No spark, No tach bounce, 2 new sensors

[fiily]

Originally Posted by Roger 911

Yes, the sensors are the same part #. They perform different functions. Obviously, if the wrong plug is attached to a sensor (speed to position, or position to speed), it won't work.

Roger

Ok, thanks for the sanity check, much appreciated.

[Roger 911]

OK, admittedly I'm fishing now. Is it plausible that the current sensor gap was adequate with the old wires (when they weren't shorting out), but is now not sending a strong enough signal with the new wires? If anything, I would think the opposite would be true, i.e., the new wires would tolerate a wider gap.

I realize an oscilloscope is what is required, but I don't have one handy at the moment.

Thanks.
Roger

[Bradical]

Its really no big deal to set the bracket right. The longest time spent was filing a washer down to the .8mm gap i needed and letting the glue dry. If you dont have a scope, its at least worth a try. I 100% agree with your logic though.

[Bradical]

It is a LOT easier if you relocate the heater control valve though, i dont remember reading what year you have.

[Roger 911]

Originally Posted by Bradical

It is a LOT easier if you relocate the heater control valve though, i dont remember reading what year you have.

Yes, I'm living this right now. Almost impossible to get to the allen heat bolts that hold the bracket on. I have a 6mm allen socket, but there isn't enough room to fit the head of the ratchet in there. If I put on an extension, then the ratchet won't clear the fire wall. I'm going to see if Sears has a longer 6mm allen socket.

This is NOT easy. I can drop the engine in my 911 in as much time as I've spent monkeying with this.

Roger

[Bradical]

I used the short side of a 6mm allen wrench with a hollow nut driver for the additional torque. The allen bolts dont have to come out, you just need to loosen them a bit so the bracket can swivel. I couldnt get a 6mm socket drive in there either as much as I wanted to.

[Roger 911]

I managed to loosen the lower one. Can't get at the top one. I'm giving up for today.

The really frustrating thing is that I had everything off the engine a couple months ago when I did rod bearings and a turbo rebuild. Would've been pretty darn easy to do this then, but of course it was running fine before and after that work.

Roger

[Roger 911]

Talked to Steve at 944online. He doubts that the gap would work for the old wires and not for the new. Therefore, maybe I won't bother trying to reset the gap.

Another interesting observation is that I get no tach bounce, but have plenty of fuel pressure at the rail. It's my understanding that a faulty speed reference sensor/connection would result in no tach bounce AND no fuel pressure. Is there something other than a reference sensor that might cause a "no tach bounce" condition?

Thanks.
Roger

[Roger 911]

Another update. I was only getting .3v for the speed sensor at the DME. I tried it with the reference sensor harness and still got the same reading. Then I hooked the sensor back up to one of the old harnesses, and I got .8v. Supposedly, the DME needs at least 1v. So I decided to reset the gap.

When I measured the gap with a metal slide gauge, it seemed to be a bit wide, maybe 1.5mm. I reset it (which was possibly the biggest pain in the ass task ever!), and rechecked the voltage. The good news is that it went up, but not enough with the new wires. I now get .5v with the new wires, but I'm up to 1.1v with the old wires. There has to be something wrong with the new wires. I'll ask the supplier to send me a new set.

Roger

[txhokie4life]

I just tried to buy a couple sensors from Rock Auto -- but upon checkout it
said for European models only -- (84 944)

Is there such a distinction?

mike

[DannoXYZ]

Originally Posted by txhokie4life

I just tried to buy a couple sensors from Rock Auto -- but upon checkout it said for European models only -- (84 944)

Is there such a distinction?

Strange, both the European and U.S. version of the sensors both cross-reference to the Porsche 944.606.115.00 part. So I would assume it's interchangeable. Photos certainly look the same. Want to order some of those Cambiare sensor and try them out?

[Roger 911]

Turns out the new wires I bought were assembled wrong (wires for the speed sensor were reversed in the plug). They sent me a replacement set, installed them and it started right up. What a pain! But certainly relieved that its running.

New problem now, the tach quit working. Well, I guess if I didn't want to work on cars, I'd drive a new Camry.

Roger

[Bradical]

Awesome! I am glad it hear it is up and alive!

[Roger 911]

All good, tach's working fine. It was actually just physically sticking. After cleaning all the connections, etc., it still wasn't working as it sat in the garage. Then I remembered that the speedo needle occasionally stuck above 80mph (professional driver on a closed course!) when we first got it. So I took it out for a drive, sure enough, after a couple minutes driving, it popped up and started working normally.

One car done...on to the next!

Roger