# Sticky  Why does JWT recommend against using an SAFC?



## Stephen Max (Aug 18, 2003)

They say it interferes with their program. Interferes how? Ben isn't too informative. Has anybody experienced this?

For reference, I have a 95 Maxima with a V1 blower, 3" pulley (~11.5 psi), 370 cc/min injectors, Z32 maf and the JWT modified ecu.


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> They say it interferes with their program. Interferes how? Ben isn't too informative. Has anybody experienced this?
> 
> For reference, I have a 95 Maxima with a V1 blower, 3" pulley (~11.5 psi), 370 cc/min injectors, Z32 maf and the JWT modified ecu.


It doesnt work so well, you tweak the a/f ratio with the AFC, you are also moving where you are in the spark map because MAF voltage is what drives the engines running location in the maps and the AFC works by tweaking the MAF output.
This makes you run in a different cell on the map on the spark side than originaly intended. In extreme cases this can cause engine damage.

Mike


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## Stephen Max (Aug 18, 2003)

morepower2 said:


> It doesnt work so well, you tweak the a/f ratio with the AFC, you are also moving where you are in the spark map because MAF voltage is what drives the engines running location in the maps and the AFC works by tweaking the MAF output.
> This makes you run in a different cell on the map on the spark side than originaly intended. In extreme cases this can cause engine damage.
> 
> Mike


By spark map, do you mean the timing map? So the AFC will have unintended effects on timing as well as afr?


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## se-r-57 (May 1, 2002)

Stephen Max said:


> By spark map, do you mean the timing map? So the AFC will have unintended effects on timing as well as afr?


 You are correct sir


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## Sentra_Industies (Oct 31, 2002)

se-r-57 said:


> You are correct sir


This is only with JWT or simularly reprogrammed ECU's right? Cause I know plenty of people that run SAFC's with no problem at all.

With other cars...who knows bout ours


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## Stephen Max (Aug 18, 2003)

Another question: will just having the SAFC connected, but with all the correction factors zeroed out, result in problems? Doesn't seem like it would, unless the very act of cutting the maf wire and routing the voltage through the SAFC is enough to significantly change the voltage the ecu eventually sees.


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## Stephen Max (Aug 18, 2003)

Yet another question.

Does JWT reference the throttle position at all in determining afr and timing maps, or are they determined entirely by maf voltage and rpm?

By the way, thanks to all of you for your help.


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## morepower2 (Apr 19, 2002)

Sentra_Industies said:


> This is only with JWT or simularly reprogrammed ECU's right? Cause I know plenty of people that run SAFC's with no problem at all.
> 
> With other cars...who knows bout ours


Any ECU stock or otherwise. Most people don't know how to tune SAFC's and don't even know if their car is running correctly.

Mike


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> Yet another question.
> 
> Does JWT reference the throttle position at all in determining afr and timing maps, or are they determined entirely by maf voltage and rpm?
> 
> By the way, thanks to all of you for your help.


JWT's ECU and the stock ECU looks at Throttle position, RPM and MAF voltage.

Mike


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## Stephen Max (Aug 18, 2003)

morepower2 said:


> Any ECU stock or otherwise. Most people don't know how to tune SAFC's and don't even know if their car is running correctly.
> 
> Mike


Thanks, Mike.

Do you have any tips, or do you know of any references that talk about tuning with the SAFC?

It seemed pretty straightforward to me, but I'm finding out it's a bit trickier than I thought. For one thing, with Maximas at least, don't bother with low throttle position afr adjustments since the ecu will try to adjust back to what it is programmed to think is right.


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## chimmike (Oct 17, 2002)

Stephen Max said:


> Thanks, Mike.
> 
> Do you have any tips, or do you know of any references that talk about tuning with the SAFC?
> 
> It seemed pretty straightforward to me, but I'm finding out it's a bit trickier than I thought. For one thing, with Maximas at least, don't bother with low throttle position afr adjustments since the ecu will try to adjust back to what it is programmed to think is right.


