Bob W. Posted February 27, 2012 Share Posted February 27, 2012 Hi All, I was looking for some suggestions for what is causing my 1991 Toyota V6 3.0 to be showing codes 25 & 26 which I believe are too lean and too rich. When I clear these codes it always takes longer for the 26 code(too rich) to come up probably next morning when started cold. The following are things I have checked for: Vacuum leaks MAF is very clean Fuel filter has about 18,000 mile on it. Just had complete tune up. Plugs, rotor, Cap, plug wires and fresh air filter Mechanic checked both oxigen sensor's and seemed to be doing thier job As far as how it runs, it runs very good and strong, only exception is a slightly rough idle but smooths out quickly when giving it the gas. I'm about to give up on it and just put black electrical tape over the check engine light and forgetting about it I'm presntly not at home and will not have a chance to take it to my regular mechanic until April. Maybe there is something simple i'm missing? Thanks in advance, Bob I Quote Link to comment Share on other sites More sharing options...
Totem Posted February 27, 2012 Share Posted February 27, 2012 Assuming the MAF tested ok (looking clean is not enough) the things that should be tested on rich lean issues would be the injectors (get them cleaned). Fuel line clog if lean, if rich then the EFI system and injectors would be where I wold start the witch hunt. Quote Link to comment Share on other sites More sharing options...
Bob W. Posted February 27, 2012 Author Share Posted February 27, 2012 Assuming the MAF tested ok (looking clean is not enough) the things that should be tested on rich lean issues would be the injectors (get them cleaned). Fuel line clog if lean, if rich then the EFI system and injectors would be where I wold start the witch hunt. Thanks Totem I'll give it a shot. Bob Quote Link to comment Share on other sites More sharing options...
Maineah Posted February 27, 2012 Share Posted February 27, 2012 The O2 sensor reads the mix and it can't be rich and lean at the same time (that's what your two codes are) how did he check the O2 sensor? The diagnostic connector under the hood will have a pin marked OX connect one meter probe to it and the other to a good ground it will range from .1 volts to a max of 1 volt and it should be very active and random not a slow steady voltage you can do this at a hot idle. If it is not actively changing replace it. If the MAF sensor is toes up it will run terrible but you may not even notice a difference if the O2 sensor is bad it has some effect on the overall mix but it is more of a sensor to tell the rest of the system what it sees. A rich mix detected by the O2 sensor will be high voltage some thing close to 1volt a lean mix will be low voltage closer to .1 volt the ECU expects to see an actively changing voltage. Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted March 1, 2012 Share Posted March 1, 2012 I would make sure the harness attached at MAF (Air cleaner housing) is well attached - next i would replace the oxygen sensor - it can make those codes. I had a bad one on mine & wasted a lot of time & mechanic hours before we changed that - all is well now. About $100 bucks at major autoparts - a bit more at toyota. Hi All, I was looking for some suggestions for what is causing my 1991 Toyota V6 3.0 to be showing codes 25 & 26 which I believe are too lean and too rich. When I clear these codes it always takes longer for the 26 code(too rich) to come up probably next morning when started cold. The following are things I have checked for: Vacuum leaks MAF is very clean Fuel filter has about 18,000 mile on it. Just had complete tune up. Plugs, rotor, Cap, plug wires and fresh air filter Mechanic checked both oxigen sensor's and seemed to be doing thier job As far as how it runs, it runs very good and strong, only exception is a slightly rough idle but smooths out quickly when giving it the gas. I'm about to give up on it and just put black electrical tape over the check engine light and forgetting about it I'm presntly not at home and will not have a chance to take it to my regular mechanic until April. Maybe there is something simple i'm missing? Thanks in advance, Bob I Quote Link to comment Share on other sites More sharing options...
gregor Posted April 27, 2013 Share Posted April 27, 2013 Is there a reasonable priced code reader out there for toyota efi system,or can the codes be read with a good volt ohm meter.ebay has one for around $30.00 but dont know how reliable they are My sunrader check engine light comes on randomly but seems to run smooth with good idle. Quote Link to comment Share on other sites More sharing options...
linda s Posted April 27, 2013 Share Posted April 27, 2013 Is there a reasonable priced code reader out there for toyota efi system,or can the codes be read with a good volt ohm meter.ebay has one for around $30.00 but dont know how reliable they are My sunrader check engine light comes on randomly but seems to run smooth with good idle. No code reader.Have to by pass a thingy in the engine compartment and read the blinking on the dash. I have seen this problem come up many times on toyota techy sites. http://www.toyotanation.com/forum/80-89-95-toyota-pickup-hilux/267124-trouble-codes-25-26-where-start.html Google it and you will find a bunch more. I don't think there is an easy answer Linda S Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted April 27, 2013 Share Posted April 27, 2013 Is there a reasonable priced code reader out there for toyota efi system,or can the codes be read with a good volt ohm meter.ebay has one for around $30.00 but dont know how reliable they are My sunrader check engine light comes on randomly but seems to run smooth with good idle. you do not need a code reader -- toyota campers are pre obd1 & obd2, os code readers will not work, Hence you use a jumper and read the flashes on your engine light in the dash panel. Works good --if-- you have a hard failure. Quote Link to comment Share on other sites More sharing options...
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