I've got an SES for a crank position sensor out of range or something like that. I've had it for a while now. It really doesn't feel like it has cost me an immense ammount of power, but I figure hey, sense the crank position sensor helps with the ignition timing, I suppose it stands to reason that I am leaving 10 or so RWHP on the table here.

So, can anyone tell me if I am really losing power due to this CPS code?

Is it really that important to get that procedure done?

 

I would think that it's definitely costing you power, just in the fact alone that when the SES lt is let, the PCM goes into fail safe (limp home) mode. Plus, if the crank sensor isn't properly timed, how can the spark curves be correct. Not positive, but it makes sense to me.

 

You would definintely know if your truck went into limp/safe mode, it feels like you're truck is running on 2 cylinders.
Find a buddy at a shop, it's very easy to perform if they have the right tool.

good luck,

allen

 

I work at Autozone and we have scan tools, but no "tech" tools.... and I don't have any friends at a shop. Can it be done @ any old show, or just the stealership?

And Allen:
Even if it is not in "limp mode," is it costing me power/fuel economy?

 

i dont think it would be costing you to much power.

 

I now have a crank sensor relearn SES light on my truck, but it still seams to be running lean (Second ECM). Would a relearn help?

 

Definitely need to get the crank relearn done before you can do any other tuning...I have to get the same thing done while my PCM's out getting tuned for e-fans. I'm using my backup PCM, which needs the relearn...actually doesn't run too bad, it's a little off, but driveable.

I would think that if your check engine lt is on, you'd be running rich right now...doesn't the PCM go into open loop fueling when it sees a fault such as crank variation relearn?

 

Scratch that...just checked my service manual and it made no mention of open loop fueling for that code...might have to dig a little deeper.

 

Now that I think about it, I swapped PCM's once before and the truck barely ran, after I had the relearn done, it was smooth as silk. The only code it had was for the relearn. This time around the truck seems to run fine, just has the check engine light and relearn code...maybe it depends how far off the crank variation is?

 

I took it to the dealer when I did a PCM swap and they did it for free in about 3 minutes.