AFR Spike Question

[Vansquish]

Originally Posted by joefromkocomo Jesus. So last night I was driving and giving it a little gas from 3k in 3rd gear, still on the Cobb Stage 0 which is allegedly a simulated stock map. I look down at my AP after a quick pull from 30-60 and see that the upper bound of my boost number was ~17.6 lbs. I know for damn sure a stock map should be tuned with a boost target of 15.5-15.6 lbs. I started logging so I could take a look at home to see what was going on, and sure enough I had one cell of boost spike. Shifting from 3rd to 4th, as soon as the turbo spooled in 4th it spiked to 17.68 lbs. I know the K04 is capable of 18-19 lbs safely, but if I'm 2 lbs over target that doesn't seem too great. No KR reading at all. I'm really just thinking of uninstalling the AP until it's time for tuning at this point. Am I thinking correctly, or am I just paranoid? Datalog attached.

I wouldn't install anything just yet.

Please re-take some datalogs and include the following logging parameters (some things were missing in your log, and other unnecessary parameters were present). Note that a proper WOT datalog should be taken on a flat, smooth, straight road and it should begin just under 3000rpm and run to at least 6000rpm in a single gear (preferably 3rd or 4th).

Accelerator Pedal Position
Actual AFR
Boost (psi)
Boost Air Temp
Calculated Load
Coolant Temp
HPFP Actual Pressure
Inj. Duty Cycle
Intake Temp
Intake Valve Adv.
Knock Retard
Long Term Fuel Trims (LTFT)
MAF Voltage
MAF Airflow
RPM
Short Term Fuel Trim (STFT)
Spark Advance
Throttle Position (not throttle duty cycle)
Vehicle Speed
Wastegate Duty

[joefromkocomo]

Originally Posted by Vansquish I wouldn't install anything just yet. Please re-take some datalogs and include the following logging parameters (some things were missing in your log, and other unnecessary parameters were present). Note that a proper WOT datalog should be taken on a flat, smooth, straight road and it should begin just under 3000rpm and run to at least 6000rpm in a single gear (preferably 3rd or 4th). Accelerator Pedal Position Actual AFR Boost (psi) Boost Air Temp Calculated Load Coolant Temp HPFP Actual Pressure Inj. Duty Cycle Intake Temp Intake Valve Adv. Knock Retard Long Term Fuel Trims (LTFT) MAF Voltage MAF Airflow RPM Short Term Fuel Trim (STFT) Spark Advance Throttle Position (not throttle duty cycle) Vehicle Speed Wastegate Duty

I'll edit the logging parameters and take one either tomorrow or Saturday and post. Very clearly I still have much more research to do if I wasn't aware that stock maps are load based, which would make boost spike less of an issue. It sounds like sustained values over the boost target are the real issue.

tegxsi: I don't think what I was doing there would be considered true WOT. I wasn't on a stretch of road where I felt good really laying into it for a true WOT pull. More like I saw something I didn't like and wanted to take a quick log to see if it did it again and was something I needed to look further into. Of course this is all speculation, I'll just get a proper datalog and post again with real data instead of speculative bullshit.

[MSMS3]

Originally Posted by Jeff23spl don't worry much if it happen just for 1 cell, everything electronically controlled remain mechanic with some kind of latency on the response. Especially in third gear and winter time, it is where your turbo spool the quickest...

I agree. While the logs appear a bit lean when first going under full load, they are still safe and do richen up as rpm and load rise.

One cell of 17 psi is not harmful and might be pure anomaly, since it never recurred.

OP might want to consider VersaTune as an option. Their stock maps are held in high regard. He can still use his AP for datalogging.

[joefromkocomo]

Alright, 2 logs. First one in 3rd, second one in 4th. Had to cut it off a little before 6k on the 4th log, didn't want to be hooning it up somebodies butt and I was little closer to them than I felt comfortable with.

[tegxsi]

Originally Posted by joefromkocomo Alright, 2 logs. First one in 3rd, second one in 4th. Had to cut it off a little before 6k on the 4th log, didn't want to be hooning it up somebodies butt and I was little closer to them than I felt comfortable with.

3rd gear log looks like what a stage0 map should be doing. Load looks right. WOT delay between switching from closed loop AFR (13s) to open loop AFR (10s).

4th gear has a bit of knock... probably what a stage0 map would do when it encounters more load. Stage 0 ignition timing is aggressive and may cause knock under more load.

[joefromkocomo]

Originally Posted by tegxsi 3rd gear log looks like what a stage0 map should be doing. Load looks right. WOT delay between switching from closed loop AFR (13s) to open loop AFR (10s). 4th gear has a bit of knock... probably what a stage0 map would do when it encounters more load. Stage 0 ignition timing is aggressive and may cause knock under more load.

So from what I've been reading, this is somewhat normal for this engine. That some of the KR sensors are pretty sensitive, and that the ecu would rather pull timing once it hears a knock event and then fade back to the stock trim as KR begins to fall. This means that immediate spikes of KR followed by KR falling off aren't as bad, but that I should still be paying attention to make sure that things like this aren't worsening.

