3.2 Carrera no start

[wazzz]

Originally Posted by Cevan

I just did mine and got two sensors here for $244 shipped.

https://www.***************/pn/0261210005

If you google Bosch 0261210002 you'll find quite a few offers at around $60 each.
They are original Bosch parts. Probably too late for you but this may serve others here.

[Paul Shepherd]

Was supposed to be going away but the weather is miserable so decided to do a bit more on the car instead.
Tried to measure all 3 sensors resistance and weirdly none of them would register anything when trying all combinations across 3 terminals as outlined in the Bentley, it seems that every circuit is broken on all 3
In the Bentley the testing for the CHT sensor shows 2 pins whereas mine only has 1 so guessing they have the updated 964 upgrade that I will also do
And yes my multimeter is working correctly as I tested it on a couple of other things including number 1 injector and it measured correctly
I have taken them all out which was surprisingly easy and only took 30 minutes
Is there an alternative part to the CHT sensor

[mysocal911]

Originally Posted by Paul Shepherd

Was supposed to be going away but the weather is miserable so decided to do a bit more on the car instead.
Tried to measure all 3 sensors resistance and weirdly none of them would register anything when trying all combinations across 3 terminals as outlined in the Bentley, it seems that every circuit is broken on all 3
In the Bentley the testing for the CHT sensor shows 2 pins whereas mine only has 1 so guessing they have the updated 964 upgrade that I will also do
And yes my multimeter is working correctly as I tested it on a couple of other things including number 1 injector and it measured correctly
I have taken them all out which was surprisingly easy and only took 30 minutes
Is there an alternative part to the CHT sensor

1. The single wire temp sensor is measured to chassis ground.
2. On ref & RPM sensors, there're three wires for each (one is a shield).
Only one of the three connection combinations should indicate a resistance measurement.
3. It's unlikely that all three sensors are bad.

[Paul Shepherd]

Originally Posted by mysocal911

1. The single wire temp sensor is measured to chassis ground.
2. On ref & RPM sensors, there're three wires for each (one is a shield).
Only one of the three connection combinations should indicate a resistance measurement.
3. It's unlikely that all three sensors are bad.

Yes thank you I know the CHT is to ground I was just remarking that the Bentley shows 2 and they also show over 1000000 ohms for for the other combinations on the speed and reference.
Anyway I had another look and got the correct reading on the reference sensor after cleaning the terminals a bit but the CHT and speed are completely dead

[mysocal911]

Originally Posted by Paul Shepherd

Yes thank you I know the CHT is to ground I was just remarking that the Bentley shows 2 and they also show over 1000000 ohms for for the other combinations on the speed and reference.
Anyway I had another look and got the correct reading on the reference sensor after cleaning the terminals a bit but the CHT and speed are completely dead

The CHT doesn't really matter at this point, just use a paper clip for now when the RPM is replaced and when the engine warms up.

[Paul Shepherd]

Originally Posted by mysocal911

The CHT doesn't really matter at this point, just use a paper clip for now when the RPM is replaced and when the engine warms up.

Is the paper clip to bridge? There is only one terminal so should it be grounded? Or is there a ground terminal that is unused in the plug I’ll go and check when I’m back
Is RPM a typo?

[mysocal911]

Originally Posted by Paul Shepherd

Is the paper clip to bridge?

Yes.

Originally Posted by Paul Shepherd

There is only one terminal so should it be grounded? Or is there a ground terminal that is unused in the plug I’ll go and check when I’m back

The female connector has two pins (signal & ground) which go to the DME ECM.

Originally Posted by Paul Shepherd

Is RPM a typo?

No. Actually, using RPM (engine speed) is the more correct indication of what the DME ECM is looking for, and not speed which typically relates to MPH.

[Paul Shepherd]

Originally Posted by mysocal911

Yes.



The female connector has two pins (signal & ground) which go to the DME ECM.



No. Actually, using RPM (engine speed) is the more correct indication of what the DME ECM is looking for, and not speed which typically relates to MPH.

