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front three plugs fouled, 99 v6

1253 Views 7 Replies 4 Participants Last post by  gaijin666
I recently purchased this 99 solara for my daughter. We have been working out the bugs, as the previous owner did little maintanence (had a title loan on it, so i asume she did NO maintanence).

I am getting the infamous p0171 code (lean bank 1) which from what I read could mean that almost anything is wrong with the car. The car is running smoothly, and doing decent on gas (in the mid 20's) so maybe its not an issue (I live in the lovely state of SC where you can drive anything on the road regardless of its condition, ie no inspections).

When I changed the spark plugs, wires, and coil packs the front three spark plugs were fouled pretty well with carbon. The back three looked great. They were factory type plugs (could have been original, I don't know, but were the correct factory plugs). I changed these because car was running rough sometimes previously and we had misfire codes. Car has run smoothly since. But I do have the p0171 code.

I don't recall if I ever found out which bank of cylinders is bank one and which is bank two. I am curious if the condition of the plugs could be a clue as to the CEL problem, or if rather it is a consequence. Also the PCV valve was fouled up worse than any I've ever seen, so I replaced it too. Just thought someone more knowledgeable than myself might say AHA!
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bank 1 is the hard one to reach.
the long term fuel trims are out of range and the computer can't compensate for the 'too lean' condition with short term fuel trims.

some causes are vacuum leaks (could be a bad hose on that pcv valve you replaced?) in any of the old hoses or intake snorkle. do a cigar smoke test to verify and fix/replace hose(s). (google scotty kilmer cigar smoke test)

could also be dirty maf wires. dont' have one of them there oily k&n filters do ya? clean with cotton swab and alcohol and be careful. (see haynes manual for pics of the part)

could also be not enough fuel but if it's running ok, that probably isn't it. does it ever stumble/hesitate?

put an obd2 monitor on it when you think it's fixed and reset the cel and then graph out your ltft's on bank1 to verify they are near zero.

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Also check timing marks. Bank 1 may have skipped teeth.
john, not disagreeing on the tooth skip, but if that were the case, would it be possible to have "The car () running smoothly, and doing decent on gas"?
just curious?
The ECU thinks Bank 1 is lean (P0171), so it's dumping extra fuel into the three cylinders, fouling things up. So my guess is that the MPG could be better.
roger that. sounds about right. i am envious though. a v6 getting mid 20's...i don't believe for one minute it's my driving habits, but i usually get around 19...haha
Bank 2 = set of 3 cylinders close to mechanic standing in front of car
Bank 1 = ' ' ' ' ' FAR FROM ' ' ' ' ' ' '

So the far, back, hard-to-reach half of the engine is sad, the front is happy --you gotta make the back happy:

90% chance it's a black hose that has come off or has a leak, or maybe your PCV valve.

I'm a TOTAL NOOB but I just faced this ZACT code with a 96 Camry yesterday and the guys here helped me and I fixed it 5 minutes ago, no kidding:

I leaned waaaay over and stared at the hoses behind the silver air intake plenum and SURE ENOUGH there was a single hose just dangling like a sailor on leave and a nearby naked metal spigot (don't know the proper word) begging for a hose, like a single bar girl at closing time.

Jammed that sucker on there, and BAM, no more code!

Seriously, this is a huge coincidence. This is such a weird feeling, pretending to be a mechanic..!!! ^_^

I'm a total fraud..! Yet everything I said is TRUE!

You'll prolly see my photos in 5 minutes.
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Yeah, the bottom black tube inside the red circle attacked to that spigot was not there, initially.

I snapped this photo (looking down behind the air intake plenum, behind Bank 1 of cylinders) after I reconnected 1 of the 2 tubes there.

Ah won't let me attach the photo cuz I already have uploaded 3 photos, just 10 minutes ago (there is a daily limit).

So lean back there with a flashlight and start staring and gently tugging on stuff.

And if you still find nothing then maybe one of those hoses has a bad abrasion or leak.

And if you still fail there, then stare at your PCV valve (on corner of crankcase, prolly) and confirm it is seated flush in there and that the tube to it is secure.

And they say in 90% of cases you will find your problem on one of those three avenues.
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