Wideband 02 install questions

[Marv [uk]]

Ok, so First, Hello everybody

I've been lurking about for a while unregistered and I'm seriously considering an VEMS WBo2 for my Bus

I've a type 2 VW camper with a 2017cc carburated (Dual twin Dellorto DRLA 36's but maybe going bigger) type 1 aircooled engine that I need to keep an eye on to make sure it doesn't melt and to do that and make sure I get the best possible MPG, i'm going to go o2. Innovate motorsports LC-1 caught my eye but it doesn't do what I want it to. The VEMS unit nearly does and there are a couple of points I want to clear up before I stump up the cash.

My questions are several fold and begin with the cable.

I understand that the o2 sensor has to be where it has to be and that the Vems cable can't be altered in any way or it won't work properly. The only problem is that my exhaust is 13 feet away and 2 feet below my dash so I need a cable that is 18 feet long as a minimum.

How can the cable be extended especially without altering the accuracy of the thermocouple input to the gauge?

I am currently assuming that the cable is about 3 feet long and that I will have to make up the missing 15 feet or so out of suitable cable with suitable connectors. What is the gauge of cable that I will need to ensure there is no signal degradation and what are the part numbers of the connectors that I'm going to have to get?

Secondly, as my bus is aircooled, the exhaust gas temperature thermocouple is not as important as taking a reading of the cylinder head temperature on number 3 cylinder. it seems that the EGT sensor is a simple K thermocouple so switching this to a spark plug ring is not a difficult task, but the instructions do not clear up where the thermocouple connects to. Does it connect into the back of the gauge? If not, where. And if you don't order the EGT probe thermocouple, can you still connect a K thermocouple to it or is that part disabled?

In aircooled VW's, knowing what the exhaust gas temperature is won't be an indicator of your engines efficiency so much as CHT. VW heads are aluminium so they start to soften at around 400*C and melt not long afterwards. a quick way to a broken motor.

Thirdly, i'm also keen to carry out some datalogging on my laptop while i'm dailing in my carbs, but as it's an old technology vehicle, it runs from a bosch blue coil from brazil. I understand that the datalogging port is in the back of the gauge, but how would I go about collecting RPM data from the coil. I have a tachometer, but it's only got positive, earth and coil signal input as it's an aftermarket Elliot Design unit. No ECU output if you like.

The other thing I am keen to know is that, when my carbs are dialed in and the o2 has served it's main purpose, i'm going to disconnect the o2 and plug the boss and just use the system as a cold junction compensated CHT gauge. If I disconnect the o2 and essentially terminate that part of the systems function, will the gauge continue to display anything or can it be selectively turned off to preserve the display and internal gauge hardware, or will I have to almost permanently have the o2 running so as not to fry the thing?

Your help is greatly appreciated as the LC-1 just won't cut the mustard

Cheers

Marv

[rob@vems.co.uk]

Hi Marv,

I've installed a VEMS wideband in a dyno cell with a 5meter extension without problems.

The rest of your questions are pretty straightforward, yes you can do pretty much all you want, but I'd leave the wideband in place.
YHPMBTW

[Marv [uk]]

Excellent

OK, now to the technical Q's

How do I extend it exactly? The connector at the end of the o2 cable will need a counterpart to extend it and then another one to sit in the back of the gauge. Where do I get the connectors and cable terminals from?

The o2 sensor heating element draws a current which I assume is supposed to be from a switched fused live connection. Given the geometry of my bus (engine in back, fuse box in front) running a cable from the battery to the fuse box, then from the fuse box back to the sensor is 26 feet of cable. My intention is to take a signal from the switched live on the coil, through a relay straight from the battery but i'll need to put a fuse inline. What is the current draw on the sensor and what is your recommended fuse size?

For the remaining connections, I'm going to use a length of multicore cable, but do you recommend shielded cable for the extension and what sort of shielding would be appropriate as I don't think the cable I have available is shielded, just insulated. What sort of signal voltages are likely to be seen through the cable so that I can make sure that the gauge of cable is sufficient?

How can I take an RPM signal from the coil without frying the electronics in the gauge. WHat is the max input signal strength so I can check my coil is not going to pump out voltages of gauge death

Where does the thermocouple connect to?

Cheers for the input

Marv

[rob@vems.co.uk]

Excellent

OK, now to the technical Q's

  

How do I extend it exactly? The connector at the end of the o2 cable will need a counterpart to extend it and then another one to sit in the back of the gauge. Where do I get the connectors and cable terminals from?

