99 Suburban 5.7L P0340 code, runs rough

[dsthomspson1]

First time post. I have a 1999 suburban 5.7L with 190,000 miles. First time it's ever given me a code. It started with a P1341 code (cam-crank co-relation) and was hesitating/missing on slight acceleration. I replaced both sensors and it still ran rough. Took it to a dealer which I have never done before. They said dist. needed replacing, so I bought a new one and installed that. Auto Zone code reader says it now has code P0340 - cam position sensor. Still runs rough. I've replaced plugs, wires, cap, rotor, Cam sensor twice - no luck. Any ideas on what to troubleshoot next? Thanks, Scott

[MT-2500]

Originally Posted by dsthomspson1

First time post. I have a 1999 suburban 5.7L with 190,000 miles. First time it's ever given me a code. It started with a P1341 code (cam-crank co-relation) and was hesitating/missing on slight acceleration. I replaced both sensors and it still ran rough. Took it to a dealer which I have never done before. They said dist. needed replacing, so I bought a new one and installed that. Auto Zone code reader says it now has code P0340 - cam position sensor. Still runs rough. I've replaced plugs, wires, cap, rotor, Cam sensor twice - no luck. Any ideas on what to troubleshoot next? Thanks, Scott

Any other codes?
First I would clear codes and see what code comes back first.
Post back codes.
Also on that one you need to get it on a engine capable scanner and set the camshaft retard setting as close to 0 - or + degrees as you can get it.
What brand sensors or dist did you use?

[dsthomspson1]

Cleared all codes and started engine. Same P0340 code came on within 5 seconds. For the sensors I used Wells from AZ. Also noticing the radiator resivoir slowly going and staying lower. Could it be another intake gasket leak that is setting this code? I replaced that as well about 18 mos ago.

[MT-2500]

Originally Posted by dsthomspson1

Cleared all codes and started engine. Same P0340 code came on within 5 seconds. For the sensors I used Wells from AZ. Also noticing the radiator resivoir slowly going and staying lower. Could it be another intake gasket leak that is setting this code? I replaced that as well about 18 mos ago.

The coolant leak is different from the code.
The code P0340 is the camshaft sensor or wiring or pcm.
Wells sensors are not the best.
I would go a AC delco sensors.
And check the camshaft retard setting which may have been he first code.
On it you will have to get engine over 1K rpm for the setting to show on a scanner.

[dsthomspson1]

Thanks for the info. I can't pinpoint how I did it but by replacing the distributor with new cam sensor and driving it thru several cycles, the check engine light has gone away and now it runs very good. I did retard the distributor by hand, that might have been what it was looking for.
I have a new condition that just happened to occur at the same time the CEL lit up, at least that's when I first noticed. Now the oil pressure goes so low at an idle that teh check gages light comes on. PSI at idle is around 10 PSI while at 55 MPW it is 20 PSI when warm. I did switch from 5W30 to 10W40 and that seemed to raise it by about 5 PSI. However on the way home tonight, I heard some knocking from the engine, sounded like rods. Probably time for a complete rebuild. When it rains, it pours! It's been a great vehicle for us so I'll just keep fixing it up.

Thanks again for your input.

Scott

[MT-2500]

Originally Posted by dsthomspson1

Thanks for the info. I can't pinpoint how I did it but by replacing the distributor with new cam sensor and driving it thru several cycles, the check engine light has gone away and now it runs very good. I did retard the distributor by hand, that might have been what it was looking for.
I have a new condition that just happened to occur at the same time the CEL lit up, at least that's when I first noticed. Now the oil pressure goes so low at an idle that teh check gages light comes on. PSI at idle is around 10 PSI while at 55 MPW it is 20 PSI when warm. I did switch from 5W30 to 10W40 and that seemed to raise it by about 5 PSI. However on the way home tonight, I heard some knocking from the engine, sounded like rods. Probably time for a complete rebuild. When it rains, it pours! It's been a great vehicle for us so I'll just keep fixing it up.

Thanks again for your input.

Scott

If a coolant leak check the oil for coolant in it.
If oil pressure is dropping get a manual oil pressure test gauge on it and see what the actual oil pressure is.
If turning the dist helped on the check engine light and code get it on a scanner and check and set the camshaft retard setting.
Let us know how it goes.

[dsthomspson1]

I have a theory on my car. I think the codes were set because of excessive movement between the cam and crank due to chain/sprocket wear. The oil pressure is low because of nylon coated teeth from the cam gear lodged up in the oil pickup. My plan is to raise the engine, remove the oil pan and see if pieces of the cam gear are in the pickup. If so, Ill clean them out real good and replace the timing gear set. This should fix the problem. I'll let you know how this turns out this weekend.