Replacing 3.2 reference senders with engine in car?

[gtc]

Can anyone tell me the best way to reach the crankshaft speed and position reference senders on a 3.2? I know where they're located, but I'm not sure of the best way to get at them for replacement.

My car is stuck at the bottom of a sloped gravel driveway, so I can't really jack it up to look underneath. I guess I may need to tow it out onto level pavement.

Thanks,
Graham

[steely]

Yeah, level ground would be best, jacked up, rear drivers wheel removed. I had my shock off at the time too.

[Targa Me]

tow to level ground. lift the car so you can comfortably crawl underneath it. you under the left side of the car, lean to your left and with your right hand loosen up the cap screw holding it in place. Probably a 6mm allen if i remember correctly. if the sensor has been there for a while it won't pull out easily, you may need to twist it back and forth to loosen it. when you replace it, put a film of oil on the cylinder portion of it that way it will come out easier next time. BTW, those things rarely go bad, are you sure that's your problem?

[gtc]

Ok, thanks for the tips.

What about setting the gap between the sensors and the pin and toothed wheel? Is that necessary, or do the new sensors pretty much go in to the same depth that the old ones were at?

I'm almost certain that my problem is due to one of these sensors. Engine has 330k miles on it, so I can't say I didn't get enough enough use out of them. I just wish they had lasted a few more months until my next engine drop.

[DRACO A5OG]

Caution, do not twist it in no matter what you do, the sensors are liken to light bulbs, once you twist it, you will break the filament/element making it useless. Ask me how I know

[Targa Me]

Interesting DRACO, I've twisted mine in and out and never had a problem.

gtc, you dont need to reset the gap as long as the mount is not disturbed.

[Tippy]

I've pulled mine out several times. Hardest part is getting the huge cylinder head temp sensor grommet out that the crank sensors go through. Stick a small screwdriver in the two holes that in the grommet to aid removal. Next, like others have said, it requires some wiggling to get the cylinder out of the bore which is a PITA too. I never had to remove anything on my car, just jack it up and slide underneath.

[gregwils]

Originally Posted by gtc

Ok, thanks for the tips.

What about setting the gap between the sensors and the pin and toothed wheel? Is that necessary, or do the new sensors pretty much go in to the same depth that the old ones were at?

You don't need to reset the gap if you pull the sensors out of their mounting.

[LifeLine]

I am doing this same thing right now, but my housing is broken. Any ideas on where I can get a new one 1984 3.2 911 Cab?

[john walker's workshop]

Ohm them first so you don't waste your time. around 960 ohms give or take. an open circuit is generally what you're looking for.

[gtc]

Aw crud... the bottom two pins on the sensors give me 970 and 969 ohms. Does that mean they're still good?

[Tippy]

Yup

[Rodsrsr]

Remember to but the BMW part. Its half the price. Someone else may chime in with the part numbers, I dont remember, but there are threads on it.

[gtc]

Ya, I have the bmw replacements already.

[AtomicDog]

Just did this on my '86. Less fun than anyone will let on...

Since I had the bracket out, removing the shock was hugely helpful. Someone posted a tip that using a floor jack on the lower shock nut was the ticket. Whomever it was, bless them, because 600+ ftlbf from my IR pneumatic gun was not enough.

The BMW sensors (from our host) worked well. I was not able to get enough slack in the new cables to use the stock cable clamp at the driver's side intake manifold, but because the cables are shorter, it wasn't necessary.

I would encourage you to consider why you think these sensors are the cause of your no-start condition. While it is possible, it is much more likely that something else is keeping you from the safety of your garage. My sensors were dropping insulation like a shedding dog, but my car still ran (though poorly).

Targa Me is correct. You do not need to adjust the sensor position if the bracket is not disturbed. Draco A5OG brought up an important point - do not twist the NEW sensor into place. Whatever you have to do to get the old one out is fair game, however.

Tippy pointed out that the grommet is a PITA. Push it out (down) from the engine compartment. Lube it with some silicone grease and it will pop back into position like a charm.

My sensors were shot. My car had unbelievable vacuum leaks, but it would still start and run. I suggest you replace these sensors if they are failing, but 970 and 969 ohms are within band - this is no smoking gun. You likely have another problem. Targa Me is not the only one who thinks this might not be your issue.

Keep us posted. Since I replaced mine and my issue persists, I have great personal interest in how this works out.

[gtc]

Thanks for the replies so far, here is what I'm working with right now:
1. Engine cranks but does not fire.
2. I smell a little fuel in the exhaust. Confirmed that fuel pump runs by jumpering the DME relay connections (pins 30 & 87b)
3. No spark at a spark plug. Checked voltage at coil (11.2V - low, but possibly because battery is low from cranking) and two coil resistance measurements (within spec). I will charge battery and recheck coil voltage.
4. CHT sensor resistance measures higher than spec, but this should only make it run a bit rich, right? Ordered new sensor, regardless.
5. Plug wire resistance measures 5-6k ohms... much higher than the 3k spec in Bentley, but fairly close to Magnecor's resistance spec (2200 ohms/ft, IIRC). FWIW they are 8.5mm Magnecors, and they have lots of miles on them. But why would they cause such a sudden no-start condition?

Edit: I forgot to mention that I did try swapping out the DME relay.

[rusnak]

change the dme relay, and feel for the second "click" while cranking.

clean the battery connections, and clean your dme grounds. check voltage at the icv harness, and make sure that there is power to the system. If there is none, then go back and re-check the dme relay.

[j911brick]

In regards to the likelihood of these sensors failing, on 944s and BMWs, failed sensors are common as dirt, and its pretty much the same sensor. After the DME its the first thing I check.

[McLaren-TAG]

Originally Posted by rusnak

change the dme relay, and feel for the second "click" while cranking.

clean the battery connections, and clean your dme grounds. check voltage at the icv harness, and make sure that there is power to the system. If there is none, then go back and re-check the dme relay.

Where is the DME ground located?

[Tippy]

Originally Posted by McLaren-TAG

Where is the DME ground located?

Intake #1 runner up top.