Hey, I need some word of wisdom from you guys.
I have been fighting with this problem for about two months right now and still can't figure it out.
My check engine light comes on and off on the daily basis, I have scanned for the codes and always get P0171 code.
I have changed all O2 sensors (dealer recommendation) and also changed my sparkplugs from Autolite to NGK. It did not fix the problem. Then I have changed sparkplugs again this time for Champions and still have the same issue. I'm stuck! <img src="/forums/images/graemlins/baby.gif" alt="" />
Please help.

Thanks,

Arek

That code is system too lean (bank 1) I am kinda surprised that is the only code your getting.
It is saying that Bank 1 driverside is running lean.
Alot of times this comes from a bad intake manifold gasket.
Usually you'll get another code a P0175 which is system too rich (bank 2) caused by the system adding fuel trying to overcome the lean condition on one side,caused by the bad IMG.
Does it start good?
Does it idle good?
Does it want to die when you stop?

Oh and how about some info on the truck it's a ????

The above data/ideas refer to the 3.2/3.5 v-6 mostly.

Bansil

It is 2000 Trooper with 90k miles on it.

It starts good, and idles great. From time to time when I hit the gas it stumbles and it backfires for a second, but it is very sporadic and then it runs great. It only happens in the morning. I had an issue with it dying at the startup, but changing O2 sensors fixed the problem. I have also checked manifold gasket spraying carb cleaner around and see no problems. My old trusty vacuum gauge tells me that everything is ok, no leaks.
In addition I had a new block installed under Isuzu warranty about 12K miles ago and all the gaskets were new.
I should also add that once I also got P0109 and P0101, but once erased they never came back - that was about 5K-6K miles ago.

I can tell you from experience that you could still have an intake manifold leak even if the carb cleaner spray didnt produce results. I went round and round with the same code in my Rodeo. I finally took it to the dealer and all they did was tighten the manifold back to spec torques, before attempting to replace the gasket, and all is now fine. This was all before I knew about the common problem of the intake manifold leak. Let us know if any of this helps.

Hey Mr. Mojo, do you know by any chance what are the specs. I have had my truck at the dealer for five days and was told that O2 sensors are my problem. I have mentioned IMG, but they told me they have checked everything and all is ok. I have even talked with Isuzu factory rep for few good minutes abut EGR, manifold gasket, ect. Like I said, I have replaced the sensors, much bette, but still P0171 comes up.

Well if you have replaced all the O2 sensors, I dont understand how they can tell you its still the O2 sensors. When I get back from Thanksgiving I'll take a look at the manual for those torque specs. <img src="/forums/images/graemlins/cheers.gif" alt="" />

Arek, you should try gently cleaning the MAF sensor wires with a q-tip and alcohol, or spray them with carb cleaner.

Mark

It works. I have cleaned MAF sensor with electrical contact cleaner even though it looked very, very clean, and it has been three days without a code.
Thanks again. <img src="/forums/images/graemlins/smile.gif" alt="" />

I, for one, am very pleased with the search function on this board. This was the first thread I came across. I wish more people understod how it works before b!tch!n <img src="/forums/images/graemlins/baby.gif" alt="" />....

Anyway, my CEL has come on again; first time since my EGR cleaning about a year ago. This time I am getting P0171, P0172, P0174, and P0175 [system too lean (Bank 1), system too rich (Bank 1), system too lean (Bank 2), and system too rich (Bank 2), respectively]. I suppose this is indicating the over-compensation of the PCM as was stated previously.

It all started this past Friday, after filling up the first time subsequent to running a tank of Techron through the fuel system. It does have a slightly rough idle, and occasional hesitation upon acceleration. She cold-starts just fine. This morning the CEL turned completely *off* [yea] on my way to work only to reappear in a *FLASHING* mode [boo] as I was running errands during my lunch break. The flashing would only appear when under throttle, then the CEL would go dark as I coasted. It is currently back on in steady state.

I think my problem is one of the two as stated above... either the IMG, or the MAF. I was hoping that someone could clarify some of the above solutions. When cleaning the MAF, does it require disassembly, should I remove the screens, swab it or just spray it??? And as for the manifold bolts, what torque are they spec'ed at? Hopefully it won't need a new gasket just yet, inspection and emissions are due this month!!! <img src="/forums/images/graemlins/scared.gif" alt="" /> Besides, wouldn't a bad gasket just give the code on one bank to start? I'm kinda leaning towards the MAF, too, since I have an open element cone filter. <img src="/forums/images/graemlins/ignore.gif" alt="" />

TIA,
Eric

As for the MAF, you do not have to disassembly it, just remove it from the vehicle and spry carb or contact cleaner. Be very careful, as the wires are very thin and altogether this is a very delicate part. I do not recommend using a straw that comes with the cam, and make sure you hold it about 6" away.

Now, on the different note, flashing light is no-no - you should not drive with the flashing light - most of the time it means misfire. Check your plugs.

Can't help you with the IMG torque, as this was my original question and as you can see it has not been answered yet.

Good luck to you.