ECU Reset, performance enhancements?

[Popeye]

Lots of talk about the need to reset your ECU after making an exhaust or intake modification. Also, claims that after resetting the ECU the car (G35 in this example) will be at it's "optimal performing level" particularly in the case of the automatic trannys. Any validity to these claims?

[Q45tech]

The engine ecu adjusts itself in less than 50 miles [less than an hour]. The tcu might take a little longer but by 5 cranks [starts] they both have readjusted.

The main ecu functions [O2 stort term block learn] do so in 10 seconds and the long term in 5 minutes.

[s13sr20chris]

block learn? gm terminology isnt it? if so, gotcha!

[Q45tech]

All ecu do the same thing..........except on 1990 GM you can see separate short and long term fuel trim whereas Nissan just shows adaptive learning [%] and short term [really short - like real time].

GM shows 128 [binary] = Nissan's 100% [no adjustment to preprogrammed injector opening timeGM shows 115 [binary] = Nissan's 90% [10% adjustment to preprogrammed injector openingg time.

GM references 68F and 29.92" HG as SAE normal, so does Nissan just that the GM scanner gives more info on earlier years..........AFTER OBD2 all nomenclature converged.

At cruise remember 2.0 ms normal and 1.8 or 2.2 ms = +-10%.

The Consult rounds the injector time displayed to 0.0 ms even though the ecu changes in 0.00 millisecs...........the adaptive learning display resolves to 1%.

[LiU]

this is a bit off topic but, Q45tech, can you explain this to me:I have a 96 240sx (obd2)... I have the hotshot header which removes the first cat, and throws a CEL - anyway I went to take the emissions test and pulled the battery the ngiht before, reconnected the battery, drove 5 min to the emissions place, and passed! I had always thought that the obd2 system prevents ppl from resetting their ECU to pass emissions, since your ECU will read not ready from not having logged enough miles - but surprisingly, I passed - well now it's close to emission testing time again, I'm just wondering what happened last year that made me pass.

I still plan to get a working 3 way cat to replace the "fake" secondary one on the S14, but am wondering why I passed.

[s13sr20chris]

number one:you passed because they "clean piped" you. that happens a lot in georgia. number two: nissan obd2 did not fully conform to obd2 standards until modey year 2000. system readiness tests were put into nissan ecms in 98 as enhanced obd2. then in 00 nissan got rid of the old style consult dlc and went with the 16 pin obd2 connector. i know your car has the 16 pin but it is not the primary connector. its just there for the indy shops and to satisfy(partialy) the law.

[s13sr20chris]

i have to say i like nissans a/f alpha configuration more than the gm binary type. i did however like the gm system of having short term and long term fuel trims displayed. i used to work for gm before i realized nissan was the best.

[LiU]

number one:you passed because they "clean piped" you. that happens a lot in georgia. number two: nissan obd2 did not fully conform to obd2 standards until modey year 2000. system readiness tests were put into nissan ecms in 98 as enhanced obd2. then in 00 nissan got rid of the old style consult dlc and went with the 16 pin obd2 connector. i know your car has the 16 pin but it is not the primary connector. its just there for the indy shops and to satisfy(partialy) the law.

I understand #2, but can you explain what "clean piped" means? Thanks, no one has really explained this to me at all, everyone just told me they probably made a mistake or had a bug in their computer..

[s13sr20chris]

they dont want to fix whats broke so they just pass you and collect the fee for testing.

[LiU]

you mean in #2 that even though I have obd2, it does not have the ability to detect my ECU was just reset thus I passed? Is that what you mean by"number two: nissan obd2 did not fully conform to obd2 standards until modey year 2000. system readiness tests were put into nissan ecms in 98 as enhanced obd2. then in 00 nissan got rid of the old style consult dlc and went with the 16 pin obd2 connector. i know your car has the 16 pin but it is not the primary connector. its just there for the indy shops and to satisfy(partialy) the law."

correct me if I'm wrong plz.

[s13sr20chris]

yeah, system reset is not recorded. in 98 nissan introduced "system readiness tests". when you reset the ecm, it would take a while(depending on your driving style) for the emmission tests to take place. once they have been performed if there is no dtc then the smog shop just checks to see that everything is good. if they check and the ecm says they have not been performed(ie you just reset it) then it will fail(this part difers from state to state).

[bozuzu]

where did you get your obdII ideas? my '97 has full obdII, and the emission control stations in phoenix have full capability to detect a recent reset.

[s13sr20chris]

where did i get my ideas? a nissan engineer "learned" me. i am a dealer tech so i go to tech school every so often.