Got a '93 Runner with a check engine light. Ran the code and it is the MAF sensor. At first it says it's running too rich, then after a couple minutes it says it's running too lean. The stupid thing keeps going back and forth ever couple minutes. Basically I'd like to know if it's a faulty sensor or if it just need to get some carb cleaner through it. Would it be best to get a new one ($$$) or grab one from a u pull it (pocket part-$)???

 

Don't know how your getting a code for a MAF sensor, because this generation of trucks do not have one. What you have is a VAFM, which measures the volume of air going into the intake.

How did you get this code...?

 

There are only a few places around here that'll do it for free; AutoZone, Baxter, CarQuest, Knechts, Thriftys. But the only place that has a code reader that has the adapter for this generation Toyota truck was O'Rileys (Formerly Schucks).

 

Since you're talking about u-pull-it, you must be intending to diagnose and fix this yourself. So, since you've been on this site for 18 posts, you must know that you need the Factory Manual. http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf Otherwise, you're dependent on someone who thinks they have an "adapter" for your model truck, and thinks they know how to read their scanner.

To do the scan yourself, you'll need Special Service Tool SST 09843 –18020. Hard to get anymore, but I have a source: http://www.staples.com/Staples-1-Siz...product_525881

Once you have the correct code and have read the suggested "trouble area," feel free to post back if you have more questions.

 

Thanks. Actually at O'Rileys, you can rent the scanner for free if you leave them your ID to scan the codes in their parking lot. I read it myself, it said MAF Too Rich and after a bit said Too Lean. Left the scanner on the truck, with the motor running for a few minutes and it kept swapping back and forth between Too Rich and Too Lean. I don't remember the code number, but it indicated a faulty MAF sensor. So whether actually faulty or just needs to be cleaned is what I'm trying to figure out. I might be new to yotatech, since I "only have 18 posts," but I'm not new to trucks and I ain't no dummy. I'd just like to find the best option to spend the least amount of money. Lots of people wrench on a budget. So maybe I need to restate my question with better clarity?

I wish to spend the least amount of money possible to start, and go for the full Monty if that doesn't work. A couple bucks will get me a can of carb cleaner if that's all it takes to clean the sensor, but if it's only a temporary fix I'll pony up and go to a u pull it and find a used one in "decent" condition. But if that's no guarantee, then I'll donate my kidney and get a new $300 unit from AutoZone.

So, that said, without going back to O'Rileys or spending a whole bunch extra on a tool, what does anyone else feel to be the most cost effective fix in the long run?

I know someone is gonna say buy new for a longterm fix. But if it's not a faulty sensor and just needs to be cleaned, could that be my answer? I'd just like the check engine light gone, need new tags...

 

You don't need a fancy tool to check codes. And your truck does not have an maf. so how do you intend to clean something you dont have? You should check the codes the proper way. I dont know what your looking at that says too lean and then too rich, but the oxygen sensor is supposed to go rich-lean-rich-lean,etc.......Get the code # and do some searches on diagnostic procedures for that particular code

 

first I'd get MAF cleaner, even if its no longer called the MAF sensor, its safer for the newer sensors than carb cleaner. (its a little weaker concentration of the chemicals)

do get a FSM for your truck, and the scanner if you plan on being the backyard mechanic.

being new to the site doesn't/shouldn't mean anything about your knowledge. I'm relatively new and have plenty of questions, and I'm an auto technician (fancy way to say mechanic lol)

personally for parts I don't suggest your generic parts house. go to your local toyota and get the part if you honestly need it, you'll actually talk to someone that knows something remotely car related and more than likely get the right part. might be a few bucks more but its worth it long term.

as for cost effectiveness, get the FSM and scanner, then get the job done right the first go at it. it might sound like a lot up front, but long run you're not just trial and error swapping parts and guessing.

good luck! welcome to yotatech btw.

 

Your 93 is pre ODBII, so I am confused on how your getting a code from a scanner when there is no port on a 93 to even hook a reader up to? You pull codes on these things by jumping TE1 and E1 in the diagnosis box with a paperclip. Then you read the number of flashes of the "check engine light" which is then referenced against a code listing. Take a picture of how this scanner is operating and where it is hooked up, it got to be a gimmick.

There is no getting a can of carb cleaner and cleaning the MAF, again you don't have one. The VAFM is activated by a flap and a variable resistor on top of the flap in a box. The amount that flap is open is then relayed to the ECU...therefore no cleaning will work.

 

Let's try this again.

There is NO MAF on a 1993 Toyota ForeRunner. So if your borrowed "scanner" says "MAF Too Rich" or otherwise clearly says you have a faulty MAF, what does that tell you about the scanner? Or, maybe you read it wrong, and it said something like "AFM too rich." Since that doesn't represent an actual code, you STILL don't know what the computer is trying to tell you.

If you had followed the link I provided, you would see that the 21st century "scan tool" for your 4runner costs $0.02. Except that you probably already have a bunch of them in your desk drawer. So you can drive to O'Reilly's and borrow a scan tool that you know (now) doesn't work, OR you can stay at home at read the code accurately for 2 cents.

Using "MAF" cleaner on a non-existent MAF for a problem that probably has nothing to do with the induction system is not likely to get you very far.

If you want to go to a junkyard and try to buy a "MAF," then install it on your truck, by all means give it a shot.

 

Actually, there are "scanners" available that plug into the pre-95 diagnostic port, and do approximately the same thing as the $0.02 "Special Service Tool" the rest of us use. Of course, if the scanner reads out "faulty MAF," it's not helping.

I wonder if this mystery borrowed scanner might actually be monitoring the Ox1 or VF1 signal, which can be used to tell the state of the O2 sensor. As j2the-e points out, that signal is supposed to flop back and forth about 8 times in 10 seconds.

 

Gentlemen, the easiest thing to do is to find a friend with the samilar truck and swap the part. If that's the problem then it'll go away. Check out some toyota 4x4 clubs in the area. ....

 

My first thoughts when reading this - OBDII started in 95, so you'll want to jump the terminals - check out this page (and bookmark the site!):

http://www.4crawler.com/4x4/CheapTricks/TroubleCodes/

I used this recently after my head job - helped me identify a broken temp sender, and too lean/too rich (caused by faulty AFM - not MAF).

 

theres still the OBDI scanner guys, which i'm guessing is the one he may have used.... but they suck hence the development of the OBDII... easier to use the paper clip and check the flashy light.

also cleaning your whole intake system would be a good idea, even if that doesn't solve the problem cleaning doesn't hurt it...

I do agree with anthony1, that swapping the allegedly defective part with a known good one works for some diagnostics