P0171 Code
- Thread starter Brilliant
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4Runnermex
New member
MAF FLOW SENSOR. Bad or clean it first what year?
LittleCaesar
New member
How old are the O2 sensors?
Brilliant
New member
Looking for service manual steps.
Maf is new,
new upstream o2,
new tb gasket,
new pcv and hose,
checked for vac leaks.
Small uptick in idle when spraying rear side of the housing. A bit at a loss, maybe iac seal or sensor seal. Doesn't seem like its enough to cause the issue. St and lt trim exceed 35% combined, both 20 so that's why it's throwing the code. Ect measures 170F range, seems normal. No stalling hesitation under wot, so fuel pressure should be OK.
Throws clode n closed loop occasionally. Once cleared stays away until idle at some stoplight or low rpm high load (hill).
Federal 99
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Brilliant
New member
Front is new, no cat code for rear.
TheDurk
Elite Member
http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/di/eg5vzfe/cip0171p.pdf
Actually, AFAIK, the FSM says nothing about how to clean the MAF, This is all there is, ...inspect and replace:
http://tacoma.site40.net/4Runner_96-02_Repair&Wiring/techinfo.toyota.com/ileaf/02toyrm/02toypdf/02rmsour/2002/024runne/sf5vzfe/mafm/insp.pdf
Don't overthink this--P0171 clean your MAF. Obvious and cheap first step. Lots of DIY threads to be found with a search. Bad gas can mess up even a new MAF. Also clean throttle body.
Here is a freebie:
http://www.toyota-4runner.org/3rd-gen-t4rs/86675-help-p0171-3.html#post755548
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Brilliant
New member
Maf was cleaned, then maf was replaced, maf is new as previously mentioned.
I wouldn't be posting ifit was a matter of cleaning the maf or tb. :/
LittleCaesar
New member
I know more than one forum member has had PO171 show up due to a failing injector but I know you just replaced all six from the dealer. I wonder though if one may be the culprit.
Low compression sometimes throws this code, but I think you would probably know such.
Low compression sometimes throws this code, but I think you would probably know such.
Brilliant
New member
I didnt know low comp would throw this code. I think I am checking exhaust for leaks next, but the headers have been fine for weeks before I got into the injector issue. Like you said, all 6 were replaced recently.
Brilliant
New member
thank you!
LittleCaesar
New member
I think I have seen it once on here and once on YT for low compression. It may have been attached to a misfire code, such as 300. But it has been some time since they were posted.
Ditto on checking for exhaust leaks, especially at the gaskets.
Ditto on checking for exhaust leaks, especially at the gaskets.
A.Wilson013
New member
Every single time I have had a p0171 it has been a vacuum leak. I always get one when I take the SC off, because I always forget to hook one of the lines up.
Brilliant
New member
checked all hoses, vacuum is 22/24 at idle.
I cleared the computer again and it ran like crap at idle without the high LTFT. Once 20% trim was learned it idled ok.
I revved the engine to 2k and held for 30-60s. LTFT climbed to 35%, STFT fell to 0-5%.
TheDurk
Elite Member
Congrats. IAC is not even on the FSM list of possible causes.
Did you happen to record (or remember) the freeze frame on the P0171? I am wondering if it showed an idle RPM.
Brilliant
New member
Idle seemed about what it always was, 900 I want to say. When I cleared the 20% ltft it ran like crap so that led me to iac. I read one other guy have this code related to the iac as well.
Lost multiple weekends on this crap. Glad it's solved.