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Discussion Starter · #1 · (Edited)
I was hoping someone could help me. My car is leaning out super hard like after I fill up, when I'm leaving a stop sign or basically start to accelerate easy going through the gears. When I got tuned I was making 27 PSI in 4th now I'm only at 24psi. Maybe it's a boost leak I am going to be checking that out. Would a boost leak cause me to lean super hard? Some days the car drives nice and some days it's absolutely terrible to drive and just want to park it. As of right now I have plugs, and an air filter on the way. I'm FBO which includes:
STOCK TOP END AND BOTTOM END. Compression is 150 across the board. MAP Tubular, TPC GT SPEC, AMS DP, Test pipe, catback, walbro 450 (venturi drilled) flex fuel system (only tuned on 93 right now) inline fuel filter, 1300cc injectors, ETS intake (stock MAF housing, heatshield), GS 3 port, AFR gauge, boost gauge, ETS 3.5'" IC with upper piping, I do not have the lower piping that is still stock, TIAL QRJ (in the correct position), 22psi WG from TPC, and lastly a radium PCV catch can.

Attached I have two sets of logs. The logs where I was told it made 460hp on the virtual dyno and the log I took yesterday. I have already replaced both o2's within a year and a half so they're new. The Denso ones from RockAuto. Any insight or advice would be great I love the car and the fact it's acting up is a little frustrating. I have checked all the vacuum lines and don't see anything wrong with them, cracks, splits etc etc. All the IC lines seem fine.

I have a video too in 5'th gear giving maybe 10 percent throttle at 80mph and it leans out super hard. I know the AFR isn't bad because it's reflecting the hesitating the car does when I'm driving it. Thank you I appreciate any help.
Video link: Evo lean

Maybe it's a boost leak would that still keep me at a constant 24psi or would that fluctuate?
 

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With a leak between the turbo and throttle body, metered, pressurized air is escaping which in turn causes a rich condition.

If the leak is in the intake pipe between the MAF and turbo, it will draw in unmetered air and create a lean condition. Air in the intake pipe is not pressurized so there would be no metered air escaping. The turbo actually creates a vacuum in the intake pipe, hence drawing in unmetered air.

So, you might have a boost leak if you're seeing less boost but it wouldn't also make you lean. Is the vacuum line to your FPR still good?
 

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Discussion Starter · #3 ·
With a leak between the turbo and throttle body, metered, pressurized air is escaping which in turn causes a rich condition.

If the leak is in the intake pipe between the MAF and turbo, it will draw in unmetered air and create a lean condition. Air in the intake pipe is not pressurized so there would be no metered air escaping. The turbo actually creates a vacuum in the intake pipe, hence drawing in unmetered air.

So, you might have a boost leak if you're seeing less boost but it wouldn't also make you lean. Is the vacuum line to your FPR still good?
The intake is nice and tight to the turbo inlet. My FPR hose is attached too even ziptied when I first started to put parts in it
 

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You might have an issue with the fuel pump line inside the tank leaking or an injector/pump issue in general. Not the easiest to troubleshoot diagnose parts that aren't performing but haven't failed.
 

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Discussion Starter · #5 ·
You might have an issue with the fuel pump line inside the tank leaking or an injector/pump issue in general. Not the easiest to troubleshoot diagnose parts that aren't performing but haven't failed.
Would that also cause me to lose 3lb of boost? Or would that definitely be a boost leak?
 

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Would that also cause me to lose 3lb of boost? Or would that definitely be a boost leak?
Y'know I'm not an expert, and looking at your logs, it's kinda hard to tell. Before and after, car isn't making all that much vacuum, so I'd definitely recommend checking for boost leaks. The good old Home Depot 3.5" rubber cap + standard air compressor fitting + a drill + some epoxy is my goto. Just make sure not to crank it too high, and your ears will thank you later. I'm sure you know already, but boost leaks will make you lean at idle/takeoff, and rich during boost.

I'm not too familiar with the format you're logging in, I usually hit up one of the "Golden USDM" settings. Just to clarify, you're running lean at take off? Are you also running richer under load? If you're only running lean at takeoff, but not rich under load, it's possible your O2 sensor isn't working. I can see that your O2 sensor isn't logging (again not familiar with the format, used to having front and rear o2 sensors logged). If your O2 sensors aren't working, but you still have closed loop enabled, your car will basically starve itself of gas until it reaches enough boost for the MAF & MAP sensors to kick in, and then it will abruptly go back to normal. Does this feel familiar?
 

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Discussion Starter · #7 ·
Y'know I'm not an expert, and looking at your logs, it's kinda hard to tell. Before and after, car isn't making all that much vacuum, so I'd definitely recommend checking for boost leaks. The good old Home Depot 3.5" rubber cap + standard air compressor fitting + a drill + some epoxy is my goto. Just make sure not to crank it too high, and your ears will thank you later. I'm sure you know already, but boost leaks will make you lean at idle/takeoff, and rich during boost.

I'm not too familiar with the format you're logging in, I usually hit up one of the "Golden USDM" settings. Just to clarify, you're running lean at take off? Are you also running richer under load? If you're only running lean at takeoff, but not rich under load, it's possible your O2 sensor isn't working. I can see that your O2 sensor isn't logging (again not familiar with the format, used to having front and rear o2 sensors logged). If your O2 sensors aren't working, but you still have closed loop enabled, your car will basically starve itself of gas until it reaches enough boost for the MAF & MAP sensors to kick in, and then it will abruptly go back to normal. Does this feel familiar?
It’s funny that you say that. I did a boost leak test on Friday and nothing came up. I’m going to to an exhaust leak check this week because I smell fumes in the cabin especially after hard pulls.
At takeoff it does lean out sometimes but not consistently but also happens sometimes after I fill up it will max the gauge out in a lean condition. But as I start to creep up in boost it will go rich 10.6-11.6 as it should. So yes exactly what you said is happening. I have replaced both o2s because they were not logging. I had asked my tuner about them reading 0 and he said that’s normal but I’m not too knowledgeable to agree or disagree. So I’ll get exhaust leak checked then we will see what happens after and I’ll replace the o2s. It will obviously backfire and not sure if that will cause the o2s go burn out. I also let them warm up prior to starting the car for like a solid 30 seconds because my afr gauge won’t read properly if I don’t.
 
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