Never tune the SAFC without a correct wideband O2 sensor to reference........I highly suggest only tuning an SAFC on a dyno with wideband support.


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## Stephen Max (Aug 18, 2003)

chimmike said:


> Never tune the SAFC without a correct wideband O2 sensor to reference........I highly suggest only tuning an SAFC on a dyno with wideband support.


I use an Innovate LM-1 with a Bosch LSU4.2 wideband O2 sensor and do my tuning on the road.

Getting back to what morepower said earlier about timing maps. The timing maps I have seen (300ZX for example) show that, in general, for increasing engine load the timing is decreased from the maximum advance (there is an exception at low load and mid-rpm). So if the SAFC is used to increase the maf signal (with the intent of lowering the afr), the ecu interprets that as increased engine load and for the general case will lower the engine advance as well as increase injector pulse width. Is this understanding correct?


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> Thanks, Mike.
> 
> Do you have any tips, or do you know of any references that talk about tuning with the SAFC?
> 
> It seemed pretty straightforward to me, but I'm finding out it's a bit trickier than I thought. For one thing, with Maximas at least, don't bother with low throttle position afr adjustments since the ecu will try to adjust back to what it is programmed to think is right.


The main thing is not to try to go more than 10% or so or the ECU's long term fuel trim will try to dial it back. Go a lot farther (usualy like 20%) the ECU will think somethings wrong and go into limp home as well.


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> I use an Innovate LM-1 with a Bosch LSU4.2 wideband O2 sensor and do my tuning on the road.
> 
> Getting back to what morepower said earlier about timing maps. The timing maps I have seen (300ZX for example) show that, in general, for increasing engine load the timing is decreased from the maximum advance (there is an exception at low load and mid-rpm). So if the SAFC is used to increase the maf signal (with the intent of lowering the afr), the ecu interprets that as increased engine load and for the general case will lower the engine advance as well as increase injector pulse width. Is this understanding correct?


well thats on a turbocharged engine, with your Max, the timing table was developed for NA cars and the advance could increse more, not good for your supercharged motor.

Mike


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## Stephen Max (Aug 18, 2003)

morepower2 said:


> The main thing is not to try to go more than 10% or so or the ECU's long term fuel trim will try to dial it back. Go a lot farther (usualy like 20%) the ECU will think somethings wrong and go into limp home as well.


That's good to know and explains some odd behavior I've been seeing lately. At WOT, though, when the ecu is in open loop, there is no correction attempt by the ecu, either with afr or timing, right? 

If so, the idea then is to allow the ecu to control partial throttle operation by itself without any interference from the SAFC. So low throttle settings are kept zeroed out, and then the threshold value for transition from low to high settings should be set pretty high, say 80%, and then use SAFC high throttle settings to adjust when boosting at WOT.

The difficulty then may be in the 50-80% throttle regime where I do see boost developing, but can't effectively use the SAFC to lower afr. Fortunately that is an area that I can pretty much stay out of if I'm careful. At least for the type of driving I do.


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## Stephen Max (Aug 18, 2003)

morepower2 said:


> well thats on a turbocharged engine, with your Max, the timing table was developed for NA cars and the advance could increse more, not good for your supercharged motor.
> 
> Mike


Good point. I'll take your warning seriously.

Thanks for the input!


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## morepower2 (Apr 19, 2002)

Stephen Max said:


> That's good to know and explains some odd behavior I've been seeing lately. At WOT, though, when the ecu is in open loop, there is no correction attempt by the ecu, either with afr or timing, right?
> 
> If so, the idea then is to allow the ecu to control partial throttle operation by itself without any interference from the SAFC. So low throttle settings are kept zeroed out, and then the threshold value for transition from low to high settings should be set pretty high, say 80%, and then use SAFC high throttle settings to adjust when boosting at WOT.
> 
> The difficulty then may be in the 50-80% throttle regime where I do see boost developing, but can't effectively use the SAFC to lower afr. Fortunately that is an area that I can pretty much stay out of if I'm careful. At least for the type of driving I do.


