Is this the first time you have driven it after storing for winter? (Condensation).

Also check your plugs... water collection inside the plug tubes will cause a misfire.

 

It is my daily driver. I am located in California so I have never stored it or not driven it for more than 2-3 days. It is garaged nightly as well.

 

You mean P0171, right?

Do you have an OBD-II scanner with real time data display? Check your fuel trims (STFT, LTFT) to see if they're near the limit of +17%...

 

I have an OBD-II scanner not sure if it has real time display though

 

If it doesn't see if you can borrow one that can. Two important parameters are the Long Term Fuel Trim, and the Short Term Fuel Trim... basically it's telling you how much above or below the baseline tune the ECU is setting the fuel mixture. If the fuel trim goes above 17% (it's adding fuel, since it senses a lean condition), it usually indicates that the ECU is having trouble getting the mixture right...

What does you AFR gauge say, BTW?

CharlieX would probably have a lot more to say on this issue...

 

"larini clubsport 8 inch exhaust"

that'd be my first guess.

 

Id say cup car air box is the issue. I put it on a few months ago and I'm getting the same code...

 

I was worried you'd say that . My af gauge flucatates a little at idle it bounces around 14.5-14.7

 

for idle thats fairly normal, its trying its best to maintain 14.6

 

its possible, but just do a search on larini p0171 (or lean), and i'm talking about results we've seen on the dyno too.

 

I'd say cup box also.

There are ODB readers that will tell you fuel trims?? I bought one but it was cheap, $70. Don't think it does it. Maybe I can exchange...

 

To see fuel trims you have to get a reader that displays real time OBD-II parameters... they're a little more expensive than the ones that just read and reset DTCs (CELs). There are quite a few standard fuel/emissions related parameters (since emissions was really the point of the OBD-II standard... you can thank CARB for that)

 

i'd be shocked if it didn't, not at $70. look for short term and long term fuel trims,or STFT LTFT

 

Thread revival. I've gotten this CEL twice so far. just over a month and 1000 miles between the two incidents. I do not have an aftermarket intake. and no recent mods to the car.

My Reader shows a snapshot of what was going off when the CEL was set.

so here's that
Load PCT 33.7%
ETC (F) 172
Shrt FT 5.5
Long FT 8.6
Rpm 1650
VSS 2mph
MAF 1.041
TP 14.9%

Any ideas?

 

Check for exhaust leak

 

I had that same code and cup airbox. Went back to stock Airbox and have not had it come back. I do have the clubsport exhaust.

 

ok, I'll check for exhaust leaks, anything else I can look for/ test while I'm under the Car?


Again stock intake. and no mods in the past year except STS. This code has popped up twice in the year I've owned it. almost 1000 miles separate the two incidents.

 

Probably an exhaust leak. If you're running the stock engine mounts, check your manifold studs/bolts and make sure they're tight. In my experience it's quite common for the manifold to work loose due to the stock mounts allowing the engine to move around A LOT.

 

Interesting. will do.

Thanks guys.

 

Thread revival once more....

I have a 2007 s220. I am having this code very frequently. 4 times in a row, and counting. Outside of the first code, it seems to happen right after I fill up. I have made sure I am always closing the gas cap properly: 5+ clicks

I have a K&N high flow filter and we have tried cleaning the MAF. I have had the K&N since March 25th, 2010. I have driven to San Diego, CA with this filter, and had no problems. I had the Larini 'S' Clubsport Muffler, oval tip from Sector 111 installed on April 14th, 2010. The next day I had a check engine light.

Lotus has THOROUGHLY gone through the car and searched for any leaks all the way up to the header. In addition, we have tried giving it a "calm cruise period" to learn the changes made to the car. The entire fuel curve did adjust 3%, yet it still is throwing the code. Also, the rear O2 sensor wasn't reading right at first; Lotus switch the rear and front O2 sensors and now they are both reading properly and swinging as they should be.

After working with Lotus to read my OBDII information, it seems like it throws the code at take off. At idle, and any % of throttle after the car is moving, STFT and LTFT seem to read at decent numbers, ranging between -4% and +5%. But at take off the STFT seems to jump as high as 23%.

