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Discussion Starter · #1 · (Edited)
Like the title says. I am getting eTuned At Lachute in a couple months and need help clearing up a problem. I spoke with Brentune and it was suggested that I replace the MAF extension that comes with Cobbs Big Sf. I will start with I realize the fkl events are normal and timing corrections are normal but this is excessively persistent

Here is my issue. I was battling with af learn being -20+ on all drives and never going up to 0 or even close. I replaced my MAF (used 30,000km) and that helped but did not solve it. I replaced my MAP sensor with the one from my old engine and I re adjusted my intake piping and filter, and now I idle at 0 afl, but driving I still hover around -12. Thats when I started getting DAM drop and consistent knock events. I swapped the MAP back to the original one with lower mileage and my dam has improved a little.

I get FKL fighting between -3.81 and +1.05 and my damn dropped as low as .460(or soemthing near that, with the higher mileage map sensor) it will correct to about .812 then fall again to .600. I put the lower mileage map back in and I have a bad habit of holding the throttle at positive values to increase my DAM as I drive. But currently it's at .812 and has dropped and risen between .600 and .812 in the last 120 km with this map sensor.

I am OTS 91 with Cobbs 1+ package on a 2017 wrx. My introduction to this forum in November was about this car siezing right new into ownership. I couldn't get out of the deal but I got a free swap (motor, turbo, manifold, clutch) and I got to keep the old parts. So I have alot spare sensors and things I won't generally use long term but use to trouble shoot.


Now, I'm sitting at 65,000 on the motor maybe a bit less, and there was some vp racing fuel additive thrown in under poor judgement a few tanks ago and research. I'm guessing alot of my problem lies with bad plugs but is there a way from logs for me to tell that? It's my understanding I'm running lean right now and my car is pulling timing for it.

I have run my tank near dry twice and filled up to half tank 91 at two different shell gas stations but that's the best gas I can get around these parts.

My data log bellow is from last week (most recent log) and I will do more logs as I work on this and start learning to read the tables better of course.




Photos of the AP on my drive today

 

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I'm guessing alot of my problem lies with bad plugs but is there a way from logs for me to tell that? It's my understanding I'm running lean right now and my car is pulling timing for it.
Wrong direction. Your Fuel Trims are negative so the ECU is seeing a FUEL RICH CONDITION and reducing the injector pulse width as compensation. There are many reasons for negative fuel trims and many will be difficult to diagnose. A vac leak sees POSITIVE FUEL TRIM at idle unless the leak is after the turbo where it will transition to NEGATIVE FUEL TRIM if closed-loop fueling conditions are satisfied AND the MRP is positive. These conditions are extremely difficult to capture in a datalog.

Things that may cause negative fuel trims:
1. Sticky injector (unlikely the case for DI cars)
2. Misfires due to lack of combustion -- raw fuel dumped into the header. This is usually accompanied with afterfires and the smell of raw, unburnt fuel from the tailpipe.
3. MAF sensor poorly mapped OR damaged/dirty
4. Damage to other sensors that contribute to load calculation/compensation i.e. ECT sensor, EGT sensor (some cars), MAP senor, IAT etc.
5. O2 Sensor failure

EDIT: here's a trickier one....

Sometimes carbon deposits in the combustion chamber can cause the flame front to distort leading to incomplete combustion and a measured "rich" condition.
 

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Discussion Starter · #3 · (Edited)
Things that may cause negative fuel trims:
1. Sticky injector (unlikely the case for DI cars)
2. Misfires due to lack of combustion -- raw fuel dumped into the header. This is usually accompanied with afterfires and the smell of raw, unburnt fuel from the tailpipe.
3. MAF sensor poorly mapped OR damaged/dirty
4. Damage to other sensors that contribute to load calculation/compensation i.e. ECT sensor, EGT sensor (some cars), MAP senor, IAT etc.
5. O2 Sensor failure

EDIT: here's a trickier one....

