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-   -   3.2 wont start (http://forums.pelicanparts.com/porsche-911-technical-forum/311942-3-2-wont-start.html)

Fahrvergnuugen 10-27-2006 05:18 PM
3.2 wont start
 
My 3.2 won't start. I dropped the motor to do some transmission work and replace the clutch. Motor is back in the car now, cranks but won't fire.
I have no spark and no injector pulses (I tested using a noid light)


Quote:
Originally Posted by lorenfb
1. A missing +12 volts on DME pins 1, 18, 35, (bad DME relay) or
2. A missing ground on DME pins 5, 16, 17, or
3. A bad speed sensor on DME pins 8 & 27 (1000 ohms/2.0VAC), or
4. A bad reference sensor on DME pins 25 & 26 (1000ohms/.100VAC), or
5. A speed sensor plugged into a ref sensor connector or opposite, or
6. A bad ignition coil, or
7. A bad ignition switch (no +12volts on coil), or
8. A missing flywheel pin, or
9. A bad +12 volts on the injectors, or
1-5 & 9 checks out. 6&7 are unlikely because there is no fuel either. I tried switching the speed & ref sensors in case I plugged them in backward.

#8 scares me...


Any thoughts?

Dadofour 10-27-2006 05:57 PM
What condition are your sensor plugs? IS the plastic insulation craked or missing. I once had the sensor ground out on the bracket and the symptoms were the same as you are seeing.

bell 10-27-2006 06:06 PM
one of my crank triggers got me like this when i reinstalled my 3.2, ended up being that one of the sensors was a hair too far away to pick up a good signal, i readjusted the sensor mount and she fired right up.

Fahrvergnuugen 10-27-2006 06:09 PM
Quote:
Originally posted by bell
one of my crank triggers got me like this when i reinstalled my 3.2, ended up being that one of the sensors was a hair too far away to pick up a good signal, i readjusted the sensor mount and she fired right up.

I suppose that could be it. I didn't realize there was adjustment in the sensor mount...

Shuie 10-27-2006 07:27 PM
Make sure you didn't flip the two sensor wires. I wouldn't touch the mount unless you are absolutely sure its your problem. Try flipping the two connections first.

Check for vacuum leaks also. I learned this one the hard way. If you are not pulling enough air across the air flow sensor, its not going to start unless you push the accelerator in far enough to open the throttle body and bypass it.

Fahrvergnuugen 10-27-2006 08:42 PM
Quote:
Originally posted by Shuie
Make sure you didn't flip the two sensor wires. I wouldn't touch the mount unless you are absolutely sure its your problem. Try flipping the two connections first.

Check for vacuum leaks also. I learned this one the hard way. If you are not pulling enough air across the air flow sensor, its not going to start unless you push the accelerator in far enough to open the throttle body and bypass it.
Flipping the sensors was the first thing I tried. No spark / no fuel pulses couldn't be caused by a vacuum leak...

Shuie 10-27-2006 09:12 PM
DME relay unplugged?

911mot 10-28-2006 03:00 AM
+1 on the sensor air gap. I left mine too big after a clutch change and could only start it by running jump leads (booster cables) from another car. And when it did run it would rev to 4.5k and splutter big time on WOT

ChrisBennet 10-28-2006 05:13 AM
+2 on the sensor air gap. The bracket is adjustable, when you remove it you need to readjust the the gap to have .8mm between the end of the sensor and the toothed wheel.
-Chris

Jeff 10-28-2006 05:50 AM
Did you happen to set or trigger the alarm?

Fahrvergnuugen 10-28-2006 07:59 AM
Quote:
Originally posted by Shuie
DME relay unplugged?
Quote:
Originally posted by C U L8R
Did you happen to set or trigger the alarm?

The alarm cuts ground to the DME relay according to the wire diagram. To be sure it wasn't dme relay related, I completely bypassed it by using a jumper wire to send 12v from pin 30 to pin 87 and 87a.

Fahrvergnuugen 10-28-2006 08:01 AM
Quote:
Originally posted by 911mot
+1 on the sensor air gap. I left mine too big after a clutch change and could only start it by running jump leads (booster cables) from another car. And when it did run it would rev to 4.5k and splutter big time on WOT
Quote:
Originally posted by ChrisBennet
+2 on the sensor air gap. The bracket is adjustable, when you remove it you need to readjust the the gap to have .8mm between the end of the sensor and the toothed wheel.
-Chris
Roger!

I'm going to get a multimeter with AC volts on it and check for voltage from the ref and speed sensors. That should confirm the theory of them having too much gap. I really hope it's that simple!

hcoles 10-28-2006 08:04 AM
something like this happened to me...
I had forgot to connect the group of brown ground wires to the #1 runner....they drop down out of sight....hooked them up and all was fixed....most likely it is something simple like this..

what was funny...I went and asked my mechanic....he knew what it was without looking...the worst thing is if this group of wires is making contact somewhere and when you drive it falls off...


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