No start, no spark?

[Por_sha911]

Just had a shop replace head stud and re-time the cams and adjust the valves. I put a new clutch and re-installed the motor. Replaced the oil press sensor. Found the wires to the speed sensor and the top dead sensor had the insulation brittle and falling off. I wrapped them in rubber insulation and then electrical tape and reinstalled. I tried to remove the sensors but one nut wouldn't budge and the other loosened but the sensor didn't move so I just re-tightened the nut (don't remember which is which). When putting the pressure plate bolts back on I set the wrong torque setting and the engine was turned about a half rotation (I thought it was OK since it was going clockwise but I realized after the fact that it was being rotated backward )
I finally got the whole program back in tonight and now it won't start. I turned the motor with the coil wire disconnected 3-4 times to make sure the oil was in the right places.
Rotor is turning. Wires weren't taken off the cap so I know the order is right. I pulled the #1 plug wire and laid it with the open end up against the mounting bolt head but I'm not seeing any spark. DME relay was replaced this year. I can smell gas so the fuel pump should be working.
Where do I go from here? Am I correct in that I should be seeing a spark? Did I damage the sensors by wrapping the wires? If so, would this cause my no start problem? Did I flood it out? Help.

[slodave]

I don't think turning the engine did anything bad. I manually rotated mine a number of times when my engine was out. I don't remember if I went CCW at all though. Are the sensors plugged into the correct ports? The DME needs to know that the flywheel and ref sensor stud is moving before it gives spark.

Dave

[Por_sha911]

The sensor plugs were marked and I checked to make sure they are in the right place. Would unbolting a sensor "throw it off"?
I've been told that turning a motor CCW may cause problems with the chain tensioners but I didn't hear any noise when the motor was turning.

[slodave]

Originally posted by Por_sha911
The sensor plugs were marked and I checked to make sure they are in the right place. Would unbolting a sensor "throw it off"?
I've been told that turning a motor CCW may cause problems with the chain tensioners but I didn't hear any noise when the motor was turning.

Only if it moves. You mentioned that the old insulation fell off, They may have succumbed to time. There are threads that tell how to check them.

Dave

[slodave]

I borrowed this from one of my old threads. Thanks JTL

Terminals
1-2 960 Ohms +-96 Ohms
1-3 >100 KOhms
2-3 >100 KOhms

Top plug terminal = #3
Middle = #2
Bottom = #1

DG=speed sensor
BG=reference sensor

[Por_sha911]

slodave: TY for the measurement numbers. I'm very weak when it comes to electrical testing and need a little "edjumacation".
I assume that I take the plugs off and then apply the multimeter leads to the wires going to the sensors. Also, since I'm disconnecting the sensor, I don't need to turn the motor over.
These may seem like basic questions but I would appreciate it if you would confirm that this is correct.
Lastly, do both sensors have the same values? You said that terminal 1-2 is 960 Ohms (not KOhms) +/- 96. So a value 864 to 1056 is OK?
The other two terminal values are KOhms.

[Por_sha911]

Well, I took a stab at it but I think I measure the wrong side. I measured the plug that came off the tree and not the ones in fixed in place (duh)

[slodave]

Hi,

I was having issues last year and someone posted those values. They should be correct as posted. You want to measure the values at the engine side of plugs Yes, no need for the key in ignition for these tests.

Dave

[Por_sha911]

Well, I just tested the engine side (3 terminals in a bracket)
BG 1-2 1038 and DG 1-2 1023 at 2000 ohms BUT
both show no reading (meter stays at 1) on the 1-3 and 2-3 terminals at any ohm setting.
Does that mean they are both toast? I got the readings you said were normal but on the plug side and not the engine side (???)

[The Turk]

Did you check the clearance between the sensors and both the reference setscrew and the flywheel ?
You can do this easily from under the car, both need to be at .75mm or closer, just make sure they're not touching.
You can test that the sensors are working and that they are adjusted correctly by putting a digital multi meter on AC volts and measuring the voltage at the plug from the sensors.
Unplug the connectors, put the meter leads on the two pins and crank the motor, you should get approximately 1.5 volts on the reference sensor and 6 volts on the speed sensor.
Good luck.

[Por_sha911]

Originally posted by The Turk
You can test that the sensors are working and that they are adjusted correctly by putting a digital multi meter on AC volts and measuring the voltage at the plug from the sensors.
Unplug the connectors, put the meter leads on the two pins and crank the motor, you should get approximately 1.5 volts on the reference sensor and 6 volts on the speed sensor.

There are 3 pins in the connector. Which 2?

[The Turk]

It’s the center and bottom pin on both the reference and speed sensor, these correspond to pins 25/26 and 8/27 on the plug that goes to your Motronic under the driver’s seat, that’s actually the best place to check it.

[Por_sha911]

Originally posted by The Turk
Did you check the clearance between the sensors and both the reference setscrew and the flywheel ?
You can do this easily from under the car, both need to be at .75mm or closer, just make sure they're not touching.

Turk: thanks for the info. I just crawled out from under the car and I can't figure out how I'm going to check the gap. There's no room to get a feeler in there between the sensor and the ring gear.

[The Turk]

Do the test with the voltmeter, that will tell you if you need to check the gap.
My car has headers and I could easily get up there, your heat exchangers are probably in the way.
Did you mess with the reference setscrew on the flywheel or the bracket that holds the two sensors when you did the clutch ?

[Por_sha911]

I started to unbolt one of the sensors from the bracket but then retightened it. I didn't mess with the bracket or the setscrew so I think that its all good. I'll do the voltmeter test but I suspect I'll be replacing both sensors.

[The Turk]

If you’ve got around a 1000 ohms at the 1 / 2 pins on both sensors I doubt they’re bad.
Post the voltages once you’ve done the test.

[slodave]

Glad Gary has been able to help out. He's giving more info than I would have known. I did remove the bracket for the sensors last year while the engine was out and did not think to check upon reinstallation. No troubles for me, but I remember that the bracket could only go one way and did not seem to be adjustable.

Dave

[The Turk]

One of the two holes on the bracket is bigger than the other to allow for adjusting the proper clearance to the sensors.
I just chased down a similar problem when I installed the 3.5 motor into my car, just trying’ to help…

[slodave]

Originally posted by The Turk
One of the two holes on the bracket is bigger than the other to allow for adjusting the proper clearance to the sensors.
I just chased down a similar problem when I installed the 3.5 motor into my car, just trying’ to help…

Guess I got lucky! I did not notice the difference in hole sizes before. Noted, thanks!

Dave

[Por_sha911]

Multimeter set at 200 ACV, leads put on two bottom prongs on the motor side of BG and DG. Cranked motor 2-3 seconds each. O, zip, nill, nada.
Could this be a function of the gap being wrong? (Maybe the mount was moved by the shop that replaced my head stud and re-timed the cams) or is a sign for sure that both sensors are bad? I really "man-handled" the wires to wrap them and then to get them into the grommet. I have B&B headers but can't figure out how I can check the gap short of dropping the motor for the fourth time!
To check from the motronic plug I need to check the wire and not the ECM, right?