I noticed that a few people convert their OBD from 2 to 1 in cars that come stock w/ OBD2, why is this? Does it help out performance wise? Throw less CEL's?

Thanks

 

OBD On Board Diagnostics
was introduced when stricter emmisions laws were enforced on new cars. This also made it easyer for problems to be diagnoses quickly and with ease.
OBD2 gave the car the ability to change certain variables on some (like 5th Gen Luders) cars. Like for example if your car was OBD2, it would use a sensor before the cat to determine wether the car is running too rich or lean, so if it detected it was running very rich the ECU has the ability to change mixture parameters through the rev range in order to enhance combustion efficiency and minimize pollution. It can even adjust -ignition- timing if it is way too advanced / retarded etc.

OBD1 equipped ECUs get programmed and do exactly as its written (does as its told on the fuel map). OBD2 will try keep emmisions low and has on some cars like the 5th Gen Lude, have this ability to Re-Tune as per above.

Its just nicer to have OBD1 on a heavily built motor!

 

ott hit it right on...with the addition of an 02 sensor before and after the cat in many cases, unless the car has a cat in the exhaust mani like on many toyotas. OBD2 has the ability to re-learn its fuel and ignition tables depending on the readings it gets from the MAP, as that will change with variables like outside temp, and elevation

i converted my 97 to obd1 mostly since it was cheaper, even after the swap and conversion harness..this isnt legal in some states or in any conty where emissions will be tested, but oh well. i dont have a cat anyways, so i guess i'll deal with that when the time comes

in the case of my car, i chose the obd1 jdm h22a for the closed deck design, so i could use a power adder in the future, and not have to worry about sleeving the block. Bear in mind, that im only talking about 7psi max, or no more than a 75 shot of juice

 

actually the before and after HO2S called the primary and secondary HO2S don't refer to each other to adjust fuel trim.... the primary HO2S1 controls and monitors the air/fuel ratio, and the purpose of the second HO2S2 is to monitor the cat. This second oxygen sensor is only found on and OBD2 engine not an OBD1.

 

will OBDII detune ANY mods you make, i.e CAI?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Blackhorse6 &raquo;</TD></TR><TR><TD CLASS="quote">will OBDII detune ANY mods you make, i.e CAI?</TD></TR></TABLE>

This is what they say, but if the obd2 changes the fuel/ignition maps to match the increased air for the intake it should make more power? I know its trying to keep emissions low but it doesnt have a choice if you increase air, more fuel has to be added.

 

It was made to enforce emmision laws, it will keep the burn as clean as possible, so can in affect 'de-tune' to an extent. Ive heard of people to reset the Learnign function memory in the ecu every time they start it so it doesnt 'learn' and adapt the fuel Map


Modified by OTT at 1:02 PM 1/3/2004

 

Dtuned
::QUOTE:: actually the before and after HO2S called the primary and secondary HO2S don't refer to each other to adjust fuel trim.... the primary HO2S1 controls and monitors the air/fuel ratio, and the purpose of the second HO2S2 is to monitor the cat. This second oxygen sensor is only found on and OBD2 engine not an OBD1. ::QUOTE::

Read the thread..

Bigjussin
::QUOTE:: ..with the addition of an 02 sensor before and after the cat.. ::QUOTE::
(Reffering to OBD2)

And no one said the two sensors before and after the cat control the 'fuel trim' (mixture)
Where did you get that idea from??

These sensors are Input devices for the ECU. The ECU interperits the data given and makes adjustments accordingly; No one said anything about OBD1s with sensors after the cat. OBD2s

Read above posts man!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by OTT &raquo;</TD></TR><TR><TD CLASS="quote">It was made to enforce emmision laws, it will keep the burn as clean as possible, so can in affect 'de-tune' to an extent. Ive heard of people to reset the Learnign function memory in the ecu every time they start it so it doesnt 'learn' and adapt the fuel Map


Modified by OTT at 1:02 PM 1/3/2004</TD></TR></TABLE>

I've read and heard the same thing. But I have never been given a definitive answer on this question. I guess I just need to dyno the car w/ and w/out!

 

Dyno, add mod and dyno again. Come back a week late and re-dyno. Then go-figure where the numbers went!

 

thanks for gettign my back OTT....lol

i should have been more clear about it....there are upstream and downstream 02 sensors, or primary and secondary, like was said before, the second one is only for monitoring the efficiency of the cat, or just rip it off and get a simulator...hehe

OBD2 ecus are a biatch if you are looking to advance your base timing the old fashioned way to get more power. IF you dont jump two pins on the ecu, the comp will just retard the timing back to "normal" so if you want to turn the dizzy, u have to jump the ecu....
hittin the dyno after each mod is the best way to go, not the cheapest, but most effective...or a standalone, but dang those are mucho cash

peace all!

 

dont forget to mention the obd2 workaround Im not sure exactly how long it lasts but the difference is real noticeable, I would recomed doing it before you run people.

http://www.ntpog.org/mods/fifth-afc/ecu.shtml