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Weeza

Need to lower engine RPM at cold-start idle

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Would like to lower rpm's at cold engine start.  Our 2016 Crosstrek is set at WAY too high rpm's at cold engine start.  This means engine is too high rpms with no engine oil circulation.  I KNOW ALL ABOUT THE SUBARU "ANSWER" being that the engine is set to idle high at cold start to lower emissions...  and the Subaru dealership refuses to adjust this rpm, even if we offer to pay for it.  OK, so I looked up the ECU programming tool J-2534 that you can use with Subaru software... but want to know if anyone has used this tool to lower the cold-start engine rpm's.... OR if there is a company out there that sells custom-modified ECU units, OR that will reprogram an ECU if we sent it to them.

 

Thanks - my husband is a master mechanic, life-long, so knows engines inside and out - we just want to lower the rpm's down during cold start.  What you have here is an engine running at extremely high RPM's when there is NO OIL CIRCULATING IN THE ENGINE.  Yes, they might achieve lowered emissions but it is at the cost of the engine life - 

 

Weeza

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Extremely high rpm of 1.7-2.1k?

 

I mean i understand what you're saying. But unless the cars sat for a long while, or you're using very poor quality oil, every component is going to have oil residue on it. Enough where its not going to cause damage until the oil flows.

 

Cars have had a high cold idle for decades. Engineers wouldn't design the engine to blow up in 50k miles due to cold start, high idle, lack of oil.

 

Tbh, i don't even know if the factory tune or scan tool can actually change cold start idle rpm.... Custom ecm for sure.

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Using synthetic oil helps a lot for residual on components between running the engine.  But, since Subaru just settled a huge lawsuit not so long ago regarding breakdowns at lower mileages, I guess the engineering factor isn't as comforting as it once was.  We traded in an Outback with less than 70,000 miles that had the defect named in the class action settlement.  Do you know of a company that produces custom ECM's for Subaru's?  My husband is an engineer, also.  He owned repair shops most of his life.  He has not only had to repair and rebuild engines, transmissions, etc. that failed due to engineering design flaws, but had to re-engineer to prevent a repeat failure - in other words, if you go back with the same mentality that created the problem, you still have the problem.  Auto manufacturers will use a teflon seal in a transmission (instead of a metal one as in years gone by) to save a quarter of a quarter of a cent, that causes the whole transmission to fail.  This answer doesn't work for someone that's had to correct engineering design flaws for 30 years....  Having an engine with high rpms, like 2K rpms, before the oil has circulated will definitely have an effect on components.  No way around it!  And, if the engineers were putting out pure quality with no design flaws then there wouldn't be hundreds of TSB's...  to correct problems, and there wouldn't have been a class action lawsuit against Subaru!  The Subaru service manager told me it was not possible to change the cold-start idle rpms...  And, manufacturers have been known to produce components that will "last the length of the warranty."  Thanks for your answer....  

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If it bothers you add some dura lube the long strain triglicerides are exstremely hard to shear helping to protect the metal at start up or you could just use high mileage oil or motorcycle oil that already has the dura lube in it they have a triangle icon on the bottle but all the oil.manufactures have there own name for it i have been building engines for 30 years and tearing motors down that i built after 50000 miles and seeing no were in the engine i can say first hand it helps protect the engine however if the torque.specs arent right in the nuts and bolts that come in to contact with the oil they will come undone ask me how i know ive been doing this for a while

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Engines have oil pressure within a second or so. Longer than it takes to wind up to 2k RPM and with 0w20 oil, it's got lubrication on a cold start. 0w20 is thin and flows nice when cold

 

This type of warmup procedure is NOT new. Cars with carburetors regularly had high idles in colder climates while the choke was on. Fuel injection came around it wasn't really 'needed'

 

My 1992 Suzuki Carry pickup truck, while it's a Japanese domestic that I bought straight from an importer and not USA spec. It  idles at nearly 2,000 RPM with the choke on, and it's a coolant heated choke so it stays choked a bit longer than an exhaust heated or electric choke.

Edited by matt167

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there is no defect here

 

all subarus for decades high idle at 2000 + rpms during warmup.

 

your engine has plenty of oil at startup unless you are using very cheap oil filters.  even then all journals will be primed within a second.

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I agree with the OP.  I don't see any positive in the high revs at startup.  Especially not comfortable with putting the automatic in drive while the engine is at 2000rpm.

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CAFE rules have made manufacturers do a lot of things they'd rather not. Warming up the cat conv is one of those things.

you're lucky you don'y have air cut valves and a pump like on my WRX - they froze shut in the first 4 years of ownership. I had to use romraider and ecuflash to kill 14 codes to turn off the CEL.

Edited by 1 Lucky Texan

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