Armalite

Ok so today i pulled the codes on my 88 toyota pickup 22re. I got code 25 which means its running lean correct? The check engine light will sometimes come on everyday and sometimes not come on for days so it is pretty random but it always comes on when i am acceleratring. My question is what should i check first in order to solve this problem?

874runnersr5

AIR/FUEL RATIO LEAN INDICATOR--LEAN SIGNAL SENT TO ECU FROM O2 SENSOR

--INJECTOR FAULT(S)

--FUEL PRESSURE

--OXYGEN SENSOR

--AIRFLOW METER OR MAP SENSOR

--IGNITION


Start with those

Team420

check for vacuum leaks

abecedarian

Just to throw this out- exhaust leaks at the head or downpipe can also throw a lean code.
However, since the code is somewhat random in throwing the CEL, how are your spark plugs looking?

sb5walker

All good suggestions so far. If you want to clean your injectors, the most effective injector cleaners have a lot of polyether amine in them.

Techron, Gumout Regane and BG44K used to contain polyether amine, but they all apparently removed the chemical from their products. Techron still has some good stuff in it like xylene, but a look at the BG and Gumout products shows that these days they're pretty much garbage - just petroleum distillates and mineral spirits:
http://www.bgfleming.com/products/msds/208.pdf
http://www.pzlqs.com/Docs/GSAP_msds_00019406.PDF
https://www.cbest.chevron.com/msdsSe...true&region=NA

So you're left with two products that I know of that contain a good percent of PEA: Red Line's excellent SI-1 Complete Fuel System Cleaner at 30-50% PEA:
http://www.redlineoil.com/content/files/tech/32.pdf
http://www.redlineoil.com/content/files/tech/56.pdf

CRC's "Guaranteed to Pass Emissions Test Formula" at 25-35%:
http://www.crcindustries.com/faxdocs/msds/5063.pdf

Add a bottle of one of those to about 3/4 tank and burn it down to 1/8 or so (but no lower - bad for the fuel pump).

Armalite

ya i dont think it is a vacuum leak because it isnt constant. but ya i will check plugs and 847runners list of things. thank you all for the guidance i appreciate it.

Armalite

Injector cleaner sounds like a good idea too. Is there any side affects of using the injector cleaners?

abecedarian

Since injector cleaner is basically solvents, they can effect the air/fuel mixture, and O2 operation to some extent, so I wouldn't count on knowing if it worked until you've ran a tank or two of fuel after adding the cleaner so you know the cleaner itself isn't affecting the operation.

Armalite

awesome thanks for the info

abecedarian

I want to add that the code should only be thrown if the O2 sensor consistantly sends a lean signal to the ECU AND the ECU has adjusted it's fuel trim to the lean side as far as it can. This means that the ECU has no more room to compensate for a lean mixture and does point towards an intermittent leak of some sort, or possibly an O2 sensor malfunction. It may be the PAIR system operating when it shouldn't, may be a switched vacuum port malfunctioning, may possibly a small crack in the intake duct between the throttle body and air filter housing, may even be an exhaust leak drawing air into the exhaust ahead of the O2 sensor, or even a crack in the PCV hose to the manifold.