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02 lightning/03 cobruh
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Discussion Starter · #1 ·
Alright I need some help guys, I'm losing my marbles and it's driving me nuts RN on what's going on.



02 L, got a built short block in and had it startup fine on the stock setup. Truck sounded great but I only ran it for a little while because I guess my pumps were to much for my stock rails so I ended up redoing my fuel system and did a return setup.



After finally fixing all the leaks and whatnot and uploading a new tune for the new fuel setup, I can't get it to turn over and run now. I'm seeing 40psi at the rails and at the regulator.



Also my code I'm throwing is for a camshaft position sensor. I already put a new one in, but also swapped in another sensor from my HD. I clear the code and try to start again, it'll catch and them immediately throw the code again and die.



I don't think it's a timing issue because I had it running before. It sounded great. Has anyone had this problem before? I guess I gotta pull a schematic now but the thing I don't understand is why it ran before. The only thing thats different from now and earlier was, I added a LFP TB and the return setup. I don't think it's a tune issue, I tried to run it on stock tune/tune I had previously, and new tune for the pumps to be on constantly.



Any suggestions on what to look at before I light it on fire would be greatly appreciated! I can upload videos of it running before and trying to start it now if that'll help.
 

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02 lightning/03 cobruh
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109 Posts
Discussion Starter · #5 ·
Might have to trouble shoot the wiring for the camshaft position sensor. Could be a bad wire on the connector itself.
Wires look good in trying to see if I can find a diagram for that. If it's not that then I'm going to pull injectors and get them flow tested. After that, I'm going to pull the cover. After that I'm lighting it in fire.
 

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02 lightning/03 cobruh
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Discussion Starter · #6 ·
After the TB install, did you check TPS voltage when you swapped sensors? Codes don鈥檛 seem to relate to this issue though.
No I didn't get that far. I don't think that could be the problem but I swapped my stocker back on. No dice.
 

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02 lightning/03 cobruh
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Discussion Starter · #7 ·
Okay soooooo I unplugged the connector going to the sensor cause I was watching a old video of when it did start and noticed it was not plugged in. So I just unplugged it and guess what. It started! I have no idea what that means lol .
 

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02 lightning/03 cobruh
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Discussion Starter · #9 ·
Did u happen to forget to install the trigger wheel?
My friend assembled the motor. But I think he did everything correctly. It started before the return setup. I'm going to pull the injectors and compression test this weekend. She will start now without fluid if the sensor is unplugged but it won't stay on for long. Doesn't sound like it's misfiring. Idk
 

I paid my buck-o-five
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No I didn't get that far. I don't think that could be the problem but I swapped my stocker back on. No dice.
sounds the TPS is adjusted wrong鈥
 

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02 lightning/03 cobruh
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Discussion Starter · #11 ·
sounds the TPS is adjusted wrong鈥
It probably isn't for the lfp one, but it was for the stock one. I'm going to get to that this weekend too tho. JJ said it's probably clogged injectors so I'm going to do that first.
 

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02 lightning/03 cobruh
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Discussion Starter · #12 ·
Okay so my friends came down this morning and went thru everything. Ones a electrician and ones a mechanic. I trust them and they pinned everything out and everything is good except the crankshaft position sensor is not getting power. I had a upgraded 300amp alternator and they think that maybe it spiked or something and fried something in the PCM. When we initially started the truck for the very first few times a few months back, we never had the accessory belt hooked up. This current issue started the second round after putting the fuel system in and then finally putting the belt on. The only other thing that possibly could have done anything electrical was that I had a battery tender on it.

So what is my best option in fixing this? Should I send my pcm out to repair, find another PCM, or run the ms3 I still have? Has anyone else had a problem like this before? Ms3 should basically be plug and play, the only thing would be that I have to figure out the intercooler pump to the ms3 and I need a trans controller from megasquirt which is around 420. I'm guessing if the capacitors are fried in the PCM it probably would be around the same price as the trans controller. If I just get another lightning pcm, I would also need the odometer part in the cluster right, or I would get problems with PATS? This sucks a big bag of ** but on the bright side at least my friends were able to figure out what was going on at least, friggin my dumbass luck, is killer sometimes.

What do you guys think my best course of action is here?
 

Pilsung
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If I remember correctly, the crank sensor is a
two wire variable reluctance sensor and doesn鈥檛 have a reference voltage like a 3 wire. The sensor鈥檚 signal is messured in AC voltage. I wouldn鈥檛 rule out the PCM 100%. In most cases, the injector drivers fail on these Lightning PCM鈥檚. Not saying I am right, but I would look into it more before ripping out the computer. Breakout boxes are cool for diagnosing but pricey.
 

