Got the car about a month ago. 1992 240GL, 174K(but odo busted, so ?) - has been running rough at idle (cyl 4 missing,) with the motor shaking in the mounts (mounts broken maybe?) and has joggled the exhaust loose. Seems to run fine at speed (clock, no tach, so ~2000RPM?)

The big issue right now is, that the car sits down sometimes, will stop and won't start again. This has happened twice, so out of paranoia I have not been driving it.

First time, I drove into town (18-20 miles) in the morning, and had new front tires put on. behaved wonderfully through stop-and-go traffic all the way there. As I departed, it stalled out. It would catch and stall immediately. Sometimes it would catch and idle, but when I put it in drive, it stalled. After an hour of this, it caught, held enough to start moving, and got halfway home, but at stop lights it would croak, same thing again. Worked it home this way.

Isolated the crappy idle by pulling plug wires, and injectors too. No change when #4 disconnected during idle, but that did affect the engine when I revved it. Stethoscope heard the injector clicking. Spark tester showed fire.
Looked at the plugs (stripped a plug hole, YOICKS, waited for an IPD kit to fix that,) They look light brown and dry.
Fuel pump runs for about 1.5 secs when I turn ignition key on. Cracking the line from pump to rail during idle sprays gas everywhere. Yummy.
Replaced distributor cap, plug wires, not rotor (could not get it loose.)
Brother convinced me to get on country roads in low gears and wind the p*** out of it for about half an hour to 'blow out the carbon'. That actually WAS fun. Behaved well, back into service.

Went to work the next day. Beautiful. At lunch i drove it out about 10 miles to an errand. Beautiful. Started driving from errand back to work. Uh-oh. It had developed the "quits" on me again. Same as before, but I could not get it to catch and stay. Finally exhausted the (valiant) battery. Got a tow home.

Now, I am trying to find and squelch the rough idle, on the premise that what causes this also causes the 'Bartleby' disease.

The diagnostic pod gave me (at different junctures) 1-2-1 and 2-3-2 on pin 2 (fuel,) and 2-1-4 on pin 6 (fire.) Pulled the MAF, cleaned it with MAF cleaner. Checked that the idle switch clicks.
Even swapped the coil with an Autozone cheapie which did not start at ALL, oh well, swap that back. I see that 2-1-4 indicates a flywheel rev sensor, but also see that somebody else changed that but found it was the distrib cap. So, could the sensor cause these behaviors?

I guess I'm hung up on that number four cylinder not behaving at idle, and am missing something simpler. -or maybe not. :unsure:

Suggestions anyone?
mike

My vote is the crank position sensor - a VERY common failure which leads to random stalls. Its behind the block at the top of the flywheel housing.

Yes, that's what I really think too.
I ordered one from ipd, at 39 bucks plus $7 priority mail (vs. $76 at the NAPA counter, yeesh. I bet it's the same item too.)

It's nasty back there at the sensor, should I gumout and rinse that area clean before pulling the old one out? Guessing it's bad news if schmutz falls in?

Arrgh.
Okay, unplugged and trying to remove the Crank speed sensor.
This thing is a real PITA, and still confounding me. I can't get a wrench around the bolt. Tips, please.

I read in one topic that you go at it over the top of the engine, between that and the firewall, I can see it, but can't quite snake a hand back there, and I'm skinny. tried undoing the cable bundle and connector along the firewall and going behind, still no joy.

The one way I can reach it is by laying down on the motor and grappling it, shooting my left hand around and between the exhaust the the little red (breather?) tube, and I can grasp it. I can fit a 10MM socket on it also.

But, which way should I come at it with a wrench / ratchet / special gimmick?
Do I need an extra-stubby open-end? there seems to be no room to rotate any tool, plus I am at fully-extended fingertip length.

Help me before I cuss again @@#$* whoops too late...

I did mine a couple months ago. It' s all about the tools. I used 1/4 inch socket set because they are so much smaller, as well as extensions from several neighbors. I used a wrench as well. I hear it helps to have patience, but I was all out of that 2 minutes into the job.

Oh, and what sucks worse is putting the new one in. I put the bolt through the CPS, and then held the other end of the wire sort of tight as I lined up the hole. I don't think you have to be too woried about dropping stuff in there cause it's the bell housing, and there is usually a pile of goo at the bottom of those anyway.

Good Luck!!!

Thank you Sarge, and yes it is all about the tools.
I borrowed a short (~4") 10mm combination wrench from my brother, that and a generous spritz of WD-40 allowed me to loosen the nut and complete the change without too much heartache.

I was really mad before. Using the above tools, and an around-the-side-of-the-motor attack angle, both taking it off and putting it on were a (relative) breeze! I am NOT bragging: start to finish, this shite cost me four days. -but I did learn something.

SO, for the benefit of future CPS changers, I nominate this as an Easy Procedure:
(Using John Muir's orientation: Front is the front OF THE CAR, Left is left OF THE CAR, etc.)
1. pop the battery cable and the CPS plug.
3. Lay something canvas-like (Toro leaf-bag worked for me) across the top of the radiator and motor to cushion sensitive hipbones/belly from brutal flanges on radiator, and your clothes from yucky grease stains.
2. have your wrench, new sensor, and WD-40 at hand, laid out where you can reach them while prone on the motor (new WD40 can has a permanent straw- BRILLIANT.) -remove any watches, rings, etc, from left hand.
3. standing against the right headlight, facing rearward, lay down on the motor. I lean over the grille and just let myself roll in. No climbing required.
4. Locate the sensor by hand: put your left arm in, BEHIND the big a/c evap hose (if you have one) and put your hand between the exhaust header and the motor to go behind it. Find the sensor. You can eyeball it beforehand with a flashlight, over the top of the motor. it's on the right side. Helps to visualize what you're doing.
5. MAP THE TERRAIN AROUND THE SENSOR WITH YOUR FINGERS. Keep this "manual" image in your mind as you go. feel the sensor. feel the nut. feel the space around it. (Inhale, and say Om while exhaling, do this once as you touch each thing.)
6. retract your hand, then go back in with the WD-40 far enough to point the straw in that general direction of the job. Soak everything in there. This is because you're using a SHORT wrench and won't have good leverage to break loose the nut.
7. bring in the box end of the wrench, seat it on the nut with the wrench hanging downward and towards the right of the car (your left.) Pull on it to loosen. it should come. repeat until you can finger out the nut. remove your wrench. finger it out. remove the nut. Remove the sensor.
8. thread the new sensor plug up over the motor, so you can pull on it as needs be (thanks Sarge).
9. find the hole with your fingers, then guide the sensor into the hole. Om....
10. bring your hand out, bring the nut in, thread it into the sensor. Om....
11. bring in the wrench and tighten that sucker down. HOO-hah!!
12. plug in the connector, the battery, secure all loose bits, fire it up!

Any other helpful hints here for future aggravated changers?

Search Keywords: Crank Position Sensor Crank RPM Sensor Howto

I'd say that's a pretty good "how to".

I have to remove my starter soon. That's another of those "I can see what I'm supposed to do, but how the hell do you do it?" sort of jobs.

I'll need my instructions no later than Monday................. :grin:

Sure. It'll be the Monday after whatever date MY starter needs changing.

That does sound like a blood-sacrifice job. Those Norse Gods can get pretty hungry sometimes. I'd have plenty of Band-aids on hand. :thumbsup:

Does anybody know how many posts it takes before this "Newbie" tag falls off your profile?

Didn't even notice when mine went away. I don't know if it a post thing, or a time thing.