Thats why I think the AFC is ok to use for a fine tuning device but when used to compinsate for larger injectors, etc, its sort of sketchy. Some people will argue all day about this but they also seem to be the guys that are blowing up all the time as well!

Mike


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## chimmike (Oct 17, 2002)

I'm going to make this a sticky for the time being. It'll stay open as long as it pertains to this subject.

keep in mind, I ran SAFC because JWT wasn't an option for me. It worked, but you always want to go with a better, more thorough option, full ecu replacement or eventually standalone (very expensive)


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## webninja (Oct 15, 2002)

I was running the SAFC and JWT ECU for about 6 months on my turbo'd 200. I even had it tuned on a dyno, but the car never ran right. I corrected lots of little problems and adjusted everything from timing, tps, spark plug gap to see if that was the issue. It finnaly came down to removing the SAFC. Once I did that the car ran 100% better, the idle was steady, the part throttle acceleration had no hesitation or hick ups, no backfiring and much better gas millage. 
Now maybe I never had my SAFC tuned properly, and that may have been the issue, but I read all the posts and did lots of research, and it never worked for me. I wish it did, because the SAFC is one cool piece of hardware


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## sr20racer (Jun 29, 2002)

Stephen Max said:


> Another question: will just having the SAFC connected, but with all the correction factors zeroed out, result in problems? Doesn't seem like it would, unless the very act of cutting the maf wire and routing the voltage through the SAFC is enough to significantly change the voltage the ecu eventually sees.


This is what I am wanting to know also. Since JWT ECU's are known to run rich could you just put a correction factor of -5% without having your car run like ass?


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## chimmike (Oct 17, 2002)

it runs rich for safety. Personally, I wouldn't try to lean it out any, especially if you're on a stock 9.5:1 DE


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## sr20racer (Jun 29, 2002)

chimmike said:


> it runs rich for safety. Personally, I wouldn't try to lean it out any, especially if you're on a stock 9.5:1 DE


I didn't put all this time and effort in my car to run safe. If it blows up, oh well.


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## morepower2 (Apr 19, 2002)

sr20racer said:


> This is what I am wanting to know also. Since JWT ECU's are known to run rich could you just put a correction factor of -5% without having your car run like ass?


Its a misconseption that they run rich, they run less rich than stock. People who have that opinion don't have a wideband O2 meter.

Mike


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## Stephen Max (Aug 18, 2003)

webninja said:


> I was running the SAFC and JWT ECU for about 6 months on my turbo'd 200. I even had it tuned on a dyno, but the car never ran right. I corrected lots of little problems and adjusted everything from timing, tps, spark plug gap to see if that was the issue. It finnaly came down to removing the SAFC. Once I did that the car ran 100% better, the idle was steady, the part throttle acceleration had no hesitation or hick ups, no backfiring and much better gas millage.
> Now maybe I never had my SAFC tuned properly, and that may have been the issue, but I read all the posts and did lots of research, and it never worked for me. I wish it did, because the SAFC is one cool piece of hardware


Thankyou!!! This is the response I was hoping to see. I have been experiencing pretty much the same symptoms and experience as you ever since I got the JWT ecu. I've checked everything else, looks like it's time to remove the SAFC and see what happens.


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## Stephen Max (Aug 18, 2003)

morepower2 said:


> Its a misconseption that they run rich, they run less rich than stock. People who have that opinion don't have a wideband O2 meter.
> 
> Mike


??? I am under that misconception too. Are you talking about NA and not turbo applications?


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## myoung (Apr 15, 2002)

sr20racer said:


> I didn't put all this time and effort in my car to run safe. If it blows up, oh well.


I would imagine a very small % of people would feel that way..


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## sr20racer (Jun 29, 2002)

myoung said:


> I would imagine a very small % of people would feel that way..


And they probably have slow cars also.


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## myoung (Apr 15, 2002)

sr20racer said:


> And they probably have slow cars also.


every running car is faster than a blown car...lol


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## sr20racer (Jun 29, 2002)

myoung said:


> every running car is faster than a blown car...lol


This is true, but if you have seen a A/F ratio on a JWT equipped car you will know that there is power that is being subdued.


