# Make a DIY Dwell meter?



## Southcross (Jul 2, 2004)

I'm wondering if I can build a DIY Dwell meter, use it as an in-cabin ECU/mixture monitor...


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## rorin8v (Oct 15, 2007)

make a harness for it and run it into the cabin and hook the dwell meter up to it


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## Southcross (Jul 2, 2004)

*FV-QR*

ya, I was more like thinking... making a gauge


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## rorin8v (Oct 15, 2007)

that would something crazy, you could remove the gauge from the metter and ( say you made a hole on your dash to fit it and install it on the backside of the hole.


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (Southcross)*

Why not just get a WB o2 & A/F gauge? Im using a NB A/F gauge right now just for A/F adjusting:








The NB works great when your just reading the o2 but once its connected to the ecu the NB readings are wothless IMO but thats where a WB comes into play.
I would think a dwell for monitoring would be just a vague as a NB A/F gauge.


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *johnnyGO* »_Why not just get a WB o2 & A/F gauge?


*sigh*


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## ziddey (Apr 16, 2006)

*Re: FV-QR (Southcross)*

Measuring the dwell would be similar to watching the dpr on cis-e? I've been doing that in cabin for a while. Then I added a narrowband reading with another multimeter. A bit more useful, but more or less just snapshots.
I'm going to be hooking up my oscilloscope to the lambda circuit. Should be a bit better


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## Southcross (Jul 2, 2004)

*FV-QR*

a normal voltmeter/multi-meter can't read dwell







otherwise it would easy-peasy to make one


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## booested4door (Jun 10, 2004)

*FV-QR*

check craftsman... i have a multi meter with dwell from sears........


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## Southcross (Jul 2, 2004)

*FV-QR*

sure... I'm going to buy a Craftsman multi-meter... hack it into pieces to make an in-cabin dwell meter gauge...


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (Southcross)*

just get one of these, it tells you the same thing, just from a different part of the circuit:
http://www.autometer.com/cat_g...=2817


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

If its a narrow band then its basicly worthless for monitoring but is fine for adjusting A/F WHEN the o2 is unlugged from the ecu other wise the gauge just dances up and down (it does "ok" at WOT). The narrow band gauge just seems like it cant keep up, you get on the gas and it takes a second for it to read. So thats why a wideband is the way to go, now I know there crazy pricy (same reason I dont have one) but IMO why use an inaccurate gauge to monitor something so important as A/F and thats why I pulled the gauge from my dash and put it under my hood.

narrow band non-WOT
http://www.youtube.com/watch?v=CGE_IrC9MAc
narrow band WOT



_Modified by johnnyGO at 10:31 AM 7-3-2009_


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (johnnyGO)*

All you wideband affectionados try to sell the same story. If narrowband is worthless, why was it ever used by the manufacturers? I have run a couple different gauges on CIS-E for over 15 years with very good results. I can use them to set my base mixture and my WOT mixture with my adjustable enrichment circuit. Under steady state cruise, CIS-E goes lean anyway. The constant change is how the feedback circuit operates. The gauge is merely reflecting reality. Connect a DVM and you will see the same response. Additionally a dwell meter reacts the same as well. The gauges I have are both linear LED types, one is the early gauge from SDS (NLA), the other, my favorite was from TWM, too bad it is also NLA. I prefer either of them to the typical round gauge.


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

They used narrowbands because they didint have widebands, I mean come on the same can be said now "why do all the top tunners use widebands?". As my above post said it can be used for setting your A/F and give you a rough reading @ WOT. The wideband setups are WAY more faster and have a much higher AND lower reading range then a narrowband, narrow bands read the best around stoich.
So yes, you can use a narrowband but if you want to pull all the potential out of your car a wideband is the only way to go.




_Modified by johnnyGO at 10:32 AM 7-4-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *johnnyGO* »_
So yes, you can use a narrowband but if you want to pull all the potential out of your car a wideband is the only way to go.


for that argument... why not go MegaSquirt








anywaysies... no realistic solution to a "Dwell meter gauge"?


