xgalaz

I am currently having problems with my 2002 Chevy Tahoe with a lean bank 2 code, P0174/P0171. I have cleaned the MAF sensor, changed the fuel filter, regulator and fuel pump/module because the fuel pressure was very low. Now, my fuel pressure is reading the proper 60 psi as required by the maintenance manual. I have checked all the vacuum lines and hoses to include intake gaskets as other forums have suggested-no leaks were noted. The vehicle now starts and runs great; but, every-now-and-then it does not want to start. The check engine light does not come back on but I am still having the intermittent starting problem. What else could this be before I start looking at fuel injectors?

xgalaz

I have resoved my problem with the intermittent starting problem. I figured out that I had a different problem than original. I have changed the spark plugs and the problem has no longer returned. I hope this will help others that might experience any similar problems.

jgaff

I also have a 2002 Tahoe that is posting the p171 and P174 codes and can't determine why either. Everything looks good, can't find any vacuum leaks. I was wondering if the oxygen sensor might be getting a false reading? This lean condition must cause the fuel system to attempt to richen it up, because my fuel economy is suffering also. The only time that I have the problem is when it is cold out and I first start it up. It idles a bit rough, but always starts and runs fine, but then I get the service engine soon light.

Has anyone else ran across this problem and if so, what did you have to do to correct it?
ANY HELP WOULD BE APPRECIATED!!!! Thanks in advance, JGaff

jkgray80

I seem to be posting this alot lately, must be the cooler weather. Many of the 5.3's , mainly the e85 motor, have a problem w/the intake gaskets leaking when COLD. As the engine warms up the gaskets swell & seal, i.e. rough idle on cold start & system too lean codes that come & go.

MDTAHOE

The o2 sensor is most likely NOT you cause. The computer is seeing a lean condition on BOTH sides of the engine so both right and left front sensors would have to be bad. O2 sensor very rarely fail in the way you are describing. I too have seen many failed intake gaskets on these engines. You can have a shop smoke check it but it must have a cold engine. If they test ok then someone needs to look at coolant temp sensor readings. The computer gives the engine more fuel when it is cold but if it does not know it is cold it will not.

azmule

My 2002 Tahloe had all the same problems, Crappy Idle, chugging at the stop lites, ok on the road. I changed sparkplugs, wires, ck and cleaned all 4 O2 sensors, replaced fuel filter, cleaned MAF, No help. THEN:While replaceing intake gaskets, I had the injectors cleaned out, 15.oo Each they were all running fare before clean out. I adjusted the IAC: Idle Air Control Valve. Now running like a clock. I beleive it was the gaskets, but as went by removing and replacing, I cleaned the Thottle body and cleaned every cannon plug I could reach. I know it was not the O2 sensors or the map. Hope this helps.

f-bodyfreak

throttle body gasket make sure the intake isnt full of burnt oil and sludge sitting on the valves clean the throttle body clean the injectors with a cleaning kit not the dump in your tank crap spray the motor with carb cleaner when its running if the idle goes where you spraying theres a leak 90% of the time a lean code is a vacum leak

canderson

Sorry to open this thread back up, but...

I have a 2000 Chevy Tahoe with a 5.3L V8.

Lately I've been having a problem that sounds a lot like these.

I live in Northern Minnesota and the temperature around here has been around that when hell freezes over (-5 to 20 degrees F). In the past couple weeks I've had the "Service Engine Soon" light come on. (Not flashing, but constantly on.) It has troubles starting wether it is a cold start or warm start (by warm start I mean it has been running for at least 45 minutes and has had a chance for the engine to get warm). When I try to start it cold it usually wont start the first time, the second time it will start but it will idle very low, like around 300 - 500 rpm. If it is warm it will start, idle at/around 2000 rpm for a few seconds and then it will die; but it will then start on the second try.

1 of the past 3 times I filled up on gas, the service light shut off on its own. I am curious if this was just a fluke or if it is related?

The OBD-II codes that I've read off the vehicle are the P171 & P174 (simultaneously, not separately).

Curious what you guys think, or know. I've been told it could be the Mass Air Flow Sensor, my fuel filter, O2 sensor, dirty injectors, moisture in the fuel, and a couple other things.

I am cleaning the Mass Air Flow sensor and replacing the fuel filter in the morning, and I have had all the vacuum hoses looked at, and also had the fuel regulator checked. The hoses and the regulator were both fine.

Anyway, let me know what you guys think, because I need to solve this problem soon.

Thanks.

azmule

While I had similar problems with my 2002 Z71 Tahoe, It always started, thats maybe because I replaced the intake manifold gaskets before they went really bad. I would change the intake manifold gasket, its really not that bad if your somewhat of a garage mach. My second fix would be the IAC idle air control valve. The IAC is at the very front of the Throttle body on the right side,get a good chevy manuel. Good Luck. Paul

azmule

That seems normal for the light to go off after running, the IAC motor should have its own fault code, so it may not be that, but not a bad idea to clean or adjust it. What part of northern Minn? I grew up near Theif River.