So I got a new issue with my fresh to me engine. I've driven the car about 225 miles since my 408 went in and now it's throwing a P0336 code. It sputters and backfires and sometimes dies. I noticed when I started the car to warm it up and came back outside and it was off. It starts right up just fine, but immediately sputters. I've done a crank relearn and it seemed to help for a few minutes but it's started doing it again.
I could be answering my own question, car still has the 98 ECM and the engine came out of a 01 Silverado. And just looking at RockAuto, the cam position sensor is a different part number for 98s compared to 99+ cars. I wasn't aware of that. My only hiccup with thinking that's the issue is I've driven it 225 miles just fine, it's been my daily. I'm gonna go grab the old sensor out of my LS1 and use it and see if that fixes it, since that's free.
Is there something I could be missing? Should I also replace the crank sensor too? Ironically the 98s do use the crank sensor as a 99+ just so people know. Lol

 

Where did the crankshaft position sensor come from? Is it aftermarket? If so, carefully remove and then drop kick it into the street when a semi is passing by. Aftermarket sensors are garbage. Get a GM sensor. If you DO have a GM sensor, I'll ask this - When you put your engine together, did you paint your block? If you did, and didn't sand the area the crank sensor seats against, that could be part of the problem. The sensors are highly sensitive to distance changes from the reluctor wheel. Check that area, clean it, and reinstall the sensor. It could also be that the engine block casting is on the high side of tolerances. It can be a pain to do, but you can measure the distance from the face of the bore to the wheel and then the distance from the seating area of the sensor to the tip and it will give you a value for the gap.

 

What car is the engine in now? Sorry if I missed it. If it's a C5 Vette, maybe I can shed some light on it. Question: did the vehicle the engine came out of have a pinchbolt on the female splines of the flywheel?

 

The Crankshaft sensor was just the one in the motor when I pulled it from the truck. Which was an 01 Silverado, motor was fine when it was pulled. Only thing I changed was the camshaft and the intake manifold and like I said it ran good for 225 miles before starting this hiccup. Car is my 98 Trans Am.

It'll be a little bit before I can change the cam sensor or crank sensor since my shoulder is torn and it's doctors orders to not use it, unfortunately

Block isn't painted or anything. on my log with HP Tuners, it never dropped crank signal. That's why I'm hesitant that the crank sensor is even bad.

 

Not familiar with the TA flywheel. Does it have a pinch bolt on the flywheel or flexplate? Do you get the code only when the engine is warmed up?

 

So I threw some parts at it. Pulled the old Cam sensor out of my LS1 and used it, and I put a new Walker crank sensor in it. (Don't worry I kept the GM one since I had my suspicion that this wouldn't fix the issue) performed a crank relearn via HP Tuners and the problem still persists (though I drove it about 3 miles just fine before it came back. So next thing I'll do is take my Walmart battery back for warranty since it definitely has a dead cell. Maybe that's been culprit? Stupid of me not to try that first. Anyways, what else could I be missing? The wiring to both sensors look fine. It gets a lot worse when you apply load to the engine, specifically once it shifts into 3rd gear or trying to climb a steep hill like the road to my house.

 

You need an oscilloscope and watch the waveform to see what its doing.

 

I'll have to get my hands on an O-Scope. I replaced the bad battery that was in it, I also decided to check the fuel pressure. It seems fine it wiggles whenever the car sputters, but nothing crazy. Think the wiggle is more of reaction to the problem, not the cause. Does seem so odd to me, I can crank relearn it and it drives fine for a little bit, like 2 miles or so and then starts acting up again. Unfortunately it's looking more and more like that reluctor is spun/bent or something along those lines and I don't have the funds to yank the engine back out to get that fixed so it'll just have to sit for who knows how long again if that's the case. Sucks just cause it sat about 2 years before I was able to get it running again just for it to do this. Part of it though. I'll check the continuity of the wires to the PCM and probably replace the connector going to the sensor just to rule out some smaller things. Wiring looked fine, but might not be fine. Praying it's just some electrical gremlin, I'd take the PCM being bad at this point.

 

Went through hell with reluctor wheel problems a couple years ago with a brand new 383 short block from thompson motorsports. Had weird misfire problems, sometimes would misfire at lower RPM at higher load but couldnt get it to rev past 5k RPM..would act like it was hitting a rev limiter and not pull through it. I changed all sensors, coils, plugs, wires, cleaned the injectors, checked every ground and eventually it threw a PO336 code. Tried several ACdelco crank sensors with varying results, one wouldnt even start the engine, would just sputter and die immediately. Suspecting it may be the reluctor wheel, I pulled the starter and crank sensor and stuck my phone camera up there and rotated the motor by hand..wasn't very conclusive so I ended up pulling the motor, and found the reluctor wheel was warped from welding it to the crank. Was a stock style two piece 24x wheel and the gap between them was larger around where they welded it as well as a few teeth being slightly bent ( looked like hey tried smacking it with a hammer to force the two halves back together). Ended up sending the short block back and had them put a billet one piece reluctor wheel on luckily free of charge. And that fixed the problem.

took this video while measuring the runout..realized after cutting the video off that the wheel was actually warped from the heat of the weld.