Rich AFRs
 

I installed a 3" intake and a downpipe at the same time. I scaled the MAF table values to accommodate for the intake and after driving for about 20-30 miles the AFR starts to taper down to near 14.0-14.2 and stays there. I also get rich shifts of anywhere between 12.8-13.6, but then spikes back up to the normal 29. At WOT it's like 9.9 usually, nowhere near target. I've started troubleshooting the issue and have come up with a number of possible culprits. My trims are off, but 14.7 was the highest I saw. So I don't think that the problem is that it's maxing out the LTFTs. I'm going to run through all of these things tonight and am wondering if anyone has anything to add to the list. Datalog 28 & 29 are of the problem. 30 is an MAF Cal log.

1. I can see a small exhaust leak coming off the turbo/DP connection. There was a small crack in the weld that I fixed with some Quiksteel until next week because nobody can weld stainless here except a few people and they're busy until then, but I can still see a little bit of smoke rise when I rev with the hood open really aggressively.

2. The downpipe has 2 Primary O2 bungs. Is it possible I have the O2 in the wrong one? Gen One which should it be? (DP is eBay M2) Edit: According the How-to on the Corksport DP, I think I may have it installed in the wrong location. Is this my problem!?

3. Shift Control Tables gone goofy? - RULED OUT

4. It's a gen one, so I don't think this is it but the extended bung for the Secondary O2. Will that possibly cause this?

5. Boost Leak? - RULED OUT

Thanks guys.
@rfinkle2; @Dimenus;

The problem ended up being a combination of two things: The extra bung for the secondary O2 sensor lost it's plug and I needed to install an MAF straightener.

That leak is not helping.

Try cleaning your maf sensor.

If you have a defouler, take that off. Your 02 is likely fine. There are a number of people who are experiencing a shift in target afr.

I am going to try to talk to Cobb about it.

Ok, I have 2 bungs there, one that's extended and one that is not. So I will try moving it to the other location. Do you think that because I have my primary o2 in the wrong location (for aftermarket sensor) that could be my issue also?

You have 2 02 sensors.. and 3 bungs, explain to me in more detail the placement of the primary and secondary please.

Actually 4 bungs. The primary has 2. One of them is toward the firewall, the other toward the engine on the top of the DP. I have my sensor in the one toward the firewall, which looking at car Cobb DP install @Haltech; did looks like it is for the aftermarket sensor or wideband monitor.

The secondary bungs are a long one and a short one. I have the sensor installed in the long one.


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An extended secondary o2 bung is fine for a Gen1.

Your car is probably overshooting what it needs to hit the 14.7 because it's dumping in so much extra fuel to hit stoic. Also turn off your ac/defroster when idling to see if your AFRs settle out. I bounce back and forth between 14.2 and 14.7 when my duty cycle kicks in.

If it were a pre-tubo leak I would expect the AFRs to taper away from 0 as you rolled onto the trottle (un-metered air).

I think your AFRs are just way off because the velocity of the exhaust is slower at low throttle so it's leaking out. Fuckin' ebay! Get the pipe fixed and then we'll take another look.

Well, gunna try what Rob suggested. I will be getting it welded. Might have to pull it back off to get someone to do it, but I have a guy calling me back tomorrow about possibly doing it. Fingers crossed.