backfiring after cam swap
06-13-2015, 08:17 AM
#1
backfiring after cam swap Hey I just installed a cam in my 5.3 swap. When I went to go start it up it would spin over and hear a pop noise and flames would come out the collectors. The engine will not run @all. I had no codes from my pcm. No bent valves or pushrods.
06-13-2015, 02:31 PM
#2
Did you degree the cam in? Check push rod length?
Normally when I see one popping and not wanting to start it's the cam sensor. I had one do that last week actually. Once it was running it flagged the cam sensor. It will start eventually with a bad can sensor but it you may have to spin it over for awhile.
Normally when I see one popping and not wanting to start it's the cam sensor. I had one do that last week actually. Once it was running it flagged the cam sensor. It will start eventually with a bad can sensor but it you may have to spin it over for awhile.
06-14-2015, 08:54 PM
#3
Yeah all I did was line up the dots on the cam n crank sprocket 12 n 6 o'clock. #1 cyl is up. My pushrod length is good. Stock length to be exact. I tried to start it but it will not run to determine if it's the cam sensor to begin with.
06-16-2015, 10:06 AM
#5
I also found out that the cam may not have a cam sensor pick up. I called the company the cam is made by they stated yes but I don't trust it so I'm going to check n see for myself
06-16-2015, 10:38 AM
#6
You don't really have to have a cam sensor signal for the engine to run.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic monitors for a loss of Camshaft Position sensor signal. Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal,the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Crankshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for en Increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic monitors for a loss of Camshaft Position sensor signal. Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal,the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Crankshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for en Increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
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06-18-2015, 11:30 AM
#8
I just checked the cam everything is lined up as I thought but I didn't go through the entire process of taking the cam out of the motor. I don't know what to look for to the indicate if the sensor pick up is on it. I hope it's the cam sensor as I did replace it. If it's the cam I will get another cam. I want an easy start. Thanks 2LS1and lsxpower tuning that was some much needed info.
06-19-2015, 12:02 PM
#9
You don't really have to have a cam sensor signal for the engine to run.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic monitors for a loss of Camshaft Position sensor signal. Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal,the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Crankshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for en Increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
The CMP sensor determines whether a cylinder is on a firing stroke or on an exhaust stroke. As the camshaft rotates, the reluctor wheel interrupts a magnetic field produced by a magnet within the sensor. The sensors internal circuitry detects this and produces a signal which the PCM reads. The PCM uses this 1X signal in combination with the Crankshaft Position sensor 24X signal in order to determine crankshaft position and stroke. This diagnostic monitors for a loss of Camshaft Position sensor signal. Observe that as long as the PCM receives the Crankshaft Position sensor 24X signal,the engine will start. The PCM can determine top dead center for all cylinders by using the Crankshaft Position sensor 24X signal alone. The Crankshaft Position sensor 1X signal is used by the PCM to determine if the cylinder at top dead center is on the firing stroke, or the exhaust stroke. The system attempts synchronization and looks for en Increase in engine speed indicating the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes it incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position. A slightly longer cranking time may be a symptom of this condition.
06-21-2015, 12:50 AM
#10
Well I still have the same issue. Swapped out new crank sensor. Will the motor run if I don't have air induction installed? For instance the tb is open to free air while the maf is hooked up laying off to the side
06-21-2015, 08:53 AM
#11
depends on how your tune is set up but I'm guessing there's your problem. The MAF needs to sense some air flow and its not.
06-22-2015, 08:05 AM
#12
06-25-2015, 09:05 AM
#13
Hey guys I finally got her up n running. The reason for the backfire n popping noise was due to the coil wire harness was routed wrong on the coils. I have a coil relocation kit and just plugged them up n I didn't know they had to fire in the order of it running