Ok guys for the past couple weeks I've been having some problems with my a/f ratio, especially while cruising.

I have the descendant turn key kit which is tuned with the aem f/ic. After getting tuned the car ran great for months with a idle and cruising a/f right at 14.7 and riching out to low 11's under boost.

Now for the past couple weeks the car has been idling a bit funny, sometimes rich and sometimes lean. Though usually after being warmed up for a bit the idle will then balance out to around 14.7, but still not spot on.

Under boost the a/f ratios are still in the low 11's so now problems there.

Though just cruising the ratio is rich all the time, right around low 12s/high 11s.


Where would you guys start troubleshooting first to fix this? And is driving around with that rich of a cruising a/f ratio bad on the car? I just made a 500mile trip and it seemed fine....prly should have asked this before the trip though.

 

check your fuel trims.. did throw a rich/lean code? it could be few things like, change in weather, leaks on the pipes, faulty wideband/ o2 sensor. Rich under cruise and idle will result to bad fuel economy and foul your spark plugs

 

Ace is right. My first suspect would be the front wideband o2 sensor. I had the same problem but it kept getting worse and worse until it was well below 10 AFR at cruising and it would buck wildly but boost was still still smooth and pulled hard.

 

I had a similar problem and it was caused by a fouled/bad AFR sensor.

Running that rich could foul your plugs and eventually destroy any cats in your exhaust system.

 

Thanks for the responses guys.



The only codes I'm currently throwing are P0037 and P0031 . This is because I have the factory secondary 02 Sensor unplugged. (I had to lengthen the wires on it for my anti-fouler and they grounded out, causing a fuse to pop under the hood that was related to the fuel system.) So I just unplugged it. Though I believe this sensor is there to only monitor the CAT so it should have nothing to do with a/f ratio.

As far as weather it has been getting colder here in IL, though I figured that would cause a lean issue due to the denser air.

I don't believe the wideband is bad, the car is bucking a bit in first/second gear, especially when the motor is still cold. So the readings seem to be correct in correspondence with how the car is acting.

Leaks in the pipes may be a possibility though the car still reaches boost just as quick as it always has, I would think it would take a little longer due to the leak.

I'm thinking my Primary 02 Sensor right after the manifold may be the problem....which I think is what OuterHeaven is refering to.



Maybe I should start with replacing that 02 sensor and see what happens.

 

Get in touch wit Mike(elevationtc) he will be able to help you.

 

It seems like weather could play a major role in what is going on since the FIC can't adapt tunes to large changes in temperature or elevation.

How much is a new primary O2 sensor? I think last time I checked at an Advance Auto it was about $180.

Anyways I'm interested to see how things pan out. Good luck Cavalier!

 

Actually Ace, Outerheaven and myself were all referring to the oe Toyota/Denso AFR sensor aka primary wideband O2 sensor.

You can get a new Denso AFR sensor from Rock Auto for $127.

 

Just to make sure, it's the "Front" Denso Part#2349044? I'm thinking I need to change my Primary O2 too. Finally getting my blow through set up fabbed so I don't have any more richness decelerating or when blowing off.

 

Found it cheaper here - $106 free shipping http://www.oxygensensors.com/catalog.php?&pkey=1433579
But I do love rockauto.com I get all my OEM parts there and their shipping is so fast.

 

That's the right part #. My XB takes a different # sensor but I paid about the same for it. The $106 sensor is from Walker if that matters to you. I'd pay $20 more for the Denso but I have no factual basis for my preference.

GL with the blow-thru setup.

 

i have used the walker product with great sucess, it even comes with the wiring being like 3 inches or 4 inches longer than from the factory this is a plus if u have a turbo kit that requires extending the front o2 (ptuning)

 

my front o2 is shot on my tc symptoms= rich cruising, buccking at idle, smell of fuel being dumped at idle, then buccking at speed when it gets bad also mine throws two check engines

front o2 sensor stuck lean

and system too lean

what happens is when the sensors go bad they read lean and the ecu tries to compensate by richining it up...well if its stuck lean then your stuck rich.. at anywhere between +1-45% fuel

 

Thanks for all the input! I'm just going to go ahead and replace that sensor and see if that fixes the problem.

Is there a link to the walker sensor? Having it a couple inches longer would be great, the oem one is stretched pretty good right now.

 

try to borrow a good sensor first before you buy a new one, bad O2 sensor is just a possibility.

 

^^^Good idea.

Probably wouldn't hurt to check and carefully clean your plugs off with a wire brush while you're in your engine bay too.

 

Yeah that's what I was thinking^^^

I'll just snag the sensor off my sister's 09 automatic. I'm sure theyre the exact same thing. See if that fixes the problem.

 

^^^ Great idea^^^

While you have yours out it wouldn't hurt to try cleaning it. Carb cleaner, gas, seafoam or something similar should help remove any carbon deposits that may be fouling it.

 

dumb question but is there no obd reader that can tell what the primary O2 is reading?

 

Not dumb at all. Palmer ScanXL Pro can read the primary O2 in lambda or AFR and even voltage.