I took my 4Runner to the dealer for an alignment, brake adjust and to have them re-adjust the belts from my timing belt service (they accesory belts were slipping a bit because the tension wasn't locked down properly)

Anyway - the recommend a fuel injector cleaning service for $149, I talked her down to $109 and had them do it.

The truck does run smoother now, but 2 days later I threw a P0171 code.
I pulled the sensor and cleaned it with electrical cleaner and the next day the code came back again.

I'm wondering if thier cleaning service could have damaged my MAF, apparently it's a combination of fuel additive and having some stuff sprayed directly into my intake. I'm not sure if they removed the airbox or not for this, but it wasn't apparent that they did, because when I removed it, there were no marks on the dusty underside to show it was removed.

I'm not one to complain about a $100 R&R part, but I would be pissed if the dealer contributed to the death of my maf with some harsh cleaners, as they seem to think a barely oiled K&N filter can easily destroy one, why not harsh cleaning chemicals

BTW - K&N has PROVEN that it's oil won't harm MAFS.
http://knfilters.com/MAF/MAFTestresults.htm


Any comments would be helpful

Rook

 

I doubt it. Most fuel injector services involve adding something to the fuel tank, and an induction service which adds a cleaner to the intake, usually through a vacuum line into the intake plenum or maybe an induction tool which feeds into the throttle body. Either way, that's nowhere near the MAF.

Now, if they actually cleaned the MAF itself, that could be the problem.

 

My bet is on an air leak somewhere between your MAF and throttle body. My GF's taco had the same code for awhile and I found that the vacuum line from the FMU had a crack in it. Replaced the line and all is better again.

Check for air leaks by spraying brake cleaner around suspect areas with the truck running. If the idle increases when you spray a particular area, that will be where your leak is.

 

Pulled the MAF again and gave it a more thorough cleaning, code hasn't come back for a week. May have been a loose hose or the intial cleaning left some film on the sensor, either way - all looks good now.

Rook

 

After seeing how they do this service, my guess would be a lose vac hose or vac leak as they do typically remove a fitting on the vac side of the intake to 'suck' the cleaning fluid in.

David

 

We don't normally go through the MAF when doing this service. It's true we go through a vac hose that is closest to the intake.

 

Injector cleaning is usually done by hooking up the cleaning system to the fuel rail or filter, and not opening anything up in the intake.

I'd just throw a new MAF at the truck and be done with p0171 for a few years more...