CEL P0340 - should I be worried?

[tek9]

Hi guys,

My 4runner has a recently rebuilt engine - it's running perfectly fine except when I rev it past 4000rpm.

Practically at once P0340 comes up - nothing wrong with the engine when it happens (no sputtering, loss of power). I don't push past 4000rpm very often (happened twice in the last 2 months).

P0340 - camshaft position sensor malfunction.

I've tested the sensor using a meter and the reading seems to be in proper range (fluctuating between 1000-1600ohm when hot). I've cleared the code and there are no other issues (unless I rev it past the said 4000-4200rpm).

Should I be worried? Replace the sensor? Any suggestions would be most welcome.

cheers,

--
Luke

 

[Acidmeld]

Sounds like your timing may be a tooth off. Something to check...

 

[tek9]

is it something I can check out myself by removing timing belt cover (the plastic top part)? or it's more complicated? :/

 

[Nashvegas34]

You could, but I doubt the marks on the camshaft pulleys would just happen to be lined up with the mark on the timing belt. That means you would need to manually turn the crank at the bottom of the engine to move everything, so you'd have to drop your skid plates, grab a 19mm socket, and turn the crank a little at a time to see if the marks up top line up. Not hard, but not really easy or fun, either.

Can you give any history that might help? Do you know when the timing belt was last changed and who did it (I assume when the engine was rebuilt)?

Also, call me Grandmama, but I don't think I've ever revved past 4000. Are you trying to beat a train or something?

 

[tek9]

To cut the long story short: I bought this 1996 SR5 4runner (body in really good shape, rear e-locker, 1 owner, highway driven, no accidents) with damaged engine and had a shop that specializes in rebuilding engines (canadaengines dot com) completely rebuild the engine (and give 2 yrs / 40k kms warranty on it). The end price was similar compared to buying used truck with unknown history so I figured it's a good idea since I'd know what's been done with engine so far.

yes - timing belt / water pump was replaced when the engine has been rebuilt.

I mostly drive at 2000-2200rpm (maybe 2500 when uphill). Those 2 occurrences were when I was going downhill and trying to engine brake to put some load off the stock sr5 brakes.

so far I've done some basic maintenance myself (changed differential/t-case fluids, lubed the driveshaft, replaced the front o2 sensor, fuel filter, air filter, steering rack / end-link / sway bar bushings). Also had new bilstein hds installed (didn't feel confident enough to toy with spring compressors).

The trucks runs perfectly fine (20mpg on the highway, 14-15 in the city)... except for this one CEL.

 

[tek9]

update: removed timing belt cover - camshafts are perfectly aligned.

 

[TheDurk]

http://www.ncttora.com/fsm/1996/SIL/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0340.pdf

You have the following remaining possibilities:

1. Sensor is out of position. You should have been able to verify this when you eyeballed the timing marks. I would check this again, if you haven't already.
2. Tooth is damaged on LH camshaft. Likewise.
3. Wiring fault between ECM and sensor. I am putting this as unlikely, as it works 90% of the time.

You might check and clean the contacts on this connector on front of cover:

How long a period between the occurrences? Do I understand that it came on when you revved high? Or did MIL come on at some other time? Not sure from your post. If the former, a lack of solidity on the sensor mount or a wiring fault in that area seem like the best suspects. I'd tell you to check continuity to the ECM but I have no idea where to get the pin-outs on the ECM for a 1996. The on-line source is only for a 2002. My own manual is a '99.

If time between occurrences is pretty long, and you have been resetting quickly, I'd probably leave it alone until something changed. I am not a pro, just saying what I would probably do.

 

[tek9]

Yeah - it comes on only when I rev high (above 4000 rpm) - I can easily reproduce the occurrence. I'm wondering if the sensor may be faulty after all (maybe something changes and it's unable to 'react' fast enough when the rpm is higher than 4000rpm?).

If I stay below 4000rpm... it will never happen. Should I just forget about it?

 

[Acidmeld]

Just to be thorough, when you looked at the cams did you make sure the crank pulley was lined up. The crank pulley should be lined up with the front cover and the cam pulleys should be lined up with the notches on the timing cover behind the pulleys. All three need to be lined up properly. The code and the issues above 4k really make me think the timing is off.

 

[tek9]

it will be the best if I show you what I'm seeing. I've pulled it apart again and took some pics.

See attached. Does it look ok?

 

[TheDurk]

Just to be thorough, when you looked at the cams did you make sure the crank pulley was lined up. The crank pulley should be lined up with the front cover and the cam pulleys should be lined up with the notches on the timing cover behind the pulleys. All three need to be lined up properly. The code and the issues above 4k really make me think the timing is off.

I see your quals and I ask this in the spirit of wanting learn from an expert. The FSM says the DTC set condition for P0340 is "no signal" from the camshaft position sensor either at crank or above 600 rpm. Does 'no signal' equate to a signal a few degrees off but presumably steady that a poor TB alignment would cause?

It seemed to me that a 'no signal' condition would have to be from tooth to sensor to wires to ECM, but would not be due to advanced or re****ed valve timing. I'd appreciate an explanation. Thanks.

And I certainly agree with your point about checking the crankshaft sprocket against the camshaft.

 

[Kenjan]

To check the camshaft position sensor, unplug the harness from the sensor and probe the sensor with a Multimeter that reads OHMS

camshaft sensor cold should be between 835 and 1400

 

[tek9]

I know - I've tested it again when cold - it's fluctuating between 980-1450. A bit high? On the other hand - if there was something wrong with the sensor - it would trigger the CEL below 4000rpm as well (unless above that range it doesn't manage to 'react' fast enough'). :/

 

[Kenjan]

U won't always get a CEL

Also an trip the code when If the battery voltage gets to low during cranking, the Performance Calibration Unit will not power up properly and it will not foward the cam angle sensor on to the ECU.

If the battery gets low and the engine does not crank fast this can happen and it will set that code. If you jump it you should be able to start it. It will start with that code set and you can clear it when ever you get to it.


Are u bumping the radio
Or running a lot of lights

 

[tek9]

U won't always get a CEL

Also an trip the code when If the battery voltage gets to low during cranking, the Performance Calibration Unit will not power up properly and it will not foward the cam angle sensor on to the ECU.

If the battery gets low and the engine does not crank fast this can happen and it will set that code. If you jump it you should be able to start it. It will start with that code set and you can clear it when ever you get to it.


Are u bumping the radio
Or running a lot of lights

there are zero issues starting the vehicle and running it below 4000rpm. It's only when I occasionally hit 4000-4200rpm+ that the CEL is triggered.