Sometimes carbon deposits in the combustion chamber can cause the flame front to distort leading to incomplete combustion and a measured "rich" condition.

Well that's alot of really good knowledge to give me a start on this. Where I have messed around with my map and maf I think I may just purchase a new map sensor for the sake of starting fresh. I'm going to touch on each point separately hopefully you don't mind. I truly appreciate the help a ton!

Brentunes suggestion on the extension I will try to rule out as well right away.

Sticky injector - I actually had one replaced at the dealership that came damaged in the donor motor. They pinched the wire harness in the manifold running to solenoid B causing codes to throw sporadically. Took me a long enough time to figure that out myself. Fixed the wires, no more codes to continue trouble shooting from.

Do you think plugs being fouled by VP racing additive could be a contributer to my timing at all based on your second point? My plugs are in the mail now. I actually get a smell in the engine bay that isn't right, I almost want to say clutch but not as definitive as that. Maybe plastic. My oil doesn't change its level between changes so I don't think it's burning. But maybe fuel? Not a gas smell though again.

When it comes to changing sensors thay takes some time and miles to see changes in the numbers I assume so that's what Im In the middle of right now since I just changed the MAP back.

02 all have higher mileage so maybe I'll order a few and just hop on those as well while I'm at the plugs anyways. And a media blast is overdue as well


I read that re Tuning my ecu was a bad move when my dam is not 1.0 because the car loses its progress finding zero and it may take a while before I see the problem again. When should I be trying to retune with the same or a new map
 

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Discussion Starter · #4 · (Edited)
An update. My afl1 is still between-16 and -3.91 but new discovery.


In fourth and fifth gear to much throttle at 3000rpm results in 5.62 FKL. What could that be? I'm not wot. It may be throttle knock specifically but I never had it hit like that.


I'm going to go ahead and say it's detonation issues from the air or vac leak until someone can point me in a better direction.
 

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Discussion Starter · #5 ·
Another update. I'm at .938 dam and still have a consistent battle with FKL trying to drive right in the positive to get it to adjust timing.

Going to perform a leak test and compression test soon to rule out those types of issues.

Changing spark plugs right when subiedepot gets them to me.

New issue as damn improves, rougher idle. At a stop sign as I stop, the rpm will hit 500 ish and feel kind of like she be d to stay then shoot up to 700 and correct to 600 where I have it set on the AP to stay.
 

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Discussion Starter · #7 ·
@XJman i know your not In on this thread but in 2017 you needed sensors and wanted denso over oem. Did you ever actually find that or did you wind up at the dealership
 

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Discussion Starter · #9 · (Edited)
Just an update. New logs showing alot better numbers but I am.unsure if I'm still running rich at all. I get some knock in WOT and under 2000 rpm with ac off but with normal driving conditions its almost non existent.

@zax if your not busy could you look the log I pulled today and tell me if what you saw before has changed?

 

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Discussion Starter · #10 · (Edited)
Update

Cobb said they wanted me to update to the v400 map because it was some changes to it regarding ghost knock. I don't see that in the revision notes but they're customer service is helping me out with this and they're awesome so when I get the answers I'll post here for anyone else searching this
 

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Sorry, haven't had a chance. Busy is an understatement. We just moved into our new house so that's 100% of my free time. I'm just hear for regular mod work and not much else. Sorry.
 
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Discussion Starter · #12 ·
Sorry, haven't had a chance. Busy is an understatement. We just moved into our new house so that's 100% of my free time. I'm just hear for regular mod work and not much else. Sorry.
That's all good it's not like I'm paying ya! Congrats on the new house I'm a little jealous.
 

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Discussion Starter · #13 ·
Another update for any readers!