In the one's I've extended I've spliced in the extra wire length.

The o2 sensor heating element draws a current which I assume is supposed to be from a switched fused live connection. Given the geometry of my bus (engine in back, fuse box in front) running a cable from the battery to the fuse box, then from the fuse box back to the sensor is 26 feet of cable. My intention is to take a signal from the switched live on the coil, through a relay straight from the battery but i'll need to put a fuse inline. What is the current draw on the sensor and what is your recommended fuse size?

5Amps maximum

For the remaining connections, I'm going to use a length of multicore cable, but do you recommend shielded cable for the extension and what sort of shielding would be appropriate as I don't think the cable I have available is shielded, just insulated. What sort of signal voltages are likely to be seen through the cable so that I can make sure that the gauge of cable is sufficient?

I've never used shielded I don't see that it would hurt as long as the sheild is grounded at only one end, most of the voltages are low current 5v, although the heater will draw 3A @Vbatt as it starts up.

How can I take an RPM signal from the coil without frying the electronics in the gauge. WHat is the max input signal strength so I can check my coil is not going to pump out voltages of gauge death

A suitable Zener diode should ensure the voltage isnt too high, there is one inside the gauge, but an additional external one wouldnt be a bad idea.

Where does the thermocouple connect to?

Theres a length of k-type wire on the back of the gauge, do you have a specific head temp sensor that you're planning on using?

[Marv [uk]]

Excellent

OK, now to the technical Q's

  

How do I extend it exactly? The connector at the end of the o2 cable will need a counterpart to extend it and then another one to sit in the back of the gauge. Where do I get the connectors and cable terminals from?

In the one's I've extended I've spliced in the extra wire length.

The o2 sensor heating element draws a current which I assume is supposed to be from a switched fused live connection. Given the geometry of my bus (engine in back, fuse box in front) running a cable from the battery to the fuse box, then from the fuse box back to the sensor is 26 feet of cable. My intention is to take a signal from the switched live on the coil, through a relay straight from the battery but i'll need to put a fuse inline. What is the current draw on the sensor and what is your recommended fuse size?

5Amps maximum

For the remaining connections, I'm going to use a length of multicore cable, but do you recommend shielded cable for the extension and what sort of shielding would be appropriate as I don't think the cable I have available is shielded, just insulated. What sort of signal voltages are likely to be seen through the cable so that I can make sure that the gauge of cable is sufficient?

I've never used shielded I don't see that it would hurt as long as the sheild is grounded at only one end, most of the voltages are low current 5v, although the heater will draw 3A @Vbatt as it starts up.

How can I take an RPM signal from the coil without frying the electronics in the gauge. WHat is the max input signal strength so I can check my coil is not going to pump out voltages of gauge death

A suitable Zener diode should ensure the voltage isnt too high, there is one inside the gauge, but an additional external one wouldnt be a bad idea.

Where does the thermocouple connect to?

Theres a length of k-type wire on the back of the gauge, do you have a specific head temp sensor that you're planning on using?

Cheers Rob,

So, what you're saying is it's OK to take the connector off the end and splice in the extra required length of cable and then refit the connector on the end of the added in cable and plug it in.

Won't that invalidate any warranty?

What i'd prefer to do is have a couple of connector blocks and custom make an extension from the connector on the "factory" cable to the back of the gauge. I can then do a continuity test and voltage drop test on the separate wire before plugging everything in which should keep my warranty ticking over nicely

Does the gauge run a comparison or calibration cycle once it's fully connected and the sensor is warm? The LC-1 system runs it's calibration from the factory wiring harness so i've assumed the VEMS unit does the same and altering the cable would be a bad thing. I'll be pleased if I'm wrong but i's still be worried about warranty over anything else.

Zener diode - Cool. What sort specification are we talking about? As it's just a counting signal required, i suspect the voltage is irrelevant, but what are the gauges trigger voltages for data logging? I can connect a multimeter and tune the input signal accordingly, but want to get the characteristics of the signal for the gauge as close as possible to maximise accuracy.

As for the head temperature thermocouple, a simple K type spark plug thermocouple was what I was looking at, it's just finding one that is long enough. Provided I can "plug" one in without having to fork out £60 for something i'll never use, thats fine

[rob@vems.co.uk]

So, what you're saying is it's OK to take the connector off the end and splice in the extra required length of cable and then refit the connector on the end of the added in cable and plug it in.

Yes.

Won't that invalidate any warranty?

