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Old 01-06-2021, 08:27 PM   #1
savagesoob
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Default Help with tune issues or mechanical maybe 2015 STI

Can anyone look at these logs and tell me what I should look for if it's a mechanical issue.

First a breakdown. Bought the 2015 STI with 56,000 miles 6 weeks ago. It had a AP and coob intake OTS stage 1 tune. Car ran fine and I drove on a 1000 mile trip with it.

3 weeks ago.. I had a build done with the parts below:

ID 1050x injectors
Invidia Catless Downpipe
Cobb Flex fuel
Turbo inlet
Cobb Fuel pressure sensor
Cobb air intake
TGV deletes
Cobb 3 port ecbs
Evap delete
IAG Street series AOS
Rear o2 delete
Rear AFR logging on
AEM 340 LPH fuel pump
Base pressure set 45 psi
step cooler spark plug

It was pro e-tuned and ran well when I picked it up from the shop that did the work.

The next morning I noticed that the AF learning was way negative 18-20% during idle.
I continued to drive it and ran it on e85.

4 days ago I filled up with 93 from top tier gas (costco). and the car ran worse than ever. Was getting FKL up to 3.5 on acceleration. The AFL went to negative 25 at idle. Also idle, especially cold start, is rough and the AFR is very jumpy.


I put a brand new MAF sensor and O2 sensor. Smoke test. And I cleaned and oiled the air filter. No change really.

Also, my coolant reservoir was low and I filled to full.. three days later it was down some. Not sure if I have a leak but will investigate that tomorrow. Also when I do a cold start I hear scratching/scraping noise on the drivers side until the engine is warmed up.. thought it was the air pump.. but now I'm worried it's more sinister.


If you have read this far, thanks so much. I attached two logs. one is a cold start with the air condition off and the other is with the air condition on. The car was at idle. It almost even stalled and the afr was lean the rich very erratic..

Do you know where I should look next? Fuel injectors possibly? Thanks for any advice.


https://docs.google.com/spreadsheets...u984AB/pubhtml
https://docs.google.com/spreadsheets...CxdDZx/pubhtml
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Last edited by savagesoob; 01-06-2021 at 08:38 PM.
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Old 01-06-2021, 08:48 PM   #2
jesseisbeast
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Do you have any smoke coming out of the exhaust? Have you checked for vacuum leaks? Do you have any logs of driving the car or just those idles?
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Old 01-06-2021, 09:44 PM   #3
savagesoob
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Quote:
Originally Posted by jesseisbeast View Post
Do you have any smoke coming out of the exhaust? Have you checked for vacuum leaks? Do you have any logs of driving the car or just those idles?
No smoke. I don't have any logs driving but I can do some tomorrow. A little scared to drive the thing.. Yes a shop did a smoke test and saw nothing out of the ordinary.
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Old 01-06-2021, 10:46 PM   #4
jesseisbeast
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Your afr goes pretty lean a few times in the log (above 15) which is pretty high for idle in my experience. That led me to think it might have a vacuum leak, but if not, then you might not be getting enough fuel in those instances. Your afr learning is constantly in the negative and fluctuating. I've never been a fan of eTunes. It might behoove you to get a tuner in person who can monitor and make adjustments in real time.
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Old 01-07-2021, 08:51 AM   #5
86Dreams
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Double check on the loss of coolant issue. if youre actually loosing coolant and its not just showing up in a puddle on the ground you might have a head gasket issue.

Who tuned this?

Looking at the second log the AFRs and RPM are hunting. Idle is very hard to tune in my experience. especially with injectors and tgv deletes. if its had idling issues since the tune there are a number of problems that this behavior could be related to.

Another thing in the log is the actual ethanol content is reading at 26%. fill up with gas again and try to get the ethanol content down to where the ethanol conent is 10-15% and see if operation improves.
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Old 01-07-2021, 02:33 PM   #6
spoolinsti05
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Was a recall on engine harness check there first. It's a ground wire issue.
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Old 01-07-2021, 02:45 PM   #7
Stretch18
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Quote:
Originally Posted by savagesoob View Post
Rear o2 delete

The next morning I noticed that the AF learning was way negative 18-20% during idle.
So.... why delete the rear o2 sensor? The narrowband sensor is manages AFR during idle and is much more accurate for stoich than the wideband o2.
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Old 01-07-2021, 04:35 PM   #8
kopele
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It's running rich. What FPR do you have? Is the vacuum line still connected to it? What do your fuel pump duty cycle and injector scalar look like? Coolant expands and contracts, so your overflow should be closer to low when cold and full when hot.
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Old 01-07-2021, 07:10 PM   #9
savagesoob
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Quote:
Originally Posted by kopele View Post
It's running rich. What FPR do you have? Is the vacuum line still connected to it? What do your fuel pump duty cycle and injector scalar look like? Coolant expands and contracts, so your overflow should be closer to low when cold and full when hot.
FPR is a cobb. here is quick log from a cold start right now. Running rich for sure I can smell the exhaust pretty bad plus uncatted.

It ran better on the e85, when I filled it with gas and fuel is e26ish.. it started running like ****. The AFL was very negative the whole time since the tune. But ran good on e. fuel pump was 33% at idle jut now.