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## morepower2 (Apr 19, 2002)

sr20racer said:


> This is true, but if you have seen a A/F ratio on a JWT equipped car you will know that there is power that is being subdued.


I have seen it and its not subdued for 95% of customers, in fact the margin is more narrow than stock.

For instance mid 11's for a turbo a/f ratio and mid 12's for NA, some engines even leaner.

Its the exact same I would recomend for anyone other than someone like Andreas Miko who dosent need my advice anyway.

Mike


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## morepower2 (Apr 19, 2002)

sr20racer said:


> This is true, but if you have seen a A/F ratio on a JWT equipped car you will know that there is power that is being subdued.


I have seen it and its not subdued for 95% of customers, in fact the margin is more narrow than stock.

For instance mid 11's for a turbo a/f ratio and mid 12's for NA, some engines even leaner. I mean really, what would you recomend for pump gas? Certanly not leaner than that for 92 or less octane.

Its the exact same I would recomend for anyone other than someone like Andreas Miko who dosent need my advice anyway.

Mike


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## sr20racer (Jun 29, 2002)

Well I guess when most people have JWT tune their ECU's for 53mm and they really run a 54mm that would take up some of the rich A/F correct?


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## sr20racer (Jun 29, 2002)

I forgot about the 91 OCT here also.


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## morepower2 (Apr 19, 2002)

sr20racer said:


> Well I guess when most people have JWT tune their ECU's for 53mm and they really run a 54mm that would take up some of the rich A/F correct?


you mean MAF diameter? Andreas Miko's bored MAF program compensates for the bigger diameter.

I don't see how you think those A/F ratios are too rich. When you come down to it, how many people out there even have a clue about rich or lean and whats appropriate. To be honest most too rich SR's I have seen are from ignition problems, not ECU tuning. Its ironic that the high port motors are not compatable with MSD's and an MSD equpped one acts like its too rich when its really misfiring.

I mean whats your target A/F ratio for what application? How do you measure it, whats your tuning experiance and background, not being a smart ass, I just want your opinion.

Mike


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## morepower2 (Apr 19, 2002)

sr20racer said:


> I forgot about the 91 OCT here also.


I feel for you man. 91 octane is the pabst blue ribbon of gas.

Mike


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## chimmike (Oct 17, 2002)

naw, I'd say it's the natty light.................the PBR of gas is Cali 87 octane


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## sr20racer (Jun 29, 2002)

morepower2 said:


> you mean MAF diameter? Andreas Miko's bored MAF program compensates for the bigger diameter.
> 
> Mike


FRom what I know the JWT bored MAF program is for a 53MM MAF anf Andread bores his out to 54MM. So wouldn't that lean out the A/F?


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## morepower2 (Apr 19, 2002)

sr20racer said:


> FRom what I know the JWT bored MAF program is for a 53MM MAF anf Andread bores his out to 54MM. So wouldn't that lean out the A/F?


its to get a little more flow before it hits 5.1 volts and stops reading. His maps are corrected for the bigger bore.

Mike


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## KA24Tech (Feb 2, 2004)

Mike has really good points about A/F ratios on the JWT maps. I chose to add the AFC here in CO on the Altima to make minor corrections in the map calibrated for low altitude. I tuned with the Lambda Wide Band O2 for the Fuel and a little tweaking with the EGT for the timing. Ideally you should data log your pulls and then send the data to Jim Wolf, they tweak the program per your info, and send you the moded-map back for the ECU reflash, but that is the ideal. However, on the 300 I felt it was totally fine the way JWT reflash came from them because here it will tend to run a little fatter but not to the extent that power is suffering just safer.
Jim Wolf does discourage the use of piggy-backs for a reason and that is 90+% of the people who purchase their products don't need or have the technical resources to tune an engine for correct A/F ratios for optimum power per the usage. I have setup several AFC's that were way off the mark because the person just did some seat of the pants testing and a narrow band (Auto Meter) guage. The JWT maps are not as far off as many people try to portray them and frankly I think that are the best plug and plug ECU because of the R&D Jim and the boys did before they released their products. The only I can say to the negative is that they should hire a couple more people to help with turn around but the big business they are doing is a testimonial to the quality.