I'm afraid so, the alternative is that I can ask the manufacturers to make a longer length cable - but I'm not sure if they'll go for it.
The problem with Warranty on products like this is that they're down to a "fair use" restriction, because its impossible to know if the purchaser installed the thing correctly they work on the understanding that if the gauge is DOA or fails after a short amount of time then it gets replaced, where as if it fails because someone connects it wrongly or burns/fouls their sensor during tuning experiements/crankcase breather failure/voltage spikes etc, it can't be said to be the gauge's fault.

What i'd prefer to do is have a couple of connector blocks and custom make an extension from the connector on the "factory" cable to the back of the gauge. I can then do a continuity test and voltage drop test on the separate wire before plugging everything in which should keep my warranty ticking over nicely

I'd prefer this too - but the problem is that the male connector is unobtainable, the wideband connector has a calibration resistor built into it.  You could get a dead wideband, cut the plug off and modify it, but it would be a pain (the pin crimps are tricky to find and you can't easily splice onto the wire as its stainless, then theres the butchering of the resistor to concern yourself with).

Does the gauge run a comparison or calibration cycle once it's fully connected and the sensor is warm? The LC-1 system runs it's calibration from the factory wiring harness so i've assumed the VEMS unit does the same and altering the cable would be a bad thing. I'll be pleased if I'm wrong but i's still be worried about warranty over anything else.

We use the calibration resistor, so as long as the wires are all good quality and roughly the same length theres not a problem, I was concerned about the dyno install but had a crack at it anyway because I wanted to see how it performed - the result was that it gave pretty much the same values as their existing sensor (that used the expensive NTK sensors) errors tended to be in the 0.0x region of the Lambda reading which can be down to filtering or sensor differences.

Zener diode - Cool. What sort specification are we talking about? As it's just a counting signal required, i suspect the voltage is irrelevant, but what are the gauges trigger voltages for data logging? I can connect a multimeter and tune the input signal accordingly, but want to get the characteristics of the signal for the gauge as close as possible to maximise accuracy.

I'll double check with the design team.

As for the head temperature thermocouple, a simple K type spark plug thermocouple was what I was looking at, it's just finding one that is long enough. Provided I can "plug" one in without having to fork out £60 for something i'll never use, thats fine

This is something you can plug extensions on to, the k-type plugs cost a bit mind you.

[Marv [uk]]

So, what you're saying is it's OK to take the connector off the end and splice in the extra required length of cable and then refit the connector on the end of the added in cable and plug it in.

Yes.

Won't that invalidate any warranty?

I'm afraid so, the alternative is that I can ask the manufacturers to make a longer length cable - but I'm not sure if they'll go for it.
The problem with Warranty on products like this is that they're down to a "fair use" restriction, because its impossible to know if the purchaser installed the thing correctly they work on the understanding that if the gauge is DOA or fails after a short amount of time then it gets replaced, where as if it fails because someone connects it wrongly or burns/fouls their sensor during tuning experiements/crankcase breather failure/voltage spikes etc, it can't be said to be the gauge's fault.

What i'd prefer to do is have a couple of connector blocks and custom make an extension from the connector on the "factory" cable to the back of the gauge. I can then do a continuity test and voltage drop test on the separate wire before plugging everything in which should keep my warranty ticking over nicely

I'd prefer this too - but the problem is that the male connector is unobtainable, the wideband connector has a calibration resistor built into it.  You could get a dead wideband, cut the plug off and modify it, but it would be a pain (the pin crimps are tricky to find and you can't easily splice onto the wire as its stainless, then theres the butchering of the resistor to concern yourself with).

Does the gauge run a comparison or calibration cycle once it's fully connected and the sensor is warm? The LC-1 system runs it's calibration from the factory wiring harness so i've assumed the VEMS unit does the same and altering the cable would be a bad thing. I'll be pleased if I'm wrong but i's still be worried about warranty over anything else.

We use the calibration resistor, so as long as the wires are all good quality and roughly the same length theres not a problem, I was concerned about the dyno install but had a crack at it anyway because I wanted to see how it performed - the result was that it gave pretty much the same values as their existing sensor (that used the expensive NTK sensors) errors tended to be in the 0.0x region of the Lambda reading which can be down to filtering or sensor differences.

Zener diode - Cool. What sort specification are we talking about? As it's just a counting signal required, i suspect the voltage is irrelevant, but what are the gauges trigger voltages for data logging? I can connect a multimeter and tune the input signal accordingly, but want to get the characteristics of the signal for the gauge as close as possible to maximise accuracy.

