ect ect. Like I said, ran great last year. Dropped new motor in it. It'll crank and spit and sputter and fire occasionally but runs like crap, revs up and then dies. It's only throwing P3042 Low voltage circuit for cam. I've tried 3 sensors, backtracked the wires all the way from the sensor it's self to the PCM. Have no breaks in connection. Checked timing kit, cam, relucter wheel on cam, all cyl driver side grounds are on. I'm damn near ready to sell it. It's been weeks of troubleshooting. Please lord someone help. Scanner shows erratic rpm reading while cranking. I have checked the harness on pass front cyl head that has the cam signal running through it. I'm out of ideas and really ready to send this thing to the yard.
Is the cam sensor In the back of the block or in the front cover on the new motor?
it's in the back of the block. No wire extensions. Someone said that bc i used the PCM as a weight to weigh down the replacement Dash, it sitting in the window in the sun, it may have baked it. But I've also heard pcm issues are incredibly rare.
Engine bay gets hot too I doubt the dashboard heat did anything. But the low voltage thing could honestly be a pcm issue, which is what I'm leaning towards. Internal power supply kind of issue. Good news is they're cheap.
On the gen3, cam sensor alone won't cause it to run poorly. Just take longer to start.
Engine bay gets hot too I doubt the dashboard heat did anything. But the low voltage thing could honestly be a pcm issue, which is what I'm leaning towards. Internal power supply kind of issue. Good news is they're cheap.
On the gen3, cam sensor alone won't cause it to run poorly. Just take longer to start.
If you have not yet, verify all your pcm fuses.
As far as I can tell it's just 1 PCM fuse under the hood. Also, the tach will work for a quick second when it fires but then it stops working while the car runs, which it runs terribly. Then it dies and is terrible to get it to hit again. I've heard of crank sensor and cam sensor issues being intertwined before. Any ideas there?
I went back and looked -- for sure I disabled code P0342 to get my tach working. Give that a try. Basically, tach works until that code is set. Once that code sets, tach quits.
I had wondered if you got a 58x crank reluctor by mistake.
Cam sensor codes will prevent tach from working. I went through that on mine. Disabled the code and the tach works again.
It's definitely a 24x relucter wheel, I have pics of the assembly. So, this is unrelated but I dropped the Ls3 intake off the car when I was assembling everything. Had a pretty knarly cracked. Fixed it, but when It fell it broke the old map sensor off. And I didn't realise for about 2 weeks, so the old broken one disappeared. I replaced it with a factory ls1 style and it fired uo after that. But you said the cam sensor won't make it run like crap? This cam is very big. 250+ duration@ 50. The cam sensor won't make it run bad even with a cam that large? Anything you can think of that would be contributing to it not staying running
On the gen3 Ecu, the cam sensor is literally a 1 for 180 degrees of cam rotation and a 0 for the other 180. All it does is tell the Ecu if cylinder 1 is on the compression stroke or the exhaust stroke. Without the cam sensor, If after 3 seconds, it does not fire, it automatically switches to the opposite stroke.
The cam sensor does not see the valve events.
Edit - kind of a rare/obscure problem. A friend of mine fought his like crazy. Had a bent tooth on the crank reluctor. No codes. Just refused to run.
On the gen3 Ecu, the cam sensor is literally a 1 for 180 degrees of cam rotation and a 0 for the other 180. All it does is tell the Ecu if cylinder 1 is on the compression stroke or the exhaust stroke. Without the cam sensor, If after 3 seconds, it does not fire, it automatically switches to the opposite stroke.
The cam sensor does not see the valve events.
Edit - kind of a rare/obscure problem. A friend of mine fought his like crazy. Had a bent tooth on the crank reluctor. No codes. Just refused to run.
I appreciate the input man. I'm hoping to find some tuning wizard or Ls dude on here that can help me. It doesn't make sense, I took my Ohm meter and checked every wire from the PCM that feed the crank sensor, all gave a audible beep meaning there wasn't any breaks in the wires. None of the sensor make any difference. It does have check guages and low oil light on the dash. It sucks man, I've put 10k in the car to get it ready for car show and drag racing season and I'm on the bench watching everyone run and show there cars. It's terrible. How can I tune the code out? It won't throw any other code, I know you said it should still run, right?
In the diagnostic portion of hptuners, the various codes are listed. Find P0342 in the list and set it to "no error reported" and the code will no longer set.
