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View Full Version : Can you tune a stock sr ecu to use a N62 maf with a AFC?

MiSuNdErStOoD
11-02-2009, 03:21 AM
I have done hours of searching and looking on various websites from the states all the way to australia and I can't seem to get a definitive answer on this. Let me tell you what I have going on right now and get you guys take on it.
I have a s15 sr20det setup that is pretty much completely stock except for the normal huge front mount setup with hks blow off valve, greddy boost controller and apexi super afc.
I am running my s15 sr with a s14 sr20det zenki ecu. I was having some idling issues and maf issues at first but have got those worked out. I am currently looking for a s15 sr ecu to install but don't have the $400 for it at the time that they are asking on Ebay or across the pond. Ok here is what is going on.
My s15 sr is supposed to run stock 7 pounds and it runs great at that. I should be able to boost at least 15 pounds pretty safely for the time being before I get my new ecu and a tune once I get a few more bolt ons. Well anytime I try and boost over 10 - 11 pounds it starts to cut out really hard at high revs like I'm hitting a fuel cut off or something.
Could this mean that I'm maxing out my mass air flow sensor? I have talked to a few people that run really huge sr setups and they have all came to that conclusing. The s15 sr engine setup is supposed to be around 250 hourse power stock and and a s14 sr setup around 215 or 220 I believe. So i'm guess with the front mount and bigger better turbo of the s15 engine and bigger injectors being 480cc that if anything around 10 pounds or so I should be getting pretty close to 300 horse power at the crank along with the fuel map that i'm ajusting with the afc.
could this be to much for the stock sr zenki maf?
If so here is my question... Can a 300zx n62 maf be tuned with a afc to work with a stock ecu smoothly without getting a real tune for the time being? Before when I didn't have the correct maf for the ecu I tried wiring in the n62 and at idle it was running so rich that it was fouling out my plugs. Can this be fixed with the afc temporarily or will I have to wait until I can get some dyno time?
On another note i'm for sure getting enough fuel because I have intalled a walboro fuel pump and richened up the fuel map with the afc using a wide band.
Please let me know what you think and let me know if you need anymore information about my setup or if I have left anything out.
Discuss. :confused
fliprayzin240sx
11-02-2009, 05:43 AM
K Im confused...how the fuck is a Zenki S14 ECU running an S15 engine?!?! You have the difference in injector size (440 vs 370) and the coilpacks (S15 doesnt have igniter chip).

But anyways, if you got it running...do you have the Walbro pump installed already? Most folks I know who had S15s cant boost more than 10 psi without the stock fuel pump being upgraded.
smelly240
11-02-2009, 06:09 AM
you arent adjusting your fuel map with the afc... all ur doing is telling the ecu that there isnt as much load as there is (it intercepts the maf signal) - this makes it give u less fuel

IT ALSO GIVES YOU MORE TIMING!

You cant expect a s15 engine to run on a s14 computer, just like you cant expect a chevy to run on a ford computer (exagerration)...

an afc is a horrible aids infested bandaid.
g6civcx
11-02-2009, 06:54 AM
Can a 300zx n62 maf be tuned with a afc to work with a stock ecu smoothly without getting a real tune for the time being? Before when I didn't have the correct maf for the ecu I tried wiring in the n62 and at idle it was running so rich that it was fouling out my plugs. Can this be fixed with the afc temporarily or will I have to wait until I can get some dyno time?

The AFC is not good for any type of major modification like you're doing.

As said above, all the AFC does is intercept the sensor signals and modify these signals to trick your ECU into doing something else. Keep in mind that the ECU is limited by its stock programming so don't expect the flexibility of a true standalone.
clark
11-02-2009, 06:54 AM
you need to upgrade your fuel pump and fuel filter if you already haven't.

i also agree with the criticisms about your ecu choice.
MiSuNdErStOoD
11-02-2009, 10:20 AM
IF you read the entire thread I already swapped in the walboro fuel pump and I'm able to run the S15 sr on S14 ecu because i'm using the entire s14 sr wiring harness as well.

This setup isn't permanent it is very temporary just had a basic question about the N62 being able to be turned with a AFC to work for the time being? Anyone have a answer to that?

i know the engine isn't going to run great with this current setup but until I get more funds its all I have.
renegade_ewok
11-02-2009, 10:44 AM
I am running a #62 ecu on a Zenki S14 SR... its not hard, just wire it right... Duh. For those that don't know thats a redtop auto ECU on a manual notchtop. Of course my car was on the dyno for hours so it doesn't really matter what the base map was.

Just get a proper tune, AFC won't do much and your tune will never be right if thats all you want to do.
MiSuNdErStOoD
11-02-2009, 10:52 AM
I am running a #62 ecu on a Zenki S14 SR... its not hard, just wire it right... Duh. For those that don't know thats a redtop auto ECU on a manual notchtop. Of course my car was on the dyno for hours so it doesn't really matter what the base map was.

Just get a proper tune, AFC won't do much and your tune will never be right if thats all you want to do.


ok but did you run the n62 before you had it dynoed?
renegade_ewok
11-02-2009, 11:04 AM
Yeah, and it broke up all over the place like mad.

Its dumb to replace the MAF and not have it tuned. Its borderline impossible to have it running right at all since the MAF scaling is completely different and thats NOT something you can adjust with an AFC. You could potentially run a resistor off the MAF and dump fuel, but its still gonna run like ass and ghetto rigging a tune is just dumb.

Its dumb I tell you, dumb. Do it right or do it twice.
MiSuNdErStOoD
11-02-2009, 11:07 AM
[quote=renegade_ewok;3113663]Yeah, and it broke up all over the place like mad.

quote]

yeah that is what happened to mine as well, just wasn't sure if there was a temp quick fix until I got the new ecu, wiring harness and bolt ons before I got a tune. :ugh:
renegade_ewok
11-02-2009, 11:08 AM
You dont need a new ECU or wiring harness to run that motor on that ECU.

Just a tune. If everything is wired right (custom harness) it will run right with a tune.
MiSuNdErStOoD
11-02-2009, 11:13 AM
You dont need a new ECU or wiring harness to run that motor on that ECU.

Just a tune. If everything is wired right (custom harness) it will run right with a tune.

Yeah it runs great now, just can't boost over 10 pounds for some reason, that is why i'm assuming its because of my maf being maxed out since its still the stock one. I'm getting enough fuel, what do you think?
renegade_ewok
11-05-2009, 12:37 PM
stock MAF sucks, but I have no experience with it... When my wiring was done and the tuning was done it was all with a bigger MAF already. The car was driven out of the shop onto the trailer with no tuning on my 555cc/Z32 setup and goddamn... it didn't like it.
JVD
11-05-2009, 12:42 PM
Yeah it runs great now, just can't boost over 10 pounds for some reason, that is why i'm assuming its because of my maf being maxed out since its still the stock one. I'm getting enough fuel, what do you think?
MAFS won't max out at 10lbs.

It's your entire haggard setup.

Just do it right.
mptjimmy
11-05-2009, 08:39 PM
check for a dirty fuel filter on the fuel pump, I have had that happen with a s14 before, and boost leaks,