# adjusting copot..



## Flavourless (Jun 23, 2001)

when adjusting the copot how far can you adjust it, or how far can you adjust it safely? 
right now my co pot reads 508 ohms
and lesser amount of ohms is leaner correct?


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## mrkrad (Nov 9, 2000)

*Re: adjusting copot.. (Flavourless)*

higher the ohms the leaner it gets. i found stage 4 G60 at 800 ohms to run about 13.5-14:1 across powerband until about 13psi where they go static.
this would be bad.
your range is probably 200-1800ohms, it has no effect around 12-13psi.


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## Flavourless (Jun 23, 2001)

*Re: adjusting copot.. (mrkrad)*

aight thanks sam..ya the car is running super rich plugs are pretty dark at 500 ohms...the car has the stage 5 chip, 2.0L bottom end, 68mm pulley, 30# injectors, front mount and 268 cam


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## TBT-Syncro (Apr 28, 2001)

*Re: adjusting copot.. (Flavourless)*

co pot tuning will give you a max tuning range of 2% fueling on boost, and 5% off boost.


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## Montana Green (Sep 24, 2003)

*Re: adjusting copot.. (TBT-PassatG60)*


_Quote, originally posted by *TBT-PassatG60* »_co pot tuning will give you a max tuning range of 2% fueling on boost, and 5% off boost.

2% and 5% of what?


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## LagunaSecaBlueMK3 (Mar 16, 2003)

*Re: adjusting copot.. (Montana Green)*

can the co-pot be on the wrong way?


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## TBT-Syncro (Apr 28, 2001)

*Re: adjusting copot.. (Montana Green)*


_Quote, originally posted by *Montana Green* »_2% and 5% of what?

+/- 2% fuel, or +/- 5% fuel.


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## Montana Green (Sep 24, 2003)

*Re: adjusting copot.. (TBT-PassatG60)*

Sorry I still don't understand, I'm a little slow I guess. A percentage is just an obscure number to me unless it is referenced to something. If I handed you 2% of Pepsi it won't mean anything to you unless I tell you that I gave you 2% of a 2L bottle, or 2% of the amount I drank last night or 2% of the sugar that is in it or 2% of what the company produced last year.... you know what I mean? What is that 2% and 5% in reference to?


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## TBT-Syncro (Apr 28, 2001)

*Re: adjusting copot.. (Montana Green)*

I'm assuming you haven't read this rest of the thread. We're talking about trimming or adding fuel. So if we're trimming 2% of the fuel, the system is now only recieving 98% of the fuel it was previously seeing. That amount of fuel does not matter, as its inconsequential to what we're talking about.
its a fuel scaler. So its scaling a percentage of the fuel that would have normally been alloted.
So if you would have normally gotten X, you would now only get 98%of X if it's removing 2%....


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## Montana Green (Sep 24, 2003)

*Re: adjusting copot.. (TBT-PassatG60)*


_Quote, originally posted by *TBT-PassatG60* »_I'm assuming you haven't read this rest of the thread. 

Actually I read the entire thread, otherwise I wouldn't have made it as far as your post. My appologies for seeking clarifcation. Thanks for the response, maybe next time you can do it with -5% of the attitude.


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## TBT-Syncro (Apr 28, 2001)

*Re: adjusting copot.. (Montana Green)*


_Quote, originally posted by *Montana Green* »_ maybe next time you can do it with -5% of the attitude.









probably not.


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## KeithMac (Oct 10, 2002)

*Re: adjusting copot.. (TBT-PassatG60)*

I`ve read +- 20% at idle, +-10% at part thottle and not change at WOT from the VW technical booklet?


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## mrkrad (Nov 9, 2000)

*Re: adjusting copot.. (KeithMac)*

well i've posted the graph a few times. it will do about not much at closed loop since the o2 sensor will refocus the air fuel anyways. most of the change is off boost, sweeping down to 0% change at about 12psi+.


