My car is throwing a p0336 for the cps. Idle is smooth and consistant. The car doesn't run bad, just doesn't see to have full power. There is an occasional high-end stumble under load. Also both exhaust manifolds glow orange after driving around for a while. I have replaced one of the cats with a new one last month. I went on shbox and did the opti and spark test. Terminals A&B to ground showed >10v dc and terminal B to ground showed 2-4v ac. So my opti and coil check out right? Any help would be greatly appreciated. Thanks.

 

Forgot to mention that I replaced the sensor, and I know that it doesn't affect performance. And another symptom is that the car backfires upon deceleration more than normal. I have a code scanner after erasing the code, it stays off for a while but it always comes back after startup. I don't know if this helps, but here is the freeze frame data:
DTC that caused freeze frame - P0336
Throttle Position - 0.0%
Engine RPM - 971
Load Value - 4.7%
Air Flow Rate - 12.64 gr/sec
MAP Sensor - 43 kpa
Coolant Temp - 230 F
Short Term Fuel Trim 1 - 0.0%
Long Term Fuel Trim 1 - 0.0%
Short Term Fuel Trim 2 - 0.0%
Long Term Fuel Trim 2 - 1.5% (3.1% different readout, different time)
Short Term Fuel Trim 3 - 50%
Long Term Fuel Trim 3 - -38.3%
Short Term Fuel Trim 4 - 57%
Long Term Fuel Trim 4 - -3.4% (-61.6% different readout, different time)
Vehicle Speed - 0 mph
Fuel System 1 - open
Fuel System 2 - open

 

If you have a misfire and fix that it should also fix you crank position sensor code.

 

Would a simple misfire cause the backfiring and the exhaust manifolds to glow orange? I have recently replaced the wires, the plugs are only a few months old, and as I stated I passed the opti and spark test. Does the test rule out ignition problems?

 

Back firing and glowing manifolds are common signs that something is amiss with the valves. Suggest you take the valve covers off or if you want to you can test it for compression and that could lead you to the side with the problem. That is if they all don't read the same.

 

Did you replace the wires right? Could be as simple as wires on the opti wrong.

 

The wires are new, and I put them on correctly. I'm probly gonna cough up the dough and buy a new opti, figuring the car does have 140K on it. Accel, MSD, or GM? I have read about applying thread lock on the screws inside. What do I need for the job, just a new opti and new water pump gaskets? Is the procedure: remove radiator and fans, remove water pump, disconnect and remove opti, and then reverse of removal?

 

This morning, while on the freeway, the rpm's started to fall, rise, and fall again, like it was struggling to stay alive, backfiring too. I found a place to pull over and it died. I won't start now, just cranks forever. I pulled the codes and I am getting:
P0101 Mass Air Flow System Performance
P0336 Crankshaft Position Sensor Performance
P0400 EGR Flow Malfunction
Can I assume that this is still opti related?

 

P0101 is telling you that the flow numbers the PCM is seeing from the MAF sensor don't make any sense. The PCM does a rationality check, using its speed-density calculation, to see if the MAF sensor readings are correct. The code sets when the MAF data differs from the speed-density calculation by more than 40% at low flow conditions, and more than 25% at high flow.

That doesn't mean that the MAF is the reason the engine will not start, but it does indicate there is a problem with it.

A failed optical sensor in the Opti would set codes, so it appears that portion of the Opti is still OK. However, the hight voltage section does not set any codes.

The CKP code is telling you the sensor's duty cycle is outside the expected range. Could be a faulty CKP sensor. But the PCM needs to compare the CKP data with something to determine the expected readings, and it may check the duty cycle based on the high resolution signal from the Opti.... hence a faulty Opti may cause a CKP code.

I have never heard any indication that "If you have a misfire and fix that it should also fix you crank position sensor code.".... that's news to me. Not sure how a misfire would throw the CKP duty cycle so far off that it causes P0336. The whole purpose of the CKP is to detect misfires, so it would make no sense at all to set the CKP code when there is a misfire, and the CKP is supposed to be measuring crank velocity to detect that misfire.

 

The sensor is new. When cranking sometimes the car fires, but immediately dies. The first thing I did was disconnect the MAF, it still didn't start. Also I disconnected the MAF about a week ago, when the car was running, when I drove it around it had the same symptoms as with it connected. I ordered a new opti, gonna replace it tomorrow. I will post the results.

 

I predict the opti will not solve the problem. Only EGR could kill the engine. The other 2 codes would not. Nor will the opti have an effect on the MAF code OR the EGR code. So I fail to understand how you came to the conclusion the OPTI was bad. But I hope your money experiment proves me wrong.

 

I posted on a few forums and a few people told me that a P0336, back firing, and glowing manifolds all could be caused by a bad opti. And if its not, I guess it won't hurt.
After work my car fired up and died. Then I got it to stay started, and I was able to drive it home, less than 5 miles away. We'll see what happens with the new opti, I'll cross my fingers.

 

You have misfiring but don't get a misfire code

You get a CKP code for tolerance and it's presumed it MAY come from the opti. Specifically when the PCM compares the CKP signal duty cycle to that of the opti. BUT there is no code for opti feedback signals

If you read back, your only initial complaint was popping during deceleration and a 336 code.

Then you start to stall and set 2 more codes. Well when the engine begins to run so slowly that it stalls, the result of the low voltage from a slow turning alternator could be any code.

You should have simply pulled the cap off the distributor and looked at the condition of the contacts and the rotor.

 

I don't think it's the opti either.

Before you tear the old one off, test it and make sure the signals coming out of it are correct.

Take a look at the opti harness that comes out of the opti on the drivers side.

Take 5 minutes to diagnose and make sure there's no easy stuff wrong like burned wires or things like that before you toss a pile of cash at it.

 

It won't set a misfire code (P0300) when you have a CKP code (P0336).