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## johnnyGO (Feb 23, 2009)

*Re: FV-QR (Southcross)*

that is a awsome point and I agree, EFI is the best way to go. But some people like CIS and others like carbs, its all in what you want from the car. As we all know A/F is high on the CIS performance list so why not use the best tool for the job (IE wideband), if down the line you plan on going with EFI or any other fuel system the o2 can tag along so its $200 well spent.
As for the dwell meter, why not make it so it can be mounted inside then when you need to adjust things you can unhook it to bring it under the hood?
Or what about opening up the meter then just lengther the wires that go to the lcd screen and flush mount it in the dash, then you can tuck the meter itself anyplace you want.



_Modified by johnnyGO at 11:20 AM 7-4-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*

well... as for mounting a "true" needle type dwell meter, they usually aren't balanced to be used in the vertical, they are meant to be used laying down level. I did a little googleing and apparently the Dwell meter uses the same pulse interpretation as a tach... I'm almost tempted to try a cheapo electronic tach from my local Harbor Freight. It will not have the same reading pattern as a dwell meter (10%-90%) but I guess I might be able to determine what "RPM" coresponds to the usual 45-55% reading on the dwell.


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## johnnyGO (Feb 23, 2009)

Also I wonder if you would have issues using a analog meter while driving do to normal road vibrations and bumps, I know my analog meters are pretty sensitive.


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## Southcross (Jul 2, 2004)

*FV-QR*

another very good point


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (johnnyGO)*

how is a wideband gonna make CIS anthing run better when it's output is not suitable for the ECU?? Even if the wideband gives you more data, there is nothing more you can do with it on a CIS system. If you have the idle mixture set correctly and correct fueling at WOT, that's as good as its gonna get with CIS.
We are not talking SEM here. DOH










_Modified by antichristonwheels at 7:59 PM 7-4-2009_


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

you dont hook the wideband to the ecu, you just use it for tuning. I know the the LC-1's have an 0-1v option so Im pretty sure there is a poss of hooking it to your ecu (Im not sure on that thoe) but most just use it for tuning.

Check it out, when we talk about A/F and o2's there is only UP TO 1v, a diff between .10v or even .05v can make or brake your performance. Narrow bands just dont have the accuracy that a wideband does, end of story.


_Modified by johnnyGO at 10:58 PM 7-4-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *johnnyGO* »_I know the the LC-1's have an 0-1v option so Im pretty sure there is a poss of hooking it to your ecu 


yep.. BUT THERE'S MORE!








using your laptop you can change the output curve and "stoich" point... make the car a touch leaner, or richer for your needs


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## johnnyGO (Feb 23, 2009)

southcross I know this may be a little out there but what about filling a analog dwell meter with mineral oil, so its the same concept as the auto oil filled gauges.


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## Southcross (Jul 2, 2004)

*FV-QR*

most of the Dwell meters I've seen aren't "sealed"... would be kind of interesting to keep the fluid in the "needle" area and not all over the electronics and your interior


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (johnnyGO)*

CIS doesn't have the tunabiltiy of SEM end of story. Jeesh you try to help and the Fast and the Furious appear, unable to function without their wideband...
CIS has a single adjustment, base mixture, which when set correctly, even with big cams is about .80 VDC, well within the capabilities of a old school O2 sensor. The only reason I can adjust WOT fuel is because I made djustable enrichment circuits, which I have used in multiple cars for more than 15 years. There is no ability to alter individual points of the fuel curve. I can tune a CIS or CIS-E engine with one of my meters or just a DVM to run as good as it is going to. Even with a wideband, it's the same drill. On a plain CIS car with no O2 sensor, I can do it by ear, even with big cams. Of course I was doing that before you were born because that was the only way. My 2 liter Scirocco made 150 on a dynojet, fueling was spot on. A wideband would not have helped at all.


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

If you dont run a o2 then its not CIS-E thus your point/idea/what ever wouldint be valid in a cis-"E" conversation.

