Been a while since posting on here. I have had my S2 for about 10 years now and has been trouble free for the most part. Last couple years it spent more time stored than usual. I drove it from time to time, but not much. Last time I took it out, I had some lumps in the power delivery and it hit a wall at around 6k rpm along with the p0302 code. My assumption at the time was a coil finally went bad again. Been about 40k miles since last replacing them. So, I got a BHR set with plugs and wire. Same power issues and code.

I took it out after putting the new coils in discovered the issues still existed. I hooked up my OBD2 reader and looked at things on my phone. The only thing that stood out while driving was that the A/F ratio got pretty lean. Around 11-12 when the power drops / misfires happened. Seems to be a fuel issue at this point? Thoughts going forward.

I am guessing one of the following is an issue.
-airflow sensor
-SSV issue
-fuel pump and/or injector
-plugged cat
-maybe bad gas? The gas in it is pretty old, so maybe it is an issue.
Am I looking at the right things or am I missing something

 

An additional note, the battery was dead after being stored, so could it be an ECU issue?

 

Tomorrow I plan to clean the airflow sensor and fill the tank with fresh fuel. It is about half full now. See if that helps. If not, my next assumption is the cat.

One other symptom I forgot to mention, is the issue is worse after getting some heat into the motor. When first driving after warming, it is better at lower RPM. Runs pretty normal. And the CEL only comes on if I try to push through 6-7k wall. Then the flashing cell comes up. There are some smaller dips in power in the 3k rpm and higher range, but it drives right through those. This area gets worse once being driven a bit. Idle is fine. Consistent and smooth with the new coils, wires, and plugs. And the plugs that came out did not look bad. Just the usual brownish fine soot you expect. Nothing is wet or black.

 

Try doing the eshaft reset, that has worked for some members on here, there’s a post on how to do it.
i had a similar issue and what I noticed was one of my battery terminals was loose, after tightening it the stuttering went away, I eventually just replaced the whole battery since it was already 5 years old and haven’t experienced the issue since, good luck.

 

First of all AFRs of 11/12 is rich not lean.
Yes fresh gasoline mmmm unburnt hydrocarbons
Second as mentioned try the NVRam reset using the 20 brake pedal tap method.
Recheck your plug leads are installed correctly.
Clean ESS sensor and Maf .
Could your catalytic be clogged?

 

I had a brain fart on the rich/lean. It happens. Lol
I did check all the leads again. Everything is tight and connected correctly.

Gonna drain the fuel tonight using the fuel pump. Then put some fresh fuel in. Plus sensor cleaning.

As for cat, not sure if it is plugged or not. I have not tried pushing it all that hard the few times I drove it since this started. Not may daily, so it sits a fair bit. More the last couple years than normal. So, have not looked to see if it is glowing. I might just try and knock it off and do a quick drive with an open exhaust to see if it runs better.

 

Working on car now between rain shows. Gotta love FL this time of year. Draining fuel via the pump now. MAF cleaned and drying. Once drained and filled, I will do the reset.

On the reset. I have not needed to do it since buying the car back in 2011. I have read conflicting things as to the procedure. At least for the S2. There is the brake pedal dance for the S1, but apparently this is not the case for S2? One thing I read said you need to disconnect the battery negative, press brake once then reconnect and start the car. What one is correct?

 

Think I found the issue. May be the cat after all. After swapping fuel and cleaning the MAF, took it for a 22 mile drive. Half way in I ran it till it hit the rev wall. Pulled over and looked under the car. Since it was getting dark I could see the bright glow of the pipe ahead of the cat and the front half of the cat. The ring around base of the O2 sensor on the cat was also very brightly glowing. So, pretty sure this is the issue.

 

Yikes
At the very least it is worth the effort to check

I don't know about the S2 and the 20 brake stomp sorry. But on the S1 you just turn the key to the on position tap the brake pedal until you see the oil needle sweep across and done.

Thanks for the updates.
Looking forward to what you find out about the catalytic

 

Parts on order. Hoping things arrive by the weekend. Will the computer play nice if there is no O2 sensor connected at all? Not 100% sure I can get the old one out of the cat and I am putting a catless midpipe on. I know I will get a CEL either way. Just not sure if it will cause the computer to freak out if no sensor is detected at all. Don't really want to fork over another $120+ for a sensor when a $2 plug will work.

 

Found the issue. Cat totally collapsed inside. Had a local shop make me a mid pipe that would use factory connectors with a resonator on it. New hardware and new OEM gaskets and she is running like she is new again. I have not felt her pull this hard and smooth in a long time. Between the free breathing and the new BHR ignition, it is like the car is brand new again. The pops and bangs at redline with quick shifts make me giggle inside a bit as well.

 

Haha! That's great 👍
Thanks for the update post.

Zoom zoom
Oh and the sensor in the Catalytic you were mentioning is only for the Catalytic efficiency
The ECU should play nice if it unplugged.
Can't say that I've tried however I've always used and old one to place in the sensor hole.

FWIW the wide band front O2 sensor is located in the exhaust manifold.

It is also known to fail and can be a bit of a pig to replace

 

Yeah, I know the sensor is just for the cat. Hence wondering what the ECU would do with out it. Had a GMC truck that got real angry when the down stream sensor wire got ripped off when driving on rough terrain. Spliced the wires together and it was fine again.

So far after a little over 100 miles, no CEL or anything. Engine seems to run a little cooler as well. At least based off my phone app reading the factory sensors. Makes sense, since the heat can escape more easily now. I managed to get the old sensor out of the cat with an impact, so I put it back on the midpipe. So, all is good. Not bad, 10+ years of ownership and this is the only issue I have had besides bad synchros in the transmission when I got it. Had those replaced under warranty and the car has been solid since. I take care of the car as best as I can and run it hard often. Seems to be the biggest key to keeping these engines running strong for a long time.

 

Just got back from a 2200 mile road trip. Car is running good still. CEL is coming on now. Just for the cat. Happens about every 200 miles or so. I just clear it with my phone. Might play with spacers or one of the tiny cat things for the sensor. But for now I will keep clearing it.