Thanks for your help all 3 sensors have been ordered

[Quicksilver]

Instead of the "Replace the reference sensors just to see" it makes much more sense to test them. (Always test, test, test instead of replace, replace, replace!)

You can get a very basic oscilloscope for dirt cheap now. When cranking you should see a 2.5v signal on the reference sensors. Obviously one is multiple signals per revolution and the other is once per rotation.

[Paul Shepherd]

Originally Posted by Quicksilver

Instead of the "Replace the reference sensors just to see" it makes much more sense to test them. (Always test, test, test instead of replace, replace, replace!)

You can get a very basic oscilloscope for dirt cheap now. When cranking you should see a 2.5v signal on the reference sensors. Obviously one is multiple signals per revolution and the other is once per rotation.

In principle I agree with you but they are all the original parts and in pretty bad shape so I would change them anyway
I did test them and 2 are not in spec

[RobFrost]

If issues with multiple sensors then check earth strap. In fact check it anyway. My money's on crank position sensor cable.

Sent from my SM-G988B using Tapatalk

[mysocal911]

Originally Posted by RobFrost

If issues with multiple sensors then check earth strap. In fact check it anyway. My money's on crank position sensor cable.

Sent from my SM-G988B using Tapatalk

He said it was OK in post #24.

[Mr. Merk]

Originally Posted by mysocal911

The female connector has two pins (signal & ground) which go to the DME ECM

When mine failed, I grounded my DME connector to the intake manifold and drove 9 hours home without issue. It was a ***** to cold start though.

[Paul Shepherd]

Just an update
Installed my 3 new sensors today reference, speed and CHT, a pretty easy job took less than an hour which was nice. Turned her over and she started straight away so very happy
Thanks to everyone for their help

[Mr. Merk]

Originally Posted by Paul Shepherd

Just an update
Installed my 3 new sensors today reference, speed and CHT, a pretty easy job took less than an hour which was nice. Turned her over and she started straight away so very happy
Thanks to everyone for their help

That's great!

Based on trends we've been seeing, replacing these three sensors are right up there with replacing the fuel lines and having the injectors serviced on every 3.2 still running original gear.

[GH85Carrera]

Originally Posted by Mr. Merk

That's great!

Based on trends we've been seeing, replacing these three sensors are right up there with replacing the fuel lines and having the injectors serviced on every 3.2 still running original gear.

I totally agree. If you still have the original sensors, even if it a 10,000 mile show queen, replace them if you plan of driving the car. Electronic parts just don't last forever.

I had replaced mine 12 or so years ago. when I got a no start issue. Then a few year back my car acted like it was haunted. The idle would go up and down at random up to 2,500 RPM. Then die, hard to restart and very little power. It did that right at the very busiest intersection in my town. I got home and replaced them. They would test out fine when cold. Once they were hot, they would fail, then be ok, then fail.

[Paul Shepherd]

Originally Posted by Mr. Merk

That's great!

Based on trends we've been seeing, replacing these three sensors are right up there with replacing the fuel lines and having the injectors serviced on every 3.2 still running original gear.

I have just done my fuel lines since the car was off the road and I was waiting for the sensors
All original marked 86 looked like new in the car but couldn’t believe how stiff they were and there were small cracks starting to develop on the inner layer
Maybe I need to look at the injectors in the near future, do they fail or is it a performance thing

[Mr. Merk]

Originally Posted by Paul Shepherd

Maybe I need to look at the injectors in the near future, do they fail or is it a performance thing

You'd be surprised how poorly they work at this point. I had a flat spot in the power band that was resolved after having them cleaned. They can also leak into your cylinders while the car is off.

[ant7]

Good to hear you got it sorted.

Originally Posted by Paul Shepherd

Just an update
Installed my 3 new sensors today reference, speed and CHT, a pretty easy job took less than an hour which was nice. Turned her over and she started straight away so very happy
Thanks to everyone for their help

[Mr. Merk]

This is the injector service I've been using.