I swapped in another MAF sensor. Getting P0174 code. Is there a diagram in the RAVE that shows vacuum lines to test? Should I be looking at o2 sensors?

 

My friend ran smoke test today at his shop and didn't find a leak. Couldn't see near the fuel injectors though. Should I take it to another shop I don't know and retest it or is there something else to consider?

 

If you have a scan tool with live data you can look at the fuel trims and see if it's really lean on just one bank. If it only has high fuel trims on one bank, then I would lean towards fuel injector O-rings or possibly fuel injectors that aren't working. If both banks are lean, see if the fuel trims increase or decrease when you rev the engine. If they decrease, it's most likely a vacuum leak. If they increase, I would check the fuel pressure.
If the fuel pressure drops when you rev the engine, the pump or its wiring most likely has a problem. That would be my guess anyway. Unless the shop somehow missed a leak during the smoke test. Which isn't impossible. Depending where leaks are, you can overlook them.
Though it's unlikely, the MAF you installed could be defective.

 

Even though you can't see the fuel injectors you will see smoke rise up from under the aluminum intake plenum if you have one or more bad o-rings. It is easy enough to do the test yourself with a cigar or cigarette.

Disconnect the PCV hose coming from the RH side valve cover to the aluminum plenum and temporarily attach a piece of fuel hose to the end of the plenum. Blaze up and blow several good puffs through the hose and then plug the end with your thumb and look for the presence of leaks.

If nothing else this gives you a good excuse to go outside and have a smoke. I quit many years ago so burn one for me.

 

Disc Oh No,
I can read live data. I can read 4 Fuel Trims (short and long of each) that I can read. I just looked at some screen shots I took a week or so ago when I got the lean error of the fuel trim values. Based on something else I read, if it's 25% on short-term that would point to a fuel injector problem? My bank 2 was at 25% on the short-term FT. But also my "bank 4" STFT was at 35.9%?

 

WOW!!!! That's running super lean! I have no idea what banks three and four is even referring to. The short and long term for each bank is the total fuel trim for each bank. So added together, the computer is adding about 50% extra fuel on each bank.
Do the fuel trims start to drop when you open the throttle? If they do, it's probably a vacuum leak. If they stay the same or climb higher you may have low fuel pressure.

 

If it's low fuel pressure then it could be fuel pump/filter? Im going to go test shortly to watch.

 

There is no filter.

 

I could be wrong, but I think the only fuel filter is in the tank. So either way, if you find that you have low fuel pressure, you'll have to get to the pump.

 

I have a Disco II 2003 V8 Petrol.
2yrs ago put a new engine in it.. It now has 50,000km on it. Reason why - long story
Just 6 weeks ago, had it serviced because it was running like crap, and leaking like a sieve>
Replaced all the seals (oil, water, sump, valley, head, crankshaft front/rear, intake and exhaust.
Replaced a leaking power steering pump along with all its associated hoses
Replaced a few coolant hoses that were looking a bit dodgy. Also fixed a leak found in top of radiator...very small but annoying enough
Replaced the alternator because it exhibited problems
Replaced the coils, the ignition leads, and put new plugs etc etc
It also has a new MAF, and new temp sensor and a new crankshaft sensor (it went bad because it got all sorts of gunk leaked on it).
During all this work - I ended up also replacing the shuttle valve because I got the 3 amigos.
BTW when I put the new engine in I also put in new catalytic converters, new y pipe, and new O2 sensors all around.

OK so fast forward to now
Truck is running very well. However, I am now getting engine check light coming on and it always reads P0147 Bank 2 too lean ...and just in the last 2 days the dang 3-amigos are back....
Really annoys the hell out of me considering all the work done.
Granted I am not 100% sure the new MAF was a bosch one.... and I read in one of the responses above to look inside the air filter box for that bent tab that allows unfiltered air in - will check that today......