dcg9381

I wouldn't assume that your ECU is OBD-I compliant. Most states don't require code scanning pre-1995 because the OBD-I protocol was a bit of a cluster.. It wasn't well adhered to across various manufacturers. They didn't get it right until 95/96 OBD-II.

If you can find a way to reprogram or reflash a Toyota truck computer, I'd be very interested....

gametom

i have tryed both the snap on mk2500 and the toyota scan tool and all i have ever been able to get out of that computer is codes

NicCantDecide

All you will ever be able to get from a stock OBD computer (OBD0, 1, 2a, or 2b) are codes because all the stock computer is supposed to do is be a diagnostic system, hence the name On-Board Diagnostics. It will tell when something is wrong and tell you where its going wrong. The actual basemaps are locked away in the chip and there is no access to them.

The only way to modify how the computer runs without cracking it open and changing out the chip or installing an add-on board is to put another box between the computer and the wires leading to it.

These are generally called piggyback units and are a very weak form of tuning an EFI vehicle. What they do is basically lie to the computer by changing the signal coming from the engine. Exampl being the piggyback telling the ECU the engine is running lean so it will push more fuel into the combustion chamber when the signal actually says its perfectly fine.

You can get a decent tune out of piggyback units, but only to a limited extent. It won't be perfect across the board, usually only in certain rpm ranges.

TRD's supercharger kit for the 3.4L comes with a retune, but I can't remember if its a piggyback unit (runs inline with the ECU) or is a reflash of the ECU.

MonsterMaxx

There's nothing you can do with the stock 3vze computer that you can't do with a paperclip & the factory service manual (jumper E1&TE1 to read the codes.)

There is no access to fuel or timing tables.
The stock comp operates on a narrowband 02
There are no 'chip reprograms' that do any good (Jet makes one, but no one has gotten results.)
You are wasting your time and money trying to do anything with the stock computer. Even if you could figure out how to read what was happening you couldn't do anything about it.

I don't know of any 'piggyback' systems for the 3VZE. I have no problems with such a system, Powercommander makes them for bikes and they work OK. Granted programming the base computer is better, but these do work. I don't know of any that work with the Toy.

A replacement system like the Megasquirt is a possible and viable solution to your request. Some users claim it can be done for $400, but having just chased that dragon I'm seeing $1000 as more realistic. The eMS-pro is supposed to work with our ign, but it's $900 just for the comp&harness, the std MS is about $500, but you mod the distrib (can't go back to stock.) You will want a wideband 02 which is $200-300 also. You'll also probably want some dyno time with a 5gas = $200 and up.

The base Megasquirt system will do what you want and can probably be done for about $1k with mods to your distrib.
To maintain stock compatibility (able to swap the stock comp in for emissions testing or an MS failure) you will either need to start with the $900 eMS-pro or carry an unmodified distributor.



Personally, having polished this turd for better than a decade I'm disgusted with it's gas-guzzling, under-powered, 80s smog design. At $400-500 I'd have probably gone ahead and done it just to be able to say "I've done everything possible to this turd", but at $1000+ it's past my tipping point. I'll put the $1k into a 'swap' fund and keep driving it as is.

Yopar

iTrader: (2)

http://www.megamanual.com/index.html

http://www.msefi.com/

http://www.diyautotune.com/catalog/m...kits-c-30.html

http://www.glensgarage.com/catalog/index.php

http://home.earthlink.net/~jcgebhart/msindex.html

Motorheadno13

Split Second PSC1-004 or 003 for piggyback tuning our ecu?

http://www.splitsec.com/products/psc1/PSC1004.htm

abecedarian

They are OBD1 compliant, but require proprietary, specialized equipment to troubleshoot.
The diagnostic check connector can give much more information than the jumper between E/T connectors can give through the check engine light but you need sophisticated equipment, which moronically, only Toyota service shops have access to in order to read and interpret the data.
Many attempts have been made to decode the data from the check connector, but different tests require putting arbitrary signals on various terminals and reading signals from various terminals, but what to do to which pin to read what is hard to find.

In essence, everything the ECU does is available on the connector, but how to read it isn't available anywhere.