OK, I've used the search and found some good info but none of it seems to quite mirror what I'm seeing. I'm trying to get everything ready to pass the new emissions test here in Austin and borrowed an Actron scan tool from a buddy to check for stored codes. Found 2 instances each of PO335 & 336 (crankshaft position sensor)...SES light hasn't been on in well over a year and the car's been running great, so cleared the codes and checked again - they came right back. Car was still running fine at this point. Next day I started it up and it was running really rough and now had an SES light. Plugged in the scanner and got the same two codes. Shut the car off, cleared the codes, turned it back on and it ran fine for two days (had an SES light with the same codes the next time I started it though). The SES never comes on while I'm driving - only after turning it off and starting back up again.
I think this is probably coincidence, but either right before or during this time, I raced a buddy of mine - went full throttle to about 5800rpm in 1st, 2nd, & 3rd. (Awesome race too!) Car ran great during and immediately after the race, but I wonder if that might have affected things somehow...

Today, I started the car and it ran fine until I got a block away from the house and it started running really rough - not like a misfire but kinda like all the timing was being pulled. Oddly, if I gave it half-throttle or more (had to pull into traffic) it would "wake-up" all of sudden, slam me in the seat and take off like the good girl she usually is.

OK, those are the symptoms, here's what I've done so far:
1. Remove and inspect CPS - looked fine other than a shiny spot in the middle of the sensor face that opposes the reluctor wheel. Kinda looked like it might have been grazed by the wheel or something. High rpms perhaps?
2. Disconnected battery and inspected sensor pigtail and wiring - all connections were tight with no cuts or abrasions but there was grime around them from a small oil leak I have at the bottom of the timing cover. Took the plastic "cap" thingy off the pigtail and cleaned it all up with electrical cleaner. Put my clean & shiny pigtail back together, plugged it in, re-connected batter and started her up - same codes & rough running after 30-45 seconds.
3. Replaced sensor - same thing (I'm clearing the codes after each thing I try and they immediately come back whether I turn the car on and off or not)
4. Probably unrelated, but I also replaced the cat today (honeycomb broke and was rattling) and had the slip joint welded on the drivers' side of my MAC headers (carbon tracks around the joint).

Other weird thing is that on the way into town to pick up the new sensor, she started running better after about 10 miles. Still rough but not nearly as bad as before. After stopping to get the part, she was really rough again but smoothed out a little after a couple of minutes.

At this point, I'm thinking it could be any one of the following possibilities:
1. Worn / loose timing chain causing general havoc for the PCM and also causing it to think the CPS is bad due to variance between it and the Opti.
2. Bad Opti or portion of the opti
3. Bad CPS connection at the PCM
4. Bad connection at the pigtail which was unaffected by my cleaning efforts
5. Shot in the dark, but maybe a problem with the reluctor wheel?

Any help would sure be appreciated....I'm stumped on how to proceed without just throwing parts at it.

 

Sounds like you have all the possibilities listed. You will just have to start trying to eliminate them.

 

I got those two codes when I removed my CPS for my cloyes timing chain install. It only sets the code after two engine cycles. I stopped it with tuning via tunercat for OBD2.

Your engine problems are probably unrelated to CPS as the CPS's only function is to be used for misfire detection in OBDII. My CPS is not even plugged in as I now have a 95 timing cover(OBDI). My engine runs fine without it.

My guess is your CPS plug or wiring is bad. But this would not cause your engine to run rough. It will however set your ses light and throw the codes you mentioned.

 

A friend at work is going to bring in his laptop w/ Autotap tomorrow....what should I be looking for? Obviously I'll want to check the output of the CPS sensor, but since this shouldn't be the cause of my rough running in closed loop, what are some of the common culprits to look for in Autotap?

 

Well, I think I found the problem
Over a two year period, the heat from my passenger side header finally melted a clip for the wiring harness close to where the CPS wires join the main wiring harness, which allowed the whole harness to get too close to the header and it basically baked the insulation right off of several wires. What a mess....

Only thing I can think to do is pull the header on that side to get clearance and solder / heatshrink new wire in there to replace the burnt sections. Anyone know what kind / gauge wire I should use?

 

Oh, for those that may be interested, we also found a loose spark plug (could see it vibrating while car was running) which probably accounts for the rough condition....

Just thought I'd let everyone know in case someone runs up against something similar and needs ideas of what to check...

 

22 gauge minimum.