resetting ecu. more power?

Ryanfz

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May 9, 2005
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Holla. In a magazine I have, one of the articles is about a MKIV build. In the build, they reset the ecu by taking out the two fuel injection system fuses, and plugging them back in after a couple minutes. "This will reset the ECU so that it doesn't pull back so much on timing." Doing this increased the power from 264whp to 275.5whp on the dyno. Will this work for the MKIII?
 

GrimJack

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It depends. This resets the memory in the ECU, so it won't remember all the behavior that it has 'learned' over the last several months.

Now if it 'learned' agressive maps, usually 'cause you drive it like you stole it, then resetting it will drop your power.

However, if it learned granny maps, 'cause you drive in California, then this will give you more.

And yes, our ECU does a fine job of pulling timing when required.
 

Disced

Pie + NYQuil = FTW
Apr 5, 2005
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Also you should note, if the ecu throws codes, which most likely results in the pulling of timing then the car accelerates like a piece of shit. Normally if you get a code, check it, reset ecu and run it until it comes back.

I just recently ran @ the track first 2 runs were 14.5 @ 101.1 and the next 3 after i reset the ECU were 14.0 @ 102.6....

Go figure.. I had probably been running w/ codes and not known, since I hadn't checked in a while but had known it was throwing a TPS code a while back that never got reset.
 

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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Sorry, slightly OT, but, do you HAVE to disconnect the battery to reset our ECUs?
 

staticpat

Supra Chair!
Mar 30, 2005
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I was wondering if I should reset the ECU or not after modding. I added new ic pipes, lex afm, safc, afpr. Would the most gain from letting it relearn, or use the old timing settings? Also is it better to reset the ECU before or after a/f tuning?

Hmmm on second thought unplugging the battery while doing fuel mods is probably a good idea.

Still though, on other mods is it better to reset the ECU or not?
 

GrimJack

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You don't have to disconnect the battery, you can just pull the EFI fuse for a minute or two.

I'd suggest resetting the ECU after making changes to your setup, lets the ECU relearn with the new parameters which is going to be a LOT faster than overwriting the existing settings.
 

Ryanfz

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May 9, 2005
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GrimJack said:
You don't have to disconnect the battery, you can just pull the EFI fuse for a minute or two.

I'd suggest resetting the ECU after making changes to your setup, lets the ECU relearn with the new parameters which is going to be a LOT faster than overwriting the existing settings.

Do I have to mess with the EFI relay too? or just the fuse?
 
N

NDBoost

Guest
Ryanfz said:
Do I have to mess with the EFI relay too? or just the fuse?
just the little 15A fuse in the engien bay fuse block. Pull it out and let it sit for a while and put it back in. start the car dont touch the gas, let it idle for a few min until the idle straightens out and then drive how you normally drive.
 
N

NDBoost

Guest
hottscennessey said:
I reset mine once, let it idle, and it stalled at idle. lol. Then i re-set it again and it was fine.
werd when im on open downpipe i have to give it a tiny bit of gas or it will stall out within 3-4 seconds.
 

chevyeater

wastegate hose is pulled
Mar 30, 2005
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I haven't seen evidence that our stock ecu uses an adaptive timing curve like the 2JZGTE does. Anyway, it is a good way for Mk4 guys to blow up thier engines, resetting the ecu for more power.
 

hottscennessey

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Jun 3, 2005
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I see your point chevyeater, the ecu is adaptive for a reason, and if it adapts to give you less power, its probably to protect something. (unless you've fixed those problems since you've last re-set your ECU).
 

GrimJack

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I don't think it does adaptive timing curves... but I'm sure it changes the fuel maps.

Same theory applies, however, if it's running less power after learning for a while, I expect it's happening for a reason.
 

Nick M

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Sep 9, 2005
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Holla. In a magazine I have, one of the articles is about a MKIV build. In the build, they reset the ecu by taking out the two fuel injection system fuses, and plugging them back in after a couple minutes. "This will reset the ECU so that it doesn't pull back so much on timing." Doing this increased the power from 264whp to 275.5whp on the dyno.
No, it does nothing. You will change your short term fuel trim, but you do that the instant you step on the pedal. You can get a 10 hp difference with just a longer cooldown on the dyno, or other manipultions.

And 101 to 102.x isnt really a change. I have gone 98 then 99 with no changes on the same day.