beaten by the damn immunity doll.. okay row back on to the island ..

 

Whew...the 944 sharks were circling(no offence 928 guys).

 

hmm .. wonder where the 944 guys banish people too ...

 

off topic. Riad's waiting.

 

so to "jump the CHT, you just litterally connect both ends of that terminal with a paperclip (or other?)

is this a "cold" or "hot" operation and what should be seen?

I have the single wire as well and although I have no real experience on this topic, it does relate to things I can learn, or might need in the future

 

well now I am fully educated .. Rus posted the chart ... when engine cold the resistance is high therefore richening the mixture ..as the engine warms up the resistance drops at the sensor and leans out the mixture, The resistance is measured between the signal line and ground .. through the thermocoupler. The ground was provided by the threads of the sensor. So only one wire went to the sensor and it grounded there .. this is the one wire system.
Porsche upgraded this to a two wire system not relying on the ground of the sensor threads . They actually feed the sensor a ground through the wiring harnes ( there is actually an upgrade procedure on Pelican tech articles ) .
To test the sensor you can either measure with an ohmeter as i did at various temperatures or you can eliminate it altogether . When the car warms up take your single lead and fasten it to ground via aligator clip or something , This is 0 ohms and lean so it should not make a difference. . if the contact breaks for whatever reason ( like unplugging it , the car will run really rich , hunt up and down and may even stall out.
You can do a quick test to see if it is working by just unplugging it on fully warmed up running engine should casue the engine to hunt up and down becasue it is rich . if it does absolutely nothing your sensor is toast.

I am going to jumper it , and test. Will update when I know more .

 

Speaking of off-topic, Ice and WB, how do you hook a 'scope? I was looking at one last week and almost bought it to mess around with. If I ever need one.....

Is there an inductive pickup or something like a coil used on a timing light? I guess I could go look at one of the EKG machines next door

WB, when you come back you'd better not be wearing one of those damned shell necklaces, I hate those.

 

Scope is mererly a voltmeter with a time function and a fast response time you can see things that happen quickly . If you lived closer i'd mail you one as I have 3 in the garage . take some practice to play around with if your not used to it . Not for high voltage and use the same precasutions as a meter.
I used mine for detecting a bad hall effect sensor as you can see the signal going up and down . you could use it for injector pulse width also.

 

So should I buy one? I see them on CL from time to time. I think I'd probably learn something new.

 

I have a 20 MHz Fluke Scopemeter that is capable of up to 600V input operation. It is great for testing injector waveforms and doing datalogging.

If you can find a scope cheap, it will help on many things and give you a visual picture of what is happening like ground bounce, O2 sensor response, etc.

You can get high voltage probe adapters for most scopes at Fry's (at least the one I visited in San Jose had them).

Ice, the CHT sensor is often referred to the NTC in the Bentley manuals for Negative Thermal Coefficient device. Literally translates into hotter = lower resistance as you guys notice

 

i wouldn't unless you are REALLY interested .. I know how to use mine and I use it once every 5 years so i have to reteach myself each time ..

 

Scott are you using the 97 ?

i didn't like the sample rate so went back to my old Hameg.

Ps they should have renamed it the NFG sensor

 

I'm using the Scopemeter 123. The sample rate of 20MHz is plenty for what I do.

http://assets.fluke.com/selectionguides/scopemeter.pdf

I got lucky and did a power supply design 10 years ago for a customer and he tipped me with the scope. I like it as it is battery operated and I can carry it into the car easily

 

"Think about it a second longer. If the O2 sensor is plugged into the harness, and is not installed or is bad, it is sending incorrect voltage signals to the dme, which would throw it off."

"Think about it", yes one needs to think about it:

1. A dead O2 sensor sends NO voltage, i.e. a voltage < .60V causes richening,
a voltage > .60V causes leaning.
2. An O2 (bad or otherwise) sensor rarely (never) generates a voltage out of the engine.
3. An O2 sensor never shorts out, i.e. other than its lead wires.
So, an O2 sensor can't cause engine problems as defined in this thread!

"You're saying a faulty CHT would cause the engine to die? And not fire back up?"

That's correct! Just unplug the sensor with a HOT engine and see what happens,
i.e. It'll start surging and making black smoke and die - the engine becomes
flooded and will be very difficult (basically impossible) to start (with it unplugged/bad).

"so to "jump the CHT, you just litterally connect both ends of that terminal with a paperclip (or other?)"

That's correct.

One rarely if ever needs an o-scope to troubleshoot a 3.2. A simple test light
and voltmeter will suffice for 98% of the 3.2 ECM problems.

Bottom line: Hopefully the mis-info from the 'Dark Side' isn't finding its way to Rennlist,
as there is a similar thread on the same topic there. Those guys with their postings are
totally misguided in their ideas, as is the usual case. Surprised someone over there
didn't suggest "replacing the ignition points".

 

I’m troubleshooting a similar 3.2 liter problem as well.

If you need a copy of the factory DME test plan you can download it from my site

http://www.coreone.net/documents/dmetestplan.pdf