After replacing stock block with TSP 370 we had identical issues as you state. The installer discovered that he has missed plugging in the map sensor wire harness into the map sensor located on the back of the intake. It plugs in only one way.
Since you state that you replaced the LS3 intake with an LS6 intake you might have lost the orange grommet that creates a seal when you press the map sensor into the hole in the intake. The map sensor snaps into place with tangs to hold it in place. Apply silicone sealer to the grommet.
If the orange rubber grommet was lost in the transition and you didn't notice it was missing from your map sensor, the sensor is not reading vacuum accurately.
IMO get a new map sensor - but - some come packaged with the orange grommet - some do not.
So you have to buy the orange rubber grommet. It's pricey at about $10. See pic below.
Some sensors come with lock down tangs on both sides. I had to grind off the tabs on one side to hold it in place when in you install it. See pic below.
Make sure that the small vacuum tube is connected to the HVAC for shutter door air control. If you have removed your ac you cap the vacuum tube. If not make sure the vacuum tube is connected below the map sensor.
The map sensor operation is based on supplying 5 volts of DC power to the sensor from the PCM (Power System Control Module). Inside the MAP sensor is a resistor that moves in response to the intake manifold pressure. The resistor alters the voltage between 1V and 4.5V (depending on engine load), and the voltage signal returns to the PCM to indicate manifold pressure (vacuum). This signal is required by the PCM to determine fuel delivery and is occasionally used to determine whether the EGR valve is functioning properly.
Last edited by dlandsvZ28; 06-19-2022 at 03:22 PM.
Reason: edit content
LS3 intake has the map in the front of the manifold. The portion with the gasket is physically larger, so I'd expect the LS1 sensor not to fit correctly.
LS3 intake has the map in the front of the manifold. The portion with the gasket is physically larger, so I'd expect the LS1 sensor not to fit correctly.
OP's Quote "So, this is unrelated but I dropped the Ls3 intake off the car when I was assembling everything. Had a pretty knarly cracked. Fixed it, but when It fell it broke the old map sensor off. And I didn't realise for about 2 weeks, so the old broken one disappeared. I replaced it with a factory ls1 style and it fired uo after that."
It's difficult to determine which sensor the OP used to replace the LS3 sensor. Or what cracked - the intake manifold housing for the sensor or the sensor itself. It's my understanding you have to use an adapter to use an LS1 sensor. Some say the pigtail plug end has to be changed as well.
Correct. The LS3 sensor is a different plug than the LS1.
So who knows what the OP actually has? He said LS3 intake. So based my comments on that.
Shoot, he said it was running with no map sensor at all! 😊
I'm not sure if it actually ran with out it or not, it was quite a while ago. I have some pics of the old sensor however they're kinda poor quality. I also have some pics of the connector. The new sensor is physically smaller. It would make sense for it running bad with the wrong map sensor, even if the plug lined up. It is indeed a ls3 rec port intake on rec port heads. The baseman tune was done whenever the original builder built the car years back. Let me see if I can find the keys and I'll run out and get some pics of the replacement map sensor.
OP: did you read my previous post with all of the links. If not please read those again. In one of the links it states the LS1 sensor is different than the LS3 sensor (internally). If you are NA - you should use a 1 bar map sensor.
There are two intake manifolds with rectangular ports - the L76 and the L3. If you have the L76 intake the sensor clips on the front of the intake. If you have the L3 the sensor in held in place with a bolt on the front of the intake. Which one do you have?
The L76—like its LS2 sibling—is a 6.0L, Gen. 4, aluminum small block engine that was used both in GM cars and trucks. The L76 is an adapted version of the LS2, featuring new rectangle port cylinder heads.
IMO you need to find out which sensor will work with your current PCM and pigtail plug end. In the links above some say yes, some say no.
Since the map sensor on the LS6 intake is in the back of the intake and the LS3 sensor is on the front of the intake, did you use an adapter harness with enough length to reach the front LS3 sensor? There are adapter harness's available to make the switch from LS1 style to LS3 sensor.
Edit - kind of a rare/obscure problem. A friend of mine fought his like crazy. Had a bent tooth on the crank reluctor. No codes. Just refused to run.
I had the same issue on my first build. The car would start, run like crap then die. Finally pulled the crank sensor and took a peek at the reluctor while a friend rotated the engine. Sure enough had a bent tooth. We were able to get it straight enough through the hole so that the car would run. Worth checking out.
06-17-2022, 08:12 PM
Impossible cam sensor problem 
