Oldsmobile/Buick Repair: One problem or two?, cam sensor, red herring

Question
Hi Van -
I have an '89 Old Regency - 3800 engine with 72,000 miles.    For 6 weeks or so my check engine light has been coming on intermittantly (more 'on' than 'off').    I checked the code and it is 41 - cam sensor circuit.     There seemed to be no ill effect, until I recently (2 weeks) began to have starting and stalling problems.  

Sometimes it will crank but not start, or start and then quickly stall, and just recently, it has begun to stall when I crest a hill and take my foot off the gas.   Watching the tach on the 'Driver information center' it looks like the system is having trouble regulating idle - it seems to hunt when stopped in neutral, and I've witnessed a case of over & under-shoot where the car was stopped in Drive and about to stall - I put it into Neutral and the idle shot up to 1700 rpm and then it came down and stalled - feels like it may be a gummed-up IAC valve.    One more potential red-herring - the day before this idling problem began, I put a can of 'gum-out' in the fuel tank and made a 300 mile highway trip.

So, aside from the big question of, 'how do I fix all this', my 3 specific questions are
1) Can a cam-sensor fail intermittantly like I am seeing, or is this more likely a wiring problem.  The sensor is a $20 part and seems like an easy change-out, but I hate to replace it and still get the same code.
2) Can this cam sensor circuit issue be the cause of my more recent stalling issues, or is that due to something else.
3) The factory manual has some trouble-shooting guidance, but it makes referance to a scan tool.   I went to the local Auto-Zone and they claimed there is no scan-tool for an OBD1 system.   I understand these systems were not standardized, but surely all GM's of this vintage must use the same tool - do you know of any on the market?

In the mean time, it looks like the IAC is pretty accessable, so I think I'll take that out and see if it needs to be cleaned.

Thanks for any help you can offer.   Sorry for the novel.

Mark in Pennsylvania


Answer
Hello Marc,
Check the wire connection to the cam sensor for loose or intermittent connection. It could contribute to the symptoms, but that sounds like the idle air control valve.\
Gumout wouldn't clean it, since it is in the air intake system before the fuel, and fuel doesn't flow through it.
Clean it with Carb/PCV valve cleaner, and you normally don't even need to remove it to clean it.

There was a scan tool for them. Monitor 2000 from OTC, as well as the GM scan tool.

Check for vacuum leaks also, including the brake power booster, and the EGR valve. If it colses on some loose carbon, it will act like a large vacuum leak. And it can be open and close after crowning a hill, or coming to a stop sign.

Have you tried the online service info at www.autozone.com

Free and easy.

Van