I'll double check with the design team.

As for the head temperature thermocouple, a simple K type spark plug thermocouple was what I was looking at, it's just finding one that is long enough. Provided I can "plug" one in without having to fork out £60 for something i'll never use, thats fine

This is something you can plug extensions on to, the k-type plugs cost a bit mind you.

well thats a PITA aint it Would said manufacturers produce a 20 foot cable for the same price as the normal one or at least supply a different connector on the end to make fabricating an extension cable easy. Bear in mind the damn things going to have to go through 2 bulkheads not to mention a load of tinware. I'd have to strip the connectors out of the terminal block anyway

(Techedge can supply the connectors so I don't see why VEMS can't on the plus side though, techedge are australian and not entirely round the corner

As for the K thermocouple..... 25 quid and another 25 for the 15 foot extension. But the cables are red and yellow, not green and white even though it's a K thermocouple. At the very worst, it'd be a 2mm thermocouple soldered into a 14mm ring terminal, not the hugely expensive things that the tuner websites offer

[rob@vems.co.uk]

well thats a PITA aint it Would said manufacturers produce a 20 foot cable for the same price as the normal one or at least supply a different connector on the end to make fabricating an extension cable easy. Bear in mind the damn things going to have to go through 2 bulkheads not to mention a load of tinware. I'd have to strip the connectors out of the terminal block anyway

When it comes it comes with the wires crimped - but out of the plug, which is why splicing an extra length doesnt seem such a bad idea.  They've added an extra meter of wire on my request for MR2's at the cost of £10.  If you want I can ask them.

(Techedge can supply the connectors so I don't see why VEMS can't on the plus side though, techedge are australian and not entirely round the corner

I can't see the male connectors on their site, it seems that they have an 8meter controller to sensor cable, that ends with an 8pin DIN connector, you could easily follow that model.

As for the K thermocouple..... 25 quid and another 25 for the 15 foot extension. But the cables are red and yellow, not green and white even though it's a K thermocouple. At the very worst, it'd be a 2mm thermocouple soldered into a 14mm ring terminal, not the hugely expensive things that the tuner websites offer

I'd just be cautious of the soldering as it might form a cold junction between the thermocouple wire and the solder material - the worst that happens is that you have to buy plugs if you're not happy with the temperature reading - you seem hands-on enough for this not to worry you.

[Marv [uk]]

well thats a PITA aint it Would said manufacturers produce a 20 foot cable for the same price as the normal one or at least supply a different connector on the end to make fabricating an extension cable easy. Bear in mind the damn things going to have to go through 2 bulkheads not to mention a load of tinware. I'd have to strip the connectors out of the terminal block anyway

When it comes it comes with the wires crimped - but out of the plug, which is why splicing an extra length doesnt seem such a bad idea.  They've added an extra meter of wire on my request for MR2's at the cost of £10.  If you want I can ask them.

(Techedge can supply the connectors so I don't see why VEMS can't on the plus side though, techedge are australian and not entirely round the corner

I can't see the male connectors on their site, it seems that they have an 8meter controller to sensor cable, that ends with an 8pin DIN connector, you could easily follow that model.

As for the K thermocouple..... 25 quid and another 25 for the 15 foot extension. But the cables are red and yellow, not green and white even though it's a K thermocouple. At the very worst, it'd be a 2mm thermocouple soldered into a 14mm ring terminal, not the hugely expensive things that the tuner websites offer

I'd just be cautious of the soldering as it might form a cold junction between the thermocouple wire and the solder material - the worst that happens is that you have to buy plugs if you're not happy with the temperature reading - you seem hands-on enough for this not to worry you.

If you wouldn't mind asking if they would do it and for how much, yes please. I know dakota digital have a thermocouple cable of 18 feet to reach from engine to cab in a type 2 VW so (without actually measuring) i'm guessing 20 feet would be ideal for this application and I wouldn't mind spending an extra tenner or so on it to cut out a ball of work for myself, but lets just leave it as an enquiry for now I've got to see whether it'd be worth it or whether a case of splicing for a day or so would be economic. Maybe the DIN cable connector would be a good idea.

Either way with the thermocouple, providing it's a K type, there should be no compatability problems. It's just a case of making sure that the polarity is the right way around. I'm assuming here that the insulation colour doesn't mean anything though. It's not green and white as an ISO thing is it?