Mike, where do you run your AFR on the street down there? In the 11's? 

Oh yeah, our 91 has 10% Ethanol but it is $1.72/gal... But I mix Sunoco 100 with it 1:1 so my cars don't hate me too much.

Troy


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## morepower2 (Apr 19, 2002)

KA24Tech said:


> Mike has really good points about A/F ratios on the JWT maps. I chose to add the AFC here in CO on the Altima to make minor corrections in the map calibrated for low altitude. I tuned with the Lambda Wide Band O2 for the Fuel and a little tweaking with the EGT for the timing. Ideally you should data log your pulls and then send the data to Jim Wolf, they tweak the program per your info, and send you the moded-map back for the ECU reflash, but that is the ideal. However, on the 300 I felt it was totally fine the way JWT reflash came from them because here it will tend to run a little fatter but not to the extent that power is suffering just safer.
> Jim Wolf does discourage the use of piggy-backs for a reason and that is 90+% of the people who purchase their products don't need or have the technical resources to tune an engine for correct A/F ratios for optimum power per the usage. I have setup several AFC's that were way off the mark because the person just did some seat of the pants testing and a narrow band (Auto Meter) guage. The JWT maps are not as far off as many people try to portray them and frankly I think that are the best plug and plug ECU because of the R&D Jim and the boys did before they released their products. The only I can say to the negative is that they should hire a couple more people to help with turn around but the big business they are doing is a testimonial to the quality.
> 
> Mike, where do you run your AFR on the street down there? In the 11's?
> ...


Exactly most people are clueless when it comes to tuning and don't have a wideband nor the knowlege to know whats an appropriate a/f ratio.

My Z is tuned for mid 11's on pump gas and my race gas program is low 12's (being conservative, my engine was expensive!)

Mike


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## Cjburn (Jan 24, 2004)

Aww...come on Mike you know most real "tuners" tune for 19 to 1 AFR....umm wait that's on decel....I do wish there was a way to adjust a fuel map on a JWT ecu rather than having to send it back in for $100. Just a crazy question though, Mike. On the 8.5 compression JWT ECU (average tune) nothing crazy here, what do they end up with at full throttle and full boost as far as total ignition advance? 



morepower2 said:


> Exactly most people are clueless when it comes to tuning and don't have a wideband nor the knowlege to know whats an appropriate a/f ratio.
> 
> My Z is tuned for mid 11's on pump gas and my race gas program is low 12's (being conservative, my engine was expensive!)
> 
> Mike


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## morepower2 (Apr 19, 2002)

Cjburn said:


> Aww...come on Mike you know most real "tuners" tune for 19 to 1 AFR....umm wait that's on decel....I do wish there was a way to adjust a fuel map on a JWT ecu rather than having to send it back in for $100. Just a crazy question though, Mike. On the 8.5 compression JWT ECU (average tune) nothing crazy here, what do they end up with at full throttle and full boost as far as total ignition advance?


I don't know, I didnt work on that program but I would guess something like 17-18 degrees. This might be less on newer 91 octane programs.

If you wanted to tell use a techtom or N-Probe and watch the total timing numbers as you drive through that part of the map.

Mike


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## Cjburn (Jan 24, 2004)

Excellent. I just may have to try the NProbe thing. Problem is after buying all the big stuff, turbo cars don't nickle and dime you to death. It always seems like another 300 dollar part. The GT30R is coming sans exhaust housing Friday or so... the HKS .73 exhaust housing came last week. Just need to get an ECU, FPR, get the head back from the porter, and finish fabbing up the intake manifold. It just never seems to stop. Sometimes I think I'm hemorraging money.