I have switched to the V400 stage 1+ 91 octane map and no improvement. If anything I got more knock. Specifically feedback knock of -9.84 and FKL-2.81 which sent DAM to .812. From there I went into a store, came out and drove a little more to catch my dam as low as .612. I sent Kyle and Cobb my logs



Just incase anyone will consider my driving style as the issue:
I really don't think im getting into LPSI territory. I try to drive around 2-3500 rpm and never really above or bellow that in any gear besides take off for casual driving. I do religiously rev match without double clutching to down shift and 90% of the time they are bang on downshifts. I never do it into first and I rarely use my engine to slow the car down at all. I'd rather wear the pads down for that. (Unless I'm coming off the highway 6-5-4 or 6-4 then breaks for the rest)
 

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Discussion Starter · #14 ·
Well sad day for me haha. Gotta keep digging hard into the issue. This was the final response from Cobb

"

You are definitely having sustained knock in the top log on your Google Drive. There are no crazy fuel trim corrections that would lead me to believe it is gas, spark, mechanical or ghost knock. Since you are having such sustained knock it may be best to have a shop look over the car because there isn't anything obvious in your datalog.

Thanks! "
 

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That's all good it's not like I'm paying ya! Congrats on the new house I'm a little jealous.
Eh, it has its days.

I can't seem to open your log files. Is it a permission problem?
 

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NVM, I was able to open.

Took a look at your last couple logs. The DAM is definitely active. Everything else in the logs look OK.

This is going to be a tough one to track down and I would agree -- Probably having a qualified shop comb through the car is a good idea. You should consider doing a compression/leakdown test just for peace of mind.
 
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Discussion Starter · #17 ·
NVM, I was able to open.

Took a look at your last couple logs. The DAM is definitely active. Everything else in the logs look OK.

This is going to be a tough one to track down and I would agree -- Probably having a qualified shop comb through the car is a good idea. You should consider doing a compression/leakdown test just for peace of mind.
I'm unfortunately not aware of a local shop I trust but I am going to rip into the engine bay and clean up and torque everything I clean and inspect and replace anything that's even remotely ugly from age. Brackets, sensors, media blasting will get done, and maybe a couple small simple upgrades along the way that make sense while the car is up on stands and torn down. TMIC and Grimspeed battery kit I'd say are 100% on there way soon anyways. Although I could be looking into a third motor if something catastrophic is happening. Fingers crossed
 

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Discussion Starter · #18 · (Edited)
Feel free to fast forward to the questions and photos bellow

Well. That response was typed before I did this work but never sent.. I started exactly what I said and took of the tmic and front impact bar, plastics, and rad shroud. I am going to pop the manifold off in a day or two to inspect the sensors themselves.

Ultimately the shop that swapped my motor had engine codes they refused to provide me with, MD they Frankensteined my new motor with some of the old motors sensors and harness. (They pinched my newer harness on the reinstall) (then the subaru shop here pinched my harness in the manifold causing egr solenoid codes... 😒)



1:
The ecu appears to have a tamper switch or aeomthing and I see red, does everyone's look like the third photo bellow?

2: what am I looking at in photo 4 when I pop the manifold ill know for sure but that leads to a detonation(knock) sensor right? (The orange harness, not the slave cylinder.)

3: could that shitty plastic pitch stop cause knock if its cracked or loose?
 

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Discussion Starter · #19 ·
Another update. Reading a thread on nasioc I found a guy comparing his problem on his own thread to the one I was reading. Both sounded relevant to my problems but turns out the second thread was sounding right up my ally.



Long story short he had my symptoms, and couldn't diagnose. Someone else Tuning with Brentuning replaced the knock sensors pre and post codes being thrown (2 first, no code, then sensor 1, post cel)

My motor did have an injector replaced 1 day after install, on #3. I was considering replacing the other 3 injectors but I may replace the knock sensors first since the cars apart and they are almost exposed and they either were in a collision and could have suffered the fat injector 3 did, or they could be from my high mileage motor. I do have two more knock sensors in my storage locker but I will take a good look on them and test them and probably purchase new before starting the car to test again.
 
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