[rob@vems.co.uk]

If you wouldn't mind asking if they would do it and for how much, yes please. I know dakota digital have a thermocouple cable of 18 feet to reach from engine to cab in a type 2 VW so (without actually measuring) i'm guessing 20 feet would be ideal for this application and I wouldn't mind spending an extra tenner or so on it to cut out a ball of work for myself, but lets just leave it as an enquiry for now I've got to see whether it'd be worth it or whether a case of splicing for a day or so would be economic. Maybe the DIN cable connector would be a good idea.

Okay I'll ask them and point out that Tech Edge do 8 meters.  It would make sense to leave the wires uncrimped then you can cut it to size without a problem.

Either way with the thermocouple, providing it's a K type, there should be no compatability problems. It's just a case of making sure that the polarity is the right way around. I'm assuming here that the insulation colour doesn't mean anything though. It's not green and white as an ISO thing is it?

Yes and no, the wire colours are important as they indicate the different metals that the wires are made from, and this dictates the polarity, the British standard is Green and White, while our American cousins favoru Yellow and Red

	British standard	American Standard
Connector	Green	Yellow
Wire insulation	Green	Yellow
+ wire	Green	Yellow
- wire	White	Red

[Marv [uk]]

If you wouldn't mind asking if they would do it and for how much, yes please. I know dakota digital have a thermocouple cable of 18 feet to reach from engine to cab in a type 2 VW so (without actually measuring) i'm guessing 20 feet would be ideal for this application and I wouldn't mind spending an extra tenner or so on it to cut out a ball of work for myself, but lets just leave it as an enquiry for now I've got to see whether it'd be worth it or whether a case of splicing for a day or so would be economic. Maybe the DIN cable connector would be a good idea.

Okay I'll ask them and point out that Tech Edge do 8 meters.  It would make sense to leave the wires uncrimped then you can cut it to size without a problem.

Either way with the thermocouple, providing it's a K type, there should be no compatability problems. It's just a case of making sure that the polarity is the right way around. I'm assuming here that the insulation colour doesn't mean anything though. It's not green and white as an ISO thing is it?

Yes and no, the wire colours are important as they indicate the different metals that the wires are made from, and this dictates the polarity, the British standard is Green and White, while our American cousins favoru Yellow and Red

	British standard	American Standard
Connector	Green	Yellow
Wire insulation	Green	Yellow
+ wire	Green	Yellow
- wire	White	Red

That would make sense provided they are not some weird specialist crimps. I'm quite capable in many things, but fiddly things and my fat fingers don't mix very well

So, let me summarize so far, and please correct me if i'm wrong

The cable length is not as important as the o2 connector as this is where the calibration resistor is, but, the cable can be spliced if you use correct gauge cable and equal lengths. THis invalidates the warranty though

Secondly, the EGT gauge can be used as a CHT gauge as the thermocouple cable connects into the back of gauge to two tails of (British Standard) K thermocouple cable. American standard K thermocouple cable can be used providing the polarity is consistent as the metals that the cables are made of SHOULD be the same. (white to red, green to yellow connectivity)

Once the gauge is connected, it's not really a good idea to disconnect the o2 and just use it as a CHT gauge as it might break it.

Are you sure there is no way that the software can temporarily disable the Wideband part of the gauge while the sensor is disconnected? I don't want it all the time, just for tuning.

[Marv [uk]]

Oh yeah, and one more thing,

A coil can be used as an RPM source to log data provided a zener diode is used to moderate voltage.


What would the software settings be for a coil input on a 4 cylinder engine?

[rob@vems.co.uk]

Its a case of experimenting starting from
Toothcount of 2
Multiplier of 228

[Bat]

Hi,
Unplugging the sensor from the gauge shouldn't be a problem from the gauges point of view, it'll just show "e" on the display.
However what you don't want to do is leave a WBO2 sensor in the exhaust without it being powered up as that does kill the sensor.
Personally I'd leave it in and working, you only need something like a fuel pressure problem to leave you running lean at WOT and you're in trouble!
Cheers,
Gavin

[Marv [uk]]

Kool and his entire gang

It's all doable then. Just waiting on some info before I decide whether to press go or not

Gavin, my plan was to take the o2 sensor out. The cheap header I have won't take a decent weld, let alone a decent bung so I'm resorting to a slip in piece with flanges and a bung, about 2 inches long like this one but from Aircooled.net (this one has a pic!)

http://cbperformance.com/catalog.asp?ProductID=598

Leaving the section in there is not advised by the manufacturers so the o2 IS coming out. I just don't want to break the gauge until I can get a half decent stainless header with a bung already welded in.