BigGun

There is no vacuum line to disconnect.

crainholio

What he said. ^^^

Just connect it, turn the key to RUN and let it prime for 2 seconds, check to be sure fuel isn't leaking at the connection, then start it up and get a pressure reading at idle.

mistermog

I bought a filter/regulator because like we said above, its due... I'll post up what the deal is after tahts swapped out tomorrow.

Lord Vetter

P0171 and P0174 are for lean fuel trim on both banks. Had the same issue with my car but at only 80K miles. But I have long tube headers on mine and LT's are murder on O2's. Changed out both front O2's and problem was solved. Me thinks you may have the same bad O2's. Good luck on the fix.

SMaster

Make sure it has the pin to depress the shrader valve.

Have you just recently put gas in it. Wife put e85 in her's and after all the normal checks she told me she bought gas at some weird place out of town. The light came on before she made it home.

Drained it, filled up with 93 Shell and it's been fine since.

I could reset the codes and the would come back right away. I hooked up HP Tuners and found the problem pretty quick.

HTH

Steve

mistermog

Yep, I've been through 2 tanks of gas since they started popping up. I am getting a rough idle after a coast down and it almost stalls and then a second later it comes back up to 700 rpm.

I have the part sitting in my garage and about to go out there right now and give it a shot. Cross all your fingers Report back in about an hour I'm guessing. (I'd say 20 minutes but i just mowed the lawn and its 93 degrees out so I'm movin slow hehe)

mistermog

Ha, you guys are gonna love this.

I get the fuel reg/filter deal swapped out no problem, crank it up... still idling rough and getting lean codes. Crap...

So, I go to put the fuel rail covers back on and when I was putting the right side on I slip and nudge the PCV valve. I must have knocked the clump of dirt loose because now I notice the GIGANTIC tear in the little rubber elbow that goes from the PCV to the engine.

someone make me feel better for spending 100 bucks on that stupid fuel filter hahahah

Off to auto zone to get a new PCV.. cursing along the way.

crainholio

With your car's mileage it was going to need a new filter/reg anyway, so not wasted $ and effort doing it now.

Un-metered air source is on the list of causes for lean error codes so its possible you found the cause. Check the rest of the under-hood rubber on the PCV tract while you're in there, especially the hoses that connect to the Throttle Body.

WillItFloat

I should start out to say that my car is a 1999 M6 convertible with 181,000 miles on it.

I just had the same problem as mrmog. About 5 minutes into a trip to Florida my check engine light came on. I chose to ignore it. It went off about two hours into the trip. After our first overnight stop it came on again under similar circumstances, about 5 minutes after a cold start. This time I checked the codes and found the P0171 and P0174 codes. Searching the forum indicated a vacuum leak was the simplest possible problem.

Once in Florida a friend and I tried to figure out where there were vacuum hoses and started to check them. He felt the rubber elbow from the PCV valve to the intake manifold and detected a big hole in the bottom.

Here's a picture of the elbow in place viewed from below:

Here's a picture of it off:

It looks like the heat got to it somehow.

We took it off, cleaned it up and wrapped electrical tape around it. We replaced it and went for drive. There was no recurrence of the problem but the car kept stalling when I took my foot off the gas. I told my friend that I hoped it was the computer relearning how to deal with getting the correct about of air and ultimately that seemed to be the case: After several restarts it once again idled properly.

The next day we went to Advanced Auto Parts (the closest parts store). Needless to say they did not have the part. However, the clerk took us in the back and pulled out a box of short pieces of hose and said, “Anything in the box is free.” I found a 3” piece of 3/8” hose and thanked the man. I installed it and everything is now OK.