Hello,

I am new to forum, just purchased a 2004 STR about two weeks ago. I have had the P0171 code pop up a few times now. Ive done a good amount of research, however there arent a whole lot of threads that deal with this code without a P0174.

I have checked for intake leaks already and i cant seem to find anything. Im thinking its an 02 sensor for the shear fact that the CEL only comes on right after start up. Once i clear it (i know, i know), it doesnt come back for awhile. My thinking is if it was a intake leak or a MAF sensor i would be getting both codes, and it would come on during a drive and not coming on intermittently during startup.

Im just not sure which O2 sensor to order?

Any input would be appreciated.
Thanks in advance,
Adam

 

Coil or coils on the associated bank. Misfires have been known to set the lean code without tripping the misfire codes.

 

Not sure it is an O2 sensor. I would add a can of BG44K to the fuel and see what takes place first.

 

Ill give this a shot, and let you know. Ive personally have never heard of BG44K. Is it available at a normal auto part store? Would any fuel injector cleaner work?

 

BG44K is available at most dealerships and most repair shops you will not find it at parts stores. I am suggesting this because you are only getting a code for one side and that code could be flagged by a clogged injector and BG44K will take care of that. You can try other stuff but nothing works as well as this does.

 

Ive been needing an excuse to go purchase a good multimeter. If the injector cleaner doesnt do anything, ill pull off the coils and see if i can detect a faulty one. I want to do spark plugs anyway

 

Ill track some down and give it a try.

Thanks!

 

A simple o2 senser test is to swap the upstream o2's from one exhaust to the other and see if the problem follows , also check that the exhaust bolt are tight and no leaks at the flange , as that will also give a lean code .

 

Try watching the fuel trims to see what they do and when plus the code has freeze frame data to show when it flagged with what other sensor etc data.

 

So if it was an O2 sensor, it would be the upstream?

 

I would assume this is something I would have to take to jaguar to do, I have a simple code reader, but it doesnt go into that much detail.

 

Yes. Although down streem plays a small part in ajusting fuel trims.
There job is primeraly to monitor cat condition . The bulk of the engine management it where o2,s are conserned are the job of up streem. If you want to be sure just swap all four across . Thay are very easy to get to ,
As. Jag v8 said above you should monitor your fuel trims , and o2 data .
I would still swap the o2 sensers after noting your values , then note them again , and if the bad values follow the o2 swap your a winner . Without having to wait for a code and risk killing a cat converer , in witch may already be the case !

 

Originally I didn't think it was related, however I have been reading all over the forum lately. I also have a weird vibration/humming at high speeds +60mph. Its hard to explain, its not a wheel bearing, and there's no sign of it unless i am on the highway. But the humming is not constant, but almost oscillates repeatedly. On my way home from work tonight ill get it up to speed and release the gas to see if it continues, but maybe it is a clogged injector or bad coil/plug. The car has 111,000 miles on it, and unfortunately i do not know any of the history. I got it for a good deal, off a shady dealer, but the car definitely has its problems. After looking around on here if its a common problem, this car has it. IE. AC problems, drooping headlights, headliner falling in the rear, center console light intermittent. Nothing crazy just the little quirks, nothing i cant fix. I just need to get the engine sorted first.

 

Don't take it to jaguar !
Get an ELM 327 obd2 reader . Wifi if your apple , Bluetooth if your not !
They are about $20

 

Just purchased one off Amazon.

Thanks!

 

Try not to drive it too much or at all till this is sorted , as your risking damage . Also wile your waiting for your scanner ,
order your self a set of spark plugs for it thay are due , and could be contributing to this isolated issue ,
Another thing to look for is any oil residue from the supercharger to charge cooler rubber connectors , and also try to look under the charge coolers at the manifolds with a torch at the gaskits , as any blow by oil coming from these connections under boost conditions
Means air will leak in under vacume conditions .

 

It could be drive shaft , quarter shaft , tire deformation .
Or a brake dragging .
Is the sound front / rear / left / right or midship ? You kind of need to pin point it .

 

Ive been driving the car as sparingly as possible. Just to and from work, which is all highway, the CEL hasnt come back in the past two days.

The vibration is really hard to pinpoint. I dont think its coming from either tire/brake/wheel bearing. Seems to coming more from the front middle, (Engine/tranny) but its hard to tell. I have never really felt anything like it. But like i said before it almost oscillates. starts very faint, gets harder, then faint again. followed by nothing, then repeats. But think of that all within a 1-2 second time frame. its hard to explain over text lol.

 

I wonder if your engine mounts are broken , it quite common .
Open bonnet/hood and watch the top of the engine Wilst you select drive ,
Aplying the brake firmly , and applying throttle pressure , also do the same in reverse , if the engine rises up a few inches , then replace them , they are jell filled so will have a blue liquid leaking from a broken one , as a dead give away .
Mine were both broken when I purchest my STR and it vibrated a lot , through the floor around the trans area , and more so under full throttle .

 

The same code came back again today on my way home. If it makes a difference, this was the first time it has actually come on whilst driving and not just at startup, and it was also the first time it didn't throw the car into performance restriction.

As for the vibration, I brought it up to 70mph, laid off the gas and put the car in neutral, and the noise was there the whole time, and didn't seem to change whatsoever.

My next day off is monday, in which I will jack up the car and see if I can see anything, as well as change the plugs (which I was planning on doing anyway) as well as try to get my hands on some BG44K. Then the scan tool should arrive tuesday.