Contour Enthusiasts Group Archives Forums General Troubleshooting Crankshaft position sensor : only for starting?

After replacing my fuel pump for nothing (lets call it preventive maintenance...), I am now convinced the CPS is the cause of my intermittent no start condition. Basically when the sensor gets hot, the car does not start.

I am wondering if this part can cause driveability problems also. Is it used for ignition timing also, or is it only useful at start-up? My car is a real dog now, it feels like timing is retarded 20 deg... It might also have a vacuum leak at the upper manifold gaskets.

Last question : My search has turned up 2 part numbers, one which is roughly 25$, and supposedly specific to duratec (5L8Z-6C315-AA) and one that only says V6 in the description, and is 11$ us. (1S7Z-6C315-AA). What is the difference? Which one did you use?

TIA

If the PCM wasnâ??t receiving a signal from the CPS it would store a code. Best thing is to pull the codes. Yes the Crank and cam sensors are use for timing. Crank and cam sensors basically work or they donâ??t. I have seen one or two that were intermittent. Hard starting when hot is usually a mixture problem, check your ECT sensor for correct hot resistance.

jeff

Jeff, Jesse,

Thanks for the posts. I will be investigating the mixture thing. Unfortunately, I do not get codes. The only way I get codes is by lugging the engine in 5th, I then get a flashing cel (random misfire and misfire cylinder 6). I got a cel once, but disappeared before I could scan

I will be replacing the CPS, at 12$, seems to be a no brainer, and might just solve my starting problems. Maybe changing the upper intake gaskets will cure my lack of power and surging idle. It is behaving alot like a vacuum leak. My short term fuel trim on bank 1 also seems weird, at like -8%, while stft2 is normal (around -1%).

Your Surging idle may be from your EGR block....Has this problem been happening since you did that mod?? Ive heard more than a few people having problems blocking off the EGR.
It does nothing for performance but no one (including me ) wants that nasty exhaust gas recirculating through their system, So i know why you did it. You might try removing the mod temporarily to see if your erratic idle goes away.
Maybe and Maybe not....

I had a no start condition on my V6 that turned out to be either a weak crank senor or the sensor wires and could have been both. I had no trouble codes to aid in the diagnosis. I tested the coil pack and detirmined the there was no signal to trigger spark, so I chose to replace the crank sensor and not the ECU and hope this was my problem. While unplugging the sensor I saw that there was also a wiring problem (the famous biodegradeable wire insulation), which I also repaired. When I compared the old sensor and the new one the ohm readings were not the same and the old senor had an oil varnish on the magnet(160,000 mile on the car). I believe this all contributed to a weak signal. Replaced the sensor, repaired the wires, and the problem was solved. Also , on a side note, I would occationally get a blinking CEL for a stuck TCC sol. that hasn't returned since this repair.

Does the CPS only cut spark? Or will it also cut fuel?

Silverbullet,

My EGR mod has never given me problems, and the hole is big enough not to trip a CEL. I found it did give me better low throttle response, and keps the upper intake MUCH cleaner. Not saying it can't be, but I will be looking at alot of things before this. Will probably be removing the upper intake and changing the gaskets, I guess I can get a look at it then.

Athos, TCC sol. ? Please explain. All I get is misfires

That really was just a side note that probably dosn't apply to this situation, but I thought I would throw it out the in case it might help someone. Now, since you asked... Every once in a while, as I drove, the CEL would begin to blink. The trouble code was for a stuck TCC sol (Torque Converter Clutch). I did the reading, did the suggested fixes, and would still get the blinking light with the same trouble code. It hasn't happened since the replcement of the crank sensor, so I can't help but think that the two were related in someway. Possibly the ECU uses the crank sensor when determining torque converter clutch control, I really don't know.

Well, it's been a while, and I still have my hot start problem. Repaced my camshaft position sensor yesterday, and that did not do much. The wiring looked ok, although I did not know what to look for exactly as far as degradation.

I guess I will be replacing the crankshaft position sensor next. My missing and surging problems did go away with an ignition wire and intake gasket replacement though. Hope the cps will do the trick, I do not know what to look for next...

BTW, can there be a stored code, without an engine CEL? My mechanic said he had scanned it and gotten intermittent camshaft position sensor fault. I have an obd2 scanner from Alex Peper, so I will verify this as soon as I am back.

BTW, is the ECT sensor easily accesible and replaceable? What is the norml hot resistance I should get?

TIA