Rock-a-Lex

iTrader: (4)

A long read but please read and let me know what you think.

Let me give you the "run down." For the last 3 YEARS I have been combatting a PO171 (bank 1 too lean code). Numerous times I have reset the ECU via pulling the negative battery terminal and it goes away and usually comes back. For the last 1.5 years or so it never came back. The car always seemed to run fine but always seemed to EAT gas; big time.

About 1 year ago I was messing with a CAI (extension of piping into the wheel well) and got that same damn CEL with the same code. I was pissed so I took it off and figured maybe it had something to do with my A/F #'s....let me get an A/F controller to adjust. So I bought the Apexi Neo about 9 months ago reset the main ECU, installed it and dyno tuned it...perfect! No CEL and the car has more power now, but this was without the CAI extension; so I left it off ever since.

Fast forward to this past Saturday...I bring my car to the Lexus dealer for an oil change and realize, crap, my NYS inspection has expired last month; so I told them to do the inspection. No problem. Half hour later the guy comes back to me and says it FAILED! I was confused as my car NEVER failed before and he said that there was a CEL (again, code PO171) up on my dash; when it wasn't there when I initially brought it in. I said find out what is causing this. This dealership labor rate is $120/hr mind you so I am real pissed but figured, hey it's Lexus I'm sure they will find out what's wrong with the car in under 2 hours...WRONG! After 3 hours I call the service rep. and ask if there is any progress...nothing he tells me and they are getting frusturated and my bill is RACKING up; I am not very happy at this point. I tell him to have the tech disconnect my Apexi Neo (eventhough that isn't what is causing my problem) so the car will basically be stock and told him to work on it for another hour. Low and behold they STILL couldn't find anything wrong with my car! Everything checked out good...O2 sensors, MAF sensor, cats etc ect. But they said that my short and long-term fuel trim is through the roof! They said stock for the GS400 is supposed to be Between -8 and +8. I was at +25; VERY rich (why I was eating so much fuel) yet I was getting a lean code!!!???

Then they started to inspect the engine and cleaned out the TB and took the spark plugs out. They noticed that they weren't the OEM spark plugs...I had installed these Torque Master plugs myself about 3 YEARS ago (hint hint from the beginning of this story). They also found out that two of them wound up being real loose! I thought to myself I even used my friend's frickin' torque wrench SPECIFICALLY to make sure they were at factory spec.

I got the car back and they still didn't fix the problem and I was looking at a $500+ bill. Ready to start raising all hell to upper managment they did the right thing 100%! They WAIVED ALL LABOR CHARGES!!! They just charged me for the oil change and the inspection (which I failed). I thanked them but still had a car with a failed inspection and now the CEL is on as well as the VSC and VSC off and the car was running like a bag of $h1t on the way home. I was hoping and betting that after they tightened and re-installed the spark plugs that they never re-set the ECU. I reset the ECU for 1 hour at my house and started her up...not one CEL ever came on still to now under all different types of loads and it feels MUCH more responsive and I didn't even have my NEO hooked up yet! So, now I am going to leave the Neo disconnected and get another damn inspection at a regular local shop because all seems well now. If it passes that would be great and I will re-connect my NEO and maybe mess around with that CAI extension again.

I still can't believe it. What can happen to a car with loose spark plugs? Loss of compression? Loss of power? Loss of gas mileage? All this was probably happening to me for the last 3 years without me knowing the TRUE cause of the problem. and here I was about a week ago ready to replace ALL my O2 sensors because I "felt" that they were the problem which obviously they weren't. Has anyone ever had any issues with Torque Master plugs? I am ready for new ones and am undecided to go back with Torque Masters or the standard Densos.

Thanks for reading guys...any and all comments are HELPFUL!

JeffTsai

iTrader: (1)

Sometimes a torque wrench is not always accurate. I usually dial mine 5ft lb higher than spec. Spec is 17ft/lb I think, and I set mine at about 22-25lb when I do the plugs. Part of the reason could be that if you used anti-seize, it acts as a thread lubricant. So the real torque setting might get thrown off due to that. I haven't had any problems thus far setting plugs to 25lb. I used to do it to 17lb spec and the plugs would come loose when it came time to change them.

