[berto07T]

What's up people, I got the service engine soon light on. It had turned on last week scanned it with my tuner and got p0174 system lean. thought maybe a hose was loose or dirty MAF sensor/filter as I have read clean both and checked all hoses, cleared it but now it came back today. When it does come back on it idles a little higher than normal too but no loss of power actually feels more responsive coming off a stop/light(guessing cause the rpms are sitting higher?) had a friend with an actual scanner scan it and same code just better detail. Came up as code p0174 bank #2 system lean. The picture of screen is hard to read but reads :
p0174
STFT B1(%) 1.56
LTFT B1(%) 31.25
STFT B2(%) -0.78
LTFT B2(%) 33.59

I see one is negative and the other really low is that 02 sensor readings? Or what's does it mean? Help me out guys!

 

[dubyam]

According to your Long Term Fuel Trims, you're running lean on both banks. Fuel trims should run between -10 to 10%, with some occasional fluctuation above that. And that's the total, which is summed by adding the Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). A sustained total greater than +/-20% will trigger the code.

Now, as to why, you're on the right track. It's either too little fuel or too much air. It could be a vacuum leak (which in this case would almost certainly have to be an intake leak somewhere because it's leaning both banks), but it could be a misfire, clogged cats, stuck EGR purge valve, a stuck injector (though it would have to be a pair, one on each bank) or the O2 sensors. If you've checked for vacuum leaks (carb cleaner or some such around all the hoses and connections), you will have to start finding the test instructions for the other line items in the system. Might be good to download the service manual for your Titan (by year) from NicoClub.com and go through the diagnostic procedure in order. Don't just throw parts at it.

 

[berto07T]

Thanks for the reply that clears it up a bit. I was wondering why both were low. Maybe it is an intake leak. Because I swapped both rear sensors side to side and it still popped up today same code. And I had a shop replace the starter about two weeks ago which involves removing the intake. I think they might have missed something or not properly seated it hence why it's both banks am I right?

 

[Pale Rider]

did the shop use all new OEM gaskets on the intake manifold? and did they torque the manifold to spec and in order? are all the hoses back on and secure? did they tear any hoses? is the brake booster hose attached at both ends?

 

[dubyam]

Time for a shop visit. Pretty sure you gave an intake leak.

 

[berto07T]

Well took it the shop today since I didn't work today. They ran the code and checked the hoses and torqued what they removed again. Said they did the spray water method to see if there was leaks but they didn't see any, this was after they re torqued everything though. They cleared the code and hopefully it was something they didn't torque right like y'all said. And it's sealed now or I'm taking it back and tell them to use a smoke machine. (I should've just done the started myself, even though it looks like a pain but least I'm sure I would've done it right. Taken forever but done right lol)

 

[berto07T]

So the light turned back on yesterday while working. But this morning it's gone again. Weird no? And to make it weirder the last time it turned when I took it to the shop and yesterday, I have noticed i had to driver her more than 100 miles then it turned on. I also had the ac on both times. Still taking it in cause the code is still saved on the computer when you plug it in.

 

[dubyam]

Yeah. Your shop didn't do something correctly, it sounds like. I'm betting they either squished a gasket, or used cheapo gaskets. But make them fix it, because I'm sure they broke it.

 

[berto07T]

Well I dropped it off Friday morning talk the mechanic and he finally agreed with me that it's the intake gaskets. So they replaced them. Let's hope it's fixed now.

 

[berto07T]

So far so good! Was the gaskets. They probably didn't replace them cause they "looked" good but were squished upon putting it back together. Thank you guys for your feedback!

 

[Pale Rider]

So far so good! Was the gaskets. They probably didn't replace them cause they "looked" good but were squished upon putting it back together. Thank you guys for your feedback!

in most cases all intake manifold gaskets get tossed and new ones installed. They simply are not pliable like new when they have had years and miles of squish and heat cycles.

glad your squared away.