Lean in combustion chamber, rich in exhaust. HOW???!! PLEASE HELp...

[7angofragger]

I just had two paragraphs typed out... but im going to go simple, and answer questions as they come... okay... here we go...:

On my 2003 neon srt 4, but it a generic question.

Why do i have a lean mixture of fuel in the combustion chamber, but have a rich mixture of fuel in the exhaust?

its almost impossible right? the car hasn't jumped timing. it will idle fine at 11's, but when the car tries to run the afr's at 14.7, it spits and sputters and eventually dies out... we thought maybe we got straight ethanol... drained the tank... thats not the case... the plugs are new. the upstream 02 is new. the upstream 02 and the wideband are all saying the same thing. the plugs are clean as heck. im uploading two audio clips of all of us thinking out loud.. they may be kinda hard to hear, but i think these clips will answer most of the easy questions.

Deposit Files

Deposit Files

so, lets the questions begin.. thanks for everyones help in advance.

[7angofragger]

ive been talking to my buddy. he just sent me this text:

"i have had 3 different sources say we need to check the cam/crank angle. one said he did an avenger and at WOT it run like a raped ape but crap at idle. exhaust cams were one tooth off..."

[shorod]

Welcome to the forum.

Question 1 is why are you bumping the thread after only and hour and a half!?! You do realize that most people on this thread have full-time jobs outside the forum, right?

What are you using to determine the AFR in the combustion chamber? Did you replace the standard upstream O2 sensor with the wideband? It sounds like you probably have some aftermarket parts on the car as well as an aftermarket ECM to take advantage of the WBO2S. Have you monitored your fuel trim values to see what the PCM is trying to do? Assuming that you are gathering information on AFR in the combustion chamber via the PCM, is the PCM properly calibrated for the size of fuel injectors that you have installed? Has the car ever functioned properly with the current mods and ECM program?

-Rod

[7angofragger]

I cant see AFR in the combustion chanber, but i can look at my plugs. The plugs have less then 50 miles on them, so there good. The plugs are clean as heck.. hardly any fuel is on them. The upstream o2 is just a replacment bosche. its a narrow band. i have basic mods. its the factory comptuer in the car. it has an intake, and it has a 3" 02 housing comming off the turbo, and going straight into the 3" open catless downpipe. when i unplug the upstream 02, the car goes into limp mode, and starts dumping tons of fuel. my afr's go to about 11 at idle. as soon as i plug the upstream back in, the pcm tries to lean the car out. it tries to reach a 14.7. when that happens, it starts to sound like it has a massive cam in it... its starving for fuel. i have a hand held tuner that has tunes for the factory injectors, and a set of 600cc's. the car has ran awesome since i have had it... over a year. after i put on the exhaust on, i drove it for 1300 miles until it started acting up.

[shorod]

Where is the wideband installed, or was that only temporary during troubleshooting?

You don't mention the downstream O2 sensor. Is that still installed? When you got rid of the catalytic converter, what did you do with the downstream sensor? What is the PCM reporting for downstream voltages (B1S2)? With the upstream sensor plugged in and the car struggling to run, what do the STFT numbers do?

-Rod

[7angofragger]

the wideband is permantlly installed. the downstream 02 is plugged in, but not in the exhaust stream. but the downstream in these cars just check for the cat. if its not there it will throw a code.

im pretty sure i may know what the problem is. i have a feeling the car has been outta time the entire time i have owned the car. i think the exhaust side is one tooth off. so at idle its sucking the fuel straight outta the head and into the exhaust. imma have to pull off my bottom cover this weekend and check timing.