BTW: I run specialized plugs(high boost application) on my car that need to be changed every 6-8k miles, but good thing they only cost $1.50 each

Rock-a-Lex

iTrader: (4)

Hey Jeff, why is it that I was getting a "lean code" yet the car was running VERY rich? Any suggestions or theories? Could I have done permanent damage to my engine driving around with these loose plugs?

jcat_350

well it could be that while the plugs were loose and you installed the neo that you got an inaccurate tuning curve once you fixed the problem. Obviously like you said after tightening the plugs it will change how your car burns gas, so you need to adjust the a/f curve accordingly.

as far as getting the lean code when you were running rich, i can only think that maybe by the plugs not completely detonating the fuel, the computer may have thought there wasn't enough fuel going in to cause a good explosion? haha i gotta admit that one even throws me for a loop.

though i had the same problem on my old benz (ml430), bank 1 was running too lean and the engine itself was running rich, maybe to compensate for the lean cylinder?

JeffTsai

iTrader: (1)

The OBD2 is kinda flipped. When it says bank too lean. It actaully means that the computer has maxed out the fuel trim and can not feed any more fuel to satisfy the stoich condition. So it's basically saying I added all the fuel I can, but the engine is not burning fuel how I want it to. So even though the car is running pig rich, the computer is trying to auto tune to a preset variable and cannot reach it so it throws a lean code. Any number of things can cause this. Bad O2 sensor, dirty/bad MAF, exhaust leak before first bank O2 sensors, obviously your loose spark plugs, and a few others. Hope my explanation helps.

evil00017

I had problems with my trq master plugs. Nothing like yours but here is what happened to me.
I picked up torque masters installed them went for a drive and after about 5 mins of some spirited driving I got a cel. Took it home ran the code was getting a misfire code on a think 8 cylinder. I remember that cylinder it was a pain in the *** to get the coil pack off so i looked at it looked fine and swapped it out with another one to see if the problem would change to a different cylinder. It did so im thinking ok so I messed up this coilpack ill get a new one. Got a new one threw it in. Started driving felt much better but not perfect. After about 5 mins got a cel. Took it back ran it got a code for misfire on multiple cylinders. All this was taking place at my parents house last xmas vacation and I was leaving the next day. I threw the old plugs back in. No more misfire car ran great.

I have decided that its just not worth the hastle. im gonna go with some densos when I change my plugs.

Rock-a-Lex

iTrader: (4)

Yeah, I'm beginning to think these TM are becoming an issue but I like the proven 5-6whp gains it yields. I might switch back to the Denso's myself though...and they're cheaper!

pwesseler

Does everyone tighten the spark plugs with a torque wrench? That sounds like overkill.

Rock-a-Lex

iTrader: (4)

******UPDATE*******

I just passed the inspection; no CEL! I just reconnected my Apexi Neo and the car runs GREAT! It must have been those pesky loose spark plugs! lol.

jcat_350

not if you're torquing them to factory spec as you should with any type of torqued fastener on your car.

marus

iTrader: (1)

so what can happen if you dont use a torque wrench and just tighten it up as tight as God given strength allows you?

Agent0024

iTrader: (4)

Well, you can definitely strip out the spark plug's threads in the cylinder head. Hello helicoil!

Rock-a-Lex

iTrader: (4)

IIRC rule of thumb is as soon as the spark plug hits the base (tightend by hand) it is another 1.5 turns with the ratchet if you don't have a torque wrench. BTW, I have Torque Master spark plugs so I don't know if the same amount of torque is required for these plugs as compared to the OEM NGK's.

TLcoats

iTrader: (11)

I just installed my plugs on friday and just tightened them moderately without a torque wrench. Is this something i should be worried about and go back and retorque them?

Rock-a-Lex

iTrader: (4)

^ It wouldn't hurt to re-check them again soon. If they are still snug then they most likely will be fine from then on out. Usually, just like lugs on your wheels if they get a little loose it would be within the first week of driving. I always re-check my lugs a couple days after I remove/re-install my wheels. If they are ok then I never re-check them...same goes for the spark plugs; at least in my situation. Oh, and I am sure that they were fully tightened the first time around. Not sure why or how they came a little loose...only 2 out of the 8 spark plugs got loose at that time.