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Electrical Gremlins
Electrical Gremlins Just came back from the garage with a couple of problems and wasn't able to diagnose in such a short time. I put my maf back in and am getting a p0103 code. Put it on the solstice pro and at first it showed that the maf wasn't reading anything. He checked something else and went back and then the maf was now reading. I also have a p0343, I replaced it a few years back after the cam swap and that lasted a couple weeks then it was back on so....F it. With that code, the same problem, the scanner at first showed nothing that all of a sudden it was showing that the sensor was reading correct. He looked at the vacuum and at idle it was showing 30.5" of vacuum. He says it should not be that low. So we hit the gas and that number didn't change. There is also a noticable missfire but was bringing up no codes. You could hear as well as feel the stumble. What could all this be releated to? I have checked all spark plugs and they look good. Could my computer be going on the fritz? Also according to the scanner, both codes popped up at the same time by the counter.
TECH Senior Member
Joined: Apr 2002
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From: So.Cal.
Scanner showed 30.5 inHg (15 psi) of vacuum at idle (impossible to achieve), and no change when engine is revved...
Does scanner show zero vacuum at KOEO as Old Geezer is asking above...?
connect a vacuum pump to the MAP sensor and observe the MAP sensor on the scanner as you pump up vacuum, if there is no correlation then the MAP sensor (and/or its connection to the intake manifold) is bad.
Also note that MAP can be viewed as vacuum (pressure relative to barometric) or as absolute pressure (relative to zero)... i.e. barometric pressure is zero vacuum and vice/versa.
Does scanner show zero vacuum at KOEO as Old Geezer is asking above...?
connect a vacuum pump to the MAP sensor and observe the MAP sensor on the scanner as you pump up vacuum, if there is no correlation then the MAP sensor (and/or its connection to the intake manifold) is bad.
Also note that MAP can be viewed as vacuum (pressure relative to barometric) or as absolute pressure (relative to zero)... i.e. barometric pressure is zero vacuum and vice/versa.
Scanner showed 30.5 inHg (15 psi) of vacuum at idle (impossible to achieve), and no change when engine is revved...
Does scanner show zero vacuum at KOEO as Old Geezer is asking above...?
connect a vacuum pump to the MAP sensor and observe the MAP sensor on the scanner as you pump up vacuum, if there is no correlation then the MAP sensor (and/or its connection to the intake manifold) is bad.
Also note that MAP can be viewed as vacuum (pressure relative to barometric) or as absolute pressure (relative to zero)... i.e. barometric pressure is zero vacuum and vice/versa.
Does scanner show zero vacuum at KOEO as Old Geezer is asking above...?
connect a vacuum pump to the MAP sensor and observe the MAP sensor on the scanner as you pump up vacuum, if there is no correlation then the MAP sensor (and/or its connection to the intake manifold) is bad.
Also note that MAP can be viewed as vacuum (pressure relative to barometric) or as absolute pressure (relative to zero)... i.e. barometric pressure is zero vacuum and vice/versa.
I logged vacuum.
I unplugged the power to the coil packs one by one to hear a change. I got to 6 and 8 and no noticable change in the engine at idle. I put a spark light tester between the spark plug wire and the spark plug. I had spark. So I went to my misfire config and modified it to add a couple parameters and logged which is what I send you. You will have to open it with the new config file. My first log I saved it wrong, I was looking at the current firing cylinder and noticed there was no #8. So I re-did it again and that was feb18. I noticed it wasn’t registering the current firing cylinder. So I saved it shut down the truck and started it and logged another as feb 18.2 which now showes the current firing cylinder. In my first botched log I notices the count in the 2 cam signals were off by a few counts and were around the 30’s and then caught on and went up to the 50’s. In the two new logs its recording nothing. I also noticed that the mass air flow in g/secs is not registering. Even more confused now. And once again you need to go here for the new config file.
http://www.performancetrucks.net/for...4/#post4871268
http://www.performancetrucks.net/for...4/#post4871268
Last edited by tweeder; Feb 19, 2012 at 07:28 PM.
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Verdad Gallardo I loaded up my tuners tune that he took a look at and noticed that my misfire tables were not stock and corrected them. On my way to work this morning I scanned for codes and noticed that I now have a p0300. So I took a look at yesterdays log as never got to look and noticed that there are multiple misfires all across the board. It doesn’t make sense that in the current firing cylinder, theres no cylinder 8 but in the misfire section it showes its active. But with alot of misfires.
Well had some luck this weekend. dumI had a broken purple wire on the drivers side small wiring harness that attaches to the valve cover between coils 3&5. dumI also found that the injector plug to injector #1 was loose and came off easily. dumJust fixing that stopped a lot of random misfire over the majority of the cylinders. dumI took it for a drive and when it started to really misfire I noticed cylinder #8 was off the charts. dumSo I went home and changed coils 3 with 8 and went for another drive. dumThe misfire followed the coil to cylinder #3. dumI did notice that on the coil what looksdumlike the outer metal casing has a small wire with a clip that clips onto the fins. dumI can move that around but on the other coil I can't. dumI will be replacing hat coil. dumI also took off the intake and pulled the camshaft position sensor. dumThe bottom was covered with oil and sludge and who know what else. dumI stuck a bore scope down there to look at the reluctor ring. dumIt had crud on it as well so I stuck an air gun down there and blew it out. dumI rotated the crank by hand a few times and it looks clean now so hopefully that's the end of the p0343 code. dumBut one thing still puzzles me is that in the pid "current firing cylinder" it still has no sensible firing order, way to scattered. dumIt still has a "0" cylinder and no #8. I did check all grounds and all looked good.
dum
dum
Heres a video of the current firing cylinder. Pay no attention to the other misfires as this video was taken before I located the misfire problem. Any clue as to whats going on? Sometimes If been loging and there is no reading for that so I have to resart.
http://youtu.be/8N7bH0TDcRY
http://youtu.be/8N7bH0TDcRY
