j-man

ok, so my supercharged 2000 4runner 4x4 5spd 3.4 "federal spec" has been having issues. Started with an intermittent chugging, surging, that went away after warmed up & threw a 172 code. Now its fully there all the time, runs like its going to die, super rich-i can smell the fuel out the exhaust. note: ive had urd's 7th inj in there for the last 10k miles with no issues - with the pnp harness, but disconnected it so i can see wtf the problem is.

Ive done a whole host of things including maf, 02 sensors, swapped throttle bodies, injectors, wires/plugs/coils, coolant temp sensor tied to the ecu...pretty much everything.

Then as my final try, i swapped in an ECU from my old 99 4runner 5spd 4x4 "california spec" and wallah, the thing runs like it did the day i bought it new - even tho the upstream 02 sensors are different between rigs - so i spliced in the correct one to the "cali spec" ecu. I even bought a known completly fine "federal spec" ecu and it does the exact same thing as the one that has been in there the whole time.

So my final question to the toyota land guru's....what is the difference between the federal spec & california spec engine's/ecu's? Why is it running completly fine on the california ecu if its a "federal spec" truck? Its got to be something simple that im missing...help me on this plz.

TheDurk

That's seriously bizarre. The Cali. spec A/F sensors do the same job as the 49-state, but the technology is very different. If you have the sensor and ECU installed, the only other major difference that I know of is you have less catalytic converter capacity and the tolerance for pollutants is supposed to be lower. Are you not throwing a P0420 given you only have the less efficient single cat?

There may be minor differences in how the Cali. handles timing and fuel metering vs. sensor input but that is above my paygrade. Any chance it was born Cali. and a PO tried to convert it to 49-state?

The other thing is emissions testing. I would think the computer would flip if it saw a Cali. ECM with a 49-state VIN.

Shot in the dark: Any chance you tried using a Bosch sensor or otherwise got the wrong one when you swapped those out? These trucks really only do well with the OEM Denso's. The one explanation that makes sense to me is a bad replacement front O2, as everything else has been covered.

Curious--Are those ECU's plug and play except for the front exhaust sensor? I'm amazed the connectors aren't different.

j-man

The truck was born a federal built truck. No mods ever prior to me owning it - completly stock.
emissions testing...not worried cause it registered in a smog exempt city.
the 02 sensors are per vin thru my local toyota stealership
The ecu's are all plug n play right up behind the glove box area.

There's definately something different between the federal spec & cali spec aside from the 02 sensors...it just doesnt make any rational sense why it all of a sudden runs like crapero with the federal ecu its supposed to have, and then runs perfect with the cali spec computer from my 99 4runner....

anyone else have any ideas, suggestions, comments?????????????