AFR mostly rich, erratic at times

[Synack]

Just developed this issue today and being that this is my first turbocharged car I would like to ask for some help diagnosing possibilities.

1. When I cold start the car, everything is fine at idle.
2. When I start to drive the car at normal throttle, the AFR tends get pegged at 10 after a minute.
3. Come to a stop and now my idle is 10 for AFR.
4. Now low throttle and normal throttle driving has awful response and is still at 10.
5. Every now and then the AFR gets back to normal or almost normal for ~30 seconds, and then it will go back to 10 AFR.

After some research I've found a broad list of issues it might be:

• Air filter (new one shipped tomorrow)
• MAF dirty (about to go buy cleaner and spray it)
• Boost leak (after MAF?)
• Fuel pump (I already have a 485LPH brand new sitting at home)
• Spark plugs (20,000 miles on the same plugs, never replaced since turbo setup)
• Injectors

I was hoping I could get it narrowed down a bit more before I start throwing money at it.

[350matt]

Hello

I'd check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.


if thats OK try replacing the 1st O2 sensor

[Synack]

Originally Posted by 350matt

Hello

I'd check for exhaust leaks before the O2 sensor as if this has been experiencing an exhaust leak then it will have been running very rich as the sensor will see the extra air pulled in as fresh / lean fuelling and be adding fuel to compensate.


if thats OK try replacing the 1st O2 sensor

Running wideband and the 2nd O2 is disconnected I believe. I'll check for leaks around the turbo.

Are you talking mostly about turbine housing exit to exhaust area?

[350matt]

yes any leaks upstream of an O2 sensor can pull air in and so give a false rich reading

you say you're running wideband, is the sensor replacing the factory wideband or is it additional?

also are you on the stock ECU with ECUtek, OFT etc? or on a standalone like Motec?

[Synack]

Originally Posted by 350matt

yes any leaks upstream of an O2 sensor can pull air in and so give a false rich reading

you say you're running wideband, is the sensor replacing the factory wideband or is it additional?

also are you on the stock ECU with ECUtek, OFT etc? or on a standalone like Motec?

Almost positive the wideband replaced factory, I'll have to double check as I haven't even had to look at it since building the car.

I use Ecutek.

[350matt]

OK if the wideband has replaced the stock item and you're not using any closed loop function in your tune then it won't be effected by any leaks or faulty sensor

from the sound of it though I suspect that you are using closed loop but have changed the sensor gains so it uses the Wide band as the main input

[Kodename47]

Have you any catalogs? Might help to see if trims are at play etc?

[Synack]

Originally Posted by Kodename47

Have you any catalogs? Might help to see if trims are at play etc?

All I have at the moment is Torque. Which I doubt can help.

Originally Posted by 350matt

OK if the wideband has replaced the stock item and you're not using any closed loop function in your tune then it won't be effected by any leaks or faulty sensor

from the sound of it though I suspect that you are using closed loop but have changed the sensor gains so it uses the Wide band as the main input

I know for a fact that the 2nd O2 is disconnected. I don't know about the closed loop or not because I didn't tune or build the car. I've only taken it apart several times for maintenance and parts/turbo replacements and the occasional cleaning.

[Synack]

Saw some improvement on the drive home for no reason whatsoever. Was running upper 12's and 13 flat AFR for most of the ride in higher gears and part throttle. I didn't go past 8psi either, which I'm not sure if it helped the situation or not. Idles at upper 13's and occasionally 14's now as of getting home.

Sprayed the MAF and several other electrical components completely clean just now too.

I suppose I'll update tomorrow but I'm very skeptical that this just randomly "fixed" itself. Unless maybe there was some bad gas or something of the sort.

I have some gaskets on the way because I'm about to buy a new turbo anyway (different reason).

I'll post more symptoms and/or hopeful good updates as soon as they come. Thanks for the help.

[Synack]

STILL HAVING ISSUES
But they aren't as bad.

• Idle is now ~12 instead of 10. (Still too rich when it used to be 14-15AFR idle)
• Light throttle ~13-14AFR. (Not really concerned about this but could be better)
• Heavy throttle 10.5-12AFR. (Definitely too rich)

Any ideas? Could this just be a wideband going bad or?

[King Tut]

Dude you gotta get an EcuTek cable and get some datalogs to trouble shoot. You still running a D3PE tune right.

[Synack]

Originally Posted by King Tut

Dude you gotta get an EcuTek cable and get some datalogs to trouble shoot. You still running a D3PE tune right.

I'm getting Nick's next week. Yes still running the D3 tune.

I'm literally waiting for the turbo to ship before my flex-fuel upgraded turbo project and now this happens. I just placed an order for a replacement wideband sensor though, I feel like this one has been put through A LOT of crap. It's had oil blasted on it numerous amounts of times before I originally fixed the oil problem. It just seems like a smart move regardless of whether it fixes this problem or not.

[Synack]

It has to be the AEM wideband sensor. Basically every tells me these things are lucky to last 2 years and I've had it for a bit more than that. Combined with said turbo oil problems above I don't see how the sensor even made it this far.

I also noticed that when the key is ON but engine off the sensor reads mid 11's. Not sure what that means.

[Kodename47]

Tried a recalibration?

I was told some time ago that the NGK sensor AFX was the best wideband if you're not going professional lab quality. It's not too badly priced either.