I have a 2002 Tahoe 5.3 z code. Recently my service engine soon light came on I had my mechanic check the code and he said it was showing a lean condition on bank 2. The engine was dropping a cylinder and He said a tune up should do the trick. I have had new plugs, plug wires, fuel filter, air filter, oil change and the truck ran like a new one. The service engine light was out for about 200 miles and is back on now. I can smell like rotten eggs when the service engine light is on and for now I have not noticed a miss at idle as I did previously. The truck has almost 80,000 miles on it. Anyone help me please?
A tune up will not cure the lean code, in fact an engine miss gives a rich code from the unburned fuel. I would suggest u verify u have no vacuum leaks, also clean the inside of the MAF sensor if so equipped and replaced the bank two O2 sensor, that is the passenger side sensor before the catalytic converter. If u have the money replace both right and left sensors, it is better to do them in pairs.
Posted on Jan 15, 2009
How about the fuel injector.
I would go with the injector, this is not a fuel pump problem, if the pressure where low the engine would run smooth but have no power. I am giving u useful correct info, i do this Fixya in my free time free of charge, could u please change my rating to helpful if you agree that I am being Helpful.
when u unplug sensors the system goes into FAILURE MODE STRATEGY so in most cases u will not see any real change in the way it runs after the stratgey kicks in,
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Check the fuel pressure regulator for gas leeking anlso these engines have lots of problems with intake gaskets leaking
Posted on Jan 15, 2009
Well at this point i would probly take it to a mechanic they can check the compression of that c lynder and also check the fuel injector
Well i was doing some research on a program we have at work there is a bullitin out about the ECM ground wire getting corroded and causing problems it say the wire is either at the right front or rear of the right head i think it should be a braded wire /ground cable look at this if in dought remove it and clean it up with some sand paper and put some dielectric greese on it when done ill see what elese i can find
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UPDATE. The truck has started missing again. I can unplug the rear passenger side coil and it makes no difference in the miss at idle. I checked the plug for spark and the coil and both have a very strong spark. The service engine soon light is still on and blinks occassionally. Here is what I have done so far, plugs, plug wires, fuel pressure regulator which was nearly impossible to get locally, fuel filter, O2 sensors, oil change, cleaned the MAF, checked for vacum leaks, sprayed the intake base to check for leaks, cleared the codes. I am baffled. Anyone please help.
It idles rough most of the time but will occassionally smooth out. Is this typical of an injector? I have also been told possible fuel pump.
I am seeing alot about the MAF. It makes more sense that it would be the injector though as it until now was singled out to one particular cylinder. I was just out side and tried unplugging the said cylinder coil and the rough idle did not change. I then plugged it back in and went to another cylinder on the same side of the engine and unplugged that coil and the idle seemed to stay the same. Is it possible that the first coil I unplugged picked back up when I unplugged the next cylinder? If that is the case could that indicate the MAF? One more thing to add, It has recently been negative 25F here. When the truck sets overnite and I start it in the morning it fires right up, but does idle rough. I let it idle yesterday morning for about 35 minutes and when I got in it was idling smooth and after driving about 1 mile it started to idle rough. I have also noticed that after driving for a while and engine is at normal op temp it is hard starting.
Last Update. I have cleaned the MAF and no change. I unplugged the MAF and the engine sputtered once and then went back to running just like it did before I unplugged it. I then decided to see just how much I could unplug with out it changing anything. I unplugged the MAF and the new fuel pressure regulator that I just installed 2 days ago and also the 2 rear coils on the passenger side and still no change. What the heck? ECM maybe? I am scared to take it to the shop, but I do have an appointment on Thursday. Why am I affraid? I have read so many posts on similar problems and people have $1,000.00 to $2,000.00 wrapped up in garage fees and still no cure. Any other suggestions would be much appreciated. If it comes down to changing component after component I can do that cheaper myself than I can have it done at the shop. Thank you for all suggestions so far. Although we haven't cured the probelm I beleive we have to be getting closer and it is that much less that I have to fork out to the shop. Thanks again.
Thank you emmisionwiz. Any comment on the ECM? Last night I made a 7 mile trip on the interstate and when I exited the truck ran perfect at the stop sign and again at the stop light about 1/4 mile up the road and again in the parking lot at Lowes, perfect idle just like new. When I came out and started it, it started hard and idled like **** again. I tried to emulate the drive back home at 55 to 60 and it still ran like **** at idle. I'm confused and frustrated, but I am not willing to give up on her. Anything else you can think of that I might try. I have 2 more days off of work so I have time on my hands. Thanks again for all your help.
I have been experienceing the same exact problem! Have you noticed your EVAP PURGE Cylnder is on whenever the truck is running "Bad"
rotten egg smell sounds like a plugged catalytic converter.a exhaust shop can do a test that checks flow before & after cat. do you drive alot of short trips? a friend with same truck with rough idle, took to shop got a big bill problem went away & came back 500 miles later. i looked at it & found loose battery cables. tightened them up, my friends been driving over ayear with no rough idle. just for *@#! & giggles check battery cables & connectipons. good luck
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