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## KeithMac (Oct 10, 2002)

*Re: adjusting copot.. (mrkrad)*

I`ve noticed it doesn`t affect the the closed loop running as well. for me it just affects the warm up cycle, until the oil hits 80 deg c.
How do you change the fueling at part thottle? would a higher rate FPR alter this at all or would the ecu just trim it back to std? Mine seems quite lean when it hits closed loop temps. (BBM chip, 3bar FPR stock G60 greens, running n/a on 16v 1.8)


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## sciroccoR (Dec 23, 2003)

*Re: adjusting copot.. (KeithMac)*

copot. is that like carbon monoxide potentiometer? are we talking about the sensor that's on the boost tube after the intercooler? if so, i was under the distinct impression that that was a air temp monitor...you know for measuring air density together with manifold pressure should give something that will allow us to adjust fuel amount. if i am nutty, let me know. (i mean about this stuff)


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## mrkrad (Nov 9, 2000)

*Re: adjusting copot.. (sciroccoR)*

it serves two purposes in one device.
Co% fuel adjustment & Air Intake Temp sensor for determining the mass of air with pressure (speed density).
Just because they are together, doesn't mean much, other than they are siamese twins lol.
The ecu can trim the **** out of the a/f as it sees the o2 sensor feedback, if you honestly believe its running lean throw it on a 5 gas analyzer and see how high the noX is and co%. But yeah a 3.5-5.0bar fpr might not be a horrible way to adjust a n/a motor car. They make adjustable fpr's too somewhere.
Grab a few cheap digifant FPR's and squish them. 3.5,4.0,4.5 That should be fine without boost, the ecu is smart enough to trim the fuel back to some degree.



_Modified by mrkrad at 6:15 PM 3-5-2005_


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## KeithMac (Oct 10, 2002)

*Re: adjusting copot.. (mrkrad)*

I`ve banged the adjustable FPR on and had a play, dives much better at 4 bar but still lean on the AFR guage between 3 to 4k rpm?
Also been told these gauges are useless with a charged engine, so I`ll be in the same boat when the charger`s fitted an I have to go back to the stock bosch FPR..


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## germanengineering g60 (Aug 20, 2007)

uuuummm, How and where do i drill my copot on corrado g60?


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## mrkrad (Nov 9, 2000)

germanengineering g60 said:


> uuuummm, How and where do i drill my copot on corrado g60?


the big metal slug. the adjustment is at the bottom of the tube. i just use some ***** or a buck knife and whittle away until the slug comes out


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## jeffKautz (Dec 29, 2009)

I have a 92 corrado i have my copot set at 425. whent to smog they said its runnin to lean. so i hope this solves the problem. i just rebuilt the motor and charger. new cat.U guys think this will solve. i hear u can run a mustang o2 is that true.


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## kerobert (Dec 28, 2006)

I run a stage 4 charger chipped with SNS stage 4, stock CAT, Co-POT set at 450 and I fly through our British Columbia Air Care Joke of a system.


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## bbwhaling (May 17, 2010)

got any pics of the copot and how to adjust it


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## jeffKautz (Dec 29, 2009)

cool thanks bro im goin to try and smog. im gettin the o2 today and hopfully it works


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## g60301 (Aug 5, 2011)

Bump, how do you adjust it? Im running a 3.5 fpr,30lb injectors, stg4 bbm eprom, what should I set it to? I think its been tampered with from p.o. because theres 2 little holes drilled in it.


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## g60301 (Aug 5, 2011)

Bump on this, im still a little confused about it. I pulled my slug out and tested it at idle. It was at 590 ohms I brought it back down to 500 ohms. How do I figure out what to set it exactly? Is 500 ohms safe? My specs are in the post right above this post. Help I dont want to burn valves or pistons up running to lean!


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## yip (Jul 14, 2003)

g60301 said:


> Bump on this, im still a little confused about it. I pulled my slug out and tested it at idle. It was at 590 ohms I brought it back down to 500 ohms. How do I figure out what to set it exactly? Is 500 ohms safe? My specs are in the post right above this post. Help I dont want to burn valves or pistons up running to lean!



