Is my skipping caused by coils, or camshaft sensor?
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Drifting
Joined: Jan 2010
Posts: 40
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From: Rock Hill SC
Is my skipping caused by coils, or camshaft sensor?
Hello, I'm back with a new problem. My 97 RR started skipping about 2 weeks ago. I changed the plugs, still skipped, changed the wires, still skips. I get no warning or check engine light. I'm thinking it could be either the coil(s), or camshaft sensor. is there a way to tell which it is? Like something that it will do for sure that says it is one or the other? Any and all help will be appreciated. Thanks
Super Moderator
Joined: Jan 2011
Posts: 16,322
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From: Savannah Georgia
In total darkness observe the engine bay and look for any spark being bled off.
As for the camshaft position sensor, engine will run with it failed. From RAVE shop manual:
timing different from crankshaft sensor signal.
As for the camshaft position sensor, engine will run with it failed. From RAVE shop manual:
Camshaft position (CMP) sensor - (up to 99MY)
The camshaft sensor is located in the engine front
cover, between the belt pulleys. It is a Hall Effect
device which produces four pulses for every two
revolutions of the engine. The signal is used for two
purposes, injector timing corrections for fully
sequential fuelling and active knock control. The CMP
sensor signal pulses are generated from four gaps on
the cam wheel, one gap is smaller than the other
three, consequently one of the pulses is longer than
the others.
If the camshaft sensor fails, default operation is to
continue normal ignition timing. The fuel injectors will
be actuated sequentially, timing the injection with
respect to top dead centre. Injection will either be
correct or one revolution out of synchronisation. The
fault is not easily detected by the driver. The fault is
indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.
Fault codes:
cover, between the belt pulleys. It is a Hall Effect
device which produces four pulses for every two
revolutions of the engine. The signal is used for two
purposes, injector timing corrections for fully
sequential fuelling and active knock control. The CMP
sensor signal pulses are generated from four gaps on
the cam wheel, one gap is smaller than the other
three, consequently one of the pulses is longer than
the others.
If the camshaft sensor fails, default operation is to
continue normal ignition timing. The fuel injectors will
be actuated sequentially, timing the injection with
respect to top dead centre. Injection will either be
correct or one revolution out of synchronisation. The
fault is not easily detected by the driver. The fault is
indicated by illumination of the malfunction indicator
light (MIL) on North American specification vehicles.
Fault codes:
•
P0340 -
Camshaft sensor circuit fault or signal
timing different from crankshaft sensor signal.
Thread Starter
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Drifting
Joined: Jan 2010
Posts: 40
Likes: 0
From: Rock Hill SC
Thanks for the info, so basically the cam sensor wouldn't cause skipping. And if the plugs and plug wires are new then it must be the coil(s). I ordered a set of coils Friday hopefully I'll have them Tuesday. So is there anything else that might cause skipping that I should check in the mean time? Thanks
Thread Starter
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Drifting
Joined: Jan 2010
Posts: 40
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From: Rock Hill SC
How do I tell if I have a "Bent tooth on reluctor disc that triggers the crank shaft position sensor"? I check in the dark, and could not see any stray arcs. If my timing is off how would it behave? Also has anyone else had these issues, if so can you tell me what your resolution was. Thanks.
Super Moderator
Joined: Jan 2011
Posts: 16,322
Likes: 88
From: Savannah Georgia
You'ld have to open inspection plate from bell housing from the underside, and look up. Would see something like this, also possible for the crank position sensor to be bent, but it usually makes more difficult problems, like no spark when hot, etc. Wiring issues can sometimes be found by shaking the harness (make it ground out). Maybe examine engine computer circuit board for corrosion/water.
Another thought - if problem only happens when in motion, not in park if engine run at various RPM.... consider the VSS sensor. When it goes bad, the truck thinks you are going over 115 mph, and starts turning off cylinders to slow you down. One test is to unplug VSS and drive. Speedometer will be dead.
Another thought - if problem only happens when in motion, not in park if engine run at various RPM.... consider the VSS sensor. When it goes bad, the truck thinks you are going over 115 mph, and starts turning off cylinders to slow you down. One test is to unplug VSS and drive. Speedometer will be dead.
Thread Starter
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Drifting
Joined: Jan 2010
Posts: 40
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From: Rock Hill SC
changed the coils problem is still there, actually think it got worse. It does the skipping, plus it sounds like it Backfires back into the intake manifold, or atleast makes a pop in there. HELP!!!!!!!!!
Thread Starter
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Drifting
Joined: Jan 2010
Posts: 40
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From: Rock Hill SC
don't know if I just didn't notice it before could only hear it with the hood up, not constant, just every now and then. if I press the gas pedal down when it skips makes a backfire down low near the exhaust manifold.
Administrator
Joined: Apr 2006
Posts: 25,707
Likes: 107
From: Denver, Colorado
First, how long have you owned the RR, what year is it, does your check engine light even work, have you tried to read codes anyway? How many miles on it? You might want to do a compression test and possibly a leak down to rule out a burned valve or flat cam.