Conversely, if the KR starts low and continues to grow up into the 5+ range as I continue to stay at WOT, THIS is that knock that I really need to be afraid of and attempt to diagnose ASAP. And then is there is also something called Partial Throttle Knock that seems to be reserved strictly for GenJuans? (this one has me scratching my head... not gonna lie)

Obviously no KR is best case. Before I start bolting more stuff on I'd like to have an understanding of what I should be looking for in terms of red flags. The relationships (inverse/linear ratios and such) between certain values, and what is normal so that I can on a very basic level troubleshoot and tell when I might need to have someone professional look at it.

[tegxsi]

Originally Posted by joefromkocomo So from what I've been reading, this is somewhat normal for this engine. That some of the KR sensors are pretty sensitive, and that the ecu would rather pull timing once it hears a knock event and then fade back to the stock trim as KR begins to fall. This means that immediate spikes of KR followed by KR falling off aren't as bad, but that I should still be paying attention to make sure that things like this aren't worsening. Conversely, if the KR starts low and continues to grow up into the 5+ range as I continue to stay at WOT, THIS is that knock that I really need to be afraid of and attempt to diagnose ASAP. And then is there is also something called Partial Throttle Knock that seems to be reserved strictly for GenJuans? (this one has me scratching my head... not gonna lie) Obviously no KR is best case. Before I start bolting more stuff on I'd like to have an understanding of what I should be looking for in terms of red flags. The relationships (inverse/linear ratios and such) between certain values, and what is normal so that I can on a very basic level troubleshoot and tell when I might need to have someone professional look at it.

I believe Gen1 occasionally try to maximize fuel economy at part throttle by gradually advancing timing. People report crazy knock numbers but it's not really a concern at part throttle. I have a Gen2 so I've never experienced this.

I think you are safe to run Stage1 and post logs. I think you posted a log before but I don't think you were logging correctly.

[joefromkocomo]

@Vansquish @MSMS3 anything to add?

[MSMS3]

Originally Posted by joefromkocomo @Vansquish @MSMS3 anything to add?

The logs looks fine from a safety standpoint. Leaving a lot on the table. Only reaching a load of 1.5 - 1.6, but that may be all that the stock OEM tune calls for.

I think you are ready to begin modding. Start with fuel pump internals. Do not try to run a big downpipe/racepipe without pump internals and an appropriate tune. Cobb OTS maps are just to “get you to a tuner” as they are not very good.

Bring a reputable e-tuner into your modding early, not later.

[joefromkocomo]

Originally Posted by MSMS3 The logs looks fine from a safety standpoint. Leaving a lot on the table. Only reaching a load of 1.5 - 1.6, but that may be all that the stock OEM tune calls for. I think you are ready to begin modding. Start with fuel pump internals. Do not try to run a big downpipe/racepipe without pump internals and an appropriate tune. Cobb OTS maps are just to “get you to a tuner” as they are not very good. Bring a reputable e-tuner into your modding early, not later.

For sure, I wouldn't expect anything more from the Stage 0 OTS tune. I was really more so worried about understanding KR and whether what I was seeing was bad. I guess I answered my own questions, but I wanted to make sure my understanding of the different types of KR is kosher.

Just got the catch can on the car yesterday. I'll have the fuel pump internals the latter half of next month. I do actually already have a downpipe, but it's not on the car and it won't be until the fuel pump internals go on. Planning on reaching out to E-tuners this week or next week to get a feel for who I want to work with.

Funny story about the downpipe... picked up a barely used ATP 3" Catless for $150 yesterday. Get to his place to pick it up and it's still attached to the CBE and the turbo; the rest of the car was completely gutted other than the interior. Very clearly didn't have the tools needed on hand to get everything separated (he was using a 6" ratchet trying to undo exhaust bolts). Spends 30 minutes under the car getting the last bolt holding the downpipe and the catback undone. Starts trying to break the bolts holding the turbo and DP loose... 10 minutes go by, not even close to budging. Ended up offering me a rebuilt K04 still attached to the DP for free. Got rebuilt turbo + DP for $150, and apparently both only have like 4-5k miles on them. So I guess I have a backup turbo if needed, just have to run by my buddy's house and borrow his impact driver for a few minutes to get them separated. Purchasing the DP first was definitely out of order, but the deal was too good to pass up and ended up getting a whole lot sweeter when he didn't even ask for anything extra for the turbo.

[Jeff23spl]

funny story. Exhaust bolts usually need impact/ + heat to get loose...or large bar to break them apart....Take a look at adaptor size as you may need all the pieces to fit it on a smaller stock cat back...

For the turbo, check for wheel play to be sure and at worst, it could serve as a book holder if it is bad and the price is still good...

[joefromkocomo]

Originally Posted by Jeff23spl funny story. Exhaust bolts usually need impact/ + heat to get loose...or large bar to break them apart....Take a look at adaptor size as you may need all the pieces to fit it on a smaller stock cat back... For the turbo, check for wheel play to be sure and at worst, it could serve as a book holder if it is bad and the price is still good...

Minimal play in the shaft as I perceive it, but I'm not sure what a bad amount of play in a shaft is as this is the first turbo I've actually held in my hands before. I'll have one of my buddies that's been wrenching for much longer take a look at it and give me his opinion.