Set it between 450-500 ohms with the car off/cold. 

It really only makes much of a difference at idle or part throttle. 

Best to hook up a wide band.

You can set it lower if you want to run richer but again it only really effects the car at part throttle. 

Are you having other issues with how your car is running?


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## g60301 (Aug 5, 2011)

yip said:


> Set it between 450-500 ohms with the car off/cold.
> 
> It really only makes much of a difference at idle or part throttle.
> 
> ...



No Actually when I lowered it to 500 from 590 idle really smoothed out and dropped to correct idle, its at 8 to 9 hundred rpms at idle. I need a wideband but cant afford it now :banghead:


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## crazynorweegian (May 8, 2006)

g60301 said:


> No Actually when I lowered it to 500 from 590 idle really smoothed out and dropped to correct idle, its at 8 to 9 hundred rpms at idle. I need a wideband but cant afford it now :banghead:


Wideband is like $170. You can't afford NOT to get it. 500 is a nice stock setting. Try a little less though. The rumor is a little less can make a better low RPM range performance. IIRC, the the Bentley has a range listed in it. It is either 350-550, or 450-550. I put mine at the low end but saw little difference.


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## rollincoal97 (Jul 8, 2011)

g60301 said:


> Bump, how do you adjust it? Im running a 3.5 fpr,30lb injectors, stg4 bbm eprom, what should I set it to? I think its been tampered with from p.o. because theres 2 little holes drilled in it.


Might have to remove that white piece aswell... Mine had it aswell an under it was the flat head adjuster


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## DigiMatrix (Apr 16, 2010)

I'm woke up early and was bored this morning so I will bring this back from the dead. I built a program that will convert the values in the ECU to output the injector pulse width in milliseconds. As anyone who has played with this knows, it takes a bit to do this. Anyway my program requires the same inputs that the ECU does, so I did a little test. Using a stock file from a 1992 G60 Passat syncro, and ECU temperature of 87 deg C, an IAT of 32 deg C and a battery voltage of 14, I get the following results adjusting the CO pot value:

*800 RPM at 37.5 mbar:*

CO pot setting vs Inj PW
0 ; 3.102 ms
200 ; 2.620 ms
400 ; 2.540 ms
495 ; 2.480 ms <-- value where fuel is neither added nor subtracted
600 ; 2.416 ms
800 ; 2.328 ms
1000; 2.254 ms
1200; 2.202 ms
1400; 2.156 ms
1600; 2.120 ms
1800; 2.088 ms
2000; 2.062 ms

*6300 RPM at 175 mbar:*

CO pot setting vs Inj PW
0 ; 9.146 ms
200 ; 9.088 ms
400 ; 9.042 ms
495 ; 9.030 ms <-- value where fuel is neither added nor subtracted
600 ; 9.006 ms
800 ; 8.984 ms
1000; 8.960 ms
1200; 8.950 ms
1400; 8.938 ms
1600; 8.926 ms
1800; 8.914 ms
2000; 8.904 ms

So.... if you calculate the percentage change around 495 ohms you can see the range the ECU adjusts the fuel. Also as was mentioned earlier, these values would only come into play when the ECU is in open loop, otherwise the O2 sensor takes over.

Screen shot of my Program:


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## Tim.vw. (Dec 9, 2008)

Awesome read. I've also got a stg. 5 Corrado with a obd1 aba bottom end bored out. Stage 4 bbm rebuilt charger stage 5 sns chip 268/270 cam, very fun build and car. I have fueling issues as well. Runs very lean at cold start up then runs 13s after warm. Under load the a/f goes down to about 9, till boost builds then turns to the 12-13s. How do u add fuel to compensate for low rpm fueling? Timing adj? Thanks in advance. Spent much time reading but not a lot of answers.


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