_Quote, originally posted by *"antichristonwheels"* »_There is no ability to alter individual points of the fuel curve
 
Ya maybe in your hay day but its 2009 now and we have things like the digital programmable WUR and guys like wclark who use there vast cis knowlage and current parts (such as a wideband) and do things like this:

_Quote, originally posted by *"wclark"* »_The 16V schematic (above) is a little like the first one I made up a few years ago for my 8V race engine...it switches in a resistor at a selected RPM and WOT (as opposed to whenever the throttle is WOT since going rich down around 2000-3000 is not productive). TT and Autotech offer something similar. The IC is a F:V converter. The fuel demand changes with RPM and load and it seems the open loop table for WOT in the ECU doesnt map this well (at least for a modified 8V and probably for any modified engine). The AFR, if using a fixed resistor inserted into the coolant temp sensor circuit, may only be right in one place in this case (one engine speed and load combination). It is better than stock enrichment as it does decrease AFR across the board, but not enough in my experience (using the values I have seen published in the 1500-200 ohm range). I saw hardly any measurable power increase on a dyno using the above resistor values floating around on the internet...AFR was in the 13.5-14.0 range on a good day. I needed a value of well over 2k for my modified 8V to get anything like 12.5-13:1.
A variation on that, and one I developed and used hillclimbing last year, is to calculate what a given engine needs for "enrichment voltage" at a typical load across the entire RPM range to reach 12.5:1. Then I created an RPM driven log-scale-like output to supply a suitable increasing-voltage-with-RPM to the temp sensor input of the "ECU". This input can be driven by a voltage from 0-5V (a warm coolanttemp resistor usually results in around 1V) or a resistance that pulls the built-in 5V bias down more or less like the temp sensor does. You can get closer to ideal AFR with a log-like curve that tries to correct for the WOT table errors (because of engine mods), but many engines will have a problem area that is hard to dial in since this method also does not actively correct for load. . My 8V counter flow engine, for instance, would go way rich at high RPM until the top end was heavily modified to flow a lot more air (head, intake and exhaust). It is a little complex to reproduce that particular demand decrease (for a near stock intake and header) in an analog circuit. When my engine (with a ported head, OEM intake and header) was using this design I could get the AFR into 12-13:1 up to 5500 but it would drop into the 10:1 range by 6000 which isnt good. When I improved intake and exhaust flow with larger intake runners and a tuned tube header the high RPM AFR improved.
This year I came up with a way to integrate my Innovate LM-1 (analyzer) or an LC-1 into the car so it manages WOT AFR based on WB O2 readings and adjusts WOT enrichment thru the cars temp sensor input to the ECU. It also replaces the stock NB O2 with a suitable simulation so only one sensor needs to be used in the car. This does a much better job of maintaining 12.5:1 across all loads and RPM. In fact the range is more tightly controlled than when the "ECU" is managing AFR at part throttle. My recorded log shows a range of 12.3-12.8 in competition from 3000-7000 RPM for the above engine at WOT in all gears and all loads. 
If anyone is interested in building and tuning either one of the last 2 for themselves, drop me an email, and I will send you a schematic for the hardware. You will need a way to measure AFR beyond what a NB sensor can do while driving to properly tune them for whatever CIS-E engine you have. The log-like analog design will require fair analog circuit design skills to tune, and the LM-1 based design requires the LM-1 or LC-1 from Innovate Motorsports (duh).
I have also worked off and on with an enrichment method suggested by Innovate but have not overcome one problem that may be unique to the Bosch CIS-E. Their method is to use the Analog 1 out of the LM-1/LC-1 set to simulate a stock NB O2 sensor normally and, via a relay, switch in Analog 2 in its place at WOT (The WOT input to the "ECU" must be disconnected so it stays in closed loop operation). The Analog 2 output would be set to output .5V at 12.5:1 AFR but otherwise appears like a normal NB sensor. This works well on Bosch CIS-L engines from reports I have read but the CIS-E "ECU" sees this change as a fault and begins a 10's-of-seconds settling process that results in open loop operation for a while. I speculated the problem is the fact that the switched-in analog output will be registering 1v or 0v as it comes into the circuit since under normal NB profiles 14.7 and 12.5 would be at the extreme ends of a typical NB sensor centered to 12.5 and 14.7 respectively. To try to address the problem thus far I tried widening the "range' of the simulated NB sensors so there was some overlap but either my speculation as to cause is wrong or I havent programmed enough overlap to make the "ECU" happy. 

