Cam position sensor
#1
Cam position sensor
97 3.4l
I just swapped my timing belt, timing marks on belt lined up when I Installed it, cams still line straight up @ 0 deg on crank pulley, but motor will barely idle @ maybe 2-300 rpm, dies or backfires under any throttle. Marks line up every 2 revolutions of the cam.
Very little spark--plugs wet with gas
Threw P0340 code--Cam Position Sensor. Sensor looks good, reads within spec on the Ohm meter (1300). The little sensor "tab" is still on the RH cam wheel
Is there a way to check the harness end of the plug that goes to the computer? Any Ideas? I'm totally stumped.
I just swapped my timing belt, timing marks on belt lined up when I Installed it, cams still line straight up @ 0 deg on crank pulley, but motor will barely idle @ maybe 2-300 rpm, dies or backfires under any throttle. Marks line up every 2 revolutions of the cam.
Very little spark--plugs wet with gas
Threw P0340 code--Cam Position Sensor. Sensor looks good, reads within spec on the Ohm meter (1300). The little sensor "tab" is still on the RH cam wheel
Is there a way to check the harness end of the plug that goes to the computer? Any Ideas? I'm totally stumped.
Last edited by blue1; 04-22-2014 at 06:26 PM.
#2
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Was the crank and cams set at TDC before installing the TB?
Is the intake completely re-assembled?
I had the low idle, backfire thing once after a TB change due to a vacuum leak at the TB metal gasket.
Is the intake completely re-assembled?
I had the low idle, backfire thing once after a TB change due to a vacuum leak at the TB metal gasket.
Last edited by rworegon; 04-22-2014 at 06:37 PM.
#3
All of the marks on the belt lined up with their respective marks on the cams gears & crank gear when I installed it. With the pulley @ 0 deg, both cam marks are straight up. I've looked for loose vacuum hoses, but havent checked for leaks w/propane or anything like that yet--I can't even get it to run long enough for that.
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It really does sound like you have a timing issue, IMHO.
Just to confirm: take a look at post 32 (pictures 4 through 6) for proper alignment of crank and cams at TDC:
http://www.nwtoys.com/forum/tech-art...ng-belt-4.html
All good on yours? Note the position of the dimple on the crank gear.
Did you clean and re-seat the Cam Position Sensor plug?
Just to confirm: take a look at post 32 (pictures 4 through 6) for proper alignment of crank and cams at TDC:
http://www.nwtoys.com/forum/tech-art...ng-belt-4.html
All good on yours? Note the position of the dimple on the crank gear.
Did you clean and re-seat the Cam Position Sensor plug?
#5
I took these pics all at the same time. I realize one looks a tiny bit off, but I think that is just the camera angle. I would certainly think its not a whole tooth off, but maybe I'm wrong. Is there any code other than cam sensor that would get thrown if I was off a tooth? I didn't get a pic of the dimple/oil pump mark, but it cant be any different that the mark on the pulley/timing cover, can it?
Last edited by blue1; 04-22-2014 at 08:16 PM.
#6
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Yes. The dimple and the crank timing mark on the pulley, as you show, can be different if the rubber layer in the pulley (harmonic balancer) separated during install. There are threads around here on that topic.
Last edited by rworegon; 04-23-2014 at 09:42 AM.
#7
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Yeah, that's a very sneaky sort of thing that happens on other sorts of cars as well.
It's not a bad idea to rotate the motor to TDC via the pulley and double check that the cams are lined up before taking the old belt off.
You can take out the sparkplug on #1 and *carefully* verify TDC with something long and skinny that will reach down through the hole and rest on the piston. Just obviously make sure what you use won't mess anything up or get broken off in there. Just use it to gently feel for the position where the piston stops rising and starts going down. Generally there will be a bit of a range where you can't feel it moving, split the difference between where you stop feeling it come up and start feeling it go down.
It's not a bad idea to rotate the motor to TDC via the pulley and double check that the cams are lined up before taking the old belt off.
You can take out the sparkplug on #1 and *carefully* verify TDC with something long and skinny that will reach down through the hole and rest on the piston. Just obviously make sure what you use won't mess anything up or get broken off in there. Just use it to gently feel for the position where the piston stops rising and starts going down. Generally there will be a bit of a range where you can't feel it moving, split the difference between where you stop feeling it come up and start feeling it go down.
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#8
Yeah, that's a very sneaky sort of thing that happens on other sorts of cars as well.
It's not a bad idea to rotate the motor to TDC via the pulley and double check that the cams are lined up before taking the old belt off.