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## morepower2 (Apr 19, 2002)

Cjburn said:


> Excellent. I just may have to try the NProbe thing. Problem is after buying all the big stuff, turbo cars don't nickle and dime you to death. It always seems like another 300 dollar part. The GT30R is coming sans exhaust housing Friday or so... the HKS .73 exhaust housing came last week. Just need to get an ECU, FPR, get the head back from the porter, and finish fabbing up the intake manifold. It just never seems to stop. Sometimes I think I'm hemorraging money.


I feel your pain, my turbo car has been parked since october waiting for me to figure out how to hook up the aac and air regulator to an O2 induction manifold. No time!

Mike


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## Cjburn (Jan 24, 2004)

Have you given the guy at O2 a call. For the life of me I can't remember his name, really nice guy. He did the intake manifold, intercooler piping, and the exhaust for my friend's stroked 3S Celica. He's pretty damned smart, with a lot of good ideas, he might have one for you. I'm going with a square surge tank so I can put them in a close to stock location. Haven't really spent too much time on it, the runners are getting cnc'd so they've just been ordered. The time thing is one thing I have, it's just that my garage is not insulated and it has just hit 60 degrees today for the first time since November. I doubt we've had back to back nice days since early October. One of the compromises of living in the midwest is the weather.


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## FourN2ner (Dec 10, 2003)

*unpluged my afc on dyno*



Stephen Max said:


> They say it interferes with their program. Interferes how? Ben isn't too informative. Has anybody experienced this?
> 
> For reference, I have a 95 Maxima with a V1 blower, 3" pulley (~11.5 psi), 370 cc/min injectors, Z32 maf and the JWT modified ecu.


went to the dyno on sunday (gtir, t28, 2.5dp, 444cc inj, ser maf) put 202whp and 207fpt 
@11psi on a jim wolf chip ! i had a 12.8-1 af from 3500rmp to 7200 rpm 
a very good tune indeed. i did 3 runs to begin with an afc hit 194 and 195 1st run but i had tuned it a little lean on the street about 13.5 so we added across the board and hit 181 and 189 but fat as hell.....took about 5% out from 2000 rpm to 4000 in the low map and added 5-6% on the high map from about 5000 to 8000 rpm and ended at 191hp and 195fp with a 
12.25 to 12.50 af @ 10 psi not bad!.....hhhhmmmm so i added fuel in the high map instead of leaning out the jwt ecu? to make more power???? aaaahhhhaa
deleted the afc and was able to add 1psi more boost and be safe on stock maf .and made decent hp for what it is now . with the tune from jwt 
it wasnt rich. but while driving around in low throttle it is rich so im going to mess around with it in the near future putting back in the afc and pulling 4-5 % on the low map on a 40-60 % high low throtle and do some tuning and readings to see where the hesitations when in low throttle and back fires after i release the gas in lower throttle (under 4500rpm) are coming from ,of corse i will be on the dyno ....and i will have some more upgrades @ that point so it should be intresting .
it will be a little while i have a few races coming up :hal: 
hope this is useful?


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## morepower2 (Apr 19, 2002)

FourN2ner said:


> went to the dyno on sunday (gtir, t28, 2.5dp, 444cc inj, ser maf) put 202whp and 207fpt
> @11psi on a jim wolf chip ! i had a 12.8-1 af from 3500rmp to 7200 rpm
> a very good tune indeed. i did 3 runs to begin with an afc hit 194 and 195 1st run but i had tuned it a little lean on the street about 13.5 so we added across the board and hit 181 and 189 but fat as hell.....took about 5% out from 2000 rpm to 4000 in the low map and added 5-6% on the high map from about 5000 to 8000 rpm and ended at 191hp and 195fp with a
> 12.25 to 12.50 af @ 10 psi not bad!.....hhhhmmmm so i added fuel in the high map instead of leaning out the jwt ecu? to make more power???? aaaahhhhaa
> ...


Either your A/F meter is malfunctioning, its an innacurate dynojet one or you are about to blow up your motor. 13.5:1 with a turbo motor is suicidal and 12.8:1 is to lean even with race gas!

Mike


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