The tuner seems puzzled bc he does these cars all the time for 10 years.. He never said not to drive it or said it was dangerous.. but can't be good. The problems are always during idle.
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Old 01-07-2021, 07:12 PM   #10
savagesoob
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Quote:
Originally Posted by spoolinsti05 View Post
Was a recall on engine harness check there first. It's a ground wire issue.
checked vin no open recalls

Quote:
Originally Posted by Stretch18 View Post
So.... why delete the rear o2 sensor? The narrowband sensor is manages AFR during idle and is much more accurate for stoich than the wideband o2.
went with installer/tuners advice.
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Old 01-07-2021, 07:22 PM   #11
savagesoob
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Quote:
Originally Posted by 86Dreams View Post
Double check on the loss of coolant issue. if youre actually loosing coolant and its not just showing up in a puddle on the ground you might have a head gasket issue.

Who tuned this?

Looking at the second log the AFRs and RPM are hunting. Idle is very hard to tune in my experience. especially with injectors and tgv deletes. if its had idling issues since the tune there are a number of problems that this behavior could be related to.

Another thing in the log is the actual ethanol content is reading at 26%. fill up with gas again and try to get the ethanol content down to where the ethanol content is 10-15% and see if operation improves.
I'll look tomorrow for leaks. The coolant is lower again tonight from last time I looked a few days ago. I have flex fuel but I guess I should keep the e at e10ish or e75 up. I thought I could run any e content and it would adjust.
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Old 01-08-2021, 10:30 AM   #12
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My tuner gave me a speed density map and so far it's running better. AFL is near 0. A/F is at 14.24 but I think it's tuned to be rich for safety.

What would cause the MAF to run like ****? It's a brand new denso sensor.
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Old 01-08-2021, 10:52 AM   #13
86Dreams
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Quote:
Originally Posted by savagesoob View Post
What would cause the MAF to run like ****? It's a brand new denso sensor.
The TGV deletes, and temperature compensation table. Its not the sensor itself.
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Old 01-08-2021, 01:45 PM   #14
jesseisbeast
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Quote:
Originally Posted by savagesoob View Post
My tuner gave me a speed density map and so far it's running better. AFL is near 0. A/F is at 14.24 but I think it's tuned to be rich for safety.

What would cause the MAF to run like ****? It's a brand new denso sensor.
After my rebuild and TGV deletes, I also had to switch to speed density. It's not exactly the maf running like ****. The TGV helps to control the amount of air flow intake past the maf and throttle body. Without those butterflies, the engine is constantly sucking a lot more air than normal which can make it choppy. A higher idle helps. Hopefully now you can get that tune dialed in nicely
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Old 01-08-2021, 02:49 PM   #15
kopele
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There's nothing abnormal in the logs from the first post (you mentioned another log but I don't see a link). Fuel pressure is fine, which means pump and fpr are doing their job. MAF V and g/s look normal, so MAF sensor and scaling should be fine. TGV deletes will cause you to be a bit rich for a limited time during warmup, but not to this extent. The MAF IAT compensation is usually 0 and 80F is normal operating temp in any case. Injector duty cycle is fine. What's left to check is fuel injector scalar and pulse width. In a flex fuel tune the injector scalar is usually adjusted based on ethanol content to regulate the amount of fuel. Although I'm not 100% sure Cobb is using the same strategy, the following leads me to believe they do:

https://cobbtuning.atlassian.net/wik...m+Monitor+List
Quote:
Fuel Injector Scale FINAL (Fuel Inj Scale) [EJ 2.5L CCF]
The current fuel injector scale value being applied to fuel injector pulse-width calculations. When flex fuel and/or differential fuel pressure custom features are active, those systems dynamically update this value to achieve calibrator requested compensations.
If AFL was the same with E85 and E26, then the adjustments are being made, but the actual scalar value could still be incorrect, so it's worth checking out. I'm not sure how this relates to speed density, but to me it sounds like it was tune problem. I don't think there can be a mechanical issue causing this much extra fuel, which can be covered up by a speed density.
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Old 01-08-2021, 07:28 PM   #16
savagesoob
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Thanks for the replies! Tuner said for "whatever" reason it's best to go with a speed density for my car.. I am getting an i/at bung on TMIC.

He is a well know tuner is the south east and does tons of cars with stage 3 mods like I have. Wish I didnt rush out and buy a MAF and O2 sensor.. pissed 400$ away.

I drove around on the tune today and it ran better and AFL was near 0. Was getting some backfire now and again. didnt ask for the burble tune.
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Old 01-09-2021, 11:10 PM   #17
spoolinsti05
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I wouldn't put the iat sensor on the tmic it will for sure heat soak and your tuner will have even more difficulty then he already seems to be having.
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Old 01-10-2021, 08:22 AM   #18
savagesoob
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Quote:
Originally Posted by spoolinsti05 View Post
I wouldn't put the iat sensor on the tmic it will for sure heat soak and your tuner will have even more difficulty then he already seems to be having.
Where can I put it?
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Old 04-18-2021, 04:10 PM   #19
mickeyspossti
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Where can I put it?
I've heard TMIC and Silicone coupler if you absolutely have to
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