Dealer ECU reset

[HokieSi]

Can anyone answer this question? Please correct me if I am wrong. Our cars learn our a/f ratio mappings right? Say you go in to a Honda dealship and get an oil change do they reset the ecu or part of it? My car was pulling hard on 93 octane then I switched to 87 and it felt like it was pulling much harder at low rpms. After the oil change the car felt much more smoother but, I could tell my ep was lacking some hp on the butt dyno.

Does anyone get a (kinda) jerky acceleration feeling between 1-4k when using 87 octane?

I'm just trying to figure out what is going on.

Thanks!

[PAsi]

haven't used anything lower than 91 octane here. sorry

[BSEVEER]

Ya, just yesterday I noticed some unevn acceleration like you're talking about. I tried to get it to do it again and it was smooth so it's not happening all the time. Oh ya, I run 87 as well.

[Si4U2NV]

umm... if u have intake (CAI or SRI) it myte be cuz ur a/c is on or off...

-Mike

[esmith13]

Have you read any of the posts about the detonation experienced with 87 octane? -- especially in warmer weather??

Eric

[HokieSi]

Yea, I have read the posts. Now I am back to 93, I just finished a 300 mile trip on 93 and I have a tank full of 93. Exxon 93. I'm still getting some slightly jerky acceleration though. I'm thinking it just may be a crappy batch of 93 octane gas. Who knows. I just wanna know how the ECU works in "learning" A/F ratios and whether that has anything to do with crappy acceleration.

[Loudpedal]

I car behaves the same when shifting at <3000 rpm when cold. Does not seem to do it when warm though. Does it whether I'm running 87 or 91.

[HokieSi]

I'm going up to natural bridge 1/8 mi track on friday. I'll let you guys know what my times are. Hopefully my car will be pullin hard. The guys i'm going with have a bmw 98 328is, and 98-99 subaru outback. I'm going to see how I fair against them. I'm expecting to loose to the bimmer but not by much cause he just got it and I have a feeling he can't drive it right yet :p but, I hope to whip the snot out of the subaru.

[BlackNRedSi]

O guys....

dont worry about it, my car does the SAME thing when its cold....but it cleaned up alot after i got my exhaust on....i know shifting has nothing to do with your exhaust, but some of it could be back pressure as well...

but my car still does what you guys are talking about....

let your car warm up alittle in the AM, dont just jump in and take off...

as for the 93 oct, i put that in today see how the car runs!

Thanks Eric1 :)

only thing is, i heard that you shouldnt put 93 octa in cars that dont really need that much octaine to push....not saying it was right what i heard, but has anyone else ever heard that?

EricII

[esmith13]

for older cars tht was true. The fuel maps were designed to stay within certain tolorances. Newer cars like ours learn and adjust the a/f ratios as you go... no harm

E.

[BlackNRedSi]

Sounds good2me...

Thanks E.

E.

[mhx]

you dont need to goto the dealer to reset your ECU..

Simply unplug your +wire to your battery.. (thats the red one)

wait 20min.. turn your lights on.. honk your horn a few times.. helps drain power in the system..

plug your battery back in..

make sure all your accessories are off.. AC, lights, etc..
start car let it run for 10min
shut it off
start it up drive off
it will reprogram itself for you

[mhx]

u can also pull the ECU fuse.. check your owners manual for its location..

[BlackNRedSi]

do you need to do this when you put on a cat back system? i didnt unplug anything, i completly forgot about doing that ....

Eric

[esmith13]

You should..... The instructions in with my thermal told me to do so.

Same with both of the intakes I had...

I think it's generally a good idea when you do ANYTHING that would change engine performance or a/f ratio.

Put it this way, unless you inspection was tomorrow, it wouldn't hurt to unplug you battery for 10 min or so....

... Unless you never finished reading you manual for your cool stereo and won't remember how to reprogram it... :angel:

...
... ERIC!....

:angel:

E.

[BlackNRedSi]

HA thanks E. yeah i should have known to do that, i always did that with my IROC, i think it was cause i was in such a rush to get it on...(ya kno, cause its something new!)

so yeah i will go out after work and do that! and if i F' up the headunit, i will just bring it back to you to fix!

EII