You can take out the sparkplug on #1 and *carefully* verify TDC with something long and skinny that will reach down through the hole and rest on the piston. Just obviously make sure what you use won't mess anything up or get broken off in there. Just use it to gently feel for the position where the piston stops rising and starts going down. Generally there will be a bit of a range where you can't feel it moving, split the difference between where you stop feeling it come up and start feeling it go down.
It's not a bad idea to rotate the motor to TDC via the pulley and double check that the cams are lined up before taking the old belt off.
You can take out the sparkplug on #1 and *carefully* verify TDC with something long and skinny that will reach down through the hole and rest on the piston. Just obviously make sure what you use won't mess anything up or get broken off in there. Just use it to gently feel for the position where the piston stops rising and starts going down. Generally there will be a bit of a range where you can't feel it moving, split the difference between where you stop feeling it come up and start feeling it go down.
#9
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I'll take a look at the pics on the big monitor later today. Too hard to see on the phone screen.
You did not have this code before the TB change, correct? Do you have a copy of the FSM (Factory Service Manual)?
You did not have this code before the TB change, correct? Do you have a copy of the FSM (Factory Service Manual)?
Last edited by rworegon; 04-23-2014 at 12:06 PM.
#10
Ran great before the TB swap. Yes, I have FSM--didn't say much about the Cam Pos Sensor except to check its ohms--which were within spec
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Those pictures look ok to my eye. The cam gear labeled "R" is on the passenger side, correct?
Any chance the spark plugs wires are not on correctly?
I did notice the P0340 code has a bit in it about the crank position signal plate i.e. the teeth on the crankshaft timing pulley....any chance a tooth broke off? One would think it would cause a P0335 code, but maybe......
Any chance the spark plugs wires are not on correctly?
I did notice the P0340 code has a bit in it about the crank position signal plate i.e. the teeth on the crankshaft timing pulley....any chance a tooth broke off? One would think it would cause a P0335 code, but maybe......
Last edited by rworegon; 04-24-2014 at 05:01 AM.
#12
Those pictures look ok to my eye. The cam gear labeled "R" is on the passenger side, correct?
Any chance the spark plugs wires are not on correctly?
I did notice the P0340 code has a bit in it about the crank position signal plate i.e. the teeth on the crankshaft timing pulley....any chance a tooth broke off? On would think it would cause a P0335 code, but maybe......
Any chance the spark plugs wires are not on correctly?
I did notice the P0340 code has a bit in it about the crank position signal plate i.e. the teeth on the crankshaft timing pulley....any chance a tooth broke off? On would think it would cause a P0335 code, but maybe......
I guess I'll get a new one and tear back into it.
Thanks for your help. I'll post back after I put it back together. Anyone have a spare crankshaft timing pulley laying around?
#13
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Sorry, I don't have an extra one.
You're not the first that has happened too. Had you pulled it to change the crank oil seal?
As a cross reference, another thread with a similar broken tooth issue.
Initial issue in post 1 of the referenced thread:
"I have an unusual problem. Recently did a timing belt job. After completion, she failed to start. Cranks, no start. Troubleshooting revealed one of the 3 coils has no fire.
I have ruled out ECU, coil packs, wiring between ecu/igniter/coil packs, timing. Crank and cam sensors are plugged in.
I failed to disconnect the battery before doing the timing belt job.
Has anyone seen an igniter fail? Is there another likely cause that I am overlooking?"
You're not the first that has happened too. Had you pulled it to change the crank oil seal?
As a cross reference, another thread with a similar broken tooth issue.
Initial issue in post 1 of the referenced thread:
"I have an unusual problem. Recently did a timing belt job. After completion, she failed to start. Cranks, no start. Troubleshooting revealed one of the 3 coils has no fire.
I have ruled out ECU, coil packs, wiring between ecu/igniter/coil packs, timing. Crank and cam sensors are plugged in.
I failed to disconnect the battery before doing the timing belt job.
Has anyone seen an igniter fail? Is there another likely cause that I am overlooking?"
Last edited by rworegon; 04-24-2014 at 06:42 AM.
#14
Sorry, I don't have an extra one.
You're not the first that has happened too. Had you pulled it to change the crank oil seal?
As a cross reference, another thread with a similar broken tooth issue.
You're not the first that has happened too. Had you pulled it to change the crank oil seal?
As a cross reference, another thread with a similar broken tooth issue.
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Ah, yes.....glad you found that thread. I remembered it being out there but did not find it when I did a quick search this morning.
Last edited by rworegon; 04-28-2014 at 07:41 PM.
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