I may be new to cis-e but I know when there is something out there that improves on the current situation.
I only wish I had a wideband when I had all my datsun 510's running DCOE's, not only would it of save me tons of time it would of save me a good amount of cash because I wouldint of had to buy so many jets. 
Love it or hate it, a wideband will help.


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (johnnyGO)*

Aren't you the same guy who doesn't understand how a CIS-E enrichment circuit works......


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## johnnyGO (Feb 23, 2009)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

That I am, arent you the guy thats been working on cis for 15+ years and only made 150hp ... Its time to grow up, fact is your wrong about the advantages of widebands and you cant admit it or the better guess is you have never even played with them and your tring to make your opinion into a fact. 
Im done with this and Im sorry to Southcross for destroying your topic, it was not my intention.


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (johnnyGO)*

My engine certainly was not low on power due to lack of a Wideband. 
What you can't seem to understand or admit is that a wideband isn't gonna make CIS make. anymore power than a regular O2 sensor, or even a CIS system without any O2 sensor.
You probably didn't know that I built a 2.1 16V 15 years ago that made even more power than my 2.0 Scirocco. It never made it to a dyno but it took out a 944T, a 968, a 240HP M3, multiple small block Chevy's and Fords...

How much years have you spent watching a narrow band meter in different conditions?
How much time did you you spend with an Autotech enrighment device to learn that they do not work 100% of the time?
Did you build your own adjustable CIS-E enrichment circuit without any diagram or assistance?
And how much HP does your 2.0 16V make on CIS-E??
I bet you can't show me 5 people who have exceeded 150 on a Dynojet with a NA 2.0 16V on CIS-E
Do you even know what the heck dwell is?
You got nothin but talk. http://****************.com/smile/emthdown.gif http://****************.com/smile/emthdown.gif


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## antichristonwheels (Jun 14, 2001)

*Re: Make a DIY Dwell meter? (antichristonwheels)*

And of course the answers would be:
How much years have you spent watching a narrow band meter in different conditions?
0
How much time did you you spend with an Autotech enrighment device to learn that they do not work 100% of the time?
0
Did you build your own adjustable CIS-E enrichment circuit without any diagram or assistance?
No
And how much HP does your 2.0 16V make on CIS-E??
never did it
I bet you can't show me 5 people who have exceeded 150 on a Dynojet with a NA 2.0 16V on CIS-E
Uh, not really

Do you even know what the heck dwell is?
No, in fact I am not even aware that we are not actually measuring dwell in this case, even thought it uses a dwell meter.


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## Southcross (Jul 2, 2004)

*FV-QR*

why don't you guys start your own thread


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## GTIspirit (Dec 13, 2002)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_It will not have the same reading pattern as a dwell meter (10%-90%) but I guess I might be able to determine what "RPM" coresponds to the usual 45-55% reading on the dwell.


Technically, isn't dwell measured in degrees? Duty cycle is measured in %. And so if you know the amplitude of the signal as a reference, then you could determine duty cycle with a multimeter. For example, if the amplitude is 12V, a 50% duty cycle reading will yield an average of 6V. At 14V amplitude, a 50% duty cycle would yield 7V. So I suppose if it wasn't practical to drive around with a multimeter displaying duty cycle, one could fashion a kind of analog circuit to do the math and display the duty cycle as a function of full scale display.
But personally, if I ever wanted to monitor CIS duty cycle while driving around I just hooked up an old analog duty cycle/dwell meter to some leads that I had already put in the passenger compartment and so I just watched the big box gauge on the passenger seat.
There used to be a Sears analog duty cycle/voltage/dwell meter measuring device. It was a kind of rectangular plastic box, maybe 6"x8"x3" or thereabouts, but I don't see it on their site anymore.


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