I'm pushing a bit of money to get this figured out. Any help or thoughts is greatly appreciated.

 

Since the clubsport breaths better it is already pushing things so the addition of the K&N just adds enough I bet to trigger the code. Drop the stock air filter back in, clear the code and see if that does it.

I had a clubsport and added the cup airbox and shortly after the same code came on. The dealer did tons of test and put the stock one back on and zero issues since.

 

At my work(toyota dealership) if we get a p0171 the first thing we do is check the maf sensor. When the maf sensor gets dirty it will throw this code, at least on toyotas it will. You'll notice that the sides of the wires in the maf sensor that are exposed to the direct airflow will get black with dirt, clean it with brake clean and erase the dtc. Also i dont own a lotus so if they dont have maf sensors then o well

 

Thank you all for the advice and input. I am unfortunately still getting the codes. Here is what's been done since my last post:

1) A new OEM air filter was installed, and the K&N high flow has been taken out
2) The car has been driven for extended periods to help it "learn"
3) The spark plugs have been checked to see if it truly is a fuel pressure problem. Because the plugs looked good, we didn't bother to check the actual injectors.
4) All vacuum lines, supercharger piping, clamps, and hoses have been checked to ensure they are all secured properly
5) The MAF sensor has been thoroughly cleaned to ensure that the MAF doesn't have any dirt that could effect it.
6) A new gas cap was purchased and installed to ensure that the cap does not have a small leak.
7) The exhaust was taken off and reinstalled to ensure that everything was securely and properly installed
8) The code has been reset numerous times (both the pending and active code).
9) The car was switched to Chevron (91 octane), instead of Shell (91 octane).

All of this has been done by the dealer so as to reduce user-error. Both the mechanic and myself are at a loss. I called Sector 111 and talked to them; they are relatively confident that the exhaust is not the problem.

Anyone have any suggestions? The only things I can think that's left is a smoke test for a leak somewhere, a fuel pressure test, a OEM stock reflash to the ECU, or plain and simple, the ECU isn't too fond of the exhaust, and causing any it to throw a code.

This problem is approaching 4 weeks of trying to deal with this code. Any help is GREATLY appreciated.

Thanks again.

 

As an addenum, I just had the ECU reflash to the OEM software on Friday (yesterday). Unfortunately, it made no difference. It came back on today after several hours of driving both yesterday and today; 30 miles after refilling the fuel tank to be exact.

It's really starting to sound like its the exhaust, no? Again any help is greatly appreciated.

 

Read My Signature

Larini SE exhaust caused this problem on my Elise. Sector 111 assured me it would not be the exhaust when I emailed Shinoo. Charliex said it would be the exhaust and it was. I went 4K miles with the stock exhaust and no codes. I really hated to give up that exhaust with the above diffuser look and that great sound, but oh well. Once it started with the Larini I would get the code every 20~40 miles or so. It didn't show up for ~2.5~3K wiles with the Larini on. I now have a BHL Raptor exhaust and have not had any problems so far in ~500 miles. Sounds close but doesn't look as good.

Dave

 

Ya, I'm really thinking mine is the same, except the CEL isn't consistently coming on at 30-40. Sometimes its 50, sometimes its 150, sometimes its 2+ tanks (225 per tank on average).

I will be putting the stock exhaust back on, and usually, when I drive, I drive enough to get it to come back within a day or two. If it doesn't come back on, I intend to send the exhaust back and receive a refund.

I am really hoping it comes back on though; I really love this exhaust. Sounds beautiful, all the way through the power band.

 

Well, I really need some help.

We put the stock exhaust back on, and the CEL still came on. The car is 100% stock now, the ECU completely reflashed and learned; I (and the dealer) are completely out of ideas, and I don't wanna keep throwing money at trying to chase it down, but I want it fixed.

Anyone have any other ideas?

Please, any help is greatly appreciated!

 

I had the same issue here is what happened

05 Elise VF2 SC, larini decat and Stage 2 exhaust........so I did the smoking, a zillion cans of starting fluid still could not find the leak.....in the end it turned out that the throttle body gasket was leaking.........but before you replace it, also make sure that your oil dipstick is seated properly and pcv hose is tight on valve cover and crank........