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02 lightning/03 cobruh
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Discussion Starter · #14 ·
If I remember correctly, the crank sensor is a
two wire variable reluctance sensor and doesn鈥檛 have a reference voltage like a 3 wire. The sensor鈥檚 signal is messured in AC voltage. I wouldn鈥檛 rule out the PCM 100%. In most cases, the injector drivers fail on these Lightning PCM鈥檚. Not saying I am right, but I would look into it more before ripping out the computer. Breakout boxes are cool for diagnosing but pricey.
Electrical and diagnosing are definitely not my strong suit. My friends showed up today and knew the pinouts and they probed everything that they needed to. I just turned the key on and off when I was told to lol.
My friends theory was this. When we first started my motor the first few times after dropping it in, we didn't have the accessory belt on the first few times..I have a upgraded 300 amp alternator. It's brand new and the rebuild shop bench tested it when I picked it up and all was good. Buuuut this time around we did hook the belt up. My friend thinks that it may be faulty and somehow has something to do with the current cam sensor issue. The alternator now being hooked up, the fuel system and the TB, are the only variables that changed. My friends were just using multimeters and a power probe I think and a diagram.

I had issues with my daily last year. It's a old ls430. Started having weird issues with shifting. Ended up sending the PCM out to I think it was s1a electronics in Florida and they ended up fixing it. They changed some capacitors I think. When I threw it back in it took care of my problem.

I'm hoping it's something similar at this point. I'm pretty sure we would want it to be the PCM at this point. Because if it doesn't turn out to be that
, It means that it's a gremlin and we're back at square one. It's not the timing, because when it does turn over it's not misfiring and sounds decent for a few seconds before it throw the code. The sensors are good. Fuel is a good. All signs point to the PCM at this point. It's weird that something happened from the first start-up and now, the main suspect is the alternator as the fault.
 

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02 lightning/03 cobruh
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Discussion Starter · #15 ·
Just updating. I pulled the PCM and dropped it off with a repair guy he bench tested and said it's a good. He suggested hard resetting the battery which I also did. Same thing. It'll turn over and then die when it throws the code. Could it be the crank sensor or something else I'm overlooking?

I also pulled injectors and had them flow tested and they're good. Still seeing 40 at rails and regulator.


I'm also showing these codes after the hard reset. Not sure if it's related.
 

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10 second street truck
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The codes are
crank sensor
Evap
Fuel pressure

The truck is throwing a crank sensor code and won't run with it plugged in.

I'd be curious if the trigger wheel is on wrong or the wrong wheel. You can't test the crank sensor key on and key off. It needs to be done cranking. As stated previously it's a magnetic signal that sends a sine wave to the ecm.

I don't know the whole story behind the truck but evap and fuel pressure could be issues with removing emissions.
 

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02 lightning/03 cobruh
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Discussion Starter · #17 ·
The codes are
crank sensor
Evap
Fuel pressure

The truck is throwing a crank sensor code and won't run with it plugged in.

I'd be curious if the trigger wheel is on wrong or the wrong wheel. You can't test the crank sensor key on and key off. It needs to be done cranking. As stated previously it's a magnetic signal that sends a sine wave to the ecm.

I don't know the whole story behind the truck but evap and fuel pressure could be issues with removing emissions.
Camshaft position sensor. The thing is that it ran before I redid the fuel system and it sounded good like in the video, but as stated I'm getting 40 psi at rails and regulator. Injectors we're flow tested and are good..i posted a video of what's going on in the previous replies here. Sensor was swapped with a known working one and same deal. I'll swap the crank sensor tomorrow from the Harley I guess to troubleshoot.

The evap codes only showed after I put the PCM back in and hard reset the battery as the guy that bench tested it suggested trying. They did not show before when it was only throwing the camshaft position code. When it starts for a few seconds, it's not misfiring.

The guy that bench tested the PCM said if the hard reset doesn't work then maybe he can update it, but I think he's yanking my chain on that one cause he said it'll cost a couple hundred to do so.
 

10 second street truck
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Camshaft position sensor. The thing is that it ran before I redid the fuel system and it sounded good like in the video, but as stated I'm getting 40 psi at rails and regulator. Injectors we're flow tested and are good..i posted a video of what's going on in the previous replies here. Sensor was swapped with a known working one and same deal. I'll swap the crank sensor tomorrow from the Harley I guess to troubleshoot.

The evap codes only showed after I put the PCM back in and hard reset the battery as the guy that bench tested it suggested trying. They did not show before when it was only throwing the camshaft position code. When it starts for a few seconds, it's not misfiring.

The guy that bench tested the PCM said if the hard reset doesn't work then maybe he can update it, but I think he's yanking my chain on that one cause he said it'll cost a couple hundred to do so.
If swapping sensors doesnt fix it, and you're having more and more issues I'd lean towards wiring. It's possible you're damaging it more and more.

Three unrelated issues that cropped up after your removal.

A dealer will also charge a few hundred to flash an ecm. So that rate isn't abnormal. But your tuner can also send you a stock tune to flash to it. That's all am "update is"

I'll read through the whole thread later and see if I see anything else that jumps out.
 

10 second street truck
Joined
11,872 Posts
I'd still be curious to see what the signal from the sensor looks like. Or an ohm reading on the wire from sensor end to connector at the main harness. It's a small two wire, it's easy to damage.

If you replaced the fuel system that explains the other two codes.

You have an EVAP code and a fuel tank